From owner-starship-design Sat Jan 25 10:59 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3269" "Sat" "25" "January" "1997" "13:59:02" "-0500" "DotarSojat@aol.com" "DotarSojat@aol.com" nil "69" "starship-design: Questions Regarding Relativistic Electric Thrusters" "^From:" nil nil "1" nil "starship-design: Questions Regarding Relativistic Electric Thrusters" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.4) id KAA09380 for starship-design-outgoing; Sat, 25 Jan 1997 10:59:36 -0800 (PST) Received: from emout19.mail.aol.com (emout19.mx.aol.com [198.81.11.45]) by darkwing.uoregon.edu (8.8.5/8.8.4) with ESMTP id KAA09342 for ; Sat, 25 Jan 1997 10:59:29 -0800 (PST) Received: (from root@localhost) by emout19.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id NAA26557 for starship-design@lists.uoregon.edu; Sat, 25 Jan 1997 13:59:02 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970125135901_1446075722@emout19.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: DotarSojat@aol.com Content-Type: text Content-Length: 3268 From: DotarSojat@aol.com Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Questions Regarding Relativistic Electric Thrusters Date: Sat, 25 Jan 1997 13:59:02 -0500 (EST) Hi all A critical component of most of the interesting interstellar propulsion concepts (e.g., fusion-powered rockets, antimatter- powered rockets, beam-driven sails in the deceleration phase) is a relativistic electric thruster. This is not an "ion rocket," which typically has ion energies in the multi-kilovolt range and ion currents in milliamps, but it is a high-energy particle accelerator with an exhaust-particle energy in the range of multi- megavolts to gigavolts (see the 1060 MeV proton energy requirement for a thruster to decelerate a beam-driven sail, in my note of 9/20/96) and particle currents in the range of kiloamps to megamps (2940 megawatts of beam power per kg of thrust, per my note of 9/26/96). I think it would be useful for us to start off by examining the characteristics of these particle accelerators to help select the most desirable configuration. In this vein, I would like to suggest a sample list of questions regarding these thrusters, to draw out any further questions you all might think of. Phrasing the question right is a significant part of solving the problem. The sample questions are as follows (I haven't tried to address any of them, so some may not be well thought out): 1. What is the best exhaust particle? Electrons, protons, alphas, etc.? What is the best parameter to compare them by? a. What is the relative thrust/amp for the options, as a function of their energy in MeV? b. What is their corresponding exhaust velocity? c. What is their "Isp" (thrust per unit rest-mass flow rate)? 2. Is there an electron energy that gives the same performance as protons? (from the so-called "mass amplification" with increasing velocity) 3. Can we estimate relative thruster weight per unit thrust? Thruster size? (to compare the different options) 4. What disadvantages/advantages accompany motion of electric charges? a. What is the effect on performance (e.g., exhaust velocity) of charging of the ship due to incomplete charge neutralization? b. What is the effect on performance of charge neutralization effected by dumping oppositely charged particles (at zero velocity, say)? c. Will the current of the exhaust beam generate a magnetic field strong enough to deflect interstellar protons (ionized by a stripping foil out in front of the ship) away from the ship, to save shielding? d. Could the electric charge from incomplete neutralization create an electric field, around a sharp point out in front of the ship, strong enough to deflect interstellar protons as in c, above? e. Could electrodes on the sides of the particle beam at the exit end of the accelerator be used to steer the "jet" (and hence the ship)? f. Is there a possibility of entrainment of interstellar protons by the particle beam to cause jet augmentation? g. What might be the damage caused by impingement of the very-high-powered particle beam on another object in space? Please feel free to add to this list and/or criticize the questions suggested above. The list is not meant to be exhaustive nor definitive, but to stimulate further thought and discussion. Rex Finke From owner-starship-design Sat Jan 25 11:53 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5113" "Sat" "25" "January" "1997" "14:52:49" "-0500" "DotarSojat@aol.com" "DotarSojat@aol.com" nil "113" "starship-design: The \"So-called\" Twin Paradox" "^From:" nil nil "1" nil "starship-design: The \"So-called\" Twin Paradox" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.4) id LAA25024 for starship-design-outgoing; Sat, 25 Jan 1997 11:53:18 -0800 (PST) Received: from emout19.mail.aol.com (emout19.mx.aol.com [198.81.11.45]) by darkwing.uoregon.edu (8.8.5/8.8.4) with ESMTP id LAA24962 for ; Sat, 25 Jan 1997 11:53:15 -0800 (PST) Received: (from root@localhost) by emout19.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id OAA25086 for starship-design@lists.uoregon.edu; Sat, 25 Jan 1997 14:52:49 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970125145248_914090032@emout19.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: DotarSojat@aol.com Content-Type: text Content-Length: 5112 From: DotarSojat@aol.com Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: The "So-called" Twin Paradox Date: Sat, 25 Jan 1997 14:52:49 -0500 (EST) Hi all I would like to return to a discussion under way at the end of November, with the idea of stimulating further thought. On 11/29/96, Nick Tosh asked: >Just a quick question: can any one explain to me in relatively >straightforward language, the solution to the twin paradox? [followed by his description of the twin paradox] On 11/29, I responded: >Twin Paradox? There really isn't any. > >All you have to do to dispel the notion that there is a "paradox" >is to ask: What does each twin see when he looks out his window >during the "trip"? The one who sees the UNIVERSE "moving" will >be the younger at the end of the trip. On 11/29, Steve VanDevender added: >However, the Twin non-Paradox would still happen even if one twin >stayed on a fast-moving spaceship while the other took a >relativistic jaunt in the ship's shuttlecraft; the one who left >and came back on the shuttlecraft would be younger. > >The critical issue is acceleration, not apparent motion of the >Universe. The twin in the rocket experiences acceleration, >because in order to make a round trip he must accelerate, turn >around, and accelerate back, and this is the fundamental >asymmetry, because the stay-at-home twin does not experience a >change in acceleration. > >Once can even construct a similar "paradox" where both twins take >round-trips with different accelerations; the twin who >experiences the greater self-measured acceleration will be >younger when they meet again. A typical statement of the "twin paradox" is the one given by Richard Feynman (p. 16-3 in his "Feynman Lectures in Physics," with R.B. Leighton and M. Sands, 1967), as follows: "To continue our discussion of the Lorentz transformation and relativistic effects, we consider a famous so-called 'paradox' of Peter and Paul, who are supposed to be twins, born at the same time. When they are old enough to drive a space ship, Paul flies away at very high speed. Because Peter, who is left on the ground, sees Paul going so fast, all of Paul's clocks appear to go slower, his heartbeats go slower, his thoughts go slower, everything goes slower, from Peter's point of view. Of course, Paul notices nothing unusual, but if he travels around and about for a while and then comes back, he will be younger than Peter, the man on the ground! That is actually right; it is one of the consequences of the theory of relativity which has been clearly demonstrated. Just as the mu-mesons last longer when they are moving, so also will Paul last longer when he is moving. This is called a 'paradox' only by the people that believe that the principle of relativity means that *all motion* is relative; they say, 'Heh, heh, heh, from the point of view of Paul, can't we say that *Peter* was moving and should therefore appear to age more slowly? By symmetry, the only possible result is that both should be the same age when they meet.' But in order for them to come back together and make the comparison, Paul must either stop at the end of the trip and make a comparison of clocks or, more simply, he has to come back, and the one who comes back must be the man who was moving, and he knows this because he had to turn around. When he turned around, all kinds of unusual things happened in his space ship--the rockets went off, things jammed up against one wall, and so on--while Peter felt nothing. "So the way to state the rule is to say that *the man who has felt the accelerations*, who has seen things fall against the walls, and so on, is the one who would be the younger; that is the difference between them in the 'absolute' sense, and it is certainly correct." Professor Feynman says essentially two things here: 1. There can be a paradox only if one believes that the two twins have experienced exactly equivalent conditions, and 2. The conditions differ in the accelerations experienced, so there is no paradox. Suppose, however, that Paul's trip involves 1-g accel/decel periods of 2 years each outbound and the same on return, accumulating 8 years of ship time in a round trip to a far point 5.822 lt-yr away. Peter is waiting in a 1-g gravitational field on Earth. Einstein says (on p.151 of his "Relativity--The Special and the General Theory," Crown, 1920), "Relative to [a system in uniform acceleration]...there exists a state which, at least to a first approximation, cannot be distinguished from a gravitational field." (This was stated by Einstein as the foundation of his General Theory of Relativity.) If you believe that Peter's dilated elapsed time, t, during one of Paul's acceleration periods is given in terms of Paul's time, t', by the relation t = (c/a) * sinh(a * t'/c) (where a = 1 g = 1.0324 lt-yr/yr2 and c = 1 lt-yr/yr), then Peter must live 15.027 years while Paul lives only 8. What difference in their experiences can be used to tell that Paul will be the younger? (We can turn Peter's house upside down at the one-quarter and three-quarter "turnover" times, etc.) If neither looks out the window, how can they explain the difference in their "trip" times? Rex Finke From owner-starship-design Sun Jan 26 07:11 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["800" "Sun" "26" "January" "1997" "16:11" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "24" "starship-design: Re: The \"So-called\" Twin Paradox" "^From:" nil nil "1" nil "starship-design: Re: The \"So-called\" Twin Paradox" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.4) id HAA24707 for starship-design-outgoing; Sun, 26 Jan 1997 07:11:49 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.4) with SMTP id HAA24677 for ; Sun, 26 Jan 1997 07:11:36 -0800 (PST) Received: from hengelo06.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0voWEs-000DoUC; Sun, 26 Jan 97 16:11 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 799 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: The "So-called" Twin Paradox Date: Sun, 26 Jan 97 16:11 MET Hi Rex, I had wondered why you had not continued the discussion about the Twin Paradox, since I know your ideas which did not agree with what was written in Steve (VanDevender)'s last letter from 11/29. >What difference in their experiences can be used to tell that Paul >will be the younger? (We can turn Peter's house upside down at >the one-quarter and three-quarter "turnover" times, etc.) > >If neither looks out the window, how can they explain the >difference in their "trip" times? Probably one can always "trick" someone in a local environment. So to find the symmetry breaking factor in the Twin Paradox you *need* to look at a global (non-homogeneous) environment. This is why it is called "relativity", this word almost inherently means comparison between global points. Timothy From owner-starship-design Mon Jan 27 01:06 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5511" "Mon" "27" "January" "1997" "01:08:52" "-0800" "Steve VanDevender" "stevev@efn.org" nil "101" "starship-design: The \"So-called\" Twin Paradox" "^From:" nil nil "1" nil "starship-design: The \"So-called\" Twin Paradox" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.4) id BAA16459 for starship-design-outgoing; Mon, 27 Jan 1997 01:06:10 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.4) with ESMTP id BAA16440 for ; Mon, 27 Jan 1997 01:06:08 -0800 (PST) Received: from tzadkiel (stevev@cisco-ts9-line11.uoregon.edu [128.223.150.92]) by wakko.efn.org (8.8.4-q-beta2/8.7.3) with ESMTP id BAA12051; Mon, 27 Jan 1997 01:05:48 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id BAA20041; Mon, 27 Jan 1997 01:08:52 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199701270908.BAA20041@tzadkiel> In-Reply-To: <970125145248_914090032@emout19.mail.aol.com> References: <970125145248_914090032@emout19.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 5510 From: Steve VanDevender Sender: owner-starship-design To: DotarSojat@aol.com Cc: starship-design@lists.uoregon.edu Subject: starship-design: The "So-called" Twin Paradox Date: Mon, 27 Jan 1997 01:08:52 -0800 DotarSojat@aol.com writes: > Hi all > > I would like to return to a discussion under way at the end of > November, with the idea of stimulating further thought. > A typical statement of the "twin paradox" is the one given by > Richard Feynman (p. 16-3 in his "Feynman Lectures in Physics," > with R.B. Leighton and M. Sands, 1967), as follows: > "To continue our discussion of the Lorentz transformation and > relativistic effects, we consider a famous so-called 'paradox' of > Peter and Paul, who are supposed to be twins, born at the same > time. When they are old enough to drive a space ship, Paul flies > away at very high speed. Because Peter, who is left on the > ground, sees Paul going so fast, all of Paul's clocks appear to go > slower, his heartbeats go slower, his thoughts go slower, > everything goes slower, from Peter's point of view. Of course, > Paul notices nothing unusual, but if he travels around and about > for a while and then comes back, he will be younger than Peter, > the man on the ground! That is actually right; it is one of the > consequences of the theory of relativity which has been clearly > demonstrated. Just as the mu-mesons last longer when they are > moving, so also will Paul last longer when he is moving. [ . . . ] > Professor Feynman says essentially two things here: > 1. There can be a paradox only if one believes that the two twins > have experienced exactly equivalent conditions, and > 2. The conditions differ in the accelerations experienced, so > there is no paradox. > Einstein says (on p.151 of his "Relativity--The Special and the > General Theory," Crown, 1920), "Relative to [a system in uniform > acceleration]...there exists a state which, at least to a first > approximation, cannot be distinguished from a gravitational > field." (This was stated by Einstein as the foundation of his > General Theory of Relativity.) Note that Einstein says "to a first approximation". The gravitational field caused by mass is measurably different from the effects of acceleration caused by change in velocity. A gravitational field will show attraction towards a single point and obey the inverse-square law, whereas acceleration produces a field that is uniform. If you read Einstein further you will also see him state the principle that the laws of physics are most simply stated in terms of infinitesimal effects over infinitesimal regions -- in a local sense, a gravitational field looks like the effects of acceleration, over a tiny area, but only over a tiny area. > What difference in their experiences can be used to tell that Paul > will be the younger? (We can turn Peter's house upside down at > the one-quarter and three-quarter "turnover" times, etc.) Given that Peter can measure that he is in a gravitational field caused by mass, he can know that he has not left Earth. Similarly Paul will be able to tell that he is in a spaceship because of the uniformity of the acceleration field that he can measure. > If neither looks out the window, how can they explain the > difference in their "trip" times? Unfortunately, if neither can look out the window to make measurements _relative to each other_, then it may be easy enough to fool them into thinking their experiences equivalent, at least if they aren't provided highly accurate accelerometers capable of distinguishing between the Earth's central-point gravitational field and the effects of acceleration in a spaceship. On the other hand, the distinction would be obvious to a third observer as much as it would be to Peter and Paul were they allowed to look out the windows. The difference in trip time is ultimately the result of different paths through spacetime. Paul's path relative to an inertial observer will clearly show that he is accelerating in a spaceship, as it will travel far away and come back. Peter, who remains on Earth, will show a much straighter path, albeit one with shallow spirals caused by the Earth's rotation and revolution about the Sun, and a slight amount of distortion caused by the Earth's mass bending spacetime. And, through the consistent but counter-intuitive logic of relativity, the straighter path -- the one that is least bent relative to the third inertial observer -- experiences the most proper time; Peter ages the most. I simplified my statement slightly by claiming that it was only acceleration that mattered, as I hoped that it would be clear I was talking about acceleration caused by motion, not by gravity, and at the time I wasn't sure anyone would be ready for the more difficult, but more powerful, concept of proper time as the integral of length (in Lorentz geometry!) over an object's worldline. It should be understood that gravity does distort time, but not to the extent that sustained acceleration to high velocity does. We experience time more slowly (by a tiny amount, less than one part in a billion) than astronauts on the Moon, because we are deeper in the Earth's gravitational field than the astronauts. However, this rate is constant over time -- after a year, we would have experienced less than a billionth of a year less time than the astronauts. On the other hand, astronauts who accelerated away from us at 1 g for a year of our time would have experienced substantially less time than we did on Earth, because their path through spacetime was more bent as a result of their acceleration than ours was bent by the Earth's gravitational field. From owner-starship-design Mon Jan 27 01:18 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2349" "Mon" "27" "January" "1997" "01:20:49" "-0800" "Steve VanDevender" "stevev@efn.org" nil "46" "starship-design: Re: The \"So-called\" Twin Paradox" "^From:" nil nil "1" nil "starship-design: Re: The \"So-called\" Twin Paradox" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.4) id BAA17968 for starship-design-outgoing; Mon, 27 Jan 1997 01:18:07 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.4) with ESMTP id BAA17958 for ; Mon, 27 Jan 1997 01:18:05 -0800 (PST) Received: from tzadkiel (stevev@cisco-ts9-line11.uoregon.edu [128.223.150.92]) by wakko.efn.org (8.8.4-q-beta2/8.7.3) with ESMTP id BAA12872; Mon, 27 Jan 1997 01:17:45 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id BAA20077; Mon, 27 Jan 1997 01:20:49 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199701270920.BAA20077@tzadkiel> In-Reply-To: References: Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 2348 From: Steve VanDevender Sender: owner-starship-design To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Cc: starship-design@lists.uoregon.edu Subject: starship-design: Re: The "So-called" Twin Paradox Date: Mon, 27 Jan 1997 01:20:49 -0800 Timothy van der Linden writes: > Hi Rex, > > I had wondered why you had not continued the discussion about the Twin > Paradox, since I know your ideas which did not agree with what was written > in Steve (VanDevender)'s last letter from 11/29. Unfortunately it's because both Rex and I were oversimplifying a bit. I think we actually still agree, but Rex has certainly pointed out some of the subtleties required in a more complete analysis of the problem, and required bringing in some concepts from general relativity. > >What difference in their experiences can be used to tell that Paul > >will be the younger? (We can turn Peter's house upside down at > >the one-quarter and three-quarter "turnover" times, etc.) > > > >If neither looks out the window, how can they explain the > >difference in their "trip" times? > > Probably one can always "trick" someone in a local environment. So to find > the symmetry breaking factor in the Twin Paradox you *need* to look at a > global (non-homogeneous) environment. > > This is why it is called "relativity", this word almost inherently means > comparison between global points. Unfortunately relativity does not recognize any sort of global reference frame, and just because Peter and Paul might think they are in identical environments doesn't mean that they will experience the same amount of time. In order to bring out more of the subtleties involved in Rex's formulation of the Twin Paradox, I postulated a third, inertial observer who would be best equipped to measure the differences in Paul's and Peter's experiences. In a sense, Rex's formulation only puts blinders on Peter and Paul, preventing them from making the observations that they could make entirely between themselves to determine who should age less. If we remove these unreasonable restrictions then they could easily determine between themselves who should have aged least when they meet again. However, even with their blinders on, we can also postulate any number of additional observers, free to make the measurements that Peter and Paul cannot, who would all agree that Paul, the traveling twin, should age less because his path through spacetime has more curvature, and who will all agree on the amount of proper time that both Paul and Peter experience between Paul's departure and return. From owner-starship-design Mon Jan 27 13:36 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["9633" "Mon" "27" "January" "1997" "13:35:57" "-0800" "Ken Wharton" "wharton@physics.ucla.edu" nil "192" "starship-design: Relativistic Electric Thrusters" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id NAA04133 for starship-design-outgoing; Mon, 27 Jan 1997 13:36:20 -0800 (PST) Received: from physics.ucla.edu (physics.ucla.edu [128.97.23.13]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id NAA04086 for ; Mon, 27 Jan 1997 13:36:16 -0800 (PST) Received: from watt by physics.ucla.edu (SMI-8.6/SMI-SVR4) id NAA08583; Mon, 27 Jan 1997 13:35:58 -0800 Received: by watt (SMI-8.6/SMI-SVR4) id NAA14879; Mon, 27 Jan 1997 13:35:57 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199701272135.NAA14879@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: wharton@physics.ucla.edu (Ken Wharton) Content-Type: text Content-Length: 9632 From: wharton@physics.ucla.edu (Ken Wharton) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Relativistic Electric Thrusters Date: Mon, 27 Jan 1997 13:35:57 -0800 Greetings to all! IÕm new here... NameÕs Ken Wharton, IÕm a 5th year physics graduate student at UCLA, currently living up in Northern California and doing research at Lawrence Livermore National Labs. IÕm currently working on experiments with a short- pulse 100 TeraWatt laser, looking into a novel Laser Fusion concept. (ThatÕll probably fit in well to at least some of the discussions) For now, though, the questions on relativistic thrusters by Rex Finke are more related to the work I did at UCLA on laser-plasma accelerators. The big advantage they have over conventional accelerators is that theyÕre much smaller, and therefore would be ideal on a spaceship. Conventional accelerators are limited by how strong an electric field they can produce; too strong and it starts to rip the apparatus apart. A plasma, on the other hand, is already ripped apart; it can handle much, much stronger E-fields. A conventional accelerator is limited to roughly 10 MeV/meter; the beatwave plasma accelerator at UCLA has already achieved 3 GeV/m (over 1cm), and other laser-plasma accelerators at Rutherford, UK and elsewhere have pushed that to 60 GeV/m (over 1mm); the ultimate limit it given only by the density of the plasma where you can create the coherent E-field, and the length of the interaction region. So, keeping plasma accelerators in mind IÕll make a first pass at RexÕs questions... 1) and 2) In deciding the best exhaust particle, the only equation you need is E^2 = P^2 c^2 + (m c^2)^2: And everything points to low mass particles being the best. Not only do they give a higher Momentum/Energy ratio, but a higher Momentum/Mass ratio as well. Assuming that the final energy of the particles will be large compared to the rest mass, the above equation simplifies to P = E/c; the rest mass becomes irrelevant to the momentum (but still important to the ÔlspÕ) The Big Problem, of course, is keeping the ship neutral. Assuming we donÕt have positrons handy (if we did, the engine design would be much easier!) we need one proton per electron, which will severely hurt the ÔlspÕ. 3) In terms of size, it really depends on the plasma accelerator. Perhaps we can assume we might get 100 GeV in acceleration per meter of accelerator. Would there be an optimal length? I would guess no: you want the device as long as possible; the entire length of the ship, I suppose. Doubling the length will not double the mass of your entire ship, but it will double the amount of thrust you can get! Of course this also depends on what youÕre using to drive the plasma wave, (lasers, I would guess) so IÕll get back to this later. Fortunately, you might only need one plasma accelerator to accelerate both electrons and protons. The actual accelerating mechanism is an electron plasma wave that travels through the plasma with a phase velocity close to the speed of light. Half of the wave will accelerate electrons and the other half will accelerate protons; an electron wonÕt slip to the ÔwrongÕ half of the wave because everythingÕs moving at near the speed of light; the correct E-field (ideally) follows the electron or proton as it is accelerated. I say ÔideallyÕ here, because while everything is moving at nearly the speed of light, small differences in velocities will cause the particles to slip back to the wrong phase of the accelerating wave. It might be possible to change the phase velocity of the wave as a function of space, allowing it to Ôkeep upÕ with the electrons and protons better, but this would be a big problem if we were trying to accelerate both at once; the electrons would speed up much faster than the protons, so the wave would eventually lose resonance with one of the species. Perhaps two accelerators would be the way to go after all. The you have huge magnetic fields, leading to the next question... 4) Disadvantages to the moving charges. In my mind, the #1 problem to any spaceship propulsion scheme was not mentioned here. There are bound to be some stray macroscopic pieces of matter in interstellar space. This is less of a problem for the accelerating half of the journey, assuming one has adequate shielding in front. But what about the decelerating portion??? All of a sudden you have the engine, the most critical portion of the ship, exposed to whatever might be speeding in your direction. If youÕre trying to shoot out fuel ahead of you, youÕre leaving yourself wide open to near-lightspeed chunks of matter coming in where the fuel comes out! The only possible way around this that I can think of is to shoot out the fuel into a wide cone angle, leaving the back of the ship protected by major shielding. This decreases the thrust, perhaps significantly, but maybe it could be made up for by applying large external magnetic fields to steer the angled beams of electrons/protons into a more normal trajectory. This, of course, assumes you have near-monoenergetic beams, which would be another tough constraint. Plus you might direct interstellar particles back into the accelerators! All in all, probably not a good solution... As for the other points: a) IÕll assume we wonÕt want to charge up the ship much. Of the things that could be adversely affected by this, computers would probably be at the top of the list. If we ground all the computers, that leaves us with dangerous potential differences. b) True; the protons (or electrons!) could just be dumped at zero velocity, but given how tight our fuel will be I imagine weÕd want to try to accelerate both species. c) I think the magnetic field produced by a beam might help deflect incoming charged particles at low velocities, but eventually the incoming protons/electrons would be energetic enough to blast right on through. Also, accelerating charges produces radiation; this might actually require more shielding, as IÕd think the relativistic particles would produce x-rays as theyÕre steered around the ship! d) I donÕt think youÕd want to charge up the whole ship just to deflect protons; if this might work itÕd be easier to just charge up the nose cone. Plus, of course, youÕd attract electrons. Still, I like the idea; protons are obviously much worse... e) The only issue I can see with steering the ship by deflecting the electron beam is this: ALL of the force has to be taken up by the electrodes before itÕs transferred to the rest of the ship. YouÕd need some pretty strong electrodes to make any difference. I donÕt think steering is going to be a big issue. f) Using the interstellar protons to augment the beam is an interesting idea, at least for the acceleration phase. Beams of particles can drive plasma waves, so if the protons were directed into the plasma accelerator at the front of the ship, and channeled out the back, it might save significantly on energy and fuel constraints. This of course would fail miserably for the decelerating portion, though... g) We donÕt have to worry about the particle beam damaging anything far away; the beam will spread out in space as it travels. As for whether it would blast apart an incoming meteor; that would be an important question. Some particular issues w/ plasma accelerators: Efficiency??? This point could be the killer. For a given accelerating structure, it is possible to Ôfill the bucketÕ with particles, preventing any additional particles from being accelerated. This is a problem with all accelerators, but I think itÕs worse in a plasma. Plus, you need energy to create and maintain the plasma in the first place, and that will hurt the efficiency as well. I like the idea of using interstellar matter to help out in the acceleration phase, as I mentioned above. How to best drive the plasma wave? The most successful experiments to date have all been done with lasers, although particle beams may also drive a plasma wave. The good thing about relying on lasers is that, like computers, they have improved exponentially in the past and may very well continue to do so in the future. Very short-pulse, high-power lasers might be ideal because they can drive strong waves with relatively little energy. The waves damp away pretty quickly, though, so youÕd need a high rep-rate, something that current high-power lasers donÕt have. How long an accelerator is feasible? So far the longest coherent accelerating structure in a plasma is 1 cm (at UCLA); a 6cm version should be working in 2 years. The limit is the focal distance of the laser we use to drive the plasma wave. Obviously, we want meters, not centimeters, so how will this work? One promising fact is that high power lasers self-focus and self-channel in plasmas; it is not inconceivable that a high-enough power laser will maintain a narrow focus over large distances. Ideally, of course, the laser will be powerful enough that we wonÕt NEED to focus it; that way the size of the accelerator will be bigger, and we could get more thrust. That will require many orders of magnitude improvement over todayÕs lasers, though. Here at LLNL, the worldÕs most powerful laser, the PetaWatt, is about to go into operation. It has 600 Joules of energy in 450 femtoseconds, and is the result of pushing current technology as far as it will go. Any additional improvement is hard to imagine at this time, but there are enough people working on the problem that ExoWatt lasers probably arenÕt more than a generation away... Enough rambling for now. More later. Ken From owner-starship-design Mon Jan 27 13:44 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["372" "Mon" "27" "January" "1997" "13:44:16" "-0800" "Steve VanDevender" "stevev@darkwing.uoregon.edu" nil "10" "starship-design: list maintainer's note" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id NAA07397 for starship-design-outgoing; Mon, 27 Jan 1997 13:44:20 -0800 (PST) Received: (from stevev@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id NAA07343; Mon, 27 Jan 1997 13:44:16 -0800 (PST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199701272144.NAA07343@darkwing.uoregon.edu> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 371 From: Steve VanDevender Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: list maintainer's note Date: Mon, 27 Jan 1997 13:44:16 -0800 (PST) These two addresses are now bouncing starship-design postings because the accounts in question no longer seem to exist: jim@bogie2.bio.purdue.edu neill@foda.math.usu.edu If anyone on the list knows their current whereabouts, I'd be willing to resubscribe them under working addresses. I will be removing the two addresses above later today if they continue to bounce. From owner-starship-design Mon Jan 27 14:17 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["141" "Mon" "27" "January" "1997" "19:41:55" "-0200" "Antonio C. T. Rocha" "arocha@bsb.nutecnet.com.br" nil "6" "starship-design: Sugested Reading" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id OAA25683 for starship-design-outgoing; Mon, 27 Jan 1997 14:17:41 -0800 (PST) Received: from srv1-bsb.bsb.nutecnet.com.br ([200.252.253.1]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id OAA25585 for ; Mon, 27 Jan 1997 14:17:34 -0800 (PST) Received: from Metacor.bsb.nutecnet.com.br (dl1157-bsb.bsb.nutecnet.com.br [200.252.253.157]) by srv1-bsb.bsb.nutecnet.com.br (8.6.8.1/SCA-6.6) with SMTP id XAA00844 for ; Mon, 27 Jan 1997 23:17:45 GMT X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <32ED2123.1376@bsb.nutecnet.com.br> Organization: It also is out there, somewhere... X-Mailer: Mozilla 3.01Gold (Win95; I) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Antonio C T Rocha Content-Type: text/plain; charset=us-ascii Content-Length: 140 From: Antonio C T Rocha Sender: owner-starship-design To: "Starship Design U.Oregon" Subject: starship-design: Sugested Reading Date: Mon, 27 Jan 1997 19:41:55 -0200 I chanced upon the following site, following up on discussions about relativity effects. ftp://ftp.univie.ac.at/archive/faq/physics-faq/ From owner-starship-design Mon Jan 27 22:25 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2742" "Tue" "28" "January" "1997" "01:24:33" "-0500" "DotarSojat@aol.com" "DotarSojat@aol.com" nil "66" "starship-design: The \"So-called\" Twin Paradox, cont'd" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id WAA09802 for starship-design-outgoing; Mon, 27 Jan 1997 22:25:00 -0800 (PST) Received: from emout17.mail.aol.com (emout17.mx.aol.com [198.81.11.43]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id WAA09778 for ; Mon, 27 Jan 1997 22:24:56 -0800 (PST) Received: (from root@localhost) by emout17.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id BAA07430 for starship-design@lists.uoregon.edu; Tue, 28 Jan 1997 01:24:33 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970128012432_-2012378925@emout17.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: DotarSojat@aol.com Content-Type: text Content-Length: 2741 From: DotarSojat@aol.com Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: The "So-called" Twin Paradox, cont'd Date: Tue, 28 Jan 1997 01:24:33 -0500 (EST) Hi all Steve VanDevender says, on 1/27 at 04:07 EST: >Note that Einstein says "to a first approximation". ... Precisely the point I make in my Relativity Paper. >The difference in trip time is ultimately the result of different >paths through spacetime. The difference in trip time could also be attributed to different paths through *space*, but relativists don't like absolutes. (I see the idea of an absolute frame of reference in Timothy's comment, in his email of 1/26 at 10:12 EST, "So to find the symmetry breaking factor in the Twin Paradox you *need* to look at a global (non-homogeneous) environment.") But, one relativist, Einstein himself (on p. 56 of his "The Meaning of Relativity," Fifth Edition, Princeton, 1956), raises the possibility of an absolute frame by citing "Mach's Principle," which postulates that "a material particle [moves] relatively to the centre of mass of the universe." [See also Holstein and Swift, Amer. J. Phys. 40, p. 749 (1972).] >Paul's path relative to an inertial observer will clearly show >that he is accelerating in a spaceship, as it will travel far >away and come back. --Through space (with respect to a "fixed" frame). Then the difference in trip time between Peter's time (delta-t) and Paul's time (delta-t') can be attributed to Paul having traversed space (delta-x) in a frame "fixed" with respect to Peter, according to the "interval" relation (for each one-way trip), which is *independent of velocity*, (delta-t)^2 = (delta-t')^2 + (delta-x/c)^2 . Steve adds, on 1/27 at 04:19 EST, (responding to Timothy): >Unfortunately it's because both Rex and I were oversimplifying a >bit. I think we actually still agree... I'll buy that. I think Steve's elaboration of his 11/29/96 remarks has brought us considerably closer together. >Unfortunately relativity does not recognize any sort of global >reference frame... Except for Einstein's comment cited above. >In a sense, Rex's formulation only puts blinders on Peter and >Paul, preventing them from making the observations that they >could make entirely between themselves to determine who should >age less. If we remove these unreasonable restrictions then they >could easily determine between themselves who should have aged >least when they meet again. However, if the "observations...entirely between themselves" are composed of Doppler-shift measurements by each of light from the other, they both measure exactly the same shift (as the Special Theory stipulates) and can't tell which one is "moving." But they *can* determine which one is moving by looking at the Doppler shift of light from the "fixed stars." That was my point that I may have oversimplified a bit in my 11/29/96 response to Nick. Rex From owner-starship-design Tue Jan 28 04:49 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2183" "Tue" "28" "January" "1997" "13:49" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "47" "starship-design: Re: The \"So-called\" Twin Paradox, cont'd" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id EAA25757 for starship-design-outgoing; Tue, 28 Jan 1997 04:49:15 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id EAA25746 for ; Tue, 28 Jan 1997 04:49:12 -0800 (PST) Received: from hengelo23.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vpCz2-000DnAC; Tue, 28 Jan 97 13:49 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 2182 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: The "So-called" Twin Paradox, cont'd Date: Tue, 28 Jan 97 13:49 MET Timothy replies to Rex writing: >The difference in trip time could also be attributed to different >paths through *space*, but relativists don't like absolutes. (I >see the idea of an absolute frame of reference in Timothy's >comment, in his email of 1/26 at 10:12 EST, "So to find the >symmetry breaking factor in the Twin Paradox you *need* to look at >a global (non-homogeneous) environment.") I really did not mean to touch the idea of an absolute reference frame. Actually I don't understand how you did derive that from what you quoted directly above. I wanted to emphasize the fact that one needs to look at more than just one point in space, in order to realize relativity (since it means that on compares between multiple points). I got the impression that Steve said the same only in much more words (which to me seemed to obscure the core of the problem). >But, one relativist, >Einstein himself (on p. 56 of his "The Meaning of Relativity," >Fifth Edition, Princeton, 1956), raises the possibility of an >absolute frame by citing "Mach's Principle," which postulates that >"a material particle [moves] relatively to the centre of mass of >the universe." [See also Holstein and Swift, Amer. J. Phys. 40, >p. 749 (1972).] Why should the centre of mass of the universe be more an absolute frame, than for example the center of the Sun? Or rephrased: What are the "special" properties of an absolute frame of reference? >However, if the "observations...entirely between themselves" are >composed of Doppler-shift measurements by each of light from the >other, they both measure exactly the same shift (as the Special >Theory stipulates) and can't tell which one is "moving." But they >*can* determine which one is moving by looking at the Doppler >shift of light from the "fixed stars." That was my point that I >may have oversimplified a bit in my 11/29/96 response to Nick. The word fixed is really not necessary, they may move or accelerate as much as they want, they are the same as Steve's 3th observer and the same as my global environment. As a result there are several other ways than Doppler shift alone to determine who intertally accelerates. Timothy From owner-starship-design Tue Jan 28 09:48 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["466" "Tue" "28" "January" "1997" "12:48:16" "-0500" "David Levine" "David@interworld.com" nil "17" "starship-design: Dr. Forward" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id JAA13384 for starship-design-outgoing; Tue, 28 Jan 1997 09:48:18 -0800 (PST) Received: from www1.interworld.com (www.InterWorld.Com [165.254.130.4]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id JAA13353 for ; Tue, 28 Jan 1997 09:48:14 -0800 (PST) Received: by www1.interworld.com with SMTP (Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63) id <01BC0D19.88F7DCA0@www1.interworld.com>; Tue, 28 Jan 1997 12:48:18 -0500 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: X-Mailer: Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: David Levine Content-Type: text/plain; charset="us-ascii" Content-Length: 465 From: David Levine Sender: owner-starship-design To: "'starship-design@lists.uoregon.edu'" Subject: starship-design: Dr. Forward Date: Tue, 28 Jan 1997 12:48:16 -0500 Just thought you guys'd be interested - I got email from Dr. Forward recently about LIT - specifically about some copyrighted text of his we had. I removed it, having totally forgotten in the last few years that it was even there. He said he'll check out the rest of the site and wasn't too harsh about the copyright stuff. ------------------ David Levine InterWorld Technology Ventures, Inc. "A stroke of the brush does not guarantee art from the bristles." From owner-starship-design Tue Jan 28 22:24 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["781" "Wed" "29" "January" "1997" "01:24:23" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "26" "Re: starship-design: Dr. Forward" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id WAA20328 for starship-design-outgoing; Tue, 28 Jan 1997 22:24:47 -0800 (PST) Received: from emout05.mail.aol.com (emout05.mx.aol.com [198.81.11.96]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id WAA20311 for ; Tue, 28 Jan 1997 22:24:45 -0800 (PST) Received: (from root@localhost) by emout05.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id BAA04010; Wed, 29 Jan 1997 01:24:23 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970129003953_1013742968@emout05.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 780 From: KellySt@aol.com Sender: owner-starship-design To: David@InterWorld.com, starship-design@lists.uoregon.edu Subject: Re: starship-design: Dr. Forward Date: Wed, 29 Jan 1997 01:24:23 -0500 (EST) In a message dated 1/28/97 12:53:19 PM, David@InterWorld.com (David Levine) wrote: >Just thought you guys'd be interested - I >got email from Dr. Forward recently about >LIT - specifically about some copyrighted >text of his we had. I removed it, having >totally forgotten in the last few years that >it was even there. He said he'll check out >the rest of the site and wasn't too harsh >about the copyright stuff. > >------------------ >David Levine Opps, retract previous post. I was confusing Forward with Bussard. What did we have of Forwards that was copywrited? For that matter, whats on the LIT site? (My web access is flakey at the moment.) Did you upload integrate the stuff from your workstation? Or download the newsletters to someplace accessable? Kelly From owner-starship-design Tue Jan 28 22:41 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["597" "Wed" "29" "January" "1997" "01:40:37" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "22" "Re: starship-design: Dr. Forward" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id WAA24773 for starship-design-outgoing; Tue, 28 Jan 1997 22:41:01 -0800 (PST) Received: from emout08.mail.aol.com (emout08.mx.aol.com [198.81.11.23]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id WAA24756 for ; Tue, 28 Jan 1997 22:40:58 -0800 (PST) Received: (from root@localhost) by emout08.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id BAA20480; Wed, 29 Jan 1997 01:40:37 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970128234942_1279306909@emout08.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 596 From: KellySt@aol.com Sender: owner-starship-design To: David@InterWorld.com, starship-design@lists.uoregon.edu Subject: Re: starship-design: Dr. Forward Date: Wed, 29 Jan 1997 01:40:37 -0500 (EST) In a message dated 1/28/97 12:53:19 PM, David@InterWorld.com (David Levine) wrote: >Just thought you guys'd be interested - I >got email from Dr. Forward recently about >LIT - specifically about some copyrighted >text of his we had. I removed it, having >totally forgotten in the last few years that >it was even there. He said he'll check out >the rest of the site and wasn't too harsh >about the copyright stuff. > >------------------ >David Levine Which text? His fusion systems papers were the basis of a lot of my Explorer and Fuel/sail starship designs and the support craft. Kelly From owner-starship-design Wed Jan 29 00:58 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4510" "Wed" "29" "January" "1997" "00:59:25" "-0800" "Steve VanDevender" "stevev@efn.org" nil "85" "starship-design: The \"So-called\" Twin Paradox, cont'd" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id AAA24591 for starship-design-outgoing; Wed, 29 Jan 1997 00:58:53 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id AAA24549 for ; Wed, 29 Jan 1997 00:58:51 -0800 (PST) Received: from tzadkiel (stevev@tzadkiel.efn.org [198.68.17.19]) by wakko.efn.org (8.8.4-q-beta2/8.7.3) with ESMTP id AAA15507 for ; Wed, 29 Jan 1997 00:58:32 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id AAA26369; Wed, 29 Jan 1997 00:59:25 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199701290859.AAA26369@tzadkiel> In-Reply-To: <970128012432_-2012378925@emout17.mail.aol.com> References: <970128012432_-2012378925@emout17.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 4509 From: Steve VanDevender Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: The "So-called" Twin Paradox, cont'd Date: Wed, 29 Jan 1997 00:59:25 -0800 DotarSojat@aol.com writes: > >The difference in trip time is ultimately the result of different > >paths through spacetime. > > The difference in trip time could also be attributed to different > paths through *space*, but relativists don't like absolutes. Relativity has its absolutes, just not the absolutes of Newtonian physics. For example, all observers will agree on the spacetime interval between two points, no matter what reference frame they measure from. So invariance of the spacetime interval between events is an absolute in relativistic physics. Furthermore, the distinction between space and spacetime in relativity is quite important. Look at the contrail of a jet in the sky. The contrail tells you its path through space. But from that path in space, you cannot tell how fast the jet was moving at any moment or the amount of acceleration it experienced to cause bends in the contrail. Relativity uses spacetime because intervals must be measured in spacetime. A path through spacetime tells you everything about the motion state of the particle at all times along the path. Placing that path in different reference frames may result in different coordinate measurements, but all observers will agree on the proper time experienced by the particle at any point along the path relative to any reference event. > (I see the idea of an absolute frame of reference in Timothy's > comment, in his email of 1/26 at 10:12 EST, "So to find the > symmetry breaking factor in the Twin Paradox you *need* to look at > a global (non-homogeneous) environment.") But, one relativist, > Einstein himself (on p. 56 of his "The Meaning of Relativity," > Fifth Edition, Princeton, 1956), raises the possibility of an > absolute frame by citing "Mach's Principle," which postulates that > "a material particle [moves] relatively to the centre of mass of > the universe." [See also Holstein and Swift, Amer. J. Phys. 40, > p. 749 (1972).] As Timothy has already pointed out, Mach's principle may define a reference frame that everyone can agree on, but there is nothing privileged about that frame; the laws of physics will be the same in all other frames. Measurements in the Mach frame may differ from measurements in some other frame, but will tell you nothing different than those other measurements. > >In a sense, Rex's formulation only puts blinders on Peter and > >Paul, preventing them from making the observations that they > >could make entirely between themselves to determine who should > >age less. If we remove these unreasonable restrictions then they > >could easily determine between themselves who should have aged > >least when they meet again. > > However, if the "observations...entirely between themselves" are > composed of Doppler-shift measurements by each of light from the > other, they both measure exactly the same shift (as the Special > Theory stipulates) and can't tell which one is "moving." But they > *can* determine which one is moving by looking at the Doppler > shift of light from the "fixed stars." That was my point that I > may have oversimplified a bit in my 11/29/96 response to Nick. Measurements of doppler shift may not tell you anything, but something very simple will. Allow Peter and Paul to have radios and clocks that they carry with them, and to send each other messages through the radios (which, through a strictly-enforced FCC regulation, are on a frequency band allocated only Peter and Paul and which no one else in the universe is allowed to transmit on, preventing Peter and Paul from communicating with anyone but each other -- assume the band is also wide enough to deal with any doppler-shifting they may experience from their relative motion). Peter and Paul use a protocol where each message they send is identified by their name and their locally-measured elapsed time since separation, and their reply to a message includes the identification of the original, as in "Peter at 20 days, 1 hour replying to Paul's message of 19 days, 15 hours". This is sufficient to allow Peter and Paul to determine which twin is experiencing acceleration, by measuring round-trip times for acknowledgment of their own messages as well as the elapsed time on the other's clock at which the other received a message and sent the acknowledgment. Because it's late (and because it will take me time to work this out to a blatantly obvious level) I'll leave this as an exercise for the more dedicated readers. From owner-starship-design Wed Jan 29 06:48 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["567" "Wed" "29" "January" "1997" "09:48:47" "-0500" "David Levine" "David@interworld.com" nil "28" "starship-design: RE: Dr. Forward" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id GAA21010 for starship-design-outgoing; Wed, 29 Jan 1997 06:48:50 -0800 (PST) Received: from www1.interworld.com (www.InterWorld.Com [165.254.130.4]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id GAA21001 for ; Wed, 29 Jan 1997 06:48:47 -0800 (PST) Received: by www1.interworld.com with SMTP (Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63) id <01BC0DC9.A05DA310@www1.interworld.com>; Wed, 29 Jan 1997 09:48:48 -0500 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: X-Mailer: Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: David Levine Content-Type: text/plain; charset="us-ascii" Content-Length: 566 From: David Levine Sender: owner-starship-design To: "'TLG.van.der.Linden@tip.nl'" Cc: "'starship-design@lists.uoregon.edu'" Subject: starship-design: RE: Dr. Forward Date: Wed, 29 Jan 1997 09:48:47 -0500 Yes http://www.whidbey.com/forward/ ------------------ David Levine InterWorld Technology Ventures, Inc. "A stroke of the brush does not guarantee art from the bristles." >---------- >From: TLG.van.der.Linden@tip.nl[SMTP:TLG.van.der.Linden@tip.nl] >Sent: Wednesday, January 29, 1997 6:45 AM >To: David Levine >Subject: Re: Dr. Forward > >Hi David, > >>Just thought you guys'd be interested - I >>got email from Dr. Forward recently about >>LIT.... > >Does he have an internet site of his own, where some of his more popular >material is shown? > >Timothy > > From owner-starship-design Thu Jan 30 06:52 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5168" "Thu" "30" "January" "1997" "15:52" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "130" "starship-design: Re: Relativistic Electric Thrusters" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id GAA21940 for starship-design-outgoing; Thu, 30 Jan 1997 06:52:15 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id GAA21923 for ; Thu, 30 Jan 1997 06:52:11 -0800 (PST) Received: from hengelo05.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vpxrD-000Dm6C; Thu, 30 Jan 97 15:52 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Transfer-Encoding: binary Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="iso-8859-1" Content-Length: 5167 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: Relativistic Electric Thrusters Date: Thu, 30 Jan 97 15:52 MET Timothy replies to Ken Wharton's 1/27 letter: >I'm currently working on experiments with a short- >pulse 100 TeraWatt laser, looking into a novel Laser Fusion >concept. Sounds interesting, we need (continuous) power outputs somewhere around 1E17 Watt (give or take an order of magnitude). >1) and 2) In deciding the best exhaust particle, the only >equation you need is E^2 = P^2 c^2 + (m c^2)^2: And >everything points to low mass particles being the best. Not >only do they give a higher Momentum/Energy ratio, but a >higher Momentum/Mass ratio as well. Sorry if I have to be picky, but the momentum/energy ratio does not depend on mass, but only on velocity. Therefore I assume that you mean that since particles with high charge/mass ratios (like electrons) will be easier to accelerate and thus achieve higher final velocities and are thus better. However high velocities do NOT mean a higher momentum/energy ratio: momentum: p=gamma m v Energy : E=m c^2 (gamma-1) p/E=1/c {v/(c-Sqrt[c^2-v^2])} For v->c it goes to 1, for v->0 it goes to infinity, so higher velocities have a LOWERr momentum/energy ratio. >3) In terms of size, it really depends on the plasma >accelerator. Perhaps we can assume we might get 100 GeV in >acceleration per meter of accelerator. Would there be an >optimal length? I would guess no: you want the device as >long as possible; the entire length of the ship, I suppose. >Doubling the length will not double the mass of your entire >ship, but it will double the amount of thrust you can get! Previous calculations have shown that optimal exhaust velocity depends (among other things) on the final velocity of the starship. Just creating the highest exhaust velocity is therefore not the main goal. (Several of these calculations are available at http://www1.tip.nl/users/t596675/sd/sd.html) >4) Disadvantages to the moving charges. > >In my mind, the #1 problem to any spaceship propulsion scheme >was not mentioned here. There are bound to be some stray >macroscopic pieces of matter in interstellar space. This is >less of a problem for the accelerating half of the journey, >assuming one has adequate shielding in front. But what about >the decelerating portion??? All of a sudden you have the >engine, the most critical portion of the ship, exposed to >whatever might be speeding in your direction.... Good point, I can't remember that we ever wrote about this before in this mailing list. However it is likely that the exhaust particles will either burn or push away everything that is in the path of the ship. It may be a very effective shield. >As for the other points: > >a) I'll assume we wonÕt want to charge up the ship much. Of >the things that could be adversely affected by this, >computers would probably be at the top of the list. If we >ground all the computers, that leaves us with dangerous >potential differences. Or worse, assuming the charge isn't static, the enormous currents would melt away the ship's hull. >b) True; the protons (or electrons!) could just be dumped at >zero velocity, but given how tight our fuel will be I imagine >we'd want to try to accelerate both species. Yes, unless the added complexity of the engine (and weight of the engine) make the whole thing less attractive >c) I think the magnetic field produced by a beam might help >deflect incoming charged particles at low velocities, but >eventually the incoming protons/electrons would be energetic >enough to blast right on through. Also, accelerating charges >produces radiation; this might actually require more >shielding, as IÕd think the relativistic particles would >produce x-rays as theyÕre steered around the ship! True, I think the best way would be to push the particles asside by use of EM-radiation (laser). And what about the accelerating of charge in the engine of the ship, won't that generate even more dangerous radiation? >d) I donÕt think youÕd want to charge up the whole ship just >to deflect protons; if this might work itÕd be easier to just >charge up the nose cone. Plus, of course, youÕd attract >electrons. Still, I like the idea; protons are obviously >much worse... I think Rex meant to charge the cone (actually even better a tip far in front of the cone). >f) Using the interstellar protons to augment the beam is an >interesting idea, at least for the acceleration phase. Actually I would think it is of more use during the deceleration phase. (see my relpy to Rex) >g) We donÕt have to worry about the particle beam damaging >anything far away; the beam will spread out in space as it >travels. As for whether it would blast apart an incoming >meteor; that would be an important question. It certainly could do that, if the beam would still be concentrated enough. The energy transfer would ionize everything inside the beam. >Some particular issues w/ plasma accelerators: > >Efficiency??? This point could be the killer. Keep in mind that bad efficiencies produce a lot of heat when you are talking about 1E17 Watt. >Enough rambling for now. More later. Keep rambling, it sounds very interesting, Tim From owner-starship-design Thu Jan 30 06:52 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4834" "Thu" "30" "January" "1997" "15:52" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "126" "starship-design: Re: Questions Regarding Relativistic Electric Thrusters" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id GAA21952 for starship-design-outgoing; Thu, 30 Jan 1997 06:52:21 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id GAA21943 for ; Thu, 30 Jan 1997 06:52:17 -0800 (PST) Received: from hengelo05.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vpxr9-000Dm8C; Thu, 30 Jan 97 15:52 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 4833 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: Questions Regarding Relativistic Electric Thrusters Date: Thu, 30 Jan 97 15:52 MET Timothy replies to Rex's 1/25 letter: >A critical component of most of the interesting interstellar >propulsion concepts (e.g., fusion-powered rockets, antimatter- >powered rockets, beam-driven sails in the deceleration phase) is a >relativistic electric thruster. Actually a *relativistic* thruster is probably not useful for a fusion powered design, since such designs in general have a optima for rather "slow" exhaust velocities (less than 0.1c). So only beam-powered or anti-matter powered ships are candidates for relativistic thrusters. >The sample questions are as follows (I haven't tried to address >any of them, so some may not be well thought out): > >1. What is the best exhaust particle? Electrons, protons, alphas, > etc.? What is the best parameter to compare them by? Actually to determine an optimum we should first decide what we want to optimize. This may seem a trivial question but it really isn't. High velocities have a low momentum:energy ratio, but of course need a lot less mass. So you always have to weigh between how much mass and how much energy. Also one would want to use most of the repulsion mass that is taken with the starship, this almost certainly means that one needs to use ions (thus not electrons). For the highest exhaust velocity, one should take the particle with the highest charge:mass ratio, this would have been an electron, so the next best thing would be a proton: Formulas in SI units. U=q dV U=m c^2 (gamma-1) q dV=m c^2 (gamma-1) --> gamma=q/m ((dV/c^2)+1) >2. Is there an electron energy that gives the same performance as > protons? (from the so-called "mass amplification" with > increasing velocity) Do you mean: For what exhaust velocity y is the total relativistic energy of a electron the same as for a proton with exhaust velocity x? (If not, what do you mean with performance?) Mp:Me = 1:1836 E=gamma m c^2 GAMMAp Mp c^2 = GAMMAe Me c^2 -> GAMMAe/GAMMAp=1836 2 Vp + 3370895 c Ve = ----------------- 3370896 (Ve, Vp are exhaust velocities of electron and proton) >3. Can we estimate relative thruster weight per unit thrust? > Thruster size? (to compare the different options) >4. What disadvantages/advantages accompany motion of electric > charges? > a. What is the effect on performance (e.g., exhaust velocity) > of charging of the ship due to incomplete charge > neutralization? It probably is neglectable, if one however only exhaust ions and not electrons, then a serious problem will rise in a matter of seconds (probably less). > b. What is the effect on performance of charge neutralization > effected by dumping oppositely charged particles (at zero > velocity, say)? This depends on the amount of dumped mass compared to the amount of exhausted mass. In the case of exhausting electrons and dumping the protons and neutrons it would seriously harm performance. In general dumping mass always decreases performance. The rate at which it decreases performance depends besides technical problems also on the kind of fuel (f-factor) that is used. > c. Will the current of the exhaust beam generate a magnetic > field strong enough to deflect interstellar protons (ionized > by a stripping foil out in front of the ship) away from the > ship, to save shielding? If the core of the linear accelerator is in the same direction as the ship moves, the magnetic field in the forward direction will be almost zero. (I'd like others to verify this.) > d. Could the electric charge from incomplete neutralization > create an electric field, around a sharp point out in front > of the ship, strong enough to deflect interstellar protons > as in c, above? Ah, I notice you are assuming the incomplete neutralization is negatively charged. I think (after having done a very rough calculation) that this might be possible, however I've little experience with charges of many positive magnitudes Coulomb. > e. Could electrodes on the sides of the particle beam at the > exit end of the accelerator be used to steer the "jet" > (and hence the ship)? > f. Is there a possibility of entrainment of interstellar > protons by the particle beam to cause jet augmentation? This depends on the exhaust velocity and the velocity of the ship. If the exhaust velocity is smaller than the velocity of the ship (not unthinkable when using fusion) then this is clearly not useful, since the protons need to be decelerated. (In a few cases the protons could be fused first, the gained energy might shift the border between useful and not useful a bit). > g. What might be the damage caused by impingement of the > very-high-powered particle beam on another object in space? What objects did you have in mind? Timothy From owner-starship-design Thu Jan 30 07:02 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["742" "Thu" "30" "January" "1997" "10:02:55" "-0500" "David Levine" "David@interworld.com" nil "22" "RE: starship-design: Dr. Forward" "^From:" nil nil "1" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id HAA23664 for starship-design-outgoing; Thu, 30 Jan 1997 07:02:57 -0800 (PST) Received: from www1.interworld.com (www.InterWorld.Com [165.254.130.4]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id HAA23653 for ; Thu, 30 Jan 1997 07:02:54 -0800 (PST) Received: by www1.interworld.com with SMTP (Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63) id <01BC0E94.C40A76A0@www1.interworld.com>; Thu, 30 Jan 1997 10:02:56 -0500 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: X-Mailer: Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: David Levine Content-Type: text/plain; charset="us-ascii" Content-Length: 741 From: David Levine Sender: owner-starship-design To: "'starship-design@lists.uoregon.edu'" , "'KellySt@aol.com'" Subject: RE: starship-design: Dr. Forward Date: Thu, 30 Jan 1997 10:02:55 -0500 >Opps, retract previous post. I was confusing Forward with Bussard. What did >we have of Forwards that was copywrited? A book excerpt submitted by Lyle Fuller. Gone now. >For that matter, whats on the LIT site? (My web access is flakey at the >moment.) Did you upload integrate the stuff from your workstation? Or >download the newsletters to someplace accessable? Heh... um... not yet. But I'm starting to get mail from people complaining about broken links and such on the old site - so I'm really planning on moving the new site over as a whole very soon. I know - you've heard this from me before. But I actually see some light at the end of the tunnel. I think I might actually have a few free hours next week. David > From owner-starship-design Fri Jan 31 21:12 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["937" "Sat" "1" "February" "1997" "00:12:08" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "30" "Re: RE: starship-design: Dr. Forward" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id VAA01281 for starship-design-outgoing; Fri, 31 Jan 1997 21:12:21 -0800 (PST) Received: from emout06.mail.aol.com (emout06.mx.aol.com [198.81.11.97]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id VAA01267 for ; Fri, 31 Jan 1997 21:12:18 -0800 (PST) Received: (from root@localhost) by emout06.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id AAA21321; Sat, 1 Feb 1997 00:12:08 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970201001208_304226508@emout06.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 936 From: KellySt@aol.com Sender: owner-starship-design To: David@InterWorld.com, starship-design@lists.uoregon.edu, KellySt@aol.com Subject: Re: RE: starship-design: Dr. Forward Date: Sat, 1 Feb 1997 00:12:08 -0500 (EST) In a message dated 1/30/97 10:04:07 AM, David@InterWorld.com (David Levine) wrote: >>Opps, retract previous post. I was confusing Forward with Bussard. What did >>we have of Forwards that was copywrited? > >A book excerpt submitted by Lyle Fuller. Gone now. > >>For that matter, whats on the LIT site? (My web access is flakey at the >>moment.) Did you upload integrate the stuff from your workstation? Or >>download the newsletters to someplace accessable? > >Heh... um... not yet. But I'm starting to get mail from >people complaining about broken links and such on the >old site - so I'm really planning on moving the new site >over as a whole very soon. I know - you've heard this >from me before. But I actually see some light at the >end of the tunnel. I think I might actually have a few >free hours next week. > >David ;) Lets hope the light at the end of the tunnel isn't on the frount of a train. ;) Kelly From owner-starship-design Sun Feb 2 12:11 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["968" "Sun" "2" "February" "1997" "15:11:28" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "20" "starship-design: Something a bit more down to earth." "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id MAA10047 for starship-design-outgoing; Sun, 2 Feb 1997 12:11:39 -0800 (PST) Received: from emout14.mail.aol.com (emout14.mx.aol.com [198.81.11.40]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id MAA10037 for ; Sun, 2 Feb 1997 12:11:37 -0800 (PST) Received: (from root@localhost) by emout14.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id PAA19281 for starship-design@lists.uoregon.edu; Sun, 2 Feb 1997 15:11:28 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970202150932_1626280287@emout14.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 967 From: KellySt@aol.com Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Something a bit more down to earth. Date: Sun, 2 Feb 1997 15:11:28 -0500 (EST) Air Force wants a spaceplane. Av Week a couple weeks back did an artical on the Air Fource space comand and their interest in fielding a squadron of spaceplanes. The listed possible missions as: launching small 2000-3000 lb satelights, on call orbital reconisance, orbital comunication relay, re-entry and delivery of weapons and cargo to the surface, and re-entry and acting as an air superiority fighter. Such a craft could get anywhere on earth in about 40 minutees. They are looking into flying x-plane concept vehicals in the 2002-2003 time period. RFPs and all that would follow, and they hope to have a sqafdron in operation by 2030. They are hoping this can be the AF's next big combat aircraft contract after JSF (the F=16, F-18, Harrier replacement). They said they had no preconceptions about it being one stage, 2 stage, vertical launch, etc. But felt current technology would be enough to develop and field development of such a system. Kelly From owner-starship-design Tue Feb 4 15:08 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["10614" "Tue" "4" "February" "1997" "18:05:13" "-0500" "DotarSojat@aol.com" "DotarSojat@aol.com" nil "241" "starship-design: Protons vs Electrons for Relativistic Electric Thrusters" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id PAA01235 for starship-design-outgoing; Tue, 4 Feb 1997 15:06:08 -0800 (PST) Received: from emout15.mail.aol.com (emout15.mx.aol.com [198.81.11.41]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id PAA00999 for ; Tue, 4 Feb 1997 15:05:36 -0800 (PST) Received: (from root@localhost) by emout15.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id SAA25404 for starship-design@lists.uoregon.edu; Tue, 4 Feb 1997 18:05:13 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970204174835_-1878385971@emout15.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: DotarSojat@aol.com Content-Type: text Content-Length: 10613 From: DotarSojat@aol.com Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Protons vs Electrons for Relativistic Electric Thrusters Date: Tue, 4 Feb 1997 18:05:13 -0500 (EST) Hi all Thanks to remarks by Ken Wharton (welcome Ken!) and Timothy concerning my example questions regarding relativistic electric thrusters, I have been able to distill an important question that I can start to address quantitatively. [Aside to Ken: I worked at UCRL/Berkeley before there was a UCRL/Livermore and then at UCRL/Livermore for 8 of its early years (during which it was renamed Lawrence Livermore Laboratory.) I'm glad you can provide information on the cutting edge of plasma accelerator technology. I was going to cite an "old" news item in the Scientific American, on p. 66 of the April 1987 issue, regarding plasma wake-field acceleration of electrons with a projected gradient of one billion volts per meter, a little less than the achieved levels you report. (The item also mentions laser-plasma-accelerator work then going on at UCLA.) I got the impression from the item, however, that we probably could not expect from that technology the kinds of current or the efficiencies that we must have for our thrusters.] Some selected quotes from Ken and Timothy that set the stage for the question I want to address in this note are the following: Ken wrote, on 1/27, >1) and 2)...And everything points to low mass particles being >the best. >Assuming that the final energy of the particles will be large >compared to the rest mass,...the rest mass becomes irrelevant to >the momentum... >The Big Problem, of course, is keeping the ship neutral. >Assuming we don[']t have positrons handy...we need one proton per >electron, which will severely hurt the [Isp]. [I can't type the symbols for punctuation marks that his word processor generates.] Timothy wrote, on 1/30 (quoting me), >>1. What is the best exhaust particle? Electrons, protons, >> alphas, etc.? What is the best parameter to compare them by? >Actually to determine an optimum we should first decide what we >want to optimize. ... High velocities have a low momentum:energy >ratio, but of course need a lot less mass. So you always have to >weigh between how much mass and how much energy. >Also one would want to use most of the repulsion mass that is >taken with the starship, this almost certainly means that one >needs to use ions (thus not electrons). >For the highest exhaust velocity, one should take the particle >with the highest charge:mass ratio, this would have been an >electron, so the next best thing would be a proton... Timothy wrote, on 1/30 (quoting Ken), >>3) In terms of size... Would there be an optimal length? I >>would guess no: you want the device as long as possible... >>Doubling the length will not double the mass of your entire >>ship, but it will double the amount of thrust you can get! >Previous calculations have shown that optimal exhaust velocity >depends (among other things) on the final velocity of the >starship. Just creating the highest exhaust velocity is >therefore not the main goal. So, I boil down these points to a single question: Q: What is the optimum (minimum-antimatter) performance of an antimatter-powered starship with its exhaust composed of accelerated PROTONS (with electrons dumped for charge neutralization), in comparison with that of one with its exhaust composed of accelerated ELECTRONS (with protons dumped at negligible velocity for charge neutralization)? ACCELERATED PROTONS The performance of an antimatter-powered starship with a PROTON exhaust velocity that is optimized to require a minimum mass of antimatter fuel was derived in my note of 4/4/96: "Optimum Interstellar Rockets (Minimum Antimatter Fuel)." The circumstance of minimum antimatter fuel is obtained by finding the exhaust velocity, for a given final vehicle velocity, that maximizes the propulsive energy efficiency, i.e., maximizes the conversion of exhaust kinetic energy to final vehicle kinetic energy. The 4/4 note included a derivation of the calculational procedure by which the results were obtained. Unfortunately, the analysis reported there was for only the case with 100 percent conversion of antimatter energy to exhaust kinetic energy (to be then converted to final vehicle kinetic energy by multiplying by the aforementioned maximized propulsive energy efficiency). Subsequent analysis, which I haven't yet reported, has expanded the calculation to cover antimatter conversion efficiencies less than 100 percent. The 4/4 results for acceleration of PROTONS were as follows: (with the tabulated quantities-- Uend = final proper velocity, ltyr/yr, of the starship at the end of the propulsive phase (at "burnout") Vend = final apparent velocity, ltyr/yr, ditto [The apparent velocity V is given in terms of the proper velocity U by the relation V = U/sqrt(1 + U^2) , (note: c = 1 ltyr/yr), and the inverse relation is U = V/sqrt(1 - V^2) .] optVexh = optimum apparent exhaust velocity, ltyr/yr optUexh = optimum proper exhaust velocity, ltyr/yr maxeff = maximum propulsive energy efficiency minMam/Mbo = minimum ratio of initial mass of antimatter fuel to the ship's burnout mass minMam/Mi = minimum ratio of initial mass of antimatter fuel to the ship's initial mass Mi/Mbo = mass ratio = ratio of ship's initial mass to ship's burnout mass.) Antimatter conversion efficiency = 1.0 Uend Vend optVexh optUexh maxeff minMam/Mbo minMam/Mi Mi/Mbo 0.2 0.196 0.124 0.125E+00 0.647 0.015 0.0031 4.97 0.5 0.447 0.291 0.304E+00 0.645 0.091 0.0175 5.23 1.0 0.707 0.492 0.566E+00 0.641 0.323 0.0540 5.99 2.0 0.894 0.691 0.957E+00 0.630 0.981 0.1215 8.07 3.0 0.949 0.777 0.123E+01 0.622 1.739 0.1675 10.38 4.0 0.970 0.823 0.145E+01 0.615 2.537 0.1992 12.74 5.0 0.981 0.852 0.163E+01 0.610 3.357 0.2222 15.11 [Values for antimatter conversion efficiencies less than 1.0 are available on request, as is the derivation of the calculational procedure. (Just remember that the calculational procedure described in my 4/4/96 note is an example, but is not complete.)] In the accelerated-PROTONS case, we have an optimum exhaust velocity and therefore an optimum accelerator length, as Timothy states. ACCELERATED ELECTRONS The calculational procedure described in my 4/4/96 note has been expanded to include dumping of mass at negligible velocity to bring about charge neutralization (as well as to include conversion efficiencies less than 1.0). The comparable results of the calculations for accelerated ELECTRONS (with dumping of one proton at negligible velocity for each electron for charge neutralization: "DUMP = 1836.") are as follows with the same nomenclature as above: Antimatter conversion efficiency = 1.0 Uend Vend optVexh optUexh maxeff minMam/Mbo minMam/Mi Mi/Mbo 0.2 0.196 1.000 0.184E+06 0.090 0.110 0.0900 1.22 0.5 0.447 1.000 0.478E+06 0.191 0.309 0.1908 1.62 1.0 0.707 1.000 0.931E+06 0.293 0.708 0.2927 2.42 2.0 0.894 1.000 0.163E+07 0.382 1.620 0.3817 4.24 3.0 0.949 1.000 0.217E+07 0.418 2.584 0.4186 6.17 4.0 0.970 1.000 0.257E+07 0.438 3.565 0.4382 8.14 5.0 0.981 1.000 0.289E+07 0.450 4.554 0.4503 10.11 For electrons, there is no maximum efficiency as a function of Uexh for finite values of Uexh; the efficiency increases monotonically as Uexh is increased. The maximum is replaced by an asymptote at infinite Uexh. The value of "maxeff" tabulated above is that efficiency when the increase in efficiency is 0.001 percent for an increase in Uexh of 1 percent; the tabulated value is within about 0.1 percent of the asymptote. (Note: This problem would have been almost hopelessly difficult if the parameter of optimization had been the conventional apparent exhaust velocity rather than the proper exhaust velocity; for the last line, the apparent exhaust velocity is 0.99999999999994 ltyr/yr for the stated proper exhaust velocity.) In the accelerated-ELECTRONS case, the kinetic energy efficiency stays virtually constant with increasing exhaust velocity above the tabulated value. In this case Ken is right (thrust increases directly with exhaust velocity without limit; "you want the device as long as possible"). COMPARISON Timothy cogently observes, "you always have to weigh between how much mass and how much energy." A succinct comparison between protons and electrons can be made with a table of the principal mass-related and energy-related properties of starships that would make use of the two choices of exhaust particles. The particle-accelerator energy for a specified Uexh is given by the relation particle kinetic energy = mc^2 * [sqrt(1 + Uexh^2) - 1] , where mc^2 is 938.9 MeV for protons and 0.511 MeV for electrons. For the protons' optUexh of 0.163E+01 ltyr/yr for the Uend of 5.0 ltyr/yr (achieved at a continuous acceleration of 1 g over a distance of 3.97 ltyr), the PROTON accelerator energy is about 850 MeV. For the electrons' "optUexh" of 0.289E+07 ltyr/yr for the Uend of 5.0 ltyr/yr, the ELECTRON accelerator energy is about 1,480 GeV. The thrust T is given by the relation T = iV sqrt[1 + (2mc^2/eV)] * (1 kgf/2,940 Mw) , where mc^2 is as above, i is current in amps, V is volts and eV is the accelerator energy in MeV; 1 amp*volt is 1 w. The values extracted from the Uend = 5.0 lines in the tables above or calculated from the above relations are as follows: Property Proton exhaust Electron exhaust Mass ratio 15.11 10.11 Maxeff 0.610 0.450 MinMam/Mbo 3.357 4.554 MinMam/Mi 0.2222 0.4503 Accelerator Energy (Mev) 850. 1,480,000. Thrust/amp (kgf) 0.520 500. "You pays your money and you takes your choice." I'll defer any further observations until I've seen your comments and further questions. This is only a start. Your suggestions may lead to significant changes in the approach. Rex Finke P.S. If anyone asks for the analysis, I'll post it in another note; this note is long enough. (This analysis reproduces earlier results for the simpler conditions consistent with their less complete calculations. None of the current results seems too surprising, not even the smaller mass ratio with the electron exhaust, when one takes into account the ultra-high exhaust velocity.) From owner-starship-design Tue Feb 4 15:22 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["460" "Tue" "4" "February" "1997" "15:23:23" "-0800" "Steve VanDevender" "stevev@efn.org" nil "10" "starship-design: Protons vs Electrons for Relativistic Electric Thrusters" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id PAA07644 for starship-design-outgoing; Tue, 4 Feb 1997 15:20:22 -0800 (PST) Received: from wakko (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id PAA07619 for ; Tue, 4 Feb 1997 15:20:18 -0800 (PST) Received: from tzadkiel (stevev@tzadkiel.efn.org [198.68.17.19]) by wakko (8.8.4-q-beta2/8.7.3) with ESMTP id PAA07292; Tue, 4 Feb 1997 15:19:56 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id PAA09905; Tue, 4 Feb 1997 15:23:23 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702042323.PAA09905@tzadkiel> In-Reply-To: <970204174835_-1878385971@emout15.mail.aol.com> References: <970204174835_-1878385971@emout15.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 459 From: Steve VanDevender Sender: owner-starship-design To: DotarSojat@aol.com Cc: starship-design@lists.uoregon.edu Subject: starship-design: Protons vs Electrons for Relativistic Electric Thrusters Date: Tue, 4 Feb 1997 15:23:23 -0800 DotarSojat@aol.com writes: > Antimatter conversion efficiency = 1.0 That's a common misconception. Unfortunately the annihilation products of matter-antimatter reactions aren't all photons, and it's really damn hard even to get the matter and antimatter to combine completely under any realistic circumstances. My understanding (bolstered by some half-remembered statements by Robert Forward) is that the practical conversion efficiency is more like 0.8. From owner-starship-design Tue Feb 4 19:27 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["331" "Tue" "4" "February" "1997" "22:25:53" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "16" "Re: starship-design: Something a bit more down to earth." "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id TAA23425 for starship-design-outgoing; Tue, 4 Feb 1997 19:27:00 -0800 (PST) Received: from emout19.mail.aol.com (emout19.mx.aol.com [198.81.11.45]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id TAA23388 for ; Tue, 4 Feb 1997 19:26:51 -0800 (PST) Received: (from root@localhost) by emout19.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id WAA24357; Tue, 4 Feb 1997 22:25:53 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970204220214_1146040572@emout19.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 330 From: KellySt@aol.com Sender: owner-starship-design To: lparker@cacaphony.net, KellySt@aol.com cc: starship-design@lists.uoregon.edu Subject: Re: starship-design: Something a bit more down to earth. Date: Tue, 4 Feb 1997 22:25:53 -0500 (EST) >Well, if you can't have commercial interest pushing space research there is >always second choice... > >> Air Force wants a spaceplane. > > >Lee Parker True. Leave it to the military to open any possible area of operations, and push the practical. Wish NASA had a fraction of their vision or pragmatism. :( Kelly Starks From owner-starship-design Tue Feb 4 22:54 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5179" "Tue" "4" "February" "1997" "22:54:42" "-0800" "Ken Wharton" "wharton@physics.ucla.edu" nil "85" "starship-design: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id WAA24543 for starship-design-outgoing; Tue, 4 Feb 1997 22:54:51 -0800 (PST) Received: from physics.ucla.edu (physics.ucla.edu [128.97.23.13]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id WAA24501 for ; Tue, 4 Feb 1997 22:54:46 -0800 (PST) Received: from watt by physics.ucla.edu (SMI-8.6/SMI-SVR4) id WAA07396; Tue, 4 Feb 1997 22:54:43 -0800 Received: by watt (SMI-8.6/SMI-SVR4) id WAA05285; Tue, 4 Feb 1997 22:54:42 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702050654.WAA05285@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: wharton@physics.ucla.edu (Ken Wharton) Content-Type: text Content-Length: 5178 From: wharton@physics.ucla.edu (Ken Wharton) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Anti-antimatter Date: Tue, 4 Feb 1997 22:54:42 -0800 First let me sound a quick note of technical confusion... Timothy's response to my post on laser-plasma accelerators came through to my mail system as a series of random characters. I assumed it happened to everyone, but since Rex just quoted Timothy's response to me in his last post I suppose the problem was more localized (I have to Telnet down to UCLA to read my mail, although I'm not sure how that would mess things up so badly in this isolated case; all Timothy's other posts come through fine.) Could someone please re-post Timothy's 1/30 Re: Relativistic Electric Thrusters so I could try to read it? Thanks! As for the ongoing discussion on Relativistic Thrusters, I'm slowly getting up to speed. I checked out Timothy's Web Page and saw why a fusion spacecraft should limit the fuel speed to 0.1c; I didn't check the numbers, but it sounds reasonable. So for self-powered ships, that seems to leave relativistic engines to the regime where you can transfer your ship mass to energy with a near-unity efficiency. The most obvious way to do this is with antimatter, of course, but here I'm a bit skeptical. Even if we're assuming some pretty amazing technological advances, I find it hard to imagine storing huge quantities of anti-matter on a ship. I don't know if this has been discussed already, but I would guess there would be some sort of theoretical minimum matter/antimatter ratio, just from containment considerations. Anyone want to tackle that one? So, keeping this in mind, here are another two ideas for "antimatter-type" engines; ways to convert mass to pure energy--without using antimatter. These are nearly as speculative as large-scale antimatter containment, but I'd still argue that they're more probable. The first is probably the most easily shot down: power the ship from an enormous relativistic or near-relativistic flywheel. There's a significant amount of research into flywheels for electric cars, but there are many big disadvantages: they have to be kept in vacuum, they need to always point in the same direction, and they need to be small enough to fit in a car. All three of these problems, of course, aren't big deals for an interstellar spacecraft. The big limiting factor is the acceleration that the rim can handle before flying apart, but for a given acceleration limit--with a hollow cylindrical flywheel--an arbitrarily high Energy/Mass ratio is possible just by making the flywheel larger. To be specific, the Energy/Mass (J/Kg) of the system is simply half the acceleration of the rim (m/s^2) times the radius of the wheel (m). Current flywheels are made out of graphite and can handle rim accelerations greater than 10^8 m/s^2. The actual limits are not public knowledge, as far as I can tell; too much competition between the people who make these things. So already, for a 200 meter radius flywheel, we're talking about an energy storage of 10^10 J/Kg. We'd probably need at least 10^14 J/Kg to make a decent spaceship. Making up four orders of magnitude as well as structurally weakening the flywheel by making it hollow seems quite a long-shot. But two possibilities that are at least credible are fullerene and diamond flywheels. I'm not sure which would be stronger; Diamond is a 3-D structure while buckytubes are 2-D, but the crystal structure of a diamond magnifies small imperfections. Perhaps a braid of buckytubes would be the best; on the other hand, if nanotechnology allows the creation of a *perfect* diamond flywheel, it's hard to see how anything could beat it. Of course, a 200 meter flywheel with 10^14 J/Kg means the rim is traveling at 10^7 m/s. Any bigger/faster and you get relativity playing a big role. Probably some problems inherent in that situation... but it might make a great gravity-wave generator! Idea #2: Catalyze nucleon decay using captured magnetic monopoles. Okay, okay... at least antimatter has been proven to exist, right? Granted, magnetic monopoles are still hypothetical particles, but on the plus side every single Grand Unified Theory predicts that they should exist. Basically, if there IS a grand unified theory, then magnetic monopoles are viable and stable particles. Unfortunately, most of the GUT's predict HUGE masses; sometimes as big as 10^19 GeV! If correct, this means we're not going to make a monopole in an accelerator: they're only going to be left over from the Big Bang, and we're going to have to find one and catch it. As I mentioned, another predicted feature of monopoles is that they should catalyze proton and neutron decay. The great thing about this is that it doesn't destroy the monopole; it's still waiting around to decay more nucleons. One can easily imagine what a great power source this would be; feed a monopole protons and neutrons and it continually converts them into pure energy. You'd probably need quite a few monopoles to make a decent spaceship engine, but it'd be a whole lot less than the needed amount of antimatter. Well, this was a pretty big tangent off the subject here, but hopefully it'll spark some ideas... Ken From owner-starship-design Wed Feb 5 05:29 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2430" "Wed" "5" "February" "1997" "14:30" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "61" "starship-design: Re: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id FAA07178 for starship-design-outgoing; Wed, 5 Feb 1997 05:29:43 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id FAA07169 for ; Wed, 5 Feb 1997 05:29:38 -0800 (PST) Received: from hengelo24.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vs7Qr-000DnAC; Wed, 5 Feb 97 14:30 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 2429 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: Anti-antimatter Date: Wed, 5 Feb 97 14:30 MET Timothy replies to Ken: >Could someone please re-post Timothy's 1/30 Re: >Relativistic Electric Thrusters so I could try to read it? Thanks! I'll sent it to you at the same time this letter is sent. > As for the ongoing discussion on Relativistic Thrusters, I'm >slowly getting up to speed. I checked out Timothy's Web Page and saw why >a fusion spacecraft should limit the fuel speed to 0.1c; I didn't check >the numbers, but it sounds reasonable. Since Rex has done similar calculations and got the same numbers, I'm quite confident about the results. > So for self-powered ships, that seems to leave relativistic >engines to the regime where you can transfer your ship mass to energy >with a near-unity efficiency. And even then, only if you want high (>0.9c) final velocities of the spaceship (high velocity means more energy) > The most obvious way to do this is with >antimatter, of course, but here I'm a bit skeptical. Even if we're >assuming some pretty amazing technological advances, I find it hard to >imagine storing huge quantities of anti-matter on a ship. I don't know >if this has been discussed already, but I would guess there would be >some sort of theoretical minimum matter/antimatter ratio, just from >containment considerations. Anyone want to tackle that one? A minimum ratio? Why would do you think that? > So, keeping this in mind, here are another two ideas for >"antimatter-type" engines; ways to convert mass to pure energy--without >using antimatter. These are nearly as speculative as large-scale >antimatter containment, but I'd still argue that they're more probable. I've thought of a flywheel before, but never mentioned it because it seemed too unpractical: - Its estimated weight was too high. - Containing/guiding a huge fly wheel that rotates with super high velocities seemed almost infeasable. >So already, for a 200 meter radius flywheel, >we're talking about an energy storage of 10^10 J/Kg. We'd probably need >at least 10^14 J/Kg to make a decent spaceship. Actually I think that 1E16 J/kg is the absolute minimum if you want to get into the direction of relativistic velocities. > Idea #2: Catalyze nucleon decay using captured magnetic >monopoles. The mean idea of using a monopole is probably it's heigh energy:weight ratio. Maybe we can find other ways to store energy. For example storing photons in a perfect mirror sphere. Timothy From owner-starship-design Wed Feb 5 10:06 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["777" "Wed" "5" "February" "1997" "10:08:44" "-0800" "Steve VanDevender" "stevev@efn.org" nil "17" "starship-design: Re: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id KAA21205 for starship-design-outgoing; Wed, 5 Feb 1997 10:05:53 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id KAA21143 for ; Wed, 5 Feb 1997 10:05:48 -0800 (PST) Received: from tzadkiel (stevev@tzadkiel.efn.org [198.68.17.19]) by wakko.efn.org (8.8.3/8.7.3) with ESMTP id KAA24205; Wed, 5 Feb 1997 10:05:24 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id KAA12429; Wed, 5 Feb 1997 10:08:44 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702051808.KAA12429@tzadkiel> In-Reply-To: References: Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 776 From: Steve VanDevender Sender: owner-starship-design To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Cc: starship-design@lists.uoregon.edu Subject: starship-design: Re: Anti-antimatter Date: Wed, 5 Feb 1997 10:08:44 -0800 Timothy van der Linden writes: > > Idea #2: Catalyze nucleon decay using captured magnetic > >monopoles. > > The mean idea of using a monopole is probably it's heigh energy:weight > ratio. Maybe we can find other ways to store energy. > For example storing photons in a perfect mirror sphere. Ken also claimed that the decay results would be "pure energy". My initial reaction is that conservation of spin and charge would preclude complete conversion; not all of the products would be photons. Anyway, what we want is the best matter-to-momentum conversion, not the best matter-to-energy conversion. Converting matter to photons does get you the most momentum for a given amount of matter, but it's probably not feasible to convert matter completely to photons. From owner-starship-design Wed Feb 5 16:05 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2304" "Wed" "5" "February" "1997" "18:03:26" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "54" "Re: starship-design: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id QAA25169 for starship-design-outgoing; Wed, 5 Feb 1997 16:04:58 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id QAA25007 for ; Wed, 5 Feb 1997 16:04:49 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p39.gnt.com [204.49.68.40]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id SAA19615; Wed, 5 Feb 1997 18:04:31 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702060004.SAA19615@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 2303 From: "L. Clayton Parker" Sender: owner-starship-design To: "Ken Wharton" Cc: Subject: Re: starship-design: Anti-antimatter Date: Wed, 5 Feb 1997 18:03:26 -0600 Hi Ken, Just a few quick observations on your ideas and questions. > some sort of theoretical minimum matter/antimatter ratio, just from > containment considerations. Anyone want to tackle that one? Theoretical efficiencies don't look promising...we won't even get into the problem of producing antimatter on an industrial scale... > The first is probably the most easily shot down: power the ship > from an enormous relativistic or near-relativistic flywheel. There's a Hmm, you mean like a rotating black hole? I think Robert Forward has already proposed this one. Check out a few of his books. Bear in mind that now you have to accelerate the mass of the black hole also...and anything spinning at relativistic speeds is going to have the same mass moments as a black hole anyway... > Idea #2: Catalyze nucleon decay using captured magnetic > monopoles. I think Forward beat you to this one also... > continually converts them into pure energy. You'd probably need quite a > few monopoles to make a decent spaceship engine, but it'd be a whole lot > less than the needed amount of antimatter. Definitely. Since we are dreamig here, I want to throw one more hypothetical propulsion mechanism into the pot (and I know it has already been speculated upon). The biggest problem with interstellar propulsion is finding a method that is simultaneously capable of generating lots of thrust (ISP) and not adding tremendous amounts of mass to the vehicle. The trick here is to find a mechanism that like a solar sail, relies upon an external source of power which we can tap directly or indirectly for propulsion. This source needs to be large, inexhaustible, and NATURALLY produced, i.e. we don't have to make it, correlate it, or concentrate it as in beamed power. What we need is to be able to unfurl a solar sail billions of miles across that weighs NOTHING, or surf on a wave of gravity, or ride on a stream of neutrinos, or... I really don't have a preference as long as the mechanism for tapping the source of power requires somewhat less than astronomical (and unrealistic) amounts of energy. There is no currently known or speculated propulsion mechanism utilizing onboard fuel that will provide realistic interstellar propulsion so maybe we need to look elsewhere. Lee From owner-starship-design Wed Feb 5 16:14 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1185" "Wed" "5" "February" "1997" "16:17:00" "-0800" "Steve VanDevender" "stevev@efn.org" nil "23" "Re: starship-design: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id QAA29769 for starship-design-outgoing; Wed, 5 Feb 1997 16:14:38 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id QAA29725 for ; Wed, 5 Feb 1997 16:14:35 -0800 (PST) Received: from tzadkiel (stevev@tzadkiel.efn.org [198.68.17.19]) by wakko.efn.org (8.8.3/8.7.3) with ESMTP id QAA14844; Wed, 5 Feb 1997 16:13:35 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id QAA13340; Wed, 5 Feb 1997 16:17:00 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702060017.QAA13340@tzadkiel> In-Reply-To: <199702060004.SAA19615@hurricane.gnt.net> References: <199702060004.SAA19615@hurricane.gnt.net> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 1184 From: Steve VanDevender Sender: owner-starship-design To: "L. Clayton Parker" Cc: "Ken Wharton" , Subject: Re: starship-design: Anti-antimatter Date: Wed, 5 Feb 1997 16:17:00 -0800 L. Clayton Parker writes: > > The first is probably the most easily shot down: power the ship > > from an enormous relativistic or near-relativistic flywheel. There's a > > Hmm, you mean like a rotating black hole? I think Robert Forward has > already proposed this one. Check out a few of his books. Bear in mind that > now you have to accelerate the mass of the black hole also...and anything > spinning at relativistic speeds is going to have the same mass moments as a > black hole anyway... I remember reading that a black hole can have up to 29% of its energy tied up in angular momentum. Unfortunately to get the energy back out you have to throw more mass into it in such a way that some of the mass is given to the black hole and the rest spews out carrying away some of the rotational energy. Of course, with a quantum black hole you can do partial conversion of mass to energy by feeding it at the same rate that it emits mass/energy due to quantum evaporation. If you run out of fuel you have to be able to toss the black hole away before it blows up due to runaway evaporation; the rate of evaporation is inversely related to the mass of the black hole. From owner-starship-design Wed Feb 5 17:52 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2378" "Wed" "5" "February" "1997" "19:50:55" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "48" "Re: starship-design: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id RAA15314 for starship-design-outgoing; Wed, 5 Feb 1997 17:52:41 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id RAA15290 for ; Wed, 5 Feb 1997 17:52:38 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p106.gnt.com [204.49.68.107]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id TAA24156; Wed, 5 Feb 1997 19:52:00 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702060152.TAA24156@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 2377 From: "L. Clayton Parker" Sender: owner-starship-design To: "Steve VanDevender" Cc: Subject: Re: starship-design: Anti-antimatter Date: Wed, 5 Feb 1997 19:50:55 -0600 Steve, It has been quite awhile since I read about spinning black holes, and I must point out that his scientific credentials notwithstanding, I think it was in a FICTION book. Nevertheless, there are several ways to extract energy from a spinning black hole. The first method as you point out is by injecting matter into it in such a manner that you get some energy back out, and as you point out this is THEORETICALLY at the expense of angular momentum (the arguments here get a little abstruse and there are two sides). The second method invloves directly braking the rotation using some sort of magnetic field and thereby transferring momentum as energy into the braking field, a method which is several orders of magnitude more difficult than the first, but which offers the advantage of not requiring on board reaction mass. Of course yo still face the problem of converting the resultant energy into PROPULSION...and as someone just pointed out it isn't necessarily a matter of energy conversion efficiency, but momentum conversion efficiency. The flaw (or hole if you will excuse the pun) in both of these propositions is that black holes (or relativistically spinning masses of any sort) have MASS and lots of it. Will you get sufficient energy usable for a change in momentum from one of these reactions? I don't think so. I therefore return to my earlier statement that the source of the energy that is being used to provide thrust must be external to the vehicle, requiring an absolute minimum of onboard reaction mass. > I remember reading that a black hole can have up to 29% of its energy > tied up in angular momentum. Unfortunately to get the energy back out > you have to throw more mass into it in such a way that some of the mass > is given to the black hole and the rest spews out carrying away some of > the rotational energy. > > Of course, with a quantum black hole you can do partial conversion of > mass to energy by feeding it at the same rate that it emits mass/energy > due to quantum evaporation. If you run out of fuel you have to be able > to toss the black hole away before it blows up due to runaway > evaporation; the rate of evaporation is inversely related to the mass of > the black hole. (P.S. at least on argument says the black hole will ALWAYS evaporate QUICKLY and therefore it is useless to attempt this...) Lee Parker From owner-starship-design Wed Feb 5 22:11 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1607" "Wed" "5" "February" "1997" "22:14:10" "-0800" "Steve VanDevender" "stevev@efn.org" nil "29" "Re: starship-design: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id WAA08400 for starship-design-outgoing; Wed, 5 Feb 1997 22:11:22 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id WAA08389 for ; Wed, 5 Feb 1997 22:11:19 -0800 (PST) Received: from tzadkiel (stevev@cisco-ts17-line10.uoregon.edu [128.223.150.227]) by wakko.efn.org (8.8.3/8.7.3) with ESMTP id WAA25656; Wed, 5 Feb 1997 22:10:46 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id WAA14117; Wed, 5 Feb 1997 22:14:10 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702060614.WAA14117@tzadkiel> In-Reply-To: <199702060152.TAA24156@hurricane.gnt.net> References: <199702060152.TAA24156@hurricane.gnt.net> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 1606 From: Steve VanDevender Sender: owner-starship-design To: "L. Clayton Parker" Cc: Subject: Re: starship-design: Anti-antimatter Date: Wed, 5 Feb 1997 22:14:10 -0800 L. Clayton Parker writes: > > Of course, with a quantum black hole you can do partial conversion of > > mass to energy by feeding it at the same rate that it emits mass/energy > > due to quantum evaporation. If you run out of fuel you have to be able > > to toss the black hole away before it blows up due to runaway > > evaporation; the rate of evaporation is inversely related to the mass of > > the black hole. > > (P.S. at least on argument says the black hole will ALWAYS evaporate > QUICKLY and therefore it is useless to attempt this...) On the other hand, if you can get the right evaporation rate and maintain it, you also get the advantage that the evaporation products will be statistically 1/2 matter and 1/2 antimatter (except for the photons). So if it is possible to keep a quantum black hole just on the edge of evaporation at a rate useful for propulsion and power generation, you also get near-total matter-to-energy conversion by recombining the evaporation products. My understanding is that evaporation rate is a function of the mass of the black hole (and hence the gravity gradient near it), with the rate going up asymptotically as the black hole mass approaches zero. You also have the problem that radiation pressure from the evaporating black hole will make it difficult to pump more mass into it to prevent runaway evaporation, especially as you want more power. Unfortunately I don't know the exact equation that relates evaporation rate to mass to know whether it would be feasible to keep a quantum black hole in a stable state and get a useful power output. From owner-starship-design Thu Feb 6 11:18 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7114" "Thu" "6" "February" "1997" "11:18:37" "-0800" "Ken Wharton" "wharton@physics.ucla.edu" nil "152" "starship-design: Lots O Stuff..." "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id LAA22276 for starship-design-outgoing; Thu, 6 Feb 1997 11:18:42 -0800 (PST) Received: from physics.ucla.edu (physics.ucla.edu [128.97.23.13]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id LAA22234 for ; Thu, 6 Feb 1997 11:18:39 -0800 (PST) Received: from watt by physics.ucla.edu (SMI-8.6/SMI-SVR4) id LAA24059; Thu, 6 Feb 1997 11:18:37 -0800 Received: by watt (SMI-8.6/SMI-SVR4) id LAA17997; Thu, 6 Feb 1997 11:18:37 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702061918.LAA17997@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: wharton@physics.ucla.edu (Ken Wharton) Content-Type: text Content-Length: 7113 From: wharton@physics.ucla.edu (Ken Wharton) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Lots O Stuff... Date: Thu, 6 Feb 1997 11:18:37 -0800 Here are some responses to recent ideas... Timothy writes: >> Even if we're >>assuming some pretty amazing technological advances, I find it hard to >>imagine storing huge quantities of anti-matter on a ship. I don't know >>if this has been discussed already, but I would guess there would be >>some sort of theoretical minimum matter/antimatter ratio, just from >>containment considerations. Anyone want to tackle that one? >A minimum ratio? Why would do you think that? Also, Lee says... >Theoretical efficiencies don't look promising...we won't even get into >the problem of producing antimatter on an industrial scale... Given you already have the antimatter, how much can you fit on a ship? What IÕm thinking of here is a twofold problem: 1) we have to contain the antimatter, and 2) we have to accelerate it with the rest of the ship. I assume itÕs a given that the fuel will be antihydrogen; (if you think fusion is tough, think of what antimatter fusion would be like!) Solid antihydrogen would be the obvious storage choice, and a spherical geometry would allow the minimum surface area with the maximum fuel. One problem, though, is that solid hydrogen isnÕt very dense; for a lot of antimatter weÕre talking about a huge container, with every point capable of generating fields to isolate the anti-H (Can solid hydrogen be repulsed by a superconducting field?) Then, when the ship accelerates, something has to accelerate the anti-H as well; and think of how much the anti-H will ÒweighÓ in 1-g acceleration. WeÕll need equipment capable of making huge fields to transfer the force, as well as huge structural supports to handle the necessary forces on this equipment: all that will take matter. Adding this structural matter to the equivalent amount of regular hydrogen matter that we need for fuel, and you start to see why I was talking about a ÒminimumÓ matter/antimatter ratio. On the flywheel subject, Timothy writes: >I've thought of a flywheel before, but never mentioned it because it >seemed too unpractical: >- Its estimated weight was too high. >- Containing/guiding a huge fly wheel that rotates with super high > velocities seemed almost infeasable. >>So already, for a 200 meter radius flywheel, >>we're talking about an energy storage of 10^10 J/Kg. We'd probably >>need at least 10^14 J/Kg to make a decent spaceship. >Actually I think that 1E16 J/kg is the absolute minimum if you want to >get into the direction of relativistic velocities. I suppose a 20-kilometer flywheel is out of the question. Anyone know how strong perfect diamond is, anyway? Or what about a two-stage engine; a flywheel to get the ship moving fast enough where a ramjet-type drive could take over. I know you guys have talked about ramjets, but IÕm not sure what the current consensus is... Lee also writes: >Hmm, you mean like a rotating black hole? I think Robert Forward has >already proposed this one. Check out a few of his books. Bear in mind >that now you have to accelerate the mass of the black hole also...and >anything spinning at relativistic speeds is going to have the same mass >moments as a black hole anyway... Very Interesting. But what is the mass moment of a black hole? DoesnÕt the mass get sucked into a singularity at the center? (Or is it also spinning infinitely fast?) But if we do have a black hole handy, I think it would be easier to use SteveÕs idea: >On the other hand, if you can get the right evaporation rate and >maintain it, you also get the advantage that the evaporation products >will be statistically 1/2 matter and 1/2 antimatter (except for the >photons). So if it is possible to keep a quantum black hole just on >the edge of evaporation at a rate useful for propulsion and power >generation, you also get near-total matter-to-energy conversion by >recombining the evaporation products. But keep in mind, before the black-hole conversation gets too deep, that small black holes will need an accepted theory of quantum gravity, which doesnÕt currently exist. The idea of using a catalyst to turn mass into energy leads straight into monopoles. Timothy writes: >> Idea #2: Catalyze nucleon decay using captured magnetic >>monopoles. >The mean idea of using a monopole is probably it's heigh energy:weight >ratio. Maybe we can find other ways to store energy. >For example storing photons in a perfect mirror sphere. If we donÕt need too many monopoles the energy:weight ratio wonÕt matter too much; the main fuel source will still be nucleons. I like the photon sphere idea, but my main concern is that for our purposes the photon pressure would probably drive the sphere unstable. HavenÕt looked at any numbers, though... Also, Steve writes: >Ken also claimed that the decay results would be "pure energy". My >initial reaction is that conservation of spin and charge would preclude >complete conversion; not all of the products would be photons. >Anyway, what we want is the best matter-to-momentum conversion, not the >best matter-to-energy conversion. Converting matter to photons does >get you the most momentum for a given amount of matter, but it's >probably not feasible to convert matter completely to photons. I did look at the numbers for this one. Turns out you get a proton decaying into a highly energetic positron (roughly 800MeV) and a slow neutral pion (or several pions...) The pions will decay into usable energy (Photons, I think, adding up to the remaining 130MeV) , and the positron can either be captured or used as propellant. Also, assuming we have 100% efficiency energy collectors and accelerators, doesnÕt the energy/momentum problem go away? WeÕll simply convert our given amount of energy to momentum in the way that best accelerates the ship. But once you start talking about efficiency losses; LeeÕs right. WeÕre better off using the end products as propellant. Anyone want to figure out what a ship could do if we could convert protons into 800MeV positrons and use them as propellant directly? Finally, Lee writes: >> Idea #2: Catalyze nucleon decay using captured magnetic >> monopoles. >I think Forward beat you to this one also... >The biggest problem with interstellar propulsion is finding a method >that is simultaneously capable of generating lots of thrust (ISP) and >not adding tremendous amounts of mass to the vehicle. The trick here is >to find a mechanism that like a solar sail, relies upon an external >source of power which we can tap directly or indirectly for propulsion. >This source needs to be large, inexhaustible, and NATURALLY produced, >i.e. we don't have to make it, correlate it, or concentrate it as in >beamed power. What book is this in? IÕve never read any Forward, but IÕd be interested to see it. One last thought: Although Lee is certainly correct about wanting to find an external source of power, there is another option: Find an external source of Inertia. If we can find something heavy to push off of itÕll be a whole lot easier to convert energy to ship-momentum. Ken From owner-starship-design Thu Feb 6 13:07 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3559" "Thu" "6" "February" "1997" "16:07:03" "-0500" "DotarSojat@aol.com" "DotarSojat@aol.com" nil "82" "starship-design: Antimatter Annihilation Products" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id NAA14252 for starship-design-outgoing; Thu, 6 Feb 1997 13:07:48 -0800 (PST) Received: from emout19.mail.aol.com (emout19.mx.aol.com [198.81.11.45]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id NAA14211 for ; Thu, 6 Feb 1997 13:07:37 -0800 (PST) Received: (from root@localhost) by emout19.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id QAA02896 for starship-design@lists.uoregon.edu; Thu, 6 Feb 1997 16:07:03 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970206130058_-1643430695@emout19.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: DotarSojat@aol.com Content-Type: text Content-Length: 3558 From: DotarSojat@aol.com Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Antimatter Annihilation Products Date: Thu, 6 Feb 1997 16:07:03 -0500 (EST) Hi all Steve wrote, on 2/4 at 18:49 EST (quoting me), >>Antimatter conversion efficiency = 1.0 [That was really just a value picked to make the analysis easier to check; it was qualified by "Unfortunately, the analysis reported there (in my 4/4/96 note) was for only the case with 100 percent conversion of antimatter energy to exhaust kinetic energy ... Subsequent analysis, which I haven't yet reported, has expanded the calculation to cover antimatter conversion efficiencies less than 100 percent."] >That's a common misconception. Unfortunately the annihilation >products of matter-antimatter reactions aren't all photons... >My understanding (bolstered by some half-remembered statements by >Robert Forward) is that the practical conversion efficiency is >more like 0.8. I have before me Robert Forward's report "Antiproton Annihilation Propulsion," AFRPL TR-85-034, September 1985 (done under US Gov't contract, so it should be in the public domain, David). It may not be the best currently available information, but should be a good reference point from which to judge progress. He said at that time (on p. 109, et seqq): "When an antiproton annihilates with a proton, the predominant reaction products (98%) are pions. A recent survey of the literature [1984 reference] found that on the average there are 3.0 charged pions, 1.5 neutral pions, 0.05 charged kaons, 0.03 neutral kaons, and 0.02 prompt gamma rays. ... The neutral pions have a lifetime of only 90 attoseconds and almost immediately convert into two high-energy gamma rays." The charged pions are stopped by matter and deposit their energy (about 2/3rds of the total) locally as heat. The energy of the gamma rays is harder to capture. He continued: "In many applications of the use of antiprotons for energy storage and propulsion, consideration is being given to annihilation of the antiprotons with heavier nuclei than protons. Since a neutron has the same baryon number as a proton and a free neutron will spontaneously decay into a proton, a neutron can be considered as an 'excited state' of a proton. Thus, antiprotons, *will* annihilate with a neutron as well as a proton inside a heavy nucleus. Since the neutron has a neutral charge and charge must be conserved in the annihilation process, the reaction products from the annihilation of an antiproton in a heavy nucleus will produce different numbers of the various types of charged and uncharged pion and kaon particles. "Annihilation inside a heavy nucleus has the potential for increasing the efficiency of an antiproton annihilation propulsion system, since the neutral pions are absorbed in the nucleus instead of decaying into gamma rays. The annihilation reaction will 'heat up' the nucleus as well as cause spallation fission of charged nuclear fragments." ... "An ideal reaction would be one where the energy from the antiproton causes the nucleus to break up into doubly charged alpha particles..." Beryllium 9? Carbon 13? ... (We could accelerate alphas.) I hope these quotes will help put us all on the same page. If anyone has more information, please share it with us. [And after we convert antimatter energy to usable energy, we still have to convert the usable energy to exhaust kinetic energy (via some kind of engine/electrical generator powering an accelerator), so the "antimatter conversion efficiency" which is the overall efficiency used in the calculation of the starship properties reported in my 2/4/97 note will be even lower than 0.8.] Rex Finke From owner-starship-design Thu Feb 6 13:57 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2630" "Thu" "6" "February" "1997" "14:00:21" "-0800" "Steve VanDevender" "stevev@efn.org" nil "58" "starship-design: Lots O Stuff..." "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id NAA11837 for starship-design-outgoing; Thu, 6 Feb 1997 13:57:25 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id NAA11816 for ; Thu, 6 Feb 1997 13:57:23 -0800 (PST) Received: from tzadkiel (stevev@tzadkiel.efn.org [198.68.17.19]) by wakko.efn.org (8.8.3/8.7.3) with ESMTP id NAA25158; Thu, 6 Feb 1997 13:56:57 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id OAA17064; Thu, 6 Feb 1997 14:00:21 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702062200.OAA17064@tzadkiel> In-Reply-To: <199702061918.LAA17997@watt> References: <199702061918.LAA17997@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 2629 From: Steve VanDevender Sender: owner-starship-design To: wharton@physics.ucla.edu (Ken Wharton) Cc: starship-design@lists.uoregon.edu Subject: starship-design: Lots O Stuff... Date: Thu, 6 Feb 1997 14:00:21 -0800 Ken Wharton writes: > What IÕm thinking of here I've noticed, Ken, that whatever editor you're using doesn't insert normal ASCII apostrophes (') but instead some funny character that doesn't show up as an apostrophe on other displays. You might want to check your editor settings. > Adding this structural matter to > the equivalent amount of regular hydrogen matter that we need for fuel, > and you start to see why I was talking about a ÒminimumÓ > matter/antimatter ratio. Calculations that Timothy and I did some time ago indicated that to reach high relativistic speeds (above 0.8 c) with a ship that carries its own fuel, you need to convert over four times as much mass to energy as you have payload mass, and the 4:1 fuel:payload ratio is only if you use matter/antimatter for fuel. > On the flywheel subject, Timothy writes: > > >I've thought of a flywheel before, but never mentioned it because it > >seemed too unpractical: > > >- Its estimated weight was too high. > >- Containing/guiding a huge fly wheel that rotates with super high > > velocities seemed almost infeasable. > > >>So already, for a 200 meter radius flywheel, > >>we're talking about an energy storage of 10^10 J/Kg. We'd probably > >>need at least 10^14 J/Kg to make a decent spaceship. > > >Actually I think that 1E16 J/kg is the absolute minimum if you want to > >get into the direction of relativistic velocities. Since 1 kg of matter converts to 9E16 J, you're still not getting much energy density out of that relativistic flywheel. The flywheel could barely accelerate itself to relativistic speeds, so getting a good speed for the ship that carries it is even more unlikely. > I suppose a 20-kilometer flywheel is out of the question. Anyone know > how strong perfect diamond is, anyway? Or what about a two-stage engine; > a flywheel to get the ship moving fast enough where a ramjet-type drive > could take over. I know you guys have talked about ramjets, but IÕm not > sure what the current consensus is... Conventional ramjets have the problem that it doesn't take long before the drag of collecting interstellar hydrogen balances the thrust from fusing it; the figure tossed around is that this is likely to happen at about 0.1 c. There has been discussion about ramjet-type drives that don't capture and fuse interstellar gas, but instead accelerate it backwards to a higher ship-relative velocity, so that it would be possible to get higher speeds. The physics involved is quite exotic, though. At high relativistic speeds you also don't have much time to work on a quantity of gas. From owner-starship-design Thu Feb 6 14:05 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1222" "Thu" "6" "February" "1997" "14:08:52" "-0800" "Steve VanDevender" "stevev@efn.org" nil "23" "starship-design: Antimatter Annihilation Products" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id OAA15616 for starship-design-outgoing; Thu, 6 Feb 1997 14:05:58 -0800 (PST) Received: from wakko.efn.org (wakko.efn.org [198.68.17.6]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id OAA15555 for ; Thu, 6 Feb 1997 14:05:54 -0800 (PST) Received: from tzadkiel (stevev@tzadkiel.efn.org [198.68.17.19]) by wakko.efn.org (8.8.3/8.7.3) with ESMTP id OAA26095; Thu, 6 Feb 1997 14:05:28 -0800 (PST) Received: (from stevev@localhost) by tzadkiel (8.8.5/8.8.5) id OAA17086; Thu, 6 Feb 1997 14:08:52 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702062208.OAA17086@tzadkiel> In-Reply-To: <970206130058_-1643430695@emout19.mail.aol.com> References: <970206130058_-1643430695@emout19.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Steve VanDevender Content-Type: text Content-Length: 1221 From: Steve VanDevender Sender: owner-starship-design To: DotarSojat@aol.com Cc: starship-design@lists.uoregon.edu Subject: starship-design: Antimatter Annihilation Products Date: Thu, 6 Feb 1997 14:08:52 -0800 DotarSojat@aol.com writes: > [And after we convert antimatter energy to usable energy, we > still have to convert the usable energy to exhaust kinetic > energy (via some kind of engine/electrical generator powering an > accelerator), so the "antimatter conversion efficiency" which is > the overall efficiency used in the calculation of the starship > properties reported in my 2/4/97 note will be even lower than > 0.8.] If the result of a proton-antiproton or proton-antineutron annihilation is a lot of high-velocity particles, there's no point to trying to capture those and turn them into electrical energy to accelerate reaction mass. Either throw the reaction products directly out the back or play them into your reaction mass to heat it, then throw the hot reaction mass out the back. I have never understood Timothy's claim that lower exhaust velocities are more efficient. My own conclusion is that, physics permitting, converting mass directly into photons provides the highest payload velocity for a given amount of fuel mass. Lower exhaust velocities mean higher fuel-and-reaction-mass-to-payload ratios and expending more energy to accelerate a given payload plus the additional reaction mass. From owner-starship-design Thu Feb 6 14:51 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1943" "Thu" "6" "February" "1997" "16:49:15" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "36" "Re: starship-design: Anti-antimatter" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id OAA08931 for starship-design-outgoing; Thu, 6 Feb 1997 14:51:22 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id OAA08903 for ; Thu, 6 Feb 1997 14:51:19 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p80.gnt.com [204.49.68.81]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id QAA32534; Thu, 6 Feb 1997 16:50:35 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702062250.QAA32534@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 1942 From: "L. Clayton Parker" Sender: owner-starship-design To: "Steve VanDevender" Cc: Subject: Re: starship-design: Anti-antimatter Date: Thu, 6 Feb 1997 16:49:15 -0600 Steve, > On the other hand, if you can get the right evaporation rate and > maintain it, you also get the advantage that the evaporation products > will be statistically 1/2 matter and 1/2 antimatter (except for the > photons). So if it is possible to keep a quantum black hole just on the > edge of evaporation at a rate useful for propulsion and power > generation, you also get near-total matter-to-energy conversion by > recombining the evaporation products. I'm not sure that I am remembering this correctly, but I think the problem was that the evaporation rate of a black hole in a convenient size for a vehicle was so fast that it made it useless. This argument was originally advanced as "proof" that miniature black holes could not exist for long and therefore could not account for the missing matter in the universe. > My understanding is that evaporation rate is a function of the mass of > the black hole (and hence the gravity gradient near it), with the rate > going up asymptotically as the black hole mass approaches zero. You > also have the problem that radiation pressure from the evaporating black > hole will make it difficult to pump more mass into it to prevent runaway > evaporation, especially as you want more power. Unfortunately I don't > know the exact equation that relates evaporation rate to mass to know > whether it would be feasible to keep a quantum black hole in a stable > state and get a useful power output. I think that the above considerations are the reasons for Robert Forward suggesting spinning the black hole in the first place. A black hole spinning at relativistic speeds might just be massive enough to exceed the evaporation limit - and besides, this has got to make for some interesting physics, a spinning black hole would tend to drag space/time with it thereby warping the fabric of space/time. The possibilities for a writer of science fiction are endless here Lee Parker From owner-starship-design Thu Feb 6 16:02 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["975" "Thu" "6" "February" "1997" "18:00:06" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "22" "Re: starship-design: Antimatter Annihilation Products" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id QAA14403 for starship-design-outgoing; Thu, 6 Feb 1997 16:02:11 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id QAA14317 for ; Thu, 6 Feb 1997 16:02:04 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p80.gnt.com [204.49.68.81]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id SAA02578; Thu, 6 Feb 1997 18:01:29 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702070001.SAA02578@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 974 From: "L. Clayton Parker" Sender: owner-starship-design To: Cc: Subject: Re: starship-design: Antimatter Annihilation Products Date: Thu, 6 Feb 1997 18:00:06 -0600 Hi Rex, > [And after we convert antimatter energy to usable energy, we > still have to convert the usable energy to exhaust kinetic > energy (via some kind of engine/electrical generator powering an > accelerator), so the "antimatter conversion efficiency" which is > the overall efficiency used in the calculation of the starship > properties reported in my 2/4/97 note will be even lower than > 0.8.] Actually, this is the key to the whole problem. It is an engineering maxim that every conversion process entails waste and in order to increase efficiency you must reduce conversions. The ideal solution therefore would be an antimatter propulsion system that converted DIRECTLY to thrust. Perhaps something similar in concept to a stellarator in design. I find the possibility of a theory of quantum gravity somewhat more interesting, having such an understanding would possily eliminate the need for anything so crude as a reaction engine in the first place.... Lee From owner-starship-design Fri Feb 7 11:27 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1341" "Fri" "7" "February" "1997" "20:28" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "36" "starship-design: Re: Lots O Stuff..." "^From:" nil nil "2" nil "starship-design: Re: Lots O Stuff..." nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id LAB05320 for starship-design-outgoing; Fri, 7 Feb 1997 11:27:58 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id LAA05287 for ; Fri, 7 Feb 1997 11:27:54 -0800 (PST) Received: from hengelo02.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vsvyO-000DnHC; Fri, 7 Feb 97 20:28 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Content-Transfer-Encoding: binary Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="iso-8859-1" Content-Length: 1340 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: Lots O Stuff... Date: Fri, 7 Feb 97 20:28 MET Ken wrote: >>> Even if we're >>>assuming some pretty amazing technological advances, I find it hard to >>>imagine storing huge quantities of anti-matter on a ship. I don't know >>>if this has been discussed already, but I would guess there would be >>>some sort of theoretical minimum matter/antimatter ratio, just from >>>containment considerations. Anyone want to tackle that one? > >>A minimum ratio? Why would do you think that? > >Given you already have the antimatter, how much can you fit on a ship? >What IÕm thinking of here is a twofold problem: 1) we have to contain >the antimatter, and 2) we have to accelerate it with the rest of the >ship. Instead of magnetic containment, my thoughts would be to use electric confinement. That is charge the hydrogen and give the containment walls the same kind of charge. If there was no decharging, it would need little energy to maintain. >I like the >photon sphere idea, but my main concern is that for our purposes the >photon pressure would probably drive the sphere unstable. HavenÕt >looked at any numbers, though... A rough expression for the pressure could be : U/(4 pi R^3) So for U=1E24 Joule, and R=1000 metres, one still has pressures that are much too big. I'd never done a calculation, the idea of less than 100% reflectivity was enough to make it unfeasable. Tim From owner-starship-design Fri Feb 7 11:28 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1055" "Fri" "7" "February" "1997" "20:28" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "23" "starship-design: Re: Antimatter Annihilation Products" "^From:" nil nil "2" nil "starship-design: Re: Antimatter Annihilation Products" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id LAA05263 for starship-design-outgoing; Fri, 7 Feb 1997 11:27:47 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id LAA05208 for ; Fri, 7 Feb 1997 11:27:39 -0800 (PST) Received: from hengelo02.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vsvyR-000Dn1C; Fri, 7 Feb 97 20:28 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 1054 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: Antimatter Annihilation Products Date: Fri, 7 Feb 97 20:28 MET Steve wrote in a reply to Rex: >If the result of a proton-antiproton or proton-antineutron annihilation >is a lot of high-velocity particles, there's no point to trying to >capture those and turn them into electrical energy to accelerate >reaction mass. Either throw the reaction products directly out the back >or play them into your reaction mass to heat it, then throw the hot >reaction mass out the back. > >I have never understood Timothy's claim that lower exhaust velocities >are more efficient. My own conclusion is that, physics permitting, >converting mass directly into photons provides the highest payload >velocity for a given amount of fuel mass. Lower exhaust velocities mean >higher fuel-and-reaction-mass-to-payload ratios and expending more >energy to accelerate a given payload plus the additional reaction mass. The difference between your and my approach is that you minimize the amount of mass of the ship, while I minimize the amount of energy needed. (At least that is what I see in a letter from you of Sep 1st, 1995) Tim From owner-starship-design Fri Feb 7 13:07 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["239" "Fri" "7" "February" "1997" "15:10:00" "-0600" "Lora Flinn" "lflinn@ja2.jsc.nasa.gov" nil "10" "starship-design: Rapid Mars Transit" "^From:" nil nil "2" nil "starship-design: Rapid Mars Transit" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id NAA28003 for starship-design-outgoing; Fri, 7 Feb 1997 13:07:39 -0800 (PST) Received: from jsc-ems-gws06.jsc.nasa.gov (jsc-ems-gws06.jsc.nasa.gov [139.169.22.17]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id NAA27985 for ; Fri, 7 Feb 1997 13:07:36 -0800 (PST) Received: by jsc-ems-gws06.jsc.nasa.gov with SMTP (Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63) id <01BC1509.00A47C80@jsc-ems-gws06.jsc.nasa.gov>; Fri, 7 Feb 1997 15:10:06 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: X-Mailer: Microsoft Exchange Server Internet Mail Connector Version 4.0.994.63 Encoding: 9 TEXT Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "Flinn, Lora" Content-Type: text Content-Length: 238 From: "Flinn, Lora" Sender: owner-starship-design To: Post to starship design Subject: starship-design: Rapid Mars Transit Date: Fri, 7 Feb 1997 15:10:00 -0600 Hi, I joined the list about 3 months ago and have been following off and on. I noted you have been discussing propulsion. Has anyone discussed the Exhaust Modulated Plasma Propulsion system? Regards, Lora Flinn lflinn@ja2.jsc.nasa.gov From owner-starship-design Sat Feb 8 23:35 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4289" "Sat" "8" "February" "1997" "23:35:05" "-0800" "Ken Wharton" "wharton@physics.ucla.edu" nil "78" "starship-design: Re: Protons vs Electrons for Relativistic Electric Thrusters" "^From:" nil nil "2" nil "starship-design: Re: Protons vs Electrons for Relativistic Electric Thrusters" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id XAA02524 for starship-design-outgoing; Sat, 8 Feb 1997 23:35:44 -0800 (PST) Received: from physics.ucla.edu (physics.ucla.edu [128.97.23.13]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id XAA02505 for ; Sat, 8 Feb 1997 23:35:41 -0800 (PST) Received: from watt by physics.ucla.edu (SMI-8.6/SMI-SVR4) id XAA14987; Sat, 8 Feb 1997 23:35:05 -0800 Received: by watt (SMI-8.6/SMI-SVR4) id XAA06135; Sat, 8 Feb 1997 23:35:05 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702090735.XAA06135@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: wharton@physics.ucla.edu (Ken Wharton) Content-Type: text Content-Length: 4288 From: wharton@physics.ucla.edu (Ken Wharton) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: Protons vs Electrons for Relativistic Electric Thrusters Date: Sat, 8 Feb 1997 23:35:05 -0800 The way I see it, Accelerating Protons will ALWAYS be better than accelerating electrons if you want to keep charge neutrality. If you want to dump a proton for every electron, you need to carry the protons along with you, and that huge mass requirement negates the advantage of using lighter-mass propellant. Let me put it this way; We will have a given amount of Energy (E) to accelerate every proton/electron pair. We want to do it in a way that will give us the maximum momentum boost. Before I was (incorrectly) using the equation E^2 = (P c)^2 + (m c^2)^2, forgetting that the E was actually the Kinetic Energy PLUS the Rest Mass Energy. If we want E to only stand for Kinetic Energy, the equation becomes: E^2 + 2 E (m c^2) = (P c)^2 In the low energy limit (E << mc^2), this goes to the well-known E = p^2/(2m). In the high energy limit (E >> mc^2) it looks like a photon, with E = P c. Comparing the momentum given by this equation for protons and electrons, its a no-brainer. Both have the same first term, but the second term is much greater for protons: Protons are always better (or as least as good) as electrons for propellant. Now without charge neutrality requirements, electrons do have a redeeming value; you dont need to carry as much propellant mass on your ship. But since you have to carry the protons along anyway, you might as well use Them for propellant. Im not saying we should focus completely on protons, though. For very high energy/mass ratios, electrons are practically identical. Therefore, if there is some reaction that produces fast-enough electrons, it would probably be more efficient to use the electrons as propellant rather then catch the energy and transfer it to protons. An example here would be the Monopole-induced proton decay which makes 800 MeV positrons. This is probably on the border-line of where it would be worth it to switch to a proton. If you take the 800MeV and transfer it to a proton, you get nearly twice the momentum that you have in the 800MeV positron. So here it would depend on what sort of capture efficiencies you can manage; if your efficiency dropped below 50% it wouldnt be worth it to switch to a proton. (Actually, this case is a no-brainer. You no longer have to dump a proton for charge neutrality; its a positron so you only have to dump an electron. We would definitely want to keep the positron as propellant.) So the example I just gave made me realize that having positrons available makes my claim invalid: if you can dump positrons at ANY energy, then electrons keep their original advantage of being light; you dont need to lug extra protons along for charge neutrality. In fact, I would guess that for an antimatter engine, the optimal design would be to get all the energy from the anti-protons, but keep the positrons around to dump for charge neutrality, and use electrons as propellant. One additional way I can see still using electrons as propellant is if you are somehow able to keep charge neutrality by capturing electrons from interstellar space. Perhaps strong fields could deflect the protons (which would be beneficial in its own right) and capture enough electrons, thereby keeping charge neutrality without carrying along extra protons. I see lots of problems here, though... So assuming we are limited to keeping charge neutrality with protons, the question of propellant should be switched from proton/electron debate to a proton/alpha debate. The higher the mass particle, the higher the momentum we can get from a given energy, but now we are dealing with carrying more mass in the ship to use as propellant. I would guess we would want to keep the ship as light as possible, which would point to protons. But of course alphas would still the propellant of choice in a fusion engine; if we have them around anyway as a reaction product, we might as well use them as propellant! Wow, now Ive done it. I started out by saying that protons are the best propellant, but my exceptions to this rule (Fusion, Antimatter, Monopole-catalyst) seem to cover most of the possibilities! Okay; I still claim that protons are the best propellant for a rotating black hole engine. Any takers? Ken From owner-starship-design Sun Feb 9 08:01 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1770" "Sun" "9" "February" "1997" "10:03:38" "-0600" "Kevin Houston" "hous0042@maroon.tc.umn.edu" nil "40" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil "starship-design: my $0.02 (finally)" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id IAA15763 for starship-design-outgoing; Sun, 9 Feb 1997 08:01:08 -0800 (PST) Received: from mhub1.tc.umn.edu (0@mhub1.tc.umn.edu [128.101.131.51]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id IAA15750 for ; Sun, 9 Feb 1997 08:01:06 -0800 (PST) Received: from maroon.tc.umn.edu by mhub1.tc.umn.edu; Sun, 9 Feb 97 10:01:07 -0600 Received: from pub-27-a-193.dialup.umn.edu by maroon.tc.umn.edu; Sun, 9 Feb 97 10:01:06 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <32FDF516.541D@maroon.tc.umn.edu> Organization: URLy Bird Productions http://www.urly-bird.com/prices.html X-Mailer: Mozilla 3.0 (Win95; U) MIME-Version: 1.0 References: <199702060004.SAA19615@hurricane.gnt.net> Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "Kevin \"Tex\" Houston" Content-Type: text/plain; charset=us-ascii Content-Length: 1769 From: "Kevin \"Tex\" Houston" Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: Re: starship-design: my $0.02 (finally) Date: Sun, 09 Feb 1997 10:03:38 -0600 Hello everybody, First let me welcome all the new members. hurrah, we're growing again! I just have a few ideas about some of the propulsion systems that have been proposed. 1) If we do end up using a black hole for any kind of thrust or conversion, I'd suggest storing it in front of the ship where it could act as a sheild. In fact, just figuring out how to get the black hole up to light speed would mean that the ship could travel along for free, riding the gravity well. i.e. we stay behind the black hole, just close enough to be pulled in at the same rate as the black hole is running away toward Tau Ceti. 2) photon spheres: Assuming we solved the pressure problem, how do we put photons inside? wherever they went in would have to be less than 100% reflective, or we'd have to have a "door" that could be slammed shut in zero time. 3) flywheels: Instead of 1 large 200-meter flywheel, how about a lot of smaller one? I know better than to suggest 200 1-meter flywheels, but you get the idea. this should help us stay on course also (angular momentum) 4) wish list: tapping the zero-point energy. estimated to be 1E16 per cubic centimeter (not sure about number, maybe 1E18.... anyone know the real figrue) The problem with this one is thermodynamic. where do you find the "cold sink" (the place with little or no zero point energy) to generate the gradient. or, how do you convert zero point energy into matter and antimatter? Virtual particle drive anyone? 5) still think beaming beats them all :-p -- Kevin "Tex" Houston http://umn.edu/~hous0042/index.html Webmaster http://www.urly-bird.com/index.html "Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods." A. Einstein From owner-starship-design Sun Feb 9 12:33 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1919" "Sun" "9" "February" "1997" "14:31:23" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "42" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil "starship-design: my $0.02 (finally)" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id MAA11447 for starship-design-outgoing; Sun, 9 Feb 1997 12:33:55 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id MAA11426 for ; Sun, 9 Feb 1997 12:33:52 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p109.gnt.com [204.49.68.110]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id OAA04032; Sun, 9 Feb 1997 14:33:50 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702092033.OAA04032@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 1918 From: "L. Clayton Parker" Sender: owner-starship-design To: "Kevin \"Tex\" Houston" Cc: Subject: Re: starship-design: my $0.02 (finally) Date: Sun, 9 Feb 1997 14:31:23 -0600 Hi Kevin, In response to your post, I have a few comments and observations... > 1) If we do end up using a black hole for any kind of thrust or > conversion, I'd suggest storing it in front of the ship where it could > act as a sheild. In fact, just figuring out how to get the black hole > up to light speed would mean that the ship could travel along for free, > riding the gravity well. i.e. we stay behind the black hole, just close > enough to be pulled in at the same rate as the black hole is running > away toward Tau Ceti. Any energy you expend accelerating a black hole will more than make up for any "free ride" you might hope to get riding on a black hole's coat tails so to speak. No, I think the best use we will get out of a black hole is to generate either thrust directly, or energy to power a thrust generating system. > 3) flywheels: Instead of 1 large 200-meter flywheel, how about a lot of > smaller one? > I know better than to suggest 200 1-meter flywheels, but you get the > idea. this should help us stay on course also (angular momentum) I'm not real confident of this flywheel idea, but I still think that the best flywheel you can hope to achieve is a spinning black hole. Especially since the event horizon would only be measured in nanometers! > > 4) wish list: tapping the zero-point energy. estimated to be 1E16 per > cubic centimeter (not sure about number, maybe 1E18.... anyone know the > real figrue) The problem with this one is thermodynamic. where do you > find the "cold sink" (the place with little or no zero point energy) to > generate the gradient. or, how do you convert zero point energy into > matter and antimatter? Virtual particle drive anyone? Ahh, now this idea I like. I have never really seen a good explanation of zero point energy, but what little I know sounds promising. (There is a rumor that even NASA is looking into this.) > Lee Parker From owner-starship-design Mon Feb 10 07:28 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3831" "Mon" "10" "February" "1997" "16:29" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "92" "starship-design: Re: Protons vs Electrons for Relativistic Electric Thrusters" "^From:" nil nil "2" nil "starship-design: Re: Protons vs Electrons for Relativistic Electric Thrusters" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id HAA14074 for starship-design-outgoing; Mon, 10 Feb 1997 07:28:27 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id HAA14052 for ; Mon, 10 Feb 1997 07:28:24 -0800 (PST) Received: from hengelo21.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vtxfW-000DliC; Mon, 10 Feb 97 16:29 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 3830 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: Protons vs Electrons for Relativistic Electric Thrusters Date: Mon, 10 Feb 97 16:29 MET Rex writes at 2/4: >So, I boil down these points to a single question: > >Q: What is the optimum (minimum-antimatter) performance of an >antimatter-powered starship with its exhaust composed of >accelerated PROTONS (with electrons dumped for charge >neutralization), in comparison with that of one with its exhaust >composed of accelerated ELECTRONS (with protons dumped at >negligible velocity for charge neutralization)? Still other ions may work as well depending on optimal exhaust velocity and "energy" of the accelerator. I compared the electron-dumping with no-dumping numbers and as expected the values differ very little. >ACCELERATED ELECTRONS > >The calculational procedure described in my 4/4/96 note has been >expanded to include dumping of mass at negligible velocity to >bring about charge neutralization (as well as to include >conversion efficiencies less than 1.0). > >The comparable results of the calculations for accelerated >ELECTRONS (with dumping of one proton at negligible velocity for >each electron for charge neutralization: "DUMP = 1836.") are as >follows with the same nomenclature as above: > >Antimatter conversion efficiency = 1.0 > > Uend Vend optVexh optUexh maxeff minMam/Mbo minMam/Mi Mi/Mbo > 0.2 0.196 1.000 0.184E+06 0.090 0.110 0.0900 1.22 > 0.5 0.447 1.000 0.478E+06 0.191 0.309 0.1908 1.62 > 1.0 0.707 1.000 0.931E+06 0.293 0.708 0.2927 2.42 > 2.0 0.894 1.000 0.163E+07 0.382 1.620 0.3817 4.24 > 3.0 0.949 1.000 0.217E+07 0.418 2.584 0.4186 6.17 > 4.0 0.970 1.000 0.257E+07 0.438 3.565 0.4382 8.14 > 5.0 0.981 1.000 0.289E+07 0.450 4.554 0.4503 10.11 I'm amazed that dumping so much mass can still give efficiencies over 25%. >For electrons, there is no maximum efficiency as a function of >Uexh for finite values of Uexh; the efficiency increases >monotonically as Uexh is increased. The maximum is replaced by an >asymptote at infinite Uexh. The value of "maxeff" tabulated above >is that efficiency when the increase in efficiency is 0.001 >percent for an increase in Uexh of 1 percent; the tabulated value >is within about 0.1 percent of the asymptote. I assume that the meaning of optUexh has the same origin? Since you propose that infinite exhaust speeds are the best, isn't Steve right saying that you could better use photons as propulsion? >COMPARISON >For the electrons' "optUexh" of 0.289E+07 ltyr/yr for the Uend of >5.0 ltyr/yr, the ELECTRON accelerator energy is about 1,480 GeV. I've a book from 1991 that says: "Several accelerators now exist capable of producing electron and positron beams of energies up to 50 GeV (and higher in the future)...." [I assume the accelerators aren't linear ones!] Also Ken's note about 60 GeV/m over 1 mm does seem far away. >The thrust T is given by the relation > T = iV sqrt[1 + (2mc^2/eV)] * (1 kgf/2,940 Mw) , > >where mc^2 is as above, i is current in amps, V is volts and >eV is the accelerator energy in MeV; 1 amp*volt is 1 w. > >The values extracted from the Uend = 5.0 lines in the tables >above or calculated from the above relations are as follows: > > Property Proton exhaust Electron exhaust > Mass ratio 15.11 10.11 > Maxeff 0.610 0.450 > MinMam/Mbo 3.357 4.554 > MinMam/Mi 0.2222 0.4503 > Accelerator Energy (Mev) 850. 1,480,000. > Thrust/amp (kgf) 0.520 500. > >"You pays your money and you takes your choice." 1000 times lower currents, 1741 times lower voltages and higher efficiency seem strong enough reasons to me to choose for proton exhaust. The 50% bigger mass ratio is almost neglectable compared to the advantages. Timothy From owner-starship-design Thu Feb 13 19:40 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1106" "Thu" "13" "February" "1997" "22:37:30" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "29" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil "starship-design: my $0.02 (finally)" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id TAA23399 for starship-design-outgoing; Thu, 13 Feb 1997 19:38:30 -0800 (PST) Received: from emout20.mail.aol.com (emout20.mx.aol.com [198.81.11.46]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id TAA23388 for ; Thu, 13 Feb 1997 19:38:28 -0800 (PST) Received: (from root@localhost) by emout20.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id WAA15322 for starship-design@lists.uoregon.edu; Thu, 13 Feb 1997 22:37:30 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970213223730_-1408332075@emout20.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 1105 From: KellySt@aol.com Sender: owner-starship-design cc: starship-design@lists.uoregon.edu Subject: Re: starship-design: my $0.02 (finally) Date: Thu, 13 Feb 1997 22:37:30 -0500 (EST) In a message dated 2/9/97 3:34:11 PM, lparker@cacaphony.net (L. Clayton Parker) wrote: >> 4) wish list: tapping the zero-point energy. estimated to be 1E16 per >> cubic centimeter (not sure about number, maybe 1E18.... anyone know the >> real figrue) The problem with this one is thermodynamic. where do you >> find the "cold sink" (the place with little or no zero point energy) to >> generate the gradient. or, how do you convert zero point energy into >> matter and antimatter? Virtual particle drive anyone? > >Ahh, now this idea I like. I have never really seen a good explanation of >zero point energy, but what little I know sounds promising. (There is a >rumor that even NASA is looking into this.) >> > >Lee Parker Hi Kev, long time etc.. Yes, recent issues of Ad Astra and Final Frounteir covered the NASA group looking into exotic theories for star travel. The Ad Astra issue also had some detail on theoretical ways to generate electricity from the Zero-point energy potential between two plates and the universe beyond them. No idea if it would work or be practical thou. Kelly From owner-starship-design Fri Feb 14 08:45 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3039" "Fri" "14" "February" "1997" "10:38:56" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "58" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil "starship-design: my $0.02 (finally)" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id IAA17702 for starship-design-outgoing; Fri, 14 Feb 1997 08:43:29 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id IAA17668 for ; Fri, 14 Feb 1997 08:43:26 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p52.gnt.com [204.49.68.53]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id KAA25645; Fri, 14 Feb 1997 10:41:04 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702141641.KAA25645@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 3038 From: "L. Clayton Parker" Sender: owner-starship-design To: Cc: Subject: Re: starship-design: my $0.02 (finally) Date: Fri, 14 Feb 1997 10:38:56 -0600 Hi Kelly, I spent a few minutes talking to some physicists about this the other day (I'm an engineer). They managed to explain to me what it was and the difficulties inherent in tapping it. They all agreed that it would be a marvelous source of energy if it could be tapped, but as you pointed out, finding something colder (less excited) than 3 degrees is not going to be easy and without a gradient there would be no "spontaneous" emission of energy. Then there is still the problem of converting it into usable form. I still think there has to be another source of external energy that can be tapped, harnessed or otherwise utilized for propulsion. The problem with all of the known methods of propulsion is that they require enormous amounts of energy to accelerate a starship to near light speed. In most cases this amount is so large that there is no reasonable chance that we can carry sufficient fuel or reaction mass to provide it directly. Since most of the discussion so far has revolved around specific technologies for GETTING THERE, I thought some consideration of general engineering design philosophies might be in order. Here are just a few of the key things to consider: 1) Minimum acceleration of 10 m/sec - Anything less would take too long to get there and expose the crew to a host of side effects. This simplifies design of the ship and eliminates the need for spinning habitat rings etc. More would be better, who knows what might come up. 2) On board reaction mass must be either sufficient for the ROUNDTRIP or easily replaceable with on board resources. Don't forget a safety margin here also. 3) Engineering of the all systems (command, control, communications, environmental and propulsion) should be sufficiently simple to permit repairs and maintenance by the crew during the mission, or self repair ability should be built in (preferably both). 4) The propulsion system must be rugged enough to withstand continuous operation without major overhaul or replacement for a period equal to at least two and a half to three times the duration of the voyage. (Note that this almost automatically excludes most current technologies.) 5) Manned exploratory missions must be roundtrip, colonization missions can be considered one way for purposes of design. But the mass of a colony ship will be corespondingly greater requiring an even more robust design. These are just some of the things that need to be considered prior to selecting a propulsion technology or method. Some methods are just plain impractical because they would never last through the trip, others fail to meet additional requirements. If I have duplicated previous conversations, please excuse this but I think it is more important at this date to define requirements before examining the technologies current or hypothesized that might fulfill them. If anybody has any additional thoughts or comments regarding things they think may be important in defining engineering requirements please feel free to post them. L. Parker From owner-starship-design Fri Feb 14 19:55 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["909" "Fri" "14" "February" "1997" "21:55:08" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "21" "starship-design: On the use of vacuum for interstellar travel" "^From:" nil nil "2" nil "starship-design: On the use of vacuum for interstellar travel" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id TAA21193 for starship-design-outgoing; Fri, 14 Feb 1997 19:55:55 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id TAA21179 for ; Fri, 14 Feb 1997 19:55:52 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p73.gnt.com [204.49.68.74]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id VAA21714 for ; Fri, 14 Feb 1997 21:55:40 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702150355.VAA21714@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 908 From: "L. Clayton Parker" Sender: owner-starship-design To: Subject: starship-design: On the use of vacuum for interstellar travel Date: Fri, 14 Feb 1997 21:55:08 -0600 This abstract is in a NASA database. Can anyone explain what it is talking about? It seems to be proposing a method of tapping ZPF without a gradient... TITLE: On the use of vacuum for interstellar travel. II Abstract: It is suggested that it may be possible to arrange the production of strange matter in such a way as to form an analytically solvable system which does not obey the second law of thermodynamics. It is further speculated that the coherence of vacuum can be broken with resonances using gauge particles, and that effects can be tunnelled from the quantum level before the coherence of the vacuum is reestablished. It is recommended that resonance tunneling be investigated as a possible mechanism for quark and gluon materialization to both bound states and the related vacuum state, in the form of solitons. Cuimhnich air na daoine o'n d'thainig thu. Le gach deagh-dhurachd, L. Parker From owner-starship-design Sat Feb 15 09:06 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2273" "Sat" "15" "February" "1997" "18:07" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "56" "starship-design: Re: On the use of vacuum for interstellar travel" "^From:" nil nil "2" nil "starship-design: Re: On the use of vacuum for interstellar travel" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id JAA27519 for starship-design-outgoing; Sat, 15 Feb 1997 09:06:42 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id JAA27499 for ; Sat, 15 Feb 1997 09:06:39 -0800 (PST) Received: from hengelo28.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vvnaZ-000DnoC; Sat, 15 Feb 97 18:07 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 2272 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: On the use of vacuum for interstellar travel Date: Sat, 15 Feb 97 18:07 MET Timothy replies: >This abstract is in a NASA database. Can anyone explain what it is talking >about? It seems to be proposing a method of tapping ZPF without a >gradient... I'll first give a few keywords, then try to translate it. Gauge particle : particle that exchange forces (eg. photon, gluon, graviton) Vacuum : absence of matter and positive energy. Analytically solvable system : theoretical possibility Second law of thermodynamics : A machine cannot give forth more energy than it absorbs. Coherent : smooth/equal, absence of disturbances. Resonance : wave (transfer of energy) Tunneling : quantum-mechanical possibility to get something on the other side of a barrier, while it has less energy than necessary according to classical-mechanics. Soliton : wave-state that does not diminish over time (matter could be a wave-state) >TITLE: On the use of vacuum for interstellar travel. II >Abstract: > >It is suggested that it may be possible to arrange the production of >strange matter in such a way as to form an analytically solvable system >which does not obey the second law of thermodynamics. Some people suggest it is possible that at least in theory energy can be produced from "nothing". >It is further >speculated that the coherence of vacuum can be broken with resonances using >gauge particles, It is further speculated that this "nothing" can be exited by sending photons, gluons, or gravitons through it. >and that effects can be tunnelled from the quantum level >before the coherence of the vacuum is reestablished. The particles created during this exited state should then be extracted before they are re-absorbed and before the exitement is gone. >It is recommended that >resonance tunneling be investigated as a possible mechanism for quark and >gluon materialization to both bound states and the related vacuum state, in >the form of solitons. Some people should study this possibility to extract something from "nothing" Timothy From owner-starship-design Sat Feb 15 12:08 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["875" "Sat" "15" "February" "1997" "14:08:23" "-0600" "Kevin C. Houston" "hous0042@maroon.tc.umn.edu" nil "28" "Re: starship-design: Re: On the use of vacuum for interstellar travel" "^From:" nil nil "2" nil "starship-design: Re: On the use of vacuum for interstellar travel" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id MAA06767 for starship-design-outgoing; Sat, 15 Feb 1997 12:08:32 -0800 (PST) Received: from mhub1.tc.umn.edu (0@mhub1.tc.umn.edu [128.101.131.51]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id MAA06758 for ; Sat, 15 Feb 1997 12:08:29 -0800 (PST) Received: from maroon.tc.umn.edu by mhub1.tc.umn.edu; Sat, 15 Feb 97 14:08:24 -0600 Received: by maroon.tc.umn.edu; Sat, 15 Feb 97 14:08:24 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f In-Reply-To: Message-ID: MIME-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Kevin C Houston Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Length: 874 From: Kevin C Houston Sender: owner-starship-design To: Timothy van der Linden cc: starship-design@lists.uoregon.edu Subject: Re: starship-design: Re: On the use of vacuum for interstellar travel Date: Sat, 15 Feb 1997 14:08:23 -0600 (CST) On Sat, 15 Feb 1997, Timothy van der Linden wrote: > Timothy replies: > > I'll first give a few keywords, then try to translate it. > > Gauge particle : particle that exchange forces (eg. photon, > gluon, graviton) > Vacuum : absence of matter and positive energy. > Analytically solvable system : theoretical possibility > Second law of thermodynamics : A machine cannot give forth more energy than > it absorbs. Um, that's the first law, the second law states that you cannot take a bunch of low-grade thermal energy, and turn it into a small amount of high grade thermal energy without wasting some of it to the environment, and importing some work. i.e. entropy. > > Timothy > other than that little bone, I agreed with what you wrote.. Kevin "tex" Houston From owner-starship-design Sun Feb 16 13:00 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["412" "Sun" "16" "February" "1997" "22:01" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "13" "starship-design: Re: On the use of vacuum for interstellar travel" "^From:" nil nil "2" nil "starship-design: Re: On the use of vacuum for interstellar travel" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id NAA03020 for starship-design-outgoing; Sun, 16 Feb 1997 13:00:08 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id NAA02991 for ; Sun, 16 Feb 1997 13:00:04 -0800 (PST) Received: from hengelo22.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0vwDi3-000DqtC; Sun, 16 Feb 97 22:01 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 411 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: On the use of vacuum for interstellar travel Date: Sun, 16 Feb 97 22:01 MET Timothy replies to Kevin: >Um, that's the first law, the second law states that you cannot take a >bunch of low-grade thermal energy, and turn it into a small amount of >high grade thermal energy without wasting some of it to the environment, >and importing some work. i.e. entropy. You're right, the second law is the law of increase of entropy, I was confused by an other statement in my book. Thanks From owner-starship-design Sun Feb 16 19:02 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4755" "Sun" "16" "February" "1997" "22:01:35" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "102" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id TAA24126 for starship-design-outgoing; Sun, 16 Feb 1997 19:02:10 -0800 (PST) Received: from emout19.mail.aol.com (emout19.mx.aol.com [198.81.11.45]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id TAA24116 for ; Sun, 16 Feb 1997 19:02:08 -0800 (PST) Received: (from root@localhost) by emout19.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id WAA15083; Sun, 16 Feb 1997 22:01:35 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970216220128_-1441598204@emout19.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 4754 From: KellySt@aol.com Sender: owner-starship-design To: lparker@cacaphony.net, KellySt@aol.com cc: starship-design@lists.uoregon.edu Subject: Re: starship-design: my $0.02 (finally) Date: Sun, 16 Feb 1997 22:01:35 -0500 (EST) In a message dated 2/14/97 1:41:59 PM, lparker@cacaphony.net (L. Clayton Parker) wrote: >Hi Kelly, hi, sorry about the delay. To much overtime. >I spent a few minutes talking to some physicists about this the other day >(I'm an engineer). They managed to explain to me what it was and the >difficulties inherent in tapping it. They all agreed that it would be a >marvelous source of energy if it could be tapped, but as you pointed out, >finding something colder (less excited) than 3 degrees is not going to be >easy and without a gradient there would be no "spontaneous" emission of >energy. Then there is still the problem of converting it into usable form. This contradicts the articals and explanations I've heard. The effect taps the quantum action of spacetime in a vacume. Some ways of taping it use voltage beteen charged plates to alter the probabilities of spontaneous emissions (and the speed of light). The 'presure' on the plates between the outside and the inside of the mechanism is tapable to produce energy. Least thats what the semi incomprehensiple explanation said was possible. Could be a fantasic source of high density power (on the order of nuclear densities according to Forward), or it could be totally useless. >I still think there has to be another source of external energy that can be >tapped, harnessed or otherwise utilized for propulsion. The problem with >all of the known methods of propulsion is that they require enormous >amounts of energy to accelerate a starship to near light speed. In most >cases this amount is so large that there is no reasonable chance that we >can carry sufficient fuel or reaction mass to provide it directly. > >Since most of the discussion so far has revolved around specific >technologies for GETTING THERE, I thought some consideration of general >engineering design philosophies might be in order. Here are just a few of >the key things to consider: > >1) Minimum acceleration of 10 m/sec - Anything less would take too long to >get there and expose the crew to a host of side effects. This simplifies >design of the ship and eliminates the need for spinning habitat rings etc. >More would be better, who knows what might come up. More would be hard on the crew unless your talking a field effect drive or something. You'ld need the hab centrafuge eiather way. The ship does intend to park in the star system for couple years after all. Besides other then packing effocencies it's not a big problem. >2) On board reaction mass must be either sufficient for the ROUNDTRIP or >easily replaceable with on board resources. Don't forget a safety margin >here also. Agreed. >3) Engineering of the all systems (command, control, communications, >environmental and propulsion) should be sufficiently simple to permit >repairs and maintenance by the crew during the mission, or self repair >ability should be built in (preferably both). Agreed >4) The propulsion system must be rugged enough to withstand continuous >operation without major overhaul or replacement for a period equal to at >least two and a half to three times the duration of the voyage. (Note that >this almost automatically excludes most current technologies.) This could be a problem. We're pushing thrust to weight ratios pretty hard, and need the drives to run for 20-30 years as it is. Thats pretty much the likly service life of the ship. We may need to rely on relyability and repairability (thou that might be a trick during drive operations.). >5) Manned exploratory missions must be roundtrip, colonization missions can >be considered one way for purposes of design. But the mass of a colony >ship will be corespondingly greater requiring an even more robust design. Agreed. In anyevent, we would be able to think of a real reason to put colony somewhere until we new a lot about it anyway. So colony missions, if attempted, would be decades after the exploration flights. By then our tech assuptions would be completly obsolete. >These are just some of the things that need to be considered prior to >selecting a propulsion technology or method. Some methods are just plain >impractical because they would never last through the trip, others fail to >meet additional requirements. If I have duplicated previous conversations, >please excuse this but I think it is more important at this date to define >requirements before examining the technologies current or hypothesized that >might fulfill them. If anybody has any additional thoughts or comments >regarding things they think may be important in defining engineering >requirements please feel free to post them. > >L. Parker We did go around a bit on these issues before. I think their was general agreement. Kelly From owner-starship-design Mon Feb 17 10:39 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["7240" "Mon" "17" "February" "1997" "19:35:59" "+0100" "Zenon Kulpa" "zkulpa@zmit1.ippt.gov.pl" nil "158" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id KAA10623 for starship-design-outgoing; Mon, 17 Feb 1997 10:39:06 -0800 (PST) Received: from zmit1.ippt.gov.pl (zmit1.ippt.gov.pl [148.81.53.40]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id KAA10470 for ; Mon, 17 Feb 1997 10:38:45 -0800 (PST) Received: by zmit1.ippt.gov.pl (4.1/SMI-4.1) id AA22837; Mon, 17 Feb 97 19:35:59 +0100 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <9702171835.AA22837@zmit1.ippt.gov.pl> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) Content-Type: text Content-Length: 7239 From: zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Cc: zkulpa@ippt.gov.pl Subject: Re: starship-design: my $0.02 (finally) Date: Mon, 17 Feb 97 19:35:59 +0100 > From: "L. Clayton Parker" > > Since most of the discussion so far has revolved around specific > technologies for GETTING THERE, I thought some consideration of general > engineering design philosophies might be in order. Here are just a few of > the key things to consider: > > 1) Minimum acceleration of 10 m/sec - Anything less would take too long to > get there and expose the crew to a host of side effects. This simplifies > design of the ship and eliminates the need for spinning habitat rings etc. > This seems a reasonable requirement. Though, at the target you may still require something like spinning habitat to provide (pseudo)gravity for stay in the system. Unless you plan to build from the start a base on some massive enough planet. > More would be better, who knows what might come up. > Not unless you plan some hibernation or "unburdening" environment for most of the crew. > 2) On board reaction mass must be either sufficient for the ROUNDTRIP or > easily replaceable with on board resources. Don't forget a safety margin > here also. > Concerning ROUNDTRIP - I disagree. I am appending my letter from some time ago addressing this issue in case you heve missed it. WARNING: I do not want to start again my standard quarrel with Kelly here. Just to state my view... > 3) Engineering of the all systems (command, control, communications, > environmental and propulsion) should be sufficiently simple to permit > repairs and maintenance by the crew during the mission, or self repair > ability should be built in (preferably both). > Agreed. However, I think that will be possoble only with considerable advances in AI and nanotechnology. > 4) The propulsion system must be rugged enough to withstand continuous > operation without major overhaul or replacement for a period equal to at > least two and a half to three times the duration of the voyage. (Note that > this almost automatically excludes most current technologies.) > Agreed. Note also that the roundtrip requirement would DOUBLE (at least!) the problem here. > 5) Manned exploratory missions must be roundtrip, colonization missions can > be considered one way for purposes of design. But the mass of a colony > ship will be corespondingly greater requiring an even more robust design. > See below: One-way has lesser requirements than both roundtrip and colonization, and differs from colonization mission in ONLY ONE aspect: reproduction is switched off (so to speak). > These are just some of the things that need to be considered prior to > selecting a propulsion technology or method. Some methods are just plain > impractical because they would never last through the trip, others fail to > meet additional requirements. If I have duplicated previous conversations, > please excuse this but I think it is more important at this date to define > requirements before examining the technologies current or hypothesized that > might fulfill them. If anybody has any additional thoughts or comments > regarding things they think may be important in defining engineering > requirements please feel free to post them. > I think that the best way of investigating different options is my old idea of formulating a "design space": a structured list of possible options with crosslinks describing interdependencies of choices in different slots in the structure. See archives of the list (or ask me to forward some relevant messages). Here goes a copy of my letter on mission types: > From zkulpa@ippt.gov.pl Wed Dec 4 22:04:02 1996 > To: starship-design@lists.uoregon.edu > Subject: Re: starship-design: Mission structure > > There was some discussion on the mission types rather long ago > (mostly, my quarrel with Kelly on one-way missions :-). > > I want to sum up briefly my opinion in this matter: > > - Note that the prerequsite for starting the interstellar > mission is prior start of the COLONIZATION OF THE SOLAR SYSTEM - > i.e., at least establishment of permanent, ALMOST self-sustaining > bases on the Moon and Mars, possibly some small space bases/colonies, > routine interplanetary manned trips, at least, say, within > the orbit of Jupiter, asteroid mining facilities and factories. > Without this, construction in space of the huge starship, > capable of sustaining significant crew > without constant resupply for tens of years, as well as > the solar-system-wide supporting propulsion system > (huge orbiting masers/lasers, etc.) is simply not possible. > Hence, the technology for building significantly large > self-sustaining manned bases in space will be available > at the time, that is, building of the space colony or > long-duration self-sustaining base in another star system > will be quite feasible and much easier than we may think today. > > - However, building somewhere. light-years away, a really > independent colony starting new permanent human habitat there > seems still a huge undertaking for me. I think, to establish > something of the sort will require a whole flotilla of starships > and tens of years of construction of all necessary infrastructure, > possibly including terraforming of some planet. > > - Therefore, a much more realistic solution for me is > establishing a LONG-DURATION OUTPOST BASE. > That is, it calls for a so-called ONE-WAY mission. > What is a difference, from the point of view of the crew, > between the one-way mission and the colonization mission? > There is a SINGLE difference: there is NO PROCRERATION > on the one-way mission. Only this, nothing more! > Hence, from technical point of view, the one-way mission > is simpler and requires much smaller resources, becoming > feasible in the "early colonization of the solar system" > conditions outlined above. Technically, the one-way mission: > -- can have much smaller crew (as the questions of genetic diversity > and all sociotechnical specialization variety are absent); > -- requires no provisions for rearing and educating children, > which include additional crew, much more elaborate > environmental control, education facilities, much more > storage (or on-board industry) for all things for > children and young; > -- the outpost does not have to be indefinitely sustainable - > it would suffice to stay operational till the longest > possible natural life of the crew, which means some 50+ years > only, certainly less than 100. > > - The outpost may be later transformed into a permanent colony, > if the conditions in the target system show to be good enough > and the technological advances within the solar system during > the time of the trip and initial exploration phase (this means > some 20 years of Earth time...) will allow for sending follow-up > starships with enough resources to establish a colony. > > So, I think that the course of events will be like this: > - robotic "pathfinder" probe (testing the starship technology > and preliminary assessing of the conditions for subsequent stages); > - one-way outpost construction mission; > - possible follow-up colonization expeditions. > > -- Zenon > Regards, -- Zenon From owner-starship-design Mon Feb 17 14:46 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5380" "Mon" "17" "February" "1997" "16:44:55" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "131" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil "starship-design: my $0.02 (finally)" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id OAA21586 for starship-design-outgoing; Mon, 17 Feb 1997 14:46:15 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id OAA21532 for ; Mon, 17 Feb 1997 14:46:10 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p102.gnt.com [204.49.68.103]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id QAA13199; Mon, 17 Feb 1997 16:45:41 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702172245.QAA13199@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 5379 From: "L. Clayton Parker" Sender: owner-starship-design To: "Zenon Kulpa" Cc: Subject: Re: starship-design: my $0.02 (finally) Date: Mon, 17 Feb 1997 16:44:55 -0600 Zenon, > This seems a reasonable requirement. > Though, at the target you may still require something like > spinning habitat to provide (pseudo)gravity for stay in the system. > Unless you plan to build from the start a base > on some massive enough planet. > > > More would be better, who knows what might come up. > > > Not unless you plan some hibernation or "unburdening" environment > for most of the crew. I was simply allowing for emergency needs, not expecting that they would sustain high-g accelerations for any considerable length of time. For instance, there have been several proposals for gravity assisted manuevers during the initial acceleration (or deceleration) phase in which having the availability of additional thrust for a short length of time would substantially alter the final velocity. > > 2) On board reaction mass must be either sufficient for the ROUNDTRIP or > > easily replaceable with on board resources. Don't forget a safety margin > > here also. > > > Concerning ROUNDTRIP - I disagree. > I am appending my letter from some time ago addressing this issue > in case you heve missed it. > WARNING: I do not want to start again my standard quarrel > with Kelly here. Just to state my view... > You and Kelly have a standard quarrel? How nice! > > > 3) Engineering of the all systems (command, control, communications, > > environmental and propulsion) should be sufficiently simple to permit > > repairs and maintenance by the crew during the mission, or self repair > > ability should be built in (preferably both). > > > Agreed. > However, I think that will be possoble only with considerable > advances in AI and nanotechnology. Ummm, some of this is even simpler than that. For example, do you honestly think we can send a starship out with off the shelf light bulbs with only a 750 hour lifespan? > > > 4) The propulsion system must be rugged enough to withstand continuous > > operation without major overhaul or replacement for a period equal to at > > least two and a half to three times the duration of the voyage. (Note that > > this almost automatically excludes most current technologies.) > > > Agreed. > Note also that the roundtrip requirement would DOUBLE (at least!) > the problem here. That is why I chose two and a half to three times the duration of the VOYAGE, a LARGE safety margin. > > 5) Manned exploratory missions must be roundtrip, colonization missions can > > be considered one way for purposes of design. But the mass of a colony > > ship will be corespondingly greater requiring an even more robust design. > > > See below: One-way has lesser requirements than > both roundtrip and colonization, > and differs from colonization mission in ONLY ONE aspect: > reproduction is switched off (so to speak). I KNOW this point has been discussed before, but I simply think it is impractical (not to mention immoral and unethical) to send our brightest people out on what amounts to a suicide mission...now for robot probes this is more than adequate. I would expect that ANY system we send a manned exploration team to would already have been visited by at least one robot probe to determine if it was even worth a second look. > I think that the best way of investigating different options > is my old idea of formulating a "design space": a structured > list of possible options with crosslinks describing > interdependencies of choices in different slots in the structure. > See archives of the list (or ask me to forward some relevant > messages). I agree with the concept of design space, it is substantially the same thing on a broader scale than what I had been saying. I have seen most of the discussions, I have been following this list for several years even though I am not a frequent contributor. I deleted the remainder for brevity... I do not necessarily disagree with what you say with the following provisos: 1) One way implies NO RETURN. Establishment of a long term base with EVENTUAL return, resupply or additional personnel is not the same thing. 2) Send robotic Pathfinders FIRST. No "one way" manned missions to systems that do not have a hope of eventual settlement or offer some other overpowering reason to establish a permanent manned presence. 3) It makes more sense to establish our base(s) in the new system in space first, then on the planetary bodies. We spent four and half million years trying to get off of this planet, what's your hurry? In other words, the industry that you assume to be in place in our outer solar system would in reality be the first settlers of the new system. Given human behavior, I suspect that it makes more sense that way anyway. 4) Under these conditions, procreation within the limits of the life support system is not only possible, it might even be desirable. You need to look at this from a "human" perspective as well as scientific and engineering. So to review, a "one way" mission to set up an initial outpost either in orbit or upon one or more satellites (not planets) with the eventual promise of additional personnel and resupply as well as a chance of rotation back to Sol, with the purpose of eventually settling the new system and its planet(s) is reasonable. A mission that is "one way" in the sense that there will be no hope of return, resupply, relief, etc., is impractical and indefensible. Lee Parker From owner-starship-design Tue Feb 18 16:57 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["174" "Tue" "18" "February" "1997" "18:53:16" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "9" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id QAA25829 for starship-design-outgoing; Tue, 18 Feb 1997 16:57:18 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id QAA25810 for ; Tue, 18 Feb 1997 16:57:14 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p44.gnt.com [204.49.68.45]) by hurricane.gnt.net (8.7.5/8.7.3) with ESMTP id SAA06028; Tue, 18 Feb 1997 18:54:36 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199702190054.SAA06028@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 173 From: "L. Clayton Parker" Sender: owner-starship-design To: Cc: Subject: Re: starship-design: my $0.02 (finally) Date: Tue, 18 Feb 1997 18:53:16 -0600 I nominate Kelly!!! > > In other words, we need a plan! > > > > I agree in full. > Who will lead, who will coordinate, who will administrate knowlegde? > Antonio From owner-starship-design Sun Feb 23 17:45 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2071" "Sun" "23" "February" "1997" "20:41:10" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "43" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id RAA22348 for starship-design-outgoing; Sun, 23 Feb 1997 17:44:58 -0800 (PST) Received: from emout16.mail.aol.com (emout16.mx.aol.com [198.81.11.42]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id RAA20863 for ; Sun, 23 Feb 1997 17:43:07 -0800 (PST) Received: (from root@localhost) by emout16.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id UAA06676; Sun, 23 Feb 1997 20:41:10 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970223204106_-1809218598@emout16.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 2070 From: KellySt@aol.com Sender: owner-starship-design To: zkulpa@zmit1.ippt.gov.pl, starship-design@lists.uoregon.edu cc: zkulpa@ippt.gov.pl Subject: Re: starship-design: my $0.02 (finally) Date: Sun, 23 Feb 1997 20:41:10 -0500 (EST) In a message dated 2/17/97 1:40:14 PM, you wrote: >> - Therefore, a much more realistic solution for me is >> establishing a LONG-DURATION OUTPOST BASE. >> That is, it calls for a so-called ONE-WAY mission. >> What is a difference, from the point of view of the crew, >> between the one-way mission and the colonization mission? >> There is a SINGLE difference: there is NO PROCRERATION >> on the one-way mission. Only this, nothing more! >> Hence, from technical point of view, the one-way mission >> is simpler and requires much smaller resources, becoming >> feasible in the "early colonization of the solar system" >> conditions outlined above. Technically, the one-way mission: >> -- can have much smaller crew (as the questions of genetic diversity >> and all sociotechnical specialization variety are absent); In case someone wanted to know the basics of my side of the Zenon - Kelly one way mission debate. In general its political suicied to try to get a one way flight funded. To put it mildly openly considering your crews as expendable resources is a political no-no. Especially when the folks back home get to watch (or read about) the aging colonists working until they drop to keep the colony runing, and then dieing when to few of them were around to do enough work to keep the place going. Beyond that their are certain practical disadvantages. - If you can get them there, its not that much harder to bring the crew back. - After a few years they are going to be learning new research at a lower and lower rates. So you might as well bring them (and samples) back until you can use the lesons learned to send another, better equiped and trained team. Assuming the place was interesting enough to spend that much time on. - Equiping a ship with the facilities to last for an extra 50 years of time on station (assuming the crew would last that long) would be harder then bringing the ship back. - Its much harder to get good personel, if the retirement plan is to be worked to death in a deing ship. Kelly From owner-starship-design Mon Feb 24 06:46 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["10697" "Mon" "24" "February" "1997" "15:46:07" "+0100" "Zenon Kulpa" "zkulpa@zmit1.ippt.gov.pl" nil "270" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id GAA16403 for starship-design-outgoing; Mon, 24 Feb 1997 06:46:51 -0800 (PST) Received: from zmit1.ippt.gov.pl (zmit1.ippt.gov.pl [148.81.53.40]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id GAA16380 for ; Mon, 24 Feb 1997 06:46:41 -0800 (PST) Received: by zmit1.ippt.gov.pl (4.1/SMI-4.1) id AA04027; Mon, 24 Feb 97 15:46:07 +0100 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <9702241446.AA04027@zmit1.ippt.gov.pl> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) Content-Type: text Content-Length: 10696 From: zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Cc: zkulpa@ippt.gov.pl Subject: Re: starship-design: my $0.02 (finally) Date: Mon, 24 Feb 97 15:46:07 +0100 Repeating the posting from Feb 19, as seemingly it was not distributed by the listserver. -- Zenon ----- Begin Included Message ----- >From zkulpa@ippt.gov.pl Wed Feb 19 20:09:34 1997 Date: Wed, 19 Feb 97 20:06:27 +0100 From: zkulpa@ippt.gov.pl (Zenon Kulpa) To: starship-design@lists.uoregon.edu Subject: Re: starship-design: my $0.02 (finally) > From: "L. Clayton Parker" > Date: Mon, 17 Feb 1997 16:44:55 -0600 > > > > > More would be better, who knows what might come up. > > > > > Not unless you plan some hibernation or "unburdening" environment > > for most of the crew. > > I was simply allowing for emergency needs, not expecting that they would > sustain high-g accelerations for any considerable length of time. For > instance, there have been several proposals for gravity assisted manuevers > during the initial acceleration (or deceleration) phase in which having the > availability of additional thrust for a short length of time would > substantially alter the final velocity. > OK, the above explanation voids my initial reservations. > > Concerning ROUNDTRIP - I disagree. > > I am appending my letter from some time ago addressing this issue > > in case you heve missed it. > > WARNING: I do not want to start again my standard quarrel > > with Kelly here. Just to state my view... > > > You and Kelly have a standard quarrel? How nice! > Yes, we do... And quite heated one at times, despite that we both are rather likable persons, even to each other... ;-)) > > > 3) Engineering of the all systems (command, control, communications, > > > environmental and propulsion) should be sufficiently simple to permit > > > repairs and maintenance by the crew during the mission, or self repair > > > ability should be built in (preferably both). > > > > > Agreed. > > However, I think that will be possoble only with considerable > > advances in AI and nanotechnology. > > Ummm, some of this is even simpler than that. For example, do you honestly > think we can send a starship out with off the shelf light bulbs with only a > 750 hour lifespan? > OK, but do you think it possible, with current technology, to produce light bulbs with 20+ years lifespan? However, I am afraid I do not fully understand your reply. I did not postulate to send the starship away with unreliable components. My point was that making the ship components reliable enough will require advanced technologies, without which building and sending away a starship is simply not possible. Replacing unreliable light bulbs with simpler components (kerosene lamps? torches?) may not be enough to solve the problem... > > > 4) The propulsion system must be rugged enough to withstand continuous > > > operation without major overhaul or replacement for a period equal to at > > > least two and a half to three times the duration of the voyage. (Note > > > that this almost automatically excludes most current technologies.) > > > > > Agreed. > > Note also that the roundtrip requirement would DOUBLE (at least!) > > the problem here. > > That is why I chose two and a half to three times the duration of the > VOYAGE, a LARGE safety margin. > OK, you may choose any safety margin, however large, on paper (or on screen, for that matter), but will it be technologically attainable? I doubt it... > > > 5) Manned exploratory missions must be roundtrip, colonization missions > > > can be considered one way for purposes of design. But the mass of a > > > colony ship will be corespondingly greater requiring an even more robust > > > design. > > > > > See below: One-way has lesser requirements than > > both roundtrip and colonization, > > and differs from colonization mission in ONLY ONE aspect: > > reproduction is switched off (so to speak). > > I KNOW this point has been discussed before, but I simply think it is > impractical (not to mention immoral and unethical) to send our brightest > people out on what amounts to a suicide mission... > Geez, the standard quarrel again... ;-) First, if the people involved FREELY AGREE to go on these conditions, I do not see anything immoral or unethical in satisfying their wishes. Is sending volunteers into veery dangerous missions (e.g., to war) immoral or unethical? Second, the one-way mission is by light years different from a suicide mission. See the "Mission types in a nutshell" section at the end - I think it can be considered as a part of our "design space". I am against suicide missions too. BTW, I strongly recommend an interesting account of a one-way mission (including the discussion of one-way vs. suicide) given by the book "Rocheworld" by. R.L. Forward. It also contains elaborate description of a laser/lightsail-powered starship concept. > now for robot probes this > is more than adequate. I would expect that ANY system we send a manned > exploration team to would already have been visited by at least one robot > probe to determine if it was even worth a second look. > Agreed. However, if the system is worth a second look, it still may be worth (and technologically attainable) to establish there a manned long-duration outpost (using a one-way mission), but still not worth (or technologically possible) to send there a (necessarily HUGE) colonization expedition. > 1) One way implies NO RETURN. Establishment of a long term base with > EVENTUAL return, resupply or additional personnel is not the same thing. > I do not think sending people to the fate hanging on "eventuals" is honest. I think it is honest to say openly - the mission is one-way, it is planned as such from the beginning, and if there will be some "eventuals" is not guaranteed in any way. > 2) Send robotic Pathfinders FIRST. No "one way" manned missions to > systems that do not have a hope of eventual settlement or offer some other > overpowering reason to establish a permanent manned presence. > Agreed. Though, we may quarrel long and hard about the meaning of the term "overpowering reason". > 3) It makes more sense to establish our base(s) in the new system in space > first, then on the planetary bodies. We spent four and half million years > trying to get off of this planet, what's your hurry? In other words, the > industry that you assume to be in place in our outer solar system would in > reality be the first settlers of the new system. Given human behavior, I > suspect that it makes more sense that way anyway. > Agreed. But remember the artificial gravity problem (rotating habitats or something). > 4) Under these conditions, procreation within the limits of the life > support system is not only possible, it might even be desirable. You need > to look at this from a "human" perspective as well as scientific and > engineering. > Sorry, I do not understand your point here. What do you mean by "procreation within the limits of the life support system"? If procreation, it MUST mean the life support system is going to last indefinitely, so what limits? > So to review, a "one way" mission to set up an initial outpost either > in orbit or upon one or more satellites (not planets) with the eventual > promise of additional personnel and resupply as well as a chance of > rotation back to Sol, with the purpose of eventually settling the new > system and its planet(s) is reasonable. > "Eventual", "chance"... This smells of cheating... If the return is sure enough, it is not a one-way mission. If you allow that some people of the crew may not want to return and thus provide for them an environment lasting their lifetime (plus safety margin), why not to allow that choice for all the crew? BTW, what is a difference between satellites and planets that makes you view the latter as not adequate for an outpost base? The physical difference [which body orbits the star and which another planetary body] seems not relevant to this decision. > A mission that is "one way" in the sense that there will be no hope of > return, resupply, relief, etc., is impractical and indefensible. > I disagree. It would be interesting to ask people - how many would like to go for a one-way mission? I, for one, would have no reservations... -- Zenon ---------------------------------------------------------------------------- Mission types in a nutshell =========================== by Zenon Kulpa 1) Suicide mission: Quarantees: - death soon after (with great chances - during) achieving the mission target. - possibly exciting job for a short time needed to achieve the basic mission objectives. Does not quarantee (or excludes): - survival (and interesting job) for any time after the short time needed to achieve the basic mission objectives; - delivery to any specific point in space (with possible exception of the mission target); - possibility of reproduction during mission. 2) One-way mission: Quarantees: - delivery to the mission target; - survival for the standard life span (plus safety margin); - exciting job for the standard life span (possibly except for the duration of the trip to the target). Does not quarantee (or excludes): - delivery to any other point in space except the mission target; - possibility of reproduction during mission. 3) Round-trip mission: Quarantees: - delivery to the mission target; - delivery to the starting point of the mission (say, Earth) [note: with less certainty than the delivery to the target]; - survival for the standard life span (plus safety margin) [note: with at least twice (than one-way mission) the chance of death during the trip]; - exciting job for the standard life span (possibly except for TWO times the duration of the trip to the target). Does not quarantee (or excludes): - possibility of reproduction during mission. 4) Colonization mission: Quarantees: - delivery to the mission target; - survival for the standard life span (plus safety margin) for the colonist and his/her children; - exciting but hard job for the standard life span; (possibly except for the duration of the trip to the target). - possibility of reproduction during mission. Does not quarantee (or excludes): - delivery to any other point in space except the mission target. NOTE: Of course, the term "quarantees" should not be understood as absolute quarantee, but only within reasonable possibilities of technology at the time of the mission. ---------------------------------------------------------------------------- I would be grateful for including the above somewhere in starship design WWW pages. -- Zenon ----- End Included Message ----- From owner-starship-design Tue Feb 25 09:56 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1015" "Tue" "25" "February" "1997" "18:55:50" "+0100" "Zenon Kulpa" "zkulpa@zmit1.ippt.gov.pl" nil "30" "starship-design: Mission types in a nutshell" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id JAA22516 for starship-design-outgoing; Tue, 25 Feb 1997 09:56:23 -0800 (PST) Received: from zmit1.ippt.gov.pl (zmit1.ippt.gov.pl [148.81.53.40]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id JAA22487 for ; Tue, 25 Feb 1997 09:56:18 -0800 (PST) Received: by zmit1.ippt.gov.pl (4.1/SMI-4.1) id AA06889; Tue, 25 Feb 97 18:55:50 +0100 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <9702251755.AA06889@zmit1.ippt.gov.pl> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) Content-Type: text Content-Length: 1014 From: zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Cc: zkulpa Subject: starship-design: Mission types in a nutshell Date: Tue, 25 Feb 97 18:55:50 +0100 Sorry for making a series of stupid typos in the "Mission types in a nutshell" section of my previous posting. I wrote "Quarantee" instead of "guarantee" all over the text. Thanx Timothy for pointing out the mistake. In case somebody wants to put the text into one of the LIT websites, please correct the mistakes, or else ask me for the corrected version. Timothy also pointed out to me the fact that my comparison of a one-way mission with going to war is wrong. After thinking a little about it, I do agree - the two differ considerably, here are the main differences, as I see them now: - going for a one-way mission you have CONSIDERABLE CHANCE to live through all your natural life span, though you have NO CHANCE to be buried in the land of your ancestors; whereas: - going to a war you have CONSIDERABLY SMALLER CHANCE to live all your natural life span, though you have CONSIDERABLE CHANCE to be buried in the land of your ancestors... Which one would you prefer? ;-) -- Zenon From owner-starship-design Thu Feb 27 21:13 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1388" "Fri" "28" "February" "1997" "00:13:05" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "42" "Re: starship-design: Mission types in a nutshell" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id VAA07719 for starship-design-outgoing; Thu, 27 Feb 1997 21:13:42 -0800 (PST) Received: from emout01.mail.aol.com (emout01.mx.aol.com [198.81.11.92]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id VAA07710 for ; Thu, 27 Feb 1997 21:13:39 -0800 (PST) Received: (from root@localhost) by emout01.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id AAA22858; Fri, 28 Feb 1997 00:13:05 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970228001304_139510683@emout01.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 1387 From: KellySt@aol.com Sender: owner-starship-design To: zkulpa@zmit1.ippt.gov.pl, starship-design@lists.uoregon.edu Subject: Re: starship-design: Mission types in a nutshell Date: Fri, 28 Feb 1997 00:13:05 -0500 (EST) In a message dated 2/25/97 1:00:14 PM, zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) wrote: >Sorry for making a series of stupid typos in the >"Mission types in a nutshell" section of my previous posting. >I wrote "Quarantee" instead of "guarantee" all over the text. >Thanx Timothy for pointing out the mistake. >In case somebody wants to put the text into one of >the LIT websites, please correct the mistakes, >or else ask me for the corrected version. > >Timothy also pointed out to me the fact that my comparison >of a one-way mission with going to war is wrong. >After thinking a little about it, I do agree - >the two differ considerably, here are the main differences, >as I see them now: > >- going for a one-way mission you have CONSIDERABLE CHANCE > to live through all your natural life span, > though you have NO CHANCE to be buried > in the land of your ancestors; > >whereas: > >- going to a war you have CONSIDERABLY SMALLER CHANCE > to live all your natural life span, > though you have CONSIDERABLE CHANCE to be buried > in the land of your ancestors... > >Which one would you prefer? ;-) > >-- Zenon Number 2. Its the only one you have any chance of living a full life expectancy in, or retiring from. Also in 2 you presumably are dieing for a better reason then to save the agencies return trip expenses (thou I doubt it would be any cheaper). Kelly From owner-starship-design Thu Feb 27 21:16 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["12567" "Fri" "28" "February" "1997" "00:13:16" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "322" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "2" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id VAA08519 for starship-design-outgoing; Thu, 27 Feb 1997 21:16:56 -0800 (PST) Received: from emout07.mail.aol.com (emout07.mx.aol.com [198.81.11.22]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id VAA08191 for ; Thu, 27 Feb 1997 21:15:08 -0800 (PST) Received: (from root@localhost) by emout07.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id AAA00905; Fri, 28 Feb 1997 00:13:16 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970228001315_951641243@emout07.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 12566 From: KellySt@aol.com Sender: owner-starship-design To: zkulpa@zmit1.ippt.gov.pl, owner-starship-design@darkwing.uoregon.edu, starship-design@lists.uoregon.edu cc: zkulpa@ippt.gov.pl Subject: Re: starship-design: my $0.02 (finally) Date: Fri, 28 Feb 1997 00:13:16 -0500 (EST) In a message dated 2/24/97 9:51:47 AM, zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa) wrote: >Repeating the posting from Feb 19, >as seemingly it was not distributed by the listserver. -- Zenon > > >----- Begin Included Message ----- > >From zkulpa@ippt.gov.pl Wed Feb 19 20:09:34 1997 >Date: Wed, 19 Feb 97 20:06:27 +0100 >From: zkulpa@ippt.gov.pl (Zenon Kulpa) >To: starship-design@lists.uoregon.edu >Subject: Re: starship-design: my $0.02 (finally) > > >> From: "L. Clayton Parker" >> Date: Mon, 17 Feb 1997 16:44:55 -0600 >> > >> > > More would be better, who knows what might come up. >> > > >> > Not unless you plan some hibernation or "unburdening" environment >> > for most of the crew. >> >> I was simply allowing for emergency needs, not expecting that they would >> sustain high-g accelerations for any considerable length of time. For >> instance, there have been several proposals for gravity assisted manuevers >> during the initial acceleration (or deceleration) phase in which having the >> availability of additional thrust for a short length of time would >> substantially alter the final velocity. >> >OK, the above explanation voids my initial reservations. As a nit. Given the speeds and drive power these ships would need. You'ld have a bout as much luck trying to slingshot around the mass of a 747. >> > Concerning ROUNDTRIP - I disagree. >> > I am appending my letter from some time ago addressing this issue >> > in case you heve missed it. >> > WARNING: I do not want to start again my standard quarrel >> > with Kelly here. Just to state my view... >> > >> You and Kelly have a standard quarrel? How nice! >> >Yes, we do... >And quite heated one at times, >despite that we both are rather likable persons, >even to each other... ;-)) Well.. give or take that letter bomb I sent him. ;) >> > > 3) Engineering of the all systems (command, control, communications, >> > > environmental and propulsion) should be sufficiently simple to permit >> > > repairs and maintenance by the crew during the mission, or self repair >> > > ability should be built in (preferably both). >> > > >> > Agreed. >> > However, I think that will be possoble only with considerable >> > advances in AI and nanotechnology. >> >> Ummm, some of this is even simpler than that. For example, do you honestly >> think we can send a starship out with off the shelf light bulbs with only a >> 750 hour lifespan? >> >OK, but do you think it possible, with current technology, >to produce light bulbs with 20+ years lifespan? > >However, I am afraid I do not fully understand your reply. >I did not postulate to send the starship away with unreliable components. >My point was that making the ship components reliable enough >will require advanced technologies, without which building >and sending away a starship is simply not possible. >Replacing unreliable light bulbs with >simpler components (kerosene lamps? torches?) >may not be enough to solve the problem... ...And the chanting, cloaked, torch bering figure stoad through the darkend starship..... ;) >> > > 4) The propulsion system must be rugged enough to withstand continuous >> > > operation without major overhaul or replacement for a period equal to at >> > > least two and a half to three times the duration of the voyage. (Note >> > > that this almost automatically excludes most current technologies.) >> > > >> > Agreed. >> > Note also that the roundtrip requirement would DOUBLE (at least!) >> > the problem here. >> >> That is why I chose two and a half to three times the duration of the >> VOYAGE, a LARGE safety margin. >> >OK, you may choose any safety margin, however large, >on paper (or on screen, for that matter), >but will it be technologically attainable? I doubt it... True, the fligh times for these birds are LONG, about as long as the service life of any of our heavy equipment. >> > > 5) Manned exploratory missions must be roundtrip, colonization missions >> > > can be considered one way for purposes of design. But the mass of a >> > > colony ship will be corespondingly greater requiring an even more robust >> > > design. >> > > >> > See below: One-way has lesser requirements than >> > both roundtrip and colonization, >> > and differs from colonization mission in ONLY ONE aspect: >> > reproduction is switched off (so to speak). >> >> I KNOW this point has been discussed before, but I simply think it is >> impractical (not to mention immoral and unethical) to send our brightest >> people out on what amounts to a suicide mission... >> >Geez, the standard quarrel again... ;-) Yes. Another has taken up the standard.... ;) >First, if the people involved FREELY AGREE to go on these conditions, >I do not see anything immoral or unethical in satisfying their wishes. >Is sending volunteers into veery dangerous missions (e.g., to war) >immoral or unethical? I could NEVER get him to understand this one, or that fact no major industrial nation could politically propose such a mission unless the fate of millions was at stake. >Second, the one-way mission is by light years different >from a suicide mission. >See the "Mission types in a nutshell" section at the end - >I think it can be considered as a part of our "design space". >I am against suicide missions too. As a nit such a mission probably would be a default suicide mission. Besides the fact the crew would expect to be stranded in a alien system in a deralic ship. (Real bad for moral.) If they don't kill themselves to avoid the boredom, they'ld wind up traped in that ship. Whith nothing to look forward to except working like hell to keep the ship runing. I.E. a race between their repairs and the unraveling ship systems. I seriously would expect a high suicide rate after the primary mission period is over. >BTW, I strongly recommend an interesting account of a one-way mission >(including the discussion of one-way vs. suicide) given by the book >"Rocheworld" by. R.L. Forward. It also contains elaborate >description of a laser/lightsail-powered starship concept. Good book if you can get past the disturbing premise. Oh, we punched holes in the laser sail concept. ;) >> now for robot probes this >> is more than adequate. I would expect that ANY system we send a manned >> exploration team to would already have been visited by at least one robot >> probe to determine if it was even worth a second look. >> >Agreed. >However, if the system is worth a second look, >it still may be worth (and technologically attainable) >to establish there a manned long-duration outpost >(using a one-way mission), but still not >worth (or technologically possible) to send there >a (necessarily HUGE) colonization expedition. > > >> 1) One way implies NO RETURN. Establishment of a long term base with >> EVENTUAL return, resupply or additional personnel is not the same thing. >> >I do not think sending people to the fate hanging on "eventuals" is honest. >I think it is honest to say openly - the mission is one-way, >it is planned as such from the beginning, and >if there will be some "eventuals" is not guaranteed in any way. > > >> 2) Send robotic Pathfinders FIRST. No "one way" manned missions to >> systems that do not have a hope of eventual settlement or offer some other >> overpowering reason to establish a permanent manned presence. >> >Agreed. >Though, we may quarrel long and hard about the meaning of the term >"overpowering reason". Why not, everyone else did. ;) >> 3) It makes more sense to establish our base(s) in the new system in space >> first, then on the planetary bodies. We spent four and half million years >> trying to get off of this planet, what's your hurry? In other words, the >> industry that you assume to be in place in our outer solar system would in >> reality be the first settlers of the new system. Given human behavior, I >> suspect that it makes more sense that way anyway. >> >Agreed. >But remember the artificial gravity problem >(rotating habitats or something). > > >> 4) Under these conditions, procreation within the limits of the life >> support system is not only possible, it might even be desirable. You need >> to look at this from a "human" perspective as well as scientific and >> engineering. >> >Sorry, I do not understand your point here. >What do you mean by "procreation within the limits of the life >support system"? If procreation, it MUST mean the life support >system is going to last indefinitely, so what limits? I think hes refering to the carrying capacity of the life support systems. >> So to review, a "one way" mission to set up an initial outpost either >> in orbit or upon one or more satellites (not planets) with the eventual >> promise of additional personnel and resupply as well as a chance of >> rotation back to Sol, with the purpose of eventually settling the new >> system and its planet(s) is reasonable. >> >"Eventual", "chance"... This smells of cheating... >If the return is sure enough, it is not a one-way mission. >If you allow that some people of the crew may not want to return >and thus provide for them an environment lasting their lifetime >(plus safety margin), why not to allow that choice for all the crew? > >BTW, what is a difference between satellites and planets >that makes you view the latter as not adequate for an outpost base? >The physical difference [which body orbits the star and >which another planetary body] seems not relevant to this decision. > > >> A mission that is "one way" in the sense that there will be no hope of >> return, resupply, relief, etc., is impractical and indefensible. >> >I disagree. >It would be interesting to ask people - >how many would like to go for a one-way mission? >I, for one, would have no reservations... Oddly, some sp[ace buffs are proposing NASA do a one way mission to Mars! >-- Zenon > >---------------------------------------------------------------------------- >Mission types in a nutshell >=========================== >by Zenon Kulpa > >1) Suicide mission: > Quarantees: > - death soon after (with great chances - during) > achieving the mission target. > - possibly exciting job for a short time needed to > achieve the basic mission objectives. > Does not quarantee (or excludes): > - survival (and interesting job) for any time after > the short time needed to achieve the basic mission objectives; > - delivery to any specific point in space > (with possible exception of the mission target); > - possibility of reproduction during mission. > >2) One-way mission: > Quarantees: > - delivery to the mission target; > - survival for the standard life span (plus safety margin); > - exciting job for the standard life span > (possibly except for the duration of the trip to the target). > Does not quarantee (or excludes): > - delivery to any other point in space except the mission target; > - possibility of reproduction during mission. > >3) Round-trip mission: > Quarantees: > - delivery to the mission target; > - delivery to the starting point of the mission (say, Earth) > [note: with less certainty than the delivery to the target]; > - survival for the standard life span (plus safety margin) > [note: with at least twice (than one-way mission) > the chance of death during the trip]; > - exciting job for the standard life span > (possibly except for TWO times the duration of the trip to the target). > Does not quarantee (or excludes): > - possibility of reproduction during mission. > >4) Colonization mission: > Quarantees: > - delivery to the mission target; > - survival for the standard life span (plus safety margin) > for the colonist and his/her children; > - exciting but hard job for the standard life span; > (possibly except for the duration of the trip to the target). > - possibility of reproduction during mission. > Does not quarantee (or excludes): > - delivery to any other point in space except the mission target. > >NOTE: Of course, the term "quarantees" should not be understood >as absolute quarantee, but only within reasonable possibilities >of technology at the time of the mission. >---------------------------------------------------------------------------- > >I would be grateful for including the above >somewhere in starship design WWW pages. > >-- Zenon Are the pages going to be loaded in SunSites LIT, or should we just use one of the prototype sites as the base site? Kelly From owner-starship-design Sun Mar 2 09:55 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4986" "Sun" "2" "March" "1997" "11:54:20" "-0600" "L. Clayton Parker" "lparker@cacaphony.net" nil "116" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id JAA17338 for starship-design-outgoing; Sun, 2 Mar 1997 09:55:12 -0800 (PST) Received: from hurricane.gnt.net (root@hurricane.gnt.net [204.49.53.3]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id JAA17316 for ; Sun, 2 Mar 1997 09:55:04 -0800 (PST) Received: from destin.gulfnet.com.gulfnet.com (p36.gnt.com [204.49.68.37]) by hurricane.gnt.net (8.8.5/8.7.3) with ESMTP id LAA08759; Sun, 2 Mar 1997 11:54:54 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199703021754.LAA08759@hurricane.gnt.net> X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1155 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "L. Clayton Parker" Content-Type: text/plain; charset=ISO-8859-1 Content-Length: 4985 From: "L. Clayton Parker" Sender: owner-starship-design To: Cc: Subject: Re: starship-design: my $0.02 (finally) Date: Sun, 2 Mar 1997 11:54:20 -0600 Kelly, > >OK, the above explanation voids my initial reservations. > > As a nit. Given the speeds and drive power these ships would need. You'ld > have a bout as much luck trying to slingshot around the mass of a 747. Well, perhaps I chose a poor example, nevertheless, I would still prefer to have acceleration to burn. > >> 750 hour lifespan? > >> > >OK, but do you think it possible, with current technology, > >to produce light bulbs with 20+ years lifespan? > > > >However, I am afraid I do not fully understand your reply. > >I did not postulate to send the starship away with unreliable components. > >My point was that making the ship components reliable enough > >will require advanced technologies, without which building > >and sending away a starship is simply not possible. > >Replacing unreliable light bulbs with > >simpler components (kerosene lamps? torches?) > >may not be enough to solve the problem... > > ...And the chanting, cloaked, torch bering figure stoad through the darkend > starship..... ;) I was simply pointing out that our society has geared its technology towards built-in obsolescence out of economic reasons. Very little in the way of current infrastructure such as light bulbs, ovens, electric motors, pumps, door knobs, hinges, furniture (in other words everything we take for granted in everyday life) is suitable for such an endeavor. I am not questioning our ability to build such items, only the cost and viability of doing so. Remember the $500 toilet seat? That might have been an abuse of the system but in this case MOST components would cost ten to a hundred times their cheaply made, engineered to fail cousins. > >OK, you may choose any safety margin, however large, > >on paper (or on screen, for that matter), > >but will it be technologically attainable? I doubt it... > > True, the fligh times for these birds are LONG, about as long as the service > life of any of our heavy equipment. This is a continuation of the above line of reasoning. We CAN engineer most of our support systems for life spans of a hundred years or more. That coupled with self repair capability should suffice for SUPPORT systems. In the case of power and propulsion it is a little more complicated. By their very nature these systems are subject to extensive and rapid wear. Additionally, most of the systems we are discussing are not even in prototype yet and are therefore not going to be ready (from a point of engineering reliability) for three generations, or about 50 to 100 years at current estimates. > >Geez, the standard quarrel again... ;-) > > Yes. Another has taken up the standard.... ;) Actually, the standard bearer precedes us both (not that I am really so gung-ho as to go into the melee with nothing more than a flagstaff ). Zenon, did not originate the one way concept, it has been argued before organizations such as NASA and the British Interplanetary Society and others for years. I don't remember the name of the person who presented your arguments, but I do remember hearing them ( I think it was David somebody). The most telling argument as has been pointed out here in this very forum is that it is political suicide, therefore not an option as long as we are dependent upon government largesse. > Oh, we punched holes in the laser sail concept. ;) I don't really think that any concept based upon a material sail is going to prove very effective for anything other than Starwisp type probes. > >> 2) Send robotic Pathfinders FIRST. No "one way" manned missions to > >> systems that do not have a hope of eventual settlement or offer some other > >> overpowering reason to establish a permanent manned presence. > >> > >Agreed. > >Though, we may quarrel long and hard about the meaning of the term > >"overpowering reason". > > Why not, everyone else did. ;) It is fairly likely that we will encounter many situations and circumstances in which we may want to establish purely scientific outposts or mining outposts, etc. where no colonization is ever expected. As such, all personnel would eventually rotate back "home". > I think hes refering to the carrying capacity of the life support systems. I mean it makes more sense to send FAMILIES on long duration voyages and to plan on human nature rather than attempt to deny it. So allow sufficient environmental mass for expansion of population in the first place. > >BTW, what is a difference between satellites and planets > >that makes you view the latter as not adequate for an outpost base? > >The physical difference [which body orbits the star and > >which another planetary body] seems not relevant to this decision. I was thinking more of orbital bases at lagrange points as a stepping stone "down" to the surface of the planet. Build the orbital infrastructure first, planet second. This helps to ensure the colonists retain access to space and prevents loss of the entire colony to unforeseen circumstances. ---------- Lee From owner-starship-design Wed Mar 5 22:40 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6065" "Thu" "6" "March" "1997" "01:40:17" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "145" "Re: starship-design: my $0.02 (finally)" "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id WAA16713 for starship-design-outgoing; Wed, 5 Mar 1997 22:40:57 -0800 (PST) Received: from emout16.mail.aol.com (emout16.mx.aol.com [198.81.11.42]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id WAA16682 for ; Wed, 5 Mar 1997 22:40:51 -0800 (PST) Received: (from root@localhost) by emout16.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id BAA12588; Thu, 6 Mar 1997 01:40:17 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970306014016_-1808120663@emout16.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 6064 From: KellySt@aol.com Sender: owner-starship-design To: lparker@cacaphony.net, owner-starship-design@darkwing.uoregon.edu, KellySt@aol.com cc: starship-design@lists.uoregon.edu Subject: Re: starship-design: my $0.02 (finally) Date: Thu, 6 Mar 1997 01:40:17 -0500 (EST) In a message dated 3/2/97 1:10:18 PM, lparker@cacaphony.net (L. Clayton Parker) wrote: >Kelly, --- >> >> 750 hour lifespan? >> >> >> >OK, but do you think it possible, with current technology, >> >to produce light bulbs with 20+ years lifespan? >> > >> >However, I am afraid I do not fully understand your reply. >> >I did not postulate to send the starship away with unreliable >components. >> >My point was that making the ship components reliable enough >> >will require advanced technologies, without which building >> >and sending away a starship is simply not possible. >> >Replacing unreliable light bulbs with >> >simpler components (kerosene lamps? torches?) >> >may not be enough to solve the problem... >> >> ...And the chanting, cloaked, torch bering figure stoad through the >darkend >> starship..... ;) > >I was simply pointing out that our society has geared its technology >towards built-in obsolescence out of economic reasons. Very little in the >way of current infrastructure such as light bulbs, ovens, electric motors, >pumps, door knobs, hinges, furniture (in other words everything we take for >granted in everyday life) is suitable for such an endeavor. I am not >questioning our ability to build such items, only the cost and viability of >doing so. Remember the $500 toilet seat? That might have been an abuse of >the system but in this case MOST components would cost ten to a hundred >times their cheaply made, engineered to fail cousins. We do market much longer lived items. These are frequently used by the militarey, but for civilian use long life isn't much of an advantage. (Why by a 20 year light bulb when you'll switch out the lamp and house a couple times by then?) Oh, the $500 tolet seat is an unrban myth, like the $100 hammer. The actual items were priced normally, the "cost" was the administrative overhead and billing games required on federal projects. (Hey its better then the tens of billions spent each year to keep up the cost of our groceries?) I'ld expect a starships systems would be a mix of long life and easy to rebuild systems. Which would be what would depend on costs and difficulty. >> >OK, you may choose any safety margin, however large, >> >on paper (or on screen, for that matter), >> >but will it be technologically attainable? I doubt it... >> >> True, the fligh times for these birds are LONG, about as long as the >service >> life of any of our heavy equipment. > >This is a continuation of the above line of reasoning. We CAN engineer most >of our support systems for life spans of a hundred years or more. That >coupled with self repair capability should suffice for SUPPORT systems. In >the case of power and propulsion it is a little more complicated. By their >very nature these systems are subject to extensive and rapid wear. >Additionally, most of the systems we are discussing are not even in >prototype yet and are therefore not going to be ready (from a point of >engineering reliability) for three generations, or about 50 to 100 years at >current estimates. Say 50 years. In a hundred they'll be archaic. >> >Geez, the standard quarrel again... ;-) >> >> Yes. Another has taken up the standard.... ;) > >Actually, the standard bearer precedes us both (not that I am really so >gung-ho as to go into the melee with nothing more than a flagstaff ). >Zenon, did not originate the one way concept, it has been argued before >organizations such as NASA and the British Interplanetary Society and >others for years. > >I don't remember the name of the person who presented your arguments, but I >do remember hearing them ( I think it was David somebody). The most telling >argument as has been pointed out here in this very forum is that it is >political suicide, therefore not an option as long as we are dependent upon >government largesse. > >> Oh, we punched holes in the laser sail concept. ;) > >I don't really think that any concept based upon a material sail is going >to prove very effective for anything other than Starwisp type probes. Hey my fuel/sail idea works pretty well! ;) >> >> 2) Send robotic Pathfinders FIRST. No "one way" manned missions to >> >> systems that do not have a hope of eventual settlement or offer some >other >> >> overpowering reason to establish a permanent manned presence. >> >> >> >Agreed. >> >Though, we may quarrel long and hard about the meaning of the term >> >"overpowering reason". >> >> Why not, everyone else did. ;) > >It is fairly likely that we will encounter many situations and >circumstances in which we may want to establish purely scientific outposts >or mining outposts, etc. where no colonization is ever expected. As such, >all personnel would eventually rotate back "home". Probably in most cases their will be little reason ever to settle a star systems, and virtually no case where we could settle a planet. >> I think hes refering to the carrying capacity of the life support >systems. > >I mean it makes more sense to send FAMILIES on long duration voyages and to >plan on human nature rather than attempt to deny it. So allow sufficient >environmental mass for expansion of population in the first place. I'ld recomend an engineered, rather then an ecological, life support system. Its lighter, more relyable, and more adaptable to changing loads. >> >BTW, what is a difference between satellites and planets >> >that makes you view the latter as not adequate for an outpost base? >> >The physical difference [which body orbits the star and >> >which another planetary body] seems not relevant to this decision. > >I was thinking more of orbital bases at lagrange points as a stepping stone >"down" to the surface of the planet. Build the orbital infrastructure >first, planet second. This helps to ensure the colonists retain access to >space and prevents loss of the entire colony to unforeseen circumstances. >---------- > > >Lee I'ld assume only a tiny fraction of the crew would be allowed down, and would only be allowed up after passing extream quarenteen. Kelly From owner-starship-design Tue Mar 11 10:46 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5739" "Tue" "11" "March" "1997" "10:46:02" "-0800" "Ken Wharton" "wharton@physics.ucla.edu" nil "96" "starship-design: Something Different..." "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id KAA11358 for starship-design-outgoing; Tue, 11 Mar 1997 10:46:25 -0800 (PST) Received: from physics.ucla.edu (physics.ucla.edu [128.97.23.13]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id KAA11313 for ; Tue, 11 Mar 1997 10:46:22 -0800 (PST) Received: from watt by physics.ucla.edu (SMI-8.6/SMI-SVR4) id KAA12884; Tue, 11 Mar 1997 10:46:03 -0800 Received: by watt (SMI-8.6/SMI-SVR4) id KAA02224; Tue, 11 Mar 1997 10:46:02 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199703111846.KAA02224@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: wharton@physics.ucla.edu (Ken Wharton) Content-Type: text Content-Length: 5738 From: wharton@physics.ucla.edu (Ken Wharton) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Something Different... Date: Tue, 11 Mar 1997 10:46:02 -0800 Hello all... I just finished a fascinating book; Time's Arrow and Archimedes' Point, by Huw Price, and Australian Philosopher/Mathematician. The main (and convincing) argument is that while practically all of the physical laws of nature are time-symmetric, our position as beings with a particular temporal orientation--we sense the "future" being distinctly different from the "past"--has interfered with taking Time-Symmetry to it's logical Conclusion. In particular, he argues that the inherent Time- Asymmetry of the Copenhagen Interpretation of Quantum Mechanics is flawed, and we need to pick a time-symmetric quantum theory, such as Cramer's Transactional Interpretation or another possible option he puts forward. Indeed, he sees the *ONLY* reason that we even perceive an "arrow" of time is because of the low-entropy boundary conditions of the Big Bang, and the fact that consciousness has to move in the same direction that entropy increases. (He argues that the radiation arrow of time also stems from the special conditions of what we call the Big Bang.) So--assuming he's correct--what does this all mean as far as this group is concerned? First of all, it would seem to rule out FTL virtual particle drives. The concept of "faster than light" virtual particles, along with non-local quantum effects, stem from our forcing our subjective time-asymmetry onto physics as a whole. Basically, what looks like a faster-than-light occurrence in our temporal frame is actually a combination of a "forward" time causation and a "backward", or advanced causation. Huw Price shows that any attempt to use a backward causation to set up a paradox will fail; the measurement itself will destroy the correlation you're looking for. In fact, it looks like you can derive all of modern quantum mechanics from two axioms; 1) Nature is Time-Symmetric, and 2) You can never set up a true paradox. But a more interesting idea I had is this: Assume that the universe is closed; i.e. that it will recontract into something we call the Big Crunch. In fact, given symmetry arguments we have no reason to expect that one "edge" of the universe will be any different from the other. But the Big Crunch will come with its own Boundary Conditions that will propagate in the reverse time direction from what we're used to. Indeed, on the other side of the universe, Entropy would be increasing in the opposite direction! You'd get (from our perspective) Inverse Stars that would be coherent radiation sinks, rather than coherent radiation sources. The laws of electromagnetics account for this possibility in the equations; it just so happens that we never see large, coherent radiation sinks--that's the radiation arrow of time. Anyway, my idea revolves around this question: what happens to an object that survives the transition from an expanding to a contracting universe? There are two possible answers here, and one of them kills my idea. If that object is equally constrained by the Boundary Conditions of the two ends of the universe (The Big Bang and the Big Crunch) then it's entropy would start to move in the other direction. If that's the case, this idea won't work. BUT - If some objects are ONLY constrained by the boundary conditions at ONE end of the universe, and they pass each other in the middle, then they would continue to be affected by the more distant end of the universe rather than the closer one they were no heading toward. If this is a possibility, then in OUR side of the universe there might be objects that "originated" from the boundary conditions of the Big Crunch; perhaps there might be large-scale radiation sinks of the kind I mentioned earlier. This would have profound implications for a starship propulsion system, if we could ever get our hands on one. An objection here might be that there aren't such objects; we don't see them. Nowhere have astronomers ever seen light coming from all directions and converging on an object in a coherent fashion. But COULD we even see such a thing? Think of the situation in the reverse-time perspective, where the "inverse-star" is radiating outward, shining photons on our eyes. Now, back in our time perspective, we don't see any light; photons are Leaving our eyes, not arriving at them. (This is also true for a photographic plate, of course...) So in our time frame, we have to spin our head around and look AWAY from the inverse-star in order to see the radiation coming toward it. But now the back of our head is blocking the light! Photons would be emerging from the back of our head and going to the inverse-star; our eyes would miss the whole thing. I think it's possible to see such an object, but it would require a completely new type of detector that would somehow be able to detect that photons were Leaving, rather than arriving, but do so it a way that wouldn't disturb the photons themselves. Anyway, the point is that a large, coherent radiation sink would get rid of a rather painful asymmetry in spaceship engines. Because there are only coherent radiation sources, we have to Expend mass to gain momentum. But why not the opposite case; gain momentum by Receiving mass? A coherent radiation sink would allow this possibility; matter would converge upon it coherently and possibly give momentum to the ship while Adding to the mass of the ship, rather than subtracting from it. A more conventional engine could then operate in tandem, keeping the mass of the ship constant while we gained momentum. A little farfetched, perhaps. But things have been awfully quiet lately, so I thought I'd toss it out and see what happens. Ken From owner-starship-design Thu Mar 13 06:14 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3342" "Thu" "13" "March" "1997" "15:14" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "68" "Re: starship-design: Something Different..." "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id GAA18447 for starship-design-outgoing; Thu, 13 Mar 1997 06:14:46 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id GAA18387 for ; Thu, 13 Mar 1997 06:14:42 -0800 (PST) Received: from hengelo04.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0w5BH9-000DlqC; Thu, 13 Mar 97 15:14 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 3341 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: Re: starship-design: Something Different... Date: Thu, 13 Mar 97 15:14 MET Hello Ken, No strange characters this time? ;) >I just finished a fascinating book; Time's Arrow and Archimedes' Point, >by Huw Price, and Australian Philosopher/Mathematician. >So--assuming he's correct--what does this all mean as far as this group >is concerned? First of all, it would seem to rule out FTL virtual >particle drives. The concept of "faster than light" virtual particles, >along with non-local quantum effects, stem from our forcing our >subjective time-asymmetry onto physics as a whole. What is a "FTL virtual particle drive"? How is it thought to work? >Basically, what >looks like a faster-than-light occurrence in our temporal frame is >actually a combination of a "forward" time causation and a "backward", >or advanced causation. Huw Price shows that any attempt to use a >backward causation to set up a paradox will fail; the measurement itself >will destroy the correlation you're looking for. In fact, it looks like >you can derive all of modern quantum mechanics from two axioms; 1) >Nature is Time-Symmetric, and 2) You can never set up a true paradox. When talking about FTL (faster than light) I'm always a bit unsure, not because of the physics involved, but about what the the phenomenon means. For example does travel trough perminent warped space also count as FTL? Anyhow, regardless of how you call it, one day there may exist a possibility to create permanent "worm-holes" to travel to distant stars in a "no-time". This phenomenon will likely not depend on tunneling (forward causation) but instead on general relativity and thus still allows for FTL travel to be possible. And regarding tunneling: Since we are "subjective" beings, does it really matter that we think that we travel faster than light, or that we actually were at the point of our destination before we really noticed it? (or for that matter before we even had decided to make the FTL trip) >But the Big Crunch will come with its own Boundary Conditions that will >propagate in the reverse time direction from what we're used to. >Indeed, on the other side of the universe, Entropy would be increasing >in the opposite direction! You'd get (from our perspective) Inverse >Stars that would be coherent radiation sinks, rather than coherent >radiation sources. The laws of electromagnetics account for this >possibility in the equations; it just so happens that we never see >large, coherent radiation sinks--that's the radiation arrow of time. What about black-holes? Aren't they coherent enough? >Anyway, the point is that a large, coherent radiation sink would get rid >of a rather painful asymmetry in spaceship engines. Because there are >only coherent radiation sources, we have to Expend mass to gain >momentum. But why not the opposite case; gain momentum by Receiving >mass? A coherent radiation sink would allow this possibility; matter >would converge upon it coherently and possibly give momentum to the ship >while Adding to the mass of the ship, rather than subtracting from it. >A more conventional engine could then operate in tandem, keeping the >mass of the ship constant while we gained momentum. Hmm, how do you get the mass out of the radiation sink (and into the conventional engine)? Would that not spoil the fun? Tim From owner-starship-design Fri Mar 14 11:13 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["5883" "Fri" "14" "March" "1997" "11:13:04" "-0800" "Ken Wharton" "wharton@physics.ucla.edu" nil "112" "starship-design: More Symmetry Stuff" "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id LAA14948 for starship-design-outgoing; Fri, 14 Mar 1997 11:13:32 -0800 (PST) Received: from physics.ucla.edu (physics.ucla.edu [128.97.23.13]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id LAA14919 for ; Fri, 14 Mar 1997 11:13:28 -0800 (PST) Received: from watt by physics.ucla.edu (SMI-8.6/SMI-SVR4) id LAA18195; Fri, 14 Mar 1997 11:13:05 -0800 Received: by watt (SMI-8.6/SMI-SVR4) id LAA17741; Fri, 14 Mar 1997 11:13:04 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199703141913.LAA17741@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: wharton@physics.ucla.edu (Ken Wharton) Content-Type: text Content-Length: 5882 From: wharton@physics.ucla.edu (Ken Wharton) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: More Symmetry Stuff Date: Fri, 14 Mar 1997 11:13:04 -0800 Thanks for your response, Tim! I had the feeling this one was just going to fall flat. Instead, you've given me a chance for one more iteration... >What is a "FTL virtual particle drive"? How is it thought to work? My understanding was that because virtual particles are "seen" (or at least inferred) to travel faster than light, some people think you can get more momentum out of them with a given amount of energy than you could with a real particle. So a virtual-particle drive would use Faster-Than-Light virtual particles as propellant, although the ship itself would not travel faster than light. >When talking about FTL (faster than light) I'm always a bit unsure, not >because of the physics involved, but about what the the phenomenon means. >For example does travel trough perminent warped space also count as FTL? >Anyhow, regardless of how you call it, one day there may exist a possibility >to create permanent "worm-holes" to travel to distant stars in a "no- time". >This phenomenon will likely not depend on tunneling (forward causation) but >instead on general relativity and thus still allows for FTL travel to be >possible. Very true. Of course, if we're worried about energy requirements NOW... >>You'd get (from our perspective) Inverse >>Stars that would be coherent radiation sinks, rather than coherent >>radiation sources. The laws of electromagnetics account for this >>possibility in the equations; it just so happens that we never see >>large, coherent radiation sinks--that's the radiation arrow of time. > >What about black-holes? Aren't they coherent enough? Actually, (According to Mr. Price) they aren't. In our forward-time view, we wouldn't expect two photons converging on a black hole (coming from different directions) to be correlated in any way. However, two photons emitted from a common source ARE considered to be correlated. This is a time-asymmetric assumption; viewed in the opposite time- direction the reverse would be true. Although we see the evidence of this asymmetry all around us, there is no time-asymmetric law of physics to explain it, and it is probably a result of the special boundary conditions of Big Bang. A coherent radiation sink would have correlations between all incoming particles. The correlation would be a result of their common Future, although they would have no common Past. We are used to seeing correlations as a result of a common past, although viewed in the right way the strange phenomenon of quantum mechanics can be seen as evidence that certain correlations can be caused by a common future. So a coherent radiation sink would be very different from a black hole. >Hmm, how do you get the mass out of the radiation sink (and into the >conventional engine)? Would that not spoil the fun? Good point. I suppose it all depends on what sort of object our coherent absorber would be, and whether it would be possible to use reverse-causal mass in a forward-causal engine. I've been thinking about this a little more and have come to a strange conclusion, based on CPT symmetry. CPT symmetry is a physical principle (in both quantum and relativity) that any system with opposite Charge, opposite Parity (mirror-image), and opposite Time-direction, must act exactly like the original un-reversed system. This would mean that if there was some form of matter causally propagating backwards in time, it would most likely be (mirror-image) antimatter. The Big Crunch, when viewed from a CPT-symmetrical standpoint, would then look exactly like the Big Bang, with the same amount of antimatter then as we have matter today. The strange thing, though, is that the future boundary conditions would not allow this backward-time antimatter to annihilate with forward-time matter. The antimatter Couldn't annihilate (in our temporal frame), because it's constrained to exist at the end of the universe! But this would mean that antimatter "created" at the Big Crunch would be very different from the antimatter that we create in particle accelerators. One obvious difference is that antimatter that we create from matter would necessarily be causally propagating forward in time, because all of its Boundary Conditions could still be traced back to the Big Bang. But if they are fundamentally the same in all other ways, you'd still expect both types of antimatter to obey the same laws of physics; instead one annihilates with matter and one doesn't. This contradiction either spells defeat for this theory, or points to some new law of physics. One possibility is the mirror-image requirement I mentioned earlier; perhaps there is a unknown conservation-of-parity law in physics that only allows annihilation of similar-parity particles (i.e. particles that had the same causal direction). Physics could not have discovered this law yet because all forward-causal particles would have the same parity. Anyway, even if this backward-causal material exists, we'd have to find some. I mentioned the problems with seeing radiation from these objects; they'd emit incoherently and absorb coherently. But it would still be gravitationally attractive. In fact, if this theory is true, it would most likely be some of the "missing" mass of the universe. The Great Attractor between the Milky Way and Andromeda galaxies, a completely dark object with roughly 10 galactic masses, would be a likely possibility, but useless for us. Instead, we'd have to hope there were chunks of this dark matter throughout our galaxy as well, and we'd have to come up with a way of detecting them. As far as I know, no one is working on devices that detect when photons Leave an object (as opposed to arriving on a piece of film), but I don't see any fundamental reason why it couldn't be done. Anyone have any ideas? Ken From owner-starship-design Sat Mar 15 10:04 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["2164" "Sat" "15" "March" "1997" "13:02:32" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "56" "starship-design: Xprize" "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id KAA00546 for starship-design-outgoing; Sat, 15 Mar 1997 10:04:08 -0800 (PST) Received: from emout02.mail.aol.com (emout02.mx.aol.com [198.81.11.93]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id KAA00512 for ; Sat, 15 Mar 1997 10:04:05 -0800 (PST) Received: (from root@localhost) by emout02.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id NAA21800; Sat, 15 Mar 1997 13:02:32 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970315130232_-1338217152@emout02.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 2163 From: KellySt@aol.com Sender: owner-starship-design To: starship-design@lists.uoregon.edu, DTaylor648@aol.com, JohnFrance@aol.com, MARK.A.JENSEN@cpmx.saic.com, schlegel@rmc1.crocker.com, Sdudley6@aol.com, Viper7997@aol.com, mgood19@idt.net, rjurmain@bix.com, MLEN3097@mercury.gc.peachnet.edu cc: kelly_starks@fmc.com Subject: starship-design: Xprize Date: Sat, 15 Mar 1997 13:02:32 -0500 (EST) Subject: X-Prize competitors announced From: "Clark S. Lindsey" Date: Sun, 02 Mar 1997 15:09:49 +0100 Message-ID: <33198A2D.256A@particle.kth.se> In case you missed it, the X-Prize Foundation announced Friday that 10 competitors have been officially registered so far. Here is the list from their press release: #1 Mr. Burt Rutan, President, Scaled Composites. Rutan is best known for the Voyager aircraft which flew non-stop around the world without refueling. #2 Mr. Gary C. Hudson, President/Mr. Bevin McKinney, CEO, HMX, Inc. Hudson and McKinney have been designing and building launch vehicles for over a decade. #3 Dr. Robert Zubrin, Co-Founder, Pioneer Rocketplane. Zubrin is the inventor of several innovative space propulsion concepts. #4 Dr. Rick Fleeter, Founder, PacAstro. Fleeter is a leading developer of microsatellites and has recently entered the launch business. #5 Mr. James Akkerman, Founder, Advent Launch Services. Akkerman has worked for NASA since the Apollo Program. #6 Mr. John Bloomer, Founder, Discraft Corporation. Bloomer is an aerospace engineer who holds more than 60 patents. #7 Mr. Mickey L. Bagero is currently on active duty in the US Air Force. He plans to begin the construction phase of his entry at the conclusion of his service. #8 Mr. William Good, President, Earth Space Transport System Corporation. ESTS provides computer consulting and programming to major aerospace companies. #9 Mr. Paul F. Tryon has worked for McDonnell Douglas and Bell Aircraft and has over 34 years of experience in aeronautical engineering. #10 Mr. John Ashford, Founder, Bristol Spaceplanes Limited. Mr. Ashford has written extensive technical papers on the subject of space tourism. Where is David Burkhead's SpaceCub? For more info see the X-PRIZE Web site at www.xprize.org and http://www.xprize.org/people/competitors.html. -- Clark S. Lindsey, lindsey@particle.kth.se Physics Dept. - Frescati http://msia02.msi.se/~lindsey/lindsey.html, Royal Institute of Technology(KTH), Frescativ.24,10405 Stockholm, Sweden tel:46-8-16-10-74, fax:46-8-15-86-74 From owner-starship-design Mon Mar 17 11:34 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["1894" "Mon" "17" "March" "1997" "20:34:05" "+0100" "Zenon Kulpa" "zkulpa@ippt.gov.pl" nil "50" "starship-design: Re: One-way to Mars?" "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id LAA06783 for starship-design-outgoing; Mon, 17 Mar 1997 11:34:47 -0800 (PST) Received: from zmit1.ippt.gov.pl (zmit1.ippt.gov.pl [148.81.53.40]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id LAA06744 for ; Mon, 17 Mar 1997 11:34:39 -0800 (PST) Received: (from zkulpa@localhost) by zmit1.ippt.gov.pl (8.8.5/8.7.3) id UAA05483; Mon, 17 Mar 1997 20:34:05 +0100 (MET) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199703171934.UAA05483@zmit1.ippt.gov.pl> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Zenon Kulpa Content-Type: text Content-Length: 1893 From: Zenon Kulpa Sender: owner-starship-design To: starship-design@lists.uoregon.edu Cc: zkulpa@ippt.gov.pl Subject: starship-design: Re: One-way to Mars? Date: Mon, 17 Mar 1997 20:34:05 +0100 (MET) Here goes an excerpt from an article: "Boston NSS February Lecture Summary" by Bruce Mackenzie, available in full at: http://www.seds.org/spaceviews/currentsv/nss-news.html#1 Look also at the other articles in the SpaceView online space journal: http://www.seds.org/spaceviews/ -- Zenon -------------------------------------------------------- No Deposit, No Return There are 2 basic reasons to go to Mars: 1. Science - to study geology, meteorology, biology. 2. To Live on Mars - Mars is a likely second home for us. If half the reason to go is to stay on Mars; then we should assume we can stay, and try it. A major cost and risk of Mars missions is bringing the people back to Earth. In Zubrin's Mars Direct plan, one of every 2 launches was devoted to the Earth return vehicle and its fuel manufacture. And, the most dangerous time may be liftoff from Mars in a relatively untested rocket which has been sitting on Mars for 4 years with minimal maintenance. Other mission plans have similar high cost and risk for the return trip. The life support systems you would have used for the long trip home could support you while you build simple building, such as these brick structures. Rather than taking fuel for the return trip, take tools and extra inflatable greenhouses. Suddenly, after the first mission, you have a permanent base. Obviously, we will not send people to Mars without the ability for them to get home. But that capability can be held in reserve and used in other ways later. Faced with half-year return trips and launch windows every two years, the new Martian would be safer to stay on Mars, then to risk a return trip to Earth. It would be the ultimate irony to never colonize Mars or anywhere else, simply because it was too expensive to insure safe passage back to Earth. ---------------------------------------------------------- From owner-starship-design Mon Mar 17 12:24 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["4143" "Mon" "17" "March" "1997" "21:23" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "80" "starship-design: Re: More Symmetry Stuff" "^From:" nil nil "3" nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id MAA00347 for starship-design-outgoing; Mon, 17 Mar 1997 12:24:08 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id MAA00279 for ; Mon, 17 Mar 1997 12:24:00 -0800 (PST) Received: from hengelo15.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0w6iwe-000Dp3C; Mon, 17 Mar 97 21:23 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 4142 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: More Symmetry Stuff Date: Mon, 17 Mar 97 21:23 MET >Thanks for your response, Tim! I had the feeling this one was just >going to fall flat. Instead, you've given me a chance for one more >iteration... > >>What is a "FTL virtual particle drive"? How is it thought to work? > >My understanding was that because virtual particles are "seen" (or at >least inferred) to travel faster than light, some people think you can >get more momentum out of them with a given amount of energy than you >could with a real particle. So a virtual-particle drive would use >Faster-Than-Light virtual particles as propellant, although the ship >itself would not travel faster than light. Hmmm, I never heard about virtual particles traveling faster than light, unless they tunneled. For example (static) electric fields are maintained by exchange of virtual photons. If indeed the field between two charged plates would be maintained by particles that move faster than light, we would have a very simple FTL communication device. >>What about black-holes? Aren't they coherent enough? > >Actually, (According to Mr. Price) they aren't. In our forward-time >view, we wouldn't expect two photons converging on a black hole (coming >from different directions) to be correlated in any way. However, two >photons emitted from a common source ARE considered to be correlated. >This is a time-asymmetric assumption; viewed in the opposite time- >direction the reverse would be true. Although we see the evidence of >this asymmetry all around us, there is no time-asymmetric law of physics >to explain it, and it is probably a result of the special boundary >conditions of Big Bang. > >A coherent radiation sink would have correlations between all incoming >particles. The correlation would be a result of their common Future, >although they would have no common Past. Am I missing something? These seem to be exactly the properties of photons being absorbed by a black hole. They often don't have a common past, but they are likely to have a common future somewhere inside the black hole. >We are used to seeing >correlations as a result of a common past, although viewed in the right >way the strange phenomenon of quantum mechanics can be seen as evidence >that certain correlations can be caused by a common future. So a >coherent radiation sink would be very different from a black hole. > >>Hmm, how do you get the mass out of the radiation sink (and into the >>conventional engine)? Would that not spoil the fun? > >Good point. I suppose it all depends on what sort of object our >coherent absorber would be, and whether it would be possible to use >reverse-causal mass in a forward-causal engine. I've been thinking >about this a little more and have come to a strange conclusion, based on >CPT symmetry. CPT symmetry is a physical principle (in both quantum and >relativity) that any system with opposite Charge, opposite Parity >(mirror-image), and opposite Time-direction, must act exactly like the >original un-reversed system. This would mean that if there was some >form of matter causally propagating backwards in time, it would most >likely be (mirror-image) antimatter. The Big Crunch, when viewed from a >CPT-symmetrical standpoint, would then look exactly like the Big Bang, >with the same amount of antimatter then as we have matter today. > >The strange thing, though, is that the future boundary conditions would >not allow this backward-time antimatter to annihilate with forward-time >matter. The antimatter Couldn't annihilate (in our temporal frame), >because it's constrained to exist at the end of the universe! But this >would mean that antimatter "created" at the Big Crunch would be very >different from the antimatter that we create in particle accelerators. Aren't you looking at the problem with "forward-time"-view? It may be that (mirror-image) antimatter annihilates with our forward-time matter, but that in the future some effect (yet not know by us temporal creatures) creates antimatter once again. (If this makes no sense, it may be because I've lost track of all the mirrors, forward/backward, anti/matters. Tim From owner-starship-design Mon Mar 17 23:38 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6252" "Tue" "18" "March" "1997" "01:35:26" "-0600" "Kevin Houston" "hous0042@maroon.tc.umn.edu" nil "138" "starship-design: Re: More Symmetry Stuff" "^From:" nil nil "3" nil "starship-design: Re: More Symmetry Stuff" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id XAA09239 for starship-design-outgoing; Mon, 17 Mar 1997 23:37:51 -0800 (PST) Received: from mhub1.tc.umn.edu (0@mhub1.tc.umn.edu [128.101.131.51]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id XAA09226 for ; Mon, 17 Mar 1997 23:37:48 -0800 (PST) Received: from maroon.tc.umn.edu by mhub1.tc.umn.edu; Tue, 18 Mar 97 01:37:48 -0600 Received: from pub-13-a-132.dialup.umn.edu by maroon.tc.umn.edu; Tue, 18 Mar 97 01:37:46 -0600 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <332E45BE.5980@maroon.tc.umn.edu> Organization: URLy-Bird Productions X-Mailer: Mozilla 3.0 (Win95; U) MIME-Version: 1.0 References: Content-Transfer-Encoding: 7bit Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: "Kevin \"Tex\" Houston" Content-Type: text/plain; charset=us-ascii Content-Length: 6251 From: "Kevin \"Tex\" Houston" Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: More Symmetry Stuff Date: Tue, 18 Mar 1997 01:35:26 -0600 Timothy van der Linden wrote: > > >>What about black-holes? Aren't they coherent enough? > > > >Actually, (According to Mr. Price) they aren't. In our forward-time > >view, we wouldn't expect two photons converging on a black hole (coming > >from different directions) to be correlated in any way. However, two > >photons emitted from a common source ARE considered to be correlated. > >This is a time-asymmetric assumption; viewed in the opposite time- > >direction the reverse would be true. Although we see the evidence of > >this asymmetry all around us, there is no time-asymmetric law of physics > >to explain it, and it is probably a result of the special boundary > >conditions of Big Bang. > > > >A coherent radiation sink would have correlations between all incoming > >particles. The correlation would be a result of their common Future, > >although they would have no common Past. > > Am I missing something? These seem to be exactly the properties of photons > being absorbed by a black hole. They often don't have a common past, but > they are likely to have a common future somewhere inside the black hole. > I think you are missing something here Tim. Although most of this discussion is as far above my head as Tau Ceti, I think I understand Ken here. Imagine you are at a black hole (far enough away to avoid nasty gravity effects) and you are assinged to count and catalog the photons that enter its event horizon. (so much for the glamour of being a cadet at the starfleet acadamy ;) Anyway, the first event you record is two photons arriving from different directions and they just happen to have the same wavelength, and are traveling in phase (even though by an estimate of their starting positions you calculate they originated 10 light-years apart) both are absorbed by the black hole (or at least you assume they have, since you never get to actually observe the crossing over) "what a strange coincidence" you say to yourself. Oh well, here comes the next photon. correction, make that photons. again, there are two more originating in different parts of the universe, traveling in phase, and having the same wavelenth (although they are a different wavelength than the first pair.) how long before you begin to suspect that this is more than coincidence? Congratulations, you have just witnessed the first coherent radiation sink. For all time, these will be known as "van der Linden black holes" ;) > >We are used to seeing > >correlations as a result of a common past, although viewed in the right > >way the strange phenomenon of quantum mechanics can be seen as evidence > >that certain correlations can be caused by a common future. So a > >coherent radiation sink would be very different from a black hole. > > Kind of like the article in the recent Scientific American about how to observe a particle WITHOUT affecting it? (don't yell at me about how this isn't possible, until you read "Quantum Shell Game" in the November 1996 issue of Scientific American) > >>Hmm, how do you get the mass out of the radiation sink (and into the > >>conventional engine)? Would that not spoil the fun? > > > >Good point. I suppose it all depends on what sort of object our > >coherent absorber would be, and whether it would be possible to use > >reverse-causal mass in a forward-causal engine. I've been thinking > >about this a little more and have come to a strange conclusion, based on > >CPT symmetry. CPT symmetry is a physical principle (in both quantum and > >relativity) that any system with opposite Charge, opposite Parity > >(mirror-image), and opposite Time-direction, must act exactly like the > >original un-reversed system. This would mean that if there was some > >form of matter causally propagating backwards in time, it would most > >likely be (mirror-image) antimatter. The Big Crunch, when viewed from a > >CPT-symmetrical standpoint, would then look exactly like the Big Bang, > >with the same amount of antimatter then as we have matter today. > > > >The strange thing, though, is that the future boundary conditions would > >not allow this backward-time antimatter to annihilate with forward-time > >matter. The antimatter Couldn't annihilate (in our temporal frame), > >because it's constrained to exist at the end of the universe! But this > >would mean that antimatter "created" at the Big Crunch would be very > >different from the antimatter that we create in particle accelerators. > > Aren't you looking at the problem with "forward-time"-view? It may be that > (mirror-image) antimatter annihilates with our forward-time matter, but that > in the future some effect (yet not know by us temporal creatures) creates > antimatter once again. > (If this makes no sense, it may be because I've lost track of all the > mirrors, forward/backward, anti/matters. Hmm, How about this: NB for best results, you must view this with a fixed width font. a simple diagram: M= matter propagating forward in time A= antimatter propagating backward in time EE= Event Energy (annihilation) ><= indicate "true" direction of propagation past<---------Time---------->future ^ M A | .> <. | .> <. S .> <. p .> <. a .> <. c .> <. e .> <. | .> <. | .><. V EE >From the view of us temporal limited creatures, a particle of Matter was exchanged for a particle of Antimatter. Don't ask me how charge conservation is maintained, I'm simply trying to make this understandable. I suppose that for the universe as a whole, charge conservation is maintained, or you might try to bring some virtual particles into this to balance it all out. -- Kevin "Tex" Houston http://umn.edu/~hous0042/index.html Webmaster http://www.urly-bird.com/index.html "Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods." A. Einstein From owner-starship-design Tue Mar 18 12:33 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["3239" "Tue" "18" "March" "1997" "21:32" "MET" "Timothy van der Linden" "TLG.van.der.Linden@tip.nl" nil "74" "starship-design: Re: More Symmetry Stuff" "^From:" nil nil "3" nil "starship-design: Re: More Symmetry Stuff" nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id MAA27499 for starship-design-outgoing; Tue, 18 Mar 1997 12:33:04 -0800 (PST) Received: from parijs.tip.nl (parijs.tip.nl [143.177.1.10]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id MAA27451 for ; Tue, 18 Mar 1997 12:32:59 -0800 (PST) Received: from hengelo12.pop.tip.nl by parijs.tip.nl with smtp (Smail3.1.29.1 #16) id m0w75Yp-000DxKC; Tue, 18 Mar 97 21:32 MET X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: X-Sender: t596675@pop1.tip.nl X-Mailer: Windows Eudora Version 1.4.3b4 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Content-Type: text/plain; charset="us-ascii" Content-Length: 3238 From: TLG.van.der.Linden@tip.nl (Timothy van der Linden) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Re: More Symmetry Stuff Date: Tue, 18 Mar 97 21:32 MET Kevin replied to me: >> Am I missing something? These seem to be exactly the properties of photons >> being absorbed by a black hole. They often don't have a common past, but >> they are likely to have a common future somewhere inside the black hole. >> > >I think you are missing something here Tim. Although most of this >discussion is as far above my head as Tau Ceti, I think I understand >Ken here. > >Imagine you are at a black hole (far enough away to avoid nasty gravity >effects) >and you are assinged to count and catalog the photons that enter its >event horizon. >(so much for the glamour of being a cadet at the starfleet acadamy ;) > >Anyway, the first event you record is two photons arriving from >different directions and they just happen to have the same wavelength, >and are traveling in phase (even though by an estimate of their starting >positions you calculate they originated 10 light-years apart) both are >absorbed by the black hole (or at least you assume they have, since you >never get to actually observe the crossing over) "what a strange >coincidence" you say to yourself. Oh well, here comes the next photon. >correction, make that photons. again, there are two more originating in >different parts of the universe, traveling in phase, and having the same >wavelenth (although they are a different wavelength than the first >pair.) how long before you begin to suspect that this is more than >coincidence? OK now that you force me to think deeper than just my initial guess, I've come up with two solutions: - Why should those photons come from different directions? Can't they just travel almost parallel and converge into the blackhole? Should the blackhole as a whole be coherent? The Sun (and most other larger photon sources) can't be coherent as a whole either. - If you could look at the photons that move near towards the event horizon, you would see them becoming more and more redshifted. In fact at the last moment they would have a frequency equal to zero. Since phase-difference has no meaning for particles with zero frequency, they would all look coherent. (One thing though, while the photons look red-shifted they actually are blueshifted.) >Congratulations, you have just witnessed the first coherent radiation >sink. For all time, these will be known as "van der Linden black holes" >;) > >> Aren't you looking at the problem with "forward-time"-view? It may be that >> (mirror-image) antimatter annihilates with our forward-time matter, but that >> in the future some effect (yet not know by us temporal creatures) creates >> antimatter once again. >> (If this makes no sense, it may be because I've lost track of all the >> mirrors, forward/backward, anti/matters. > > >Hmm, >How about this: > > > >From the view of us temporal limited creatures, a particle of Matter was >exchanged for a particle of Antimatter. Don't ask me how charge >conservation is maintained, I'm simply trying to make this >understandable. I suppose that for the universe as a whole, charge >conservation is maintained, or you might try to bring some virtual >particles into this to balance it all out. This seems to be the same as I had in mind, thanks. Tim From owner-starship-design Mon Mar 24 20:59 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["226" "Mon" "24" "March" "1997" "23:58:54" "-0500" "KellySt@aol.com" "KellySt@aol.com" nil "7" "starship-design: Dream Machines!" "^From:" nil nil "3" nil nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id UAA27795 for starship-design-outgoing; Mon, 24 Mar 1997 20:59:27 -0800 (PST) Received: from emout05.mail.aol.com (emout05.mx.aol.com [198.81.11.96]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id UAA27772 for ; Mon, 24 Mar 1997 20:59:25 -0800 (PST) Received: (from root@localhost) by emout05.mail.aol.com (8.7.6/8.7.3/AOL-2.0.0) id XAA14711; Mon, 24 Mar 1997 23:58:54 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-ID: <970324235853_1749638269@emout05.mail.aol.com> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: KellySt@aol.com Content-Type: text Content-Length: 225 From: KellySt@aol.com Sender: owner-starship-design To: owner-starship-design@darkwing.uoregon.edu, starship-design@lists.uoregon.edu Subject: starship-design: Dream Machines! Date: Mon, 24 Mar 1997 23:58:54 -0500 (EST) Hey! Ron Miller (Author of Dream Machines. A history of space ships in fact and fiction) contacted me. Seems he Likes the Explorer Class and such and wants to include them in future drafts of his book! Kelly From owner-starship-design Wed Mar 26 15:21 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["210" "Wed" "26" "March" "1997" "18:27:30" "-0500" "Bakelaar" "bakelaar@injersey.com" nil "8" "starship-design: hello everyone.. (again)" "^From:" nil nil "3" nil nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id PAA10985 for starship-design-outgoing; Wed, 26 Mar 1997 15:21:06 -0800 (PST) Received: from nj5.injersey.com (nj5.injersey.com [206.139.48.252]) by darkwing.uoregon.edu (8.8.5/8.8.5) with ESMTP id PAA10973 for ; Wed, 26 Mar 1997 15:21:03 -0800 (PST) Received: from pbakelaar.exit109.com (ppp031-tmrv.injersey.com [206.139.59.31]) by nj5.injersey.com (8.8.5/8.8.5) with SMTP id SAA08408 for ; Wed, 26 Mar 1997 18:27:30 -0500 (EST) X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199703262327.SAA08408@nj5.injersey.com> X-Sender: bakelaar@injersey.com X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: Bakelaar Content-Type: text/plain; charset="us-ascii" Content-Length: 209 From: Bakelaar Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: hello everyone.. (again) Date: Wed, 26 Mar 1997 18:27:30 -0500 (EST) yup im back for any of you that remember me. :) has anything happened recently? has anyone been developing any of the new LIT sites? if so, which ones? thanks for the info guys, ill be seeing ya around. ben From owner-starship-design Thu Mar 27 15:34 PST 1997 X-VM-v5-Data: ([nil nil nil nil nil nil nil nil nil] ["6496" "Thu" "27" "March" "1997" "15:34:19" "-0800" "Ken Wharton" "wharton@physics.ucla.edu" nil "108" "starship-design: Fast Ignition" "^From:" nil nil "3" nil nil nil nil nil] nil) Received: (from majordom@localhost) by darkwing.uoregon.edu (8.8.5/8.8.5) id PAA17856 for starship-design-outgoing; Thu, 27 Mar 1997 15:34:30 -0800 (PST) Received: from physics.ucla.edu (physics.ucla.edu [128.97.23.13]) by darkwing.uoregon.edu (8.8.5/8.8.5) with SMTP id PAA17830 for ; Thu, 27 Mar 1997 15:34:28 -0800 (PST) Received: from watt by physics.ucla.edu (SMI-8.6/SMI-SVR4) id PAA03067; Thu, 27 Mar 1997 15:34:21 -0800 Received: by watt (SMI-8.6/SMI-SVR4) id PAA27253; Thu, 27 Mar 1997 15:34:19 -0800 X-Authentication-Warning: darkwing.uoregon.edu: majordom set sender to owner-starship-design using -f Message-Id: <199703272334.PAA27253@watt> Errors-To: owner-starship-design@lists.uoregon.edu Precedence: bulk Reply-To: wharton@physics.ucla.edu (Ken Wharton) Content-Type: text Content-Length: 6495 From: wharton@physics.ucla.edu (Ken Wharton) Sender: owner-starship-design To: starship-design@lists.uoregon.edu Subject: starship-design: Fast Ignition Date: Thu, 27 Mar 1997 15:34:19 -0800 Hello all... Well, while the final-boundary condition idea did get tossed around more than I expected, I'll end it with the observation that even if those sort of objects DID exist, we wouldn't be able to interact with them (expect gravitationally and perhaps on a quantum level) without causing all sorts of impossible paradoxes. They would contain information to the future of the universe, and if we were to get that information, we could then use it to make a paradox by forcing that information to be incorrect. So, based on this fundamental problem, I'd say that, while an interesting concept, it's probably not going to get us anywhere. Just for completeness, I did a little research and found out that people HAVE tossed around the idea of inverse-antimatter galaxies de-evolving at the end of the universe. All speculation, though, seems to assume that the antimatter is no longer around, and has converted into matter. The way this would (supposedly) happen would be though baryon decay. According to all grand unified theories, protons (and neutrons) will eventually decay, leaving the universe with no stable matter except electrons and positrons. This is symmetric, so the recollapsing phase of the universe would then see electrons un-decaying into anti-protons and anti-neutrons. This would relate the proton decay time to the age of the universe. Also--and more interestingly--it might mean that all current experiments to detect proton decay may be off-base; they're looking for evidence of positrons that the protons decay into, and as I mentioned earlier, cosmological antimatter couldn't annihilate with matter because it's constrained to exist at the end of the universe. So looking for antimatter annihilations in giant underground detectors may not be the way to measure proton decay after all... Not to drop one subject without bringing up a new one, though, I just got back from the first Fast Ignitor Laser Fusion Workshop. The Fast Ignitor is a laser fusion concept that was declassified about three years ago, and is a plausible method of igniting a fusion reaction without needing Mega Joules of laser energy. (On the Mega-Joule scale, though, the DOE just authorized construction of the 192-beam National Ignition Facility. Cost: 1.2 billion.) The traditional scheme requires that a fusion-fuel pellet (DT) be uniformly illuminated with laser beams (or, indirectly, with laser-produced x-rays) until it compresses to the densities where fusion reactions will happen on a fast enough time scale. This time scale is simply the time that the fuel spends at these high densities due to its own inertia, so this type of fusion is known as ICF; Inertial Confinement Fusion. (As distinct from MCF, magnetically confined fusion, i.e. tokamaks) The way Fast Ignition would work is this: you would compress the fuel with the regular lasers to a much lower density. You need less energy in the main laser beams to do this, and there are many laser facilities in the world that are already capable of achieving the required densities. Then you'd bring in a separate short-pulse laser; the ignitor beam. This beam would be focused on the edge of the (semi- compressed) fusion pellet, and would be much more intense than the heater beams. This does not mean more energy, however; intensity is simply energy per time, and the ignitor beam would be a very short pulse. Heater beams need to be on the order of 10 nanoseconds long; the fast ignitor will be three orders of magnitude shorter; 10 picoseconds. Also, the heater beams are not at best focus; the ignitor beam needs to be as small a focus as possible. Focused down, the ignitor beam would need to have an intensity of at least 10e21 Watts per square centimeter. At these intensities, the ignitor beam will (hopefully) drill its way into the plasma of the fuel pellet, dump its energy into a beam of electrons, which would then propagate into the super-dense fuel region and ignite a fusion reaction in a small part of the pellet. The fusion burn would then spread to the rest of the pellet, and voila: fusion energy. So how realistic is this scenario? The ignitor beam is the hardest part. In a few weeks I'll be working on the first-ever experiments at 10e21 W/cm^2 intensities, using the Petawatt laser here at Livermore. However, it's only going to be 500 Joules in 0.5 picoseconds; the Fast Ignitor scenario will need the same intensity for at least twenty times longer; 10 kilo Joules in 10 picoseconds. And 50 kiloJoules would be a lot nicer. Scaling up a laser that's already pushing about five different limits isn't going to be easy. There are a lot of other problems as well, most of the big ones revolving around the electron beam; you'd need Giga Amps of high-density current to ignite the pellet. No one's even sure if the required electron beam parameters are theoretically possible, let alone how to make such a beam with a laser. But Fast Ignition would definitely be worth it. It would relax the energy requirements for fusion, and also enhance the fusion gain from 10-30x incident energy in regular ICF to over 1000x with a Fast Ignitor. Reducing laser energy also has the benefit that the lasers can fire more often; the National Ignition Facility may achieve ignition (by 2005), but it will only be able to ignite 2-3 pellets a day! Not exactly useful for a spaceship engine. The other good news is that lots of money is being poured into short- pulse laser experiments as a result of the fast ignitor concept. Lots of universities have short-pulse lasers, and can now directly contribute to fusion research without coming to the big Government laser facilities. So there will be a lot more people working on laser fusion for the next decade, and who knows, maybe something will actually come of it. At the very far stretch of the imagination, research into ultra-high intensity lasers may discover some completely unexpected physics. The electric field of a focused laser goes as the intensity times the wavelength squared, and every time a new record is set (as will happen next month on the Petawatt) there's always a remote chance for something new. Some of you have mentioned the possibility of extracting energy from vacuum and other optimistic ideas; if such a thing is possible maybe it will be huge laser fields that do it. I'll keep everyone posted... Ken