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*To*: starship-design@lists.uoregon.edu (Starship list)*Subject*: Re: starship-design: Infinite Schizophrenia*From*: kuo@bit.csc.lsu.edu (Isaac Kuo)*Date*: Thu, 28 Aug 1997 20:27:30 -0500 (CDT)*In-Reply-To*: <199708282345.QAA14701@watt> from "Ken Wharton" at Aug 28, 97 04:45:53 pm*Reply-To*: kuo@bit.csc.lsu.edu (Isaac Kuo)*Sender*: owner-starship-design

Ken Wharton wrote: > Isaac writes: >>>Ahhh - but once you start thinking in terms of multiple universes, you >lose >>>the idea of probability. What does it mean to have one universe that is >>>less probable than another? If a universe exists its probability is one; >>If a universe exists, its probability of existing is indeed 1. So? >>If we can never access that universe, what difference does that make? >Maybe this is the source of the confusion. I AM talking about jumping from >one universe to another. Well, maybe so. I knew what you were talking about. I knew what I was talking about. >We got on this thread talking about possible time >travel theories, one of which was jumping into alternate universes as a way >of avoiding various paradoxes. But jumping into an alternate universe isn't a way of avoiding time travel paradoxes, it's a way of avoiding time travel altogether. If you're jumping into an alternate universe, you are by definition not traveling back in time. The future in this alternate universe has nothing to do with your past. >Sounds to me like you're just talking about an infinite number of possible >universes, not universes that actually exist. In our current understanding of wave-particle duality, these infinite number of "possible" universes actually do exist. That's why we can get interference patterns even if only one particle is being absorbed by the photographic plate at a time. You don't get smooth interference patterns from just 1 or 2 or a dozen possibilities. Maybe a million billion possibilities would work, but by Occam's razor it's simpler just to assume they _all_ are propogated. We make an assumption that all the other universes cease to exist once the difference between them and our own becomes big enough to notice. However, this is just an assumption--one which can't be proven or disproven. >I completely agree with you that there are >infinitely many possiblilities that the universe Could evolve into. >What I don't believe is that there ARE an infinite number of >different universes, and my consciousness is continually splitting >up into an infinite number of different "selves", and this particular >"self" I find myself in is just a matter of chance. That belief can never be proven one way or another, you know. However, if we develop time travel, the infinite number of different universes model will become the simplest explanation. >I think there are some strong philisophical arguments to >support this claim, even if the number of universes involved is infinite. >Occam's razor comes to mind. Actually, Occam's razor would suggest abandoning the notion of waveform collapse altogether and that this infinite continuum of parallel universes exist. It's simply not a necessary part of our current physics models that the other universes cease to exist at some point. >>BTW, out current understanding doesn't just involve 1 or two or a >>million million million simultaneous possibilities--it involves an >>infinite continuum of possibilities. It's not even a countable >>infinity. >When you say "our current understanding" what exactly are you invoking? >The sum-over-all-possible-universes theory says that this universe is the >sum of all possibilities, but that there is still only one universe. This sum is actually a probability distribution, of all possible universes. Calling the entirety "one universe" is simply using the terminology differently. >Other >theories treat the universe as a "block" that does not evolve in time but >rather was created with all quantum events already determined. Actually, it's irrelevant in this model "when" the quantum events are deteremined (not that it makes any sense, really). The relevant notion is that the choice of which possibility is the "real" universe is ever made at all. This is that notion of waveform collapse, where the "real" universe is picked randomly from the probability distribution of all possible universes. It is a slight, but intuitively compelling, complication to our model of the universe. You know about Shroedinger's cat, right? This is a thought experiment whereby a cat is placed in an opaque box, with a radiation detector attached to a vial of cyanide. If the radiation detector is hit by an atomic particle, it will release the cyanide and kill the cat. If not, the cat lives. A radiation source is placed by the detector so that there's a roughly 50-50 chance that it will emit an atomic particle at the detector within 10 minutes. The researcher then opens the box. What happens to the cat? Is it alive or dead? When did it die? According to the former model, the cat is both alive and dead--depending upon which universe one's looking at. According to the latter model, the cat is either dead or alive, depending upon what happenned in the real universe. Now here's the disturbing thing--even in the latter model, the cat was in a very real sense in the same 50-50 limbo state as in the former model until the researcher openned the door. Otherwise, we can't explain why interference patterns occur in low light situations and such. -- _____ Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo __|_)o(_|__ /___________\ "Mari-san... Yokatta... \=\)-----(/=/ ...Yokatta go-buji de..." - Karigari Hiroshi

**References**:**starship-design: Infinite Schizophrenia***From:*wharton@physics.ucla.edu (Ken Wharton)

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