Re: Engineering Newsletter

[Kevin C Houston <hous0042@maroon.tc.umn.edu>]

On Fri, 19 Jan 1996, Timothy van der Linden wrote:

> >I think the heat could be kept below the melting point of silicon.  As 
> >the Temperature goes up, so does the blackbody radiation.
> 
> But since the doped silicon is quite temperature sensative 100 degrees extra
> may have a bigger effect than you would expect.

I guess that I have more confidence in materials science advances, I 
think that a Photovoltaic material can be manufactured that will work in 
the high temp/high rad environment
> >
> >
> >That reminds me of a great new travel method making use of Hiesenberg 
> >Uncertainty principle:  as Temperature approaches Abs Zero, Momentum 
> >becomes zero to the last decimal, and the position becomes _infinite_.  
> 
> It is not the position that becomes infinite but the PROBABILITY of its
> position that becomes infinite. May look the same, but is different. The

Ah, yes, I see.  I knew that, but must have forgotten it.  so i guess it 
would work, you just would be able to steer.  Oh well.  Back to the 
drawing board.

> The fact that a particle can move lightyears be everywhere is As you can
> see, this Although this may look as if it is conflict with the finite speed
> of light there is a deeper understanding that solves this "paradox".

I'm sorry, I don't understand your language here.  Can you please 
re-phrase, check your dictionary, or insert the word or words you may 
have dropped.

> >Solid yes.  Metal, no.  at one atm, hydrogen becomes an ice-like solid, 
> >which does not have any free electrons.  only at great pressures 
> >(ie Jovian core) does the hydrogen take on any metallic properties.
> 
> I didn't know that, do you know a subject or book about that, where I can
> search for in a library?

Sorry no, it's part of the great storehouse of knowledge that i have come 
across in almost fifteen years of reading every science magazine I can 
get my hands on.  i think this subject appeared in OMNI,  someone 
somewhere was claiming to have put a _lot_ of pressure on a small sample 
of hydrogen and gotten it to a metal state.
> >> (Note: Probably all robots will be worn out after a few years, so you may
> >> need 3 or 4 times more than you originally would think, that would only cost
> >> a few days extra)
> >
> >Any robot could probably repaired far cheaper than it could be re-built 
> >from scratch, and this could be done at any time, not just at the outset
> 
> Repairing is rather difficult, for some dumb replicating machine it is
> probably much easier to make a new one than to look for the non-working part
> and replace it. It is just like a conveyer belt, there is a gain because of
> the repetative task.

OK, I see.   but a small number of units could be devoted to the constant 
manufacture of robots (which would then go off and do other things) so 
that replacement units were always ready.
> 
> >in thinking about this, i was struck by the comment you made about the 
> >radius of the solar collector being about the same as the face of the 
> >moon, and i thought, what if instead of putting it (the collector) in 
> >orbit around the sun at Mercury's distance, why not just cover the 
> >surface of mercury with solar panels? (not too difficult if you have 
> >self-replicating robots) They could exist underground safely, and the 
> >maser array could be placed on the south pole of mercury (TC is below the 
> >ecliptic)  Mercury would provide more than enough counter-weight for the 
> >beam, and the low gravity would assist the robots in maintaining the arrays
> 
> Yes, that would also solve the problem of the solar-panels and laser-array
> being blow away by the photon pressure. A problem still present, is that the
> laser-array has to be directed, wich may be a problem on a rotating planet.

Perhaps not a problem at all, earth based telescopes track distant stars 
all the time.  Being placed at a polar position would decrease the 
rotational velocity to be countered, and if the problem is 
insurmountable, then an orbiting waveguide can be used

> 
> >> Computer circuits mostly need semi-conductors, so I think super-conductors
> >
> >Ever hear of a Josephson <sp?> junction?
> 
> Yes, but as far as I know a Josepson junction has nothing to do with
> transistor like properties. (Or am I mistaken?)
> 
> (What does <sp?> mean?)

<sp?> means spelling uncertain.  i think a Josepson <your spelling> 
junction is a tunneling transistor, and it only works in superconducting 
conditions, but don't ask me why, maybe steve knows.

> It is fundamental, it is limited by the paramagnetic energy of the
> electrons. If too many electrons are moving, the special conditions are
> distroyed and superconduction is lost. I looked through some books and found
> that the maximum magnetic field possible for a certain superconductor with
> Tc=20K was 36 Tesla (Probably enough) But I still don't know the maximum
> current.
> 
> The field would be have the same value at 1 cm distance from the center of a
> wire that conducts 350 Ampere. (rough approximation).

350 amps in a 1 cm wire ain't all that bad, but I know that the ceramic 
superconductors aren't nearly that good.

> 
> >Keivn
> 
> Is that your name in phonetic language? :)
> 

Know, eye Think That Kell'ys Bad Speeling virus Has infected me.   ;)

Kevin