From: rwallace@unix1.tcd.ie (russell wallace)
Subject: Re: Anybody? Anybody? Class?
Organization: Trinity College, Dublin
Date: Tue, 26 Jan 1993 08:45:13 GMT

In <1k1sg9INNj6n@shelley.u.washington.edu> dayne@byron.u.washington.edu (Dayne Miller) writes:

>Can anyone help with the following questions?

>1) What is the theoretical maximum density for information storage? In other
>words, using nanotech/quantum effects/whatever, could we get as dense as one
>bit per atom/molecule of the storage medium? More dense? Less? And how would 
>the info be stored; magnetically, holographically, or otherwise?

One of the great open questions of science is whether there *is* any
limit to the theoretical maximum density, i.e. it may be theoretically
possible to store infinite information in one electron. (Things like the
uncertainty principle make it seem on the whole improbable.)

A practical limit for the foreseeable future is to store one bit in a
medium-large organic molecule. It would not be stored magnetically, but
perhaps holographically, or mechanically (literally use a submicroscopic
mechanical arm to read the molecule).

>2) Is there an approximate value for the tensile/compressional/torsional
>strengths of General Products monomolecular hull material (from Niven's Known
>Space) other than "effectively infinite"?

No. I think however that it violates relativity, since the speed of
sound in a material is related to its strength and it sounds like the
speed of sound in GP hull material is greater than the speed of light.

>3) Years ago I heard about some U.S. Navy/DARPA feasability study concerning
>the possibility of using neutrinos to provide communication with submarines.
>Whatever became of that?

Nothing much I suspect, considering that neutrinos are totally
impractical as a communications medium. The data transmission rate
would be about 1 bit per millennium, and the enemy could listen in on
your transmissions from the comfort of his own home as they would pass
right through the Earth.

>4) In Dan Simmons' _Fall of Hyperion_, he makes reference to "coherent
>electron beams" ("CEBs", or "CEEBs", or something like that). Is this a
>weapon grounded in anything we have or are developing today?

No.

>5) Again from Niven: What *is* the theoretical minimum tensile strength of
>scrith (Ringworld foundation material)?

I make it about 30 million tons per square centimetre.

>6) More Niven yet: Is there any theoretical way in which to "temporarily
>neutralize the charge of the electron" in a manner similar to that of the
>Slaver disintegrator (and the proton as well, as in the Wunderland
>Treatymaker)? Maybe some aspect of superstring theory of which I am unaware?
>(Yes, that covers a *LOT* of territory.)

No. In fact the weapon seems to violate the law of conservation of
energy (where does the energy released by the disintegrating matter come
from? from the weapon's power pack? how does the weapon "know" how much
energy will be released by the matter its beam hits?).

Also, if you actually neutralized the charge on the electron in a
sizable lump of matter, the energy released would be greater than the
energy equivalent of the total mass of the object (!!!). One presumes
that the disintegrator only reduces the electron charge by a very small
percentage.

>7) Lasers consist of coherent, parallel quanta of energy emission. How perfect
>is the parallelism? In other words, how much spread will occur over, say, one
>light year in a perfect vaccuum? Or perhaps more importantly, how much spread
>(and scatter) can be expected over a given distance (AU, light year, light 
>minute, solar radius, whatever) given the mean density of solar and/or inter-
>stellar medium?

Even if your laser beam comes out perfectly parallel, there will be
diffraction. Perhaps a physicist out there can provide exact data; the
effect will in any case limit the effective range of a laser weapon to a
few tens of thousands of kilometres (perhaps longer for X-ray lasers).

>8) How feasible is David Brin's idea of using "refrigerator lasers" to cool
>objects in space? Is the idea dependant upon high-temperature superconductors
>(of heat, not necessarily electricity)? Or would any highly-efficient heat pump
>work?

The thing is thermodynamically legal as a heat pump, but there is no way
known to present-day science to actually achieve it. You would need an
*incredibly* advanced technology to make it work, if it could be done at
all.


--
"To summarize the summary of the summary: people are a problem"
Russell Wallace, Trinity College, Dublin
rwallace@unix1.tcd.ie