Re: Dyson Dumb ells: Was: Re: the ultimate refrigerator

Michael Lorrey (retroman@together.net)
Wed, 17 Dec 1997 07:59:34 -0500

Michael M. Butler wrote:
>
> At 03:19 PM 12/16/97 +0100, you wrote:
> >Michael Lorrey <retroman@together.net> writes:
> >
> >> This gives me a solution to the Cosmic Filter dillemma. Rather than a
> >> Dyson Sphere radiating its encircled star's output as black body
> >> radiation, the inside surface would be coated in thermal superconductor
> >> material.
> >
> >Are there any thermal superconductors? I have a strong feeling this is
> >a myth started by Larry Niven's mistake in some of his books that
> >electrical superconductors are thermal superconductors. Of course, I
> >see nothing wrong the idea of phonons somehow forming coherent pairs
> >or something similar, but it appears very unlikely.
>
> Appearance is not always reality. :)
>
> Superfluid He is a thermal superconductor.
>
> This means every part of a single mass of such liquid helium (in the
> form/state, I think, also called Helium-III) is (reported to be) exactly
> the same temperature, and fluctuations in temperature occur uniformly in
> the entire mass.
> At least, this is how it was reported to me some decades ago.
>
> I think the explanations you give (both re: Niven and re: phonons) are
> close to the mark. Niven did get it wrong, and the phonon coupling may be
> the limiting factor. If so, there's still be speed-of-light lag in a large
> enough mass of He-III.
>
> I *love* telling Anders something he doesn't know. It happens *so*
> rarely!!! :) :)
>

Thanks for some great info. Yeah, I can usually count on Anders to come
up with good nitpicks that usually help improve/refine things, as a few
others also can.

Now, what is the operating range of He-III for thermal
superconductivity? At what distance from a given star would a shell of
such material need to be to absorb all imput without going out of the
operating range, and what would a good shell size be for a black hole
for cooling??? WOuld the black hole radius be small enough that you'd
have a huge star shell studded by lots of small black hole shells???

-- 
TANSTAAFL!!!
			Michael Lorrey
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