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

Michael M. Butler (butler@comp*
Tue, 16 Dec 1997 10:33:06 -0800

At 03:19 PM 12/16/97 +0100, you wrote:
>Michael Lorrey <> 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!!! :) :)


>Anders Sandberg Towards Ascension!
>GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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