From: Michael M. Butler (butler@comp*lib.org)
Date: Tue Dec 16 1997 - 11:33:06 MST
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!!! :) :)
MMB
>
>--
>-----------------------------------------------------------------------
>Anders Sandberg Towards Ascension!
>asa@nada.kth.se http://www.nada.kth.se/~asa/
>GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
>
>
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