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/
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>
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