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

Anders Sandberg (
17 Dec 1997 11:27:56 +0100

Michael Lorrey <> writes:

> 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???

A quick guess is that it would correspond to the superfluid state,
around 2.14 K, which means you need an awfully large shell around the
star to keep it superfluid (and you need to do someting about the
background radiation, which is hotter; maybe it can be dealt with
using the black hole cooling).

> Michael M. Butler wrote:
> >
> > 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.

Thanks you both! Comments like that really make me happy!

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