[ExI] If you follow the developments with Tabby's star . .

[Keith Henson]

On Sat, Sep 17, 2016 at 12:49 PM, Anders <anders at aleph.se> wrote:

> Let's see if I get the basic argument: you have a shell of radius R. The
> luminosity L is absorbed, and in the standard model assumed to all be
> radiated away outwards, making an outside temperature T=[L/4piR^2
> sigma]^(1/4). Except that in practice the radiation will, if nothing else is
> done, radiate equally to the inside, which means that L/2 extra IR now is
> radiated all over the place. So this gives L/(32 pi^2 R^4 )extra input of
> heating per square meter. That doesn't *seem* too bad...

If it is really a shell, then radiation to the inside will be in net
equilibrium.  Only the outside will radiate the energy from the star.

But if you are imputing the weird behavior of Tabby's star to
megastructure building aliens, you might want to consider the kind of
thermal power satellites we developed in the last few years.  Because
you want to block sunlight from the radiator tubes, they radiate in an
anisotropic way, the waste heat goes solar north and south and you
will not see the waste heat in the plane of the local ecliptic.  This
assumes the path from the star to Earth is on the local ecliptic.

So if we continue to find no excess IR from this star, it's supportive
of certain classes of space industrial objects that radiate heat
directionally.

I kind of suspect a Dyson sphere isn't practical.

Keith