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

Anders anders at aleph.se
Sat Sep 17 19:49:54 UTC 2016

```On 2016-09-16 16:47, spike wrote:
> Ja. But if we look deeper into an argument I discovered shortly after
> Robert Bradbury perished (oy vey over five years that man has been gone, yet
> I miss his demanding presence as if he left us yesterday) that a Dyson swarm
> might need to direct its energy for a perfectly well-understood reason: it
> would overheat otherwise.  That Boyajian's star is closer than we thought
> argues for a more complete but entropy-hip Dyson swarm.
>
> Anders do you have buddies or contacts who are up to speed on this?  Do feel
> free to post them this meme sir, and feel free to take ownership of the
> idea, same goes for the rest here: A Dyson swarm might neeeeeed to direct
> that energy in a low-ish entropy state; otherwise it would cook eventually
> in its own IR band waste heat.  But by my calcs, it could do that and still
> extract pleeeeenty of energy to do what Dyson swarms do best: think.
OK, I will bring it up with Dr D.

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...

> Go Anders!  You have the science contacts and creds, I don't.  Go Anders!
> Davai Davai Davai!
Da Tovarishch! We will bury this problem in awesome equations!

--
Dr Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University

```