[ExI] fermi question alive and well

[Stuart LaForge]

John Clark wrote:

> For the zoo hypothesis to be true ET would have to somehow  
> circumvent the Second Law Of Thermodynamics (where does the waste  
> heat from ET's civilization go and why can't we find it?) and they  
> go to the trouble of performing this superhuman majical task for the  
> sole purpose of keeping ape descendants on a small planet ignorant  
> of their surroundings.  This all seems somewhat unlikely to me.

Looking for waste heat in the sky might be like trying to find needles  
in a haystack. There are plenty of invisible IR sources out there.  
Some of them even occasionally emit radio waves or x-rays. Astronomers  
classify them as brown dwarfs. 1 out 6 stars are thought to be brown  
dwarfs. Some are even thought to have halos and obscuring dust clouds.

So how precisely do we distinguish between brown dwarfs and Dyson  
swarms? Which is "waste heat" and which is just plain heat? If Tabby's  
star were permanently become dim, would we classify it as a brown dwarf?

When it comes to ET, I don't think we know precisely what we are  
looking for or how to go about looking for it.

Stuart LaForge