[ExI] The Great Silence again

[Damien Broderick]

On 4/26/2011 12:59 PM, Keith Henson wrote:

> They don't even build shells around their stars and dim them to IR.
> At least not that we notice so far.

Are you absolutely sure? Galaxies are surrounded by annuli of invisible 
mass, and there are vast voids between clumps of galaxies. Not making 
any superstitious, glib claims here, but it might not be *impossible* 
that radiating hyperintelligent cultures would leave such footprints. 
I'd been hoping to write something about this with Robert Bradbury, but 
then he upped and died on us.

Damien Broderick