[ExI] Fermi question, was is a FTL drive a dream . . .

[Eugen Leitl]

On Tue, Dec 20, 2011 at 08:26:08PM +0100, Stefano Vaj wrote:

> Could we ourselves really make us blatantly visible to a civilisation the
> other side of Andromeda even if we considered it a top civilisational
> priority?

Best bang for the buck would be lasers. You can easily outshine
the Sun in narrow enough spectral bands.
 
> I have dimmers everywhere at home, but dimming a galaxy would be a
> technological feat on quite different scale...

Dimming a galaxy would not be any more difficult than dimming a
single star. And it's pretty easy to dim a single star, provided
you have enough orbiting material in the system. You do it with
an ISRU with self-rep closure over unity. The shorter the self-rep
times the sooner you blanket it out.

With approaches like 
http://apl.aip.org/resource/1/applab/v95/i22/p223503_s1?isAuthorized=no
you need really little mass. Roughly about the mass of the Moon,
or about the entire asteroid belt, roughly. It wouldn't take long
to disassemble by a self-rep system, as the mass is predispersed
and is sitting in shallow gravity wells.