[extropy-chat] ultra-compact dwarfs found lurking

[Spike]

> Damien Broderick

> >If just a few of the
> >stars start running into each other and producing a black hole
> >that eats other stars the whole thing could go "poof" in a very
> >short period of time.
> 
> I've never understood this idea. If you have a standard 
> binary system, it's effectively as massive (in its impact on 
> stars at a decent distance) as a 
> stellar hole that's eaten a neighboring star, surely?


That's right: at a reasonable distance a black hole is
gravitationally the same as a tight binary or multiple 
system of ordinary stars.  The way writers describe black 
holes can sometimes be misleading.  Galaxies could contain
jillions of black holes and still be stable, all 
continuing in their collectively serene march about
the center of the galaxy.  This confused me many years
ago when I heard theories about the galactic centers
possibly containing large numbers of black holes, for
I wondered why they wouldn't just combine to form one biggie.
So I worked out the orbit mechanics and convinced myself
that such a system could be stable for eons.  spike