🚀 go-pugleaf

In article <29SEP199220244986@zeus.tamu.edu> dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes:
>This makes sense. What I don't understand is why a region of high density
>homogeneity does not recollapse in a time appropriate to that density. I.e.
>if the universe were filled with stars, in the density of a galaxy, the
>universe would have recollapsed long ago. The region of space which is
>inside a galaxy satisfies the same local einstein equation as the above
>recollapsing example, so why do galaxies live so long?

'Cause they're smaller.  I'm sure one can work out the math, but
it's bound to amount to just that.  For example, one can have
a fist-sized ball of iron, which will essentially never collapse
(quantum fluctuations aside), but a galaxy-sized ball of iron
would collapse mighty fast.

Galaxies are not all *that* dense and they're spinning around (at least
lots of them).  So they will take a while to collapse.  It's become
widely accepted that many galaxies have black holes at their centers.
These black holes are eating stars at a decent rate and should only
be billions and billions of years before they suck up most of the
galaxy, or at least the dense inner part.

Does anyone have estimates on how long this munching process should
take and how it will proceed?