"BC" == Bob Cain writes:

BC Joseph Lazio wrote:

This statement fails to distinguish between the observable
Universe, which did indeed once fit inside a space smaller than
the head of a pin, and the entire Universe, which may very well
be infinite in extent.

BC How long would it take such a universe to become infinite?

The Universe didn't "become" infinite in spatial extent (if in fact
it is).

BC Right, nothing can "become" infinite. It was a leading question.
BC We are left, it seems, with the idea that if the universe is
BC infinite in extent, it went spatially from nothing to infinite in
BC the initial instant.

Not really. As we currently understand physics, we cannot describe
the "initial instant." Rather we extrapolate backward in time. For
extrapolations beyond a certain point in time, our extrapolations
become increasingly less certain.

A simple naive extrapolation would indicate that at a finite time in
the past, the temperature and the density of the Universe became
infinitely large everywhere. That's the initial singularity or the
"instant" of the Big Bang. That's also what I mean by, if the
Universe is infinite, then it's always been infinite.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html