Re: GR Math Predicts a Black Hole At a Big Bang

From: Jim Black (ghytrfvbnmju7654_at_mail.com)
Date: 08/27/04 

Date: 26 Aug 2004 18:19:17 -0700

rhooker123@hotmail.com (bobbyhaqq) wrote in message news:<689922c7.0408252314.1539b3e6@posting.google.com>...
> These question comes up again and again, I raised it a couple of years
> ago as I was learning GR, which I have still to learn but now I have
> some sense of why it is so much harder than SR, and was dismissed
> though in a much more pleasant manner.

Mitchell didn't ask a question. It's only asking a question if you
want to know the answer. Many people, including myself, have tried to
give answers to these challenges, but Mitch refuses to listen to
anything. You can look for yourself on the Google archives. Mitchell
still even refuses to admit that "light speed acceleration" has no
meaning.

> Firstly the singularity, which would hold the Universe in place like a
> black hole (what ever you call it) IS as yet unresolved question of
> physics. Inflation is not a much an explanation as a word.

"Inflation" is an additional acceleration of the rate at which the
early universe was expanding, postulated to explain why the observed
universe is so flat and isotropic. I believe you are correct to say
it has not really been explained, but it actually has little to do
with the question.

> We still don't have a theory for how a singularity could explode and
> produce a universe which itself would contain singularities which, in
> theory, should prevent all energy, matter, and information for
> escaping or expanding.

No one knows what happened at the moment of the initial singularity,
if there was one, but what happened after that is not so much a
mystery. Google "Robertson-Walker metric" if you want to see the
math. General relativity definitely does not predict that the
universe ought to immediately recollapse, at least not if it started
out under the right conditions.

As far as black holes, it is not the singularity that keeps all
information from escaping, but the geometry of the space-time around
it, which was fixed by the matter that fell in when the black hole was
formed. Nothing can escape the black hole, not even gravitational
influences.

As far as what exactly what it takes to form a black hole, I'll have
to crack a few books and do a bit of work before I understand it
myself, but it's not just "enough matter within a certain amount of
space." The criterion for doom I've seen is that there exists a
closed trapped surface, which is defined by the peculiar property that
if a piece emitted light in the direction normal to the surface, the
surface formed by light would have less area than the surface it came
from, no matter whether the light was going in or out. How to relate
this to the matter that controls the geometry I don't know, but I can
tell you that in the early universe, there were closed surfaces that
had precisely the opposite property -- the area of the surfaces of
light would be larger. This has been used to show that there would
have to be a singularity at the beginning of the universe, if general
relativity as we know it applies there, which it does not.

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