RE: Big Bang from Big Black Hole

[Leigh Palmer <palmer@sfu.ca>]

Jack is right, of course. Any time we apply physics to phenomena beyond
the scale on which it has been tested in the laboratory or by relatively
reliable observational techniques (solar system mechanics, for instance)
we take a leap of faith. That is why Newton's Universal Law of gravitation
is so called. When we apply physics to the universe as a whole we take the
greatest leap of all.

> 	I partially agree with Leigh's response, although he seems to
> assume conservation of energy of the universe; I don't know why that
> needs to be true.

It doesn't; it is a leap of faith of the magnitude I stated above. In
one view of the Big bang cosmology the Universe is a vacuum fluctuation
from, presumably, a zero energy ground state, whatever that means. All
astrophysicists do not leap the same way! That would be an abandonment
of energy conservation, what someone called the greatest free lunch of
all time.

> 	The universe would emphatically not be a "super black hole".
> A black hole needs a "universe" to be in (spacetime and all that good
> stuff).  It is not at all clear what the environment that preceded the
> big bang consisted of?  Could it be characterized by a spacetime
> dimensionality?  A temperature?  A vacuum?

In any event if we are "inside" the black hole we would not necessarily
recognize the fact. After all, the size of a blacke hole with the mass
of the universe is within a couple of orders of magnitude of the size
we currently think the observable universe is. I am not a stolid
supporter of the Big bang cosmology, by the way. I feel that one of the
observational pillars on which it depends (the primordial light isotope
ratios) is insufficiently well known, and that the other pillar (the
cosmic microwave background) is its only robust support. Since the CMBR
can arise in other models (e.g. the Alfven-Arrhenius model, which is a
pulsating universe) the Big Bang is less uniquely selected without the
first pillar of nucleosynthesis.

> 	It is also not clear that the universe was in a singularity
> at the beginning.  The notion of singularity (as at the center of a
> black hole) is classical.  Possibly quantum mechanics forbids the
> existence of a "starting singularity".
> 	I think that the best that can be done today is to push the
> beginning back to t=10^(-43) seconds.  But then one must ask, "Seconds
> after what?"  That's the question.

In my view that is pushing very hard, indeed. It is a leap of faith of
a magnitude greater than my present tolerance. In between pushing back
that far and where we have got to, one must intercalate an era (or two)
of "inflation" with "negative pressure" and "faster-than-lightspeed
expansion", an a priori breach of faith in physics, and a fudge factor
larger than any I would tolerate from one of my students. Nonetheless
it is part of the "standard model" of the favored cosmology.

Ain't astrophysics great?

Leigh