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From: sharp@noao.UUCP (Nigel Sharp)
Newsgroups: net.physics
Subject: Re: Big Bang Impossible
Message-ID: <446@aquila.noao.UUCP>
Date: Tue, 11-Dec-84 11:46:03 EST
Article-I.D.: aquila.446
Posted: Tue Dec 11 11:46:03 1984
Date-Received: Sat, 15-Dec-84 02:27:34 EST
References: <185@decwrl.UUCP> <17774@lanl.ARPA>
Organization: Natl. Optical Astronomy Observatories, Tucson, AZ USA
Lines: 34

> > If the whole universe was ina speck, said spec would have been a black hole
> > and the "big bang" could not happen.  No one has yet disputed this. Why not?
> 
> The answer is that the matter in your speck never crossed the "event
> horizon" of the universe, i.e., it never escaped from the black hole........
> 
> Since this radius is much larger than the aforementioned speck (and the
> present radius of the universe), one concludes that the big bang can
> easily happen since the mass of the universe is still within the
> "black hole" radius of a Giga-Parsec.  
> 
> Of course, this means that we are all living within a black hole, and
> that nothing in the universe can travel outside our own Schwarzschild
> radius of 10**9 Parsecs.
> 
> 					    bill peter
> 					    los alamos

Oh dear me no !  Over and over again I see this confusion.  The Universe is
NOT, was NOT, and NEVER CAN BE, a black hole.  Why ? I hear you scream.
Because a black hole has an asymptotically flat spacetime around it, and the
Universe has nothing around it (in fact, not even nothing).
A black hole is only defined in terms of the spacetime around it, whilst the
Universe is defined purely internally.  The reason for the apparent
coincidence that the mass of the Universe at which it is just closed
and the apparent radius of the Universe obey the same relation as the mass
and radius of a black hole, is that they are both governed by Einstein's
equations.  In fact, if you're still not convinced, look at it this way:
if the Universe is just closed, then it's gravitational energy balances
it's kinetic energy of expansion.  Thus, the net energy of the Universe
is zero - and since it's the total mass-energy which enters into the
black hole formula, it's clearly wrong.
-- 
	Nigel Sharp   [noao!sharp  National Optical Astronomy Observatories]