Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site noao.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!zehntel!hplabs!hao!noao!sharp 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]