Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site oddjob.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!oddjob!sra From: sra@oddjob.UUCP (Scott R. Anderson) Newsgroups: net.physics Subject: Re: White Holes? Message-ID: <937@oddjob.UUCP> Date: Fri, 23-Aug-85 12:28:38 EDT Article-I.D.: oddjob.937 Posted: Fri Aug 23 12:28:38 1985 Date-Received: Sun, 25-Aug-85 05:26:22 EDT References: <3656@decwrl.UUCP> <166@prometheus.UUCP> <490@talcott.UUCP> Reply-To: sra@oddjob.UUCP (Scott R. Anderson) Organization: University of Chicago, Department of Physics Lines: 48 Summary: In article <166@prometheus.UUCP>, pmk@prometheus.UUCP (Paul M Koloc) writes: >> Two things tell us that the universe isn't continuous. First, the "big bang", >> and second, the constant "h bar" or even the fact that particles are not >> points. And in another article, >> Particles aren't points. They have a "delta function" >> over a discrete distribution width in space, and if there is an >> symmetry then there is a "delta function distribution" in time as well. So far as we know, the "fundamental" particles (quarks, leptons, etc.) ARE points. Experiments have yet to determine any finite extent for these particles. I believe that the current upper limit on the radius of the electron is 10^(-18) meters or 0.001 fermi. Such particles are described by wave functions, which under appropriate conditions (i.e. the particle is at point x) are delta functions. A delta function has no width, as it is non-zero only at x. This is how one describes a point particle quantum-mechanically. In article <490@talcott.UUCP> tmb@talcott.UUCP (Thomas M. Breuel) writes: > >Time is, of course, treated as a real variable in QM, and you >can't just go from differential equations in time to difference >equations and still have a working QT (at least I have never seen >such a theory... it would definitely be interesting, though). >.... >Your remark about QM and discreteness of space strikes me >as even odder. If you know of a way of representing QM on >a lattice, I would like to hear about it. This is done on a regular basis in field theories, although only as a calculation technique. The procedure uses the path integral formulation of QM and discretizes space-time onto a lattice with some lattice spacing 'a'. After everything is all said and done, the limit a -> 0 is taken. Lurking nearby, however, is the question of the distinguishability of small a (e.g. Planck Length) from a = 0. At this point, we can't tell the difference because the energies required are so enormous. If space were discretized, though, there would be some probability of "Umklapp" processes occurring, in which a particle could change it's momentum for no apparent reason. Scott Anderson ihnp4!oddjob!kaos!sra