Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!mtuxo!mtunh!mtung!mtunf!ariel!vax135!cornell!uw-beaver!tektronix!hplabs!sri-unix!DAM%MIT-OZ@MIT-MC.ARPA From: DAM%MIT-OZ@MIT-MC.ARPA Newsgroups: net.physics Subject: Quantum Mechanics Message-ID: <365@sri-arpa.ARPA> Date: Tue, 9-Jul-85 14:59:00 EDT Article-I.D.: sri-arpa.365 Posted: Tue Jul 9 14:59:00 1985 Date-Received: Sat, 13-Jul-85 09:38:15 EDT Lines: 50 Date: Monday, 8 July 1985 20:04-EDT From: mikes at AMES-NAS.ARPA (Peter Mikes) Some people believe that Einstein was right, rather then Bohr. I suggest that we do accept the fact that there is indeed a division of opinion concerning ... queastion whether QM is paradox free and logicaly consistent. Some people prefer not to see or face the problems - that's fine - but lets stop parroting the statement that 'all is fine and there is no paradox'. I joined this list with the hope of learning some physics and perhaps discussing some of the philosophical problems with quantum mechanics. I have been a little disapointed but maybe I can initiate the kind of discussion that I had hoped for. What bothers me about quantum mechanics is quite simple. Quantum mechanics is mathematically incomplete: there is no mathematically complete theory of what constitutes a physical system and how physical systems change over time. One approach is to say that physical systems are wave functions: points in a Hilbert space, and that the dynamics of such systems are governed by Schodingers equation. This is the most mathematically complete statement I have seen. However the Schrodinger's cat problem clearly shows that either this mathematical model is incomplete or we must accept multiple worlds. DeWitt, Hugh Everitt, and Wheeler endorse the multiple-worlds view. However most physicist seem to reject the idea that Schodingers equation is a complete model and instead choose to believe in the Copenhagen interpretation in which wave functions "collapse". In the Copenhagen interpretation the act of measurement causes the wave to change in manner not goverened by Schrodingers equation; the wave function collapses instantaneously and discontinuously into an eigenvector of the measured quantity. The problem with the Copenhagen interpretation is that there is no MATHEMATICAL theory of what constitutes a measurement; there is no mathematical theory governing wave function collapse. I would enjoy some discussion based on fairly sophisticated knowledge of the relevant mathematics. For example, if one accepts the DeWitt-Everitt-Wheller multiple worlds view then what are the philosophical consequences of the linearity of the wave function? The sum of any two solutions is a solution. Thus people "living in" one solution should not be aware of people living in another solution. Unfortunately the square-amplitute operator governing the probability distribution of the Copenhagen interpretation is non-linear. How can a non-linear effect arise from a linear equation? The square-amplitude operator is clearly important for understanding physical experiments. This seems to be a flaw in the multiple worlds view.