Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!bellcore!decvax!decwrl!greipa!pesnta!hplabs!sri-unix!AI.Mayank@MCC.ARPA From: AI.Mayank@MCC.ARPA Newsgroups: net.physics Subject: Re: Faster than light. Message-ID: <322@sri-arpa.ARPA> Date: Wed, 26-Jun-85 18:05:37 EDT Article-I.D.: sri-arpa.322 Posted: Wed Jun 26 18:05:37 1985 Date-Received: Mon, 1-Jul-85 06:59:03 EDT Lines: 55 From: Mayank PrakashFirst of all, please, please D O N O T send messages both to the bboard and me. If I am corresponding on the bboard, I read the bboard. If I don't, I will say so in the message. So please reply only to the bboard. Thanx. Now for the objections raised to my earlier message - 1. (Knutsen, Jackson) John and Mary have to decide to beforehand the duration of the influence in order to communicate. The problem here is not whether they can use this setup as a communication device (as in a telephone), but rather can they use it to produce a contradiction with the theory of relativity. Unless the communication is 100% reliable, a contradiction will not result. To improve the reliability, one will have to detect errors and retransmit, and in that case, I am willing to bet that the effective speed will have to be less than that of light (although I have not done any calculations on this yet.) 2. (Gwyn) There are really two issues here - the theory of relativity, and the quantum theory of measurement. The first is well understood and empirically confirmed to as high an accuracy as is possible with the current technology. The second has been a painful thorn in the otherwise perfect Copenhagen interpretation of quantum mechanics ever since its beginning, and despite many attempts to date, has not been satisfactorily expounded. The point of the original message by McNelly however was if the superconducting ring was in contradiction to relativity, the answer to which is no, as I explained. Let me now take up your objection - essentially that a spatially distributed wave function collapses instantaneously upon measurement, and this seems to contradict relativity. Well, yes and no. Yes because how does the wave function communicate its collapse information to points far apart instaneously? No because that still does not lead to a contradiction. Consider your photon from North Pole example. It has a spherical wave function until the point it is detected on Earth, at which time it is localized, say within your eye. Now suppose another observer is moving along say in a spaceship on the other side of the North Pole, and is also trying to detect the same photon. True, simultaneity is relative, and what appears to us as a simultaneous collapse of the wave function cannot appear simultaneous to our friend, and indeed, it does not appear to him at all. Once the photon has been seen by you, it is gone, our friend wouldn't even know it existed. So he doesn't have to worry about simultaneity. Only the wave function of the photon needs to carry out its collapse in such a way that if it is observed at a point A, then it may not be observed at a different point B, independent of the time difference between the two observations, and the states (of motion) of the two observers. Admittedly not a very satisfactory situation, but at least free of contradictions. At any rate, this is the best that can be done until we really understand the quantum theory of measurement. - mayank. ========================================================================== II Mayank Prakash AI.Mayank@MCC.ARPA (512) 834-3441 II II 9430 Research Blvd., Echelon 1, Austin, TX 78759. II ========================================================================== -------