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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 Prakash 

First 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.


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II  Mayank Prakash  AI.Mayank@MCC.ARPA      (512) 834-3441		II
II  9430 Research Blvd., Echelon 1, Austin, TX 78759.			II
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