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From: knutsen@sri-unix.ARPA
Newsgroups: net.physics
Subject: Re: Faster than light
Message-ID: <316@sri-arpa.ARPA>
Date: Tue, 25-Jun-85 21:08:11 EDT
Article-I.D.: sri-arpa.316
Posted: Tue Jun 25 21:08:11 1985
Date-Received: Fri, 28-Jun-85 03:21:02 EDT
Lines: 27

From:  knutsen (Andrew Knutsen)

> To do this, she will have to apply an
> external influence to the system for a certain duration. However, due to
> uncertainty principle, she cannot be certain that the system is an the state 1
> at the end of this duration. She can only be sure that it is in state 1 with
> probability, say 98%, and in state 0 with probability 2%. To decipher this
> message, John will now have to make a measurement on the system, and he will
> find it in state 1 with probability 98%, and in state 0 with probability 2%.
> But, no matter which state he finds the system in, he does not know what the
> probabilities are (if he did, he wouldn't have to make the measurement, as he
> already knows what state Mary INTENDED the system to be in, i.e., what she was
> trying to communicate). 

	Can't John and Mary decide beforehand what the duration of influence
is, and therefore the probabilities are? And using those probabilities come up
with a suitable ECC? There is a certain probability of mistake in any medium.

> This experiment reminds me of the so-called EPR (Einstien-Podolsky-Rosen)
> paradox 

	Its long been agreed that no info can be transmitted via EPR
(well by most people anyway)... The people receiving the particles cannot
influence their state, only measure them. The "paradox" is due to the undecided
correlation, not superluminal info transfer.

Andrew