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From: gustav@swanee.UUCP
Newsgroups: sci.philosophy.tech
Subject: Re: Causality (Was: Aspect experiment)
Message-ID: <334@swanee.OZ>
Date: Sun, 14-Jun-87 00:34:37 EDT
Article-I.D.: swanee.334
Posted: Sun Jun 14 00:34:37 1987
Date-Received: Mon, 15-Jun-87 03:35:38 EDT
References: <567@sri-arpa.ARPA> <785@klipper.cs.vu.nl> <1904@sphinx.uchicago.edu>
Organization: El. & El. Eng., Uni. of Western Australia
Lines: 30
Keywords: causality special relativity FTL hail eris
Summary: You have to reinterpret the events

When you look closely at such events, you'll see that you can still
preserve the causality, but you have to reinterepret what you observe
depending on the system of reference. If you have two particles A and B
moving with subliminal speeds and one of them, say, A emits tachyon
which is then absorbed by B (fully equivalent to your argument with
shooting the bullets at one another), from another system of
reference, this will look like B emitting an anti-tachyon which is
then absorbed by A. If the B dies upon receiving a tachyon from A in
one system of reference, in the other one it will die because of the
energy released in the emission process.

There is nothing new about particles which move back in time being
seen as antiparticles. The only novelty is that the same tachyon will
be perceived either as a particle or as an antiparticle depending on
the system of reference it is observed from.

Another thing is that if you look at events of this kind, you start
realising that the whole concept of causality is somewhat in doubt.
We can observe here some events which are connected with one another
through tachyon links, but the interpretation as to what is the cause
and what is the effect depends on system of reference. What does not
depend on system of reference is the physics of these events itself:
i.e. the fact that they are CONNECTED through tachyon links.

This shouldn't be anything new to those who studied EPR paradox
enshrined in Bell inequalities and in recent experiments which
seem to confirm that the causality as perceived by Einstein is
indeed violated in the domain of quantum mechanics. Whether it is
due to tachyon links or to something completely different still
remains to be seen.