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From: stuart@rochester.UUCP
Newsgroups: net.sf-lovers
Subject: FTL does not create paradoxes - future not past
Message-ID: <7162@rochester.UUCP>
Date: Tue, 29-May-84 11:19:10 EDT
Article-I.D.: rocheste.7162
Posted: Tue May 29 11:19:10 1984
Date-Received: Fri, 1-Jun-84 07:37:33 EDT
Sender: stuart@rochester.UUCP
Organization: U. of Rochester, CS Dept.
Lines: 43

From: Stuart Friedberg  <stuart>
References: <3894@utzoo.UUCP>, <937@dciem.UUCP>

I initially responded directly to dciem!ntt, and then decided this was
of general interest.  (assuming anyone is interested at all)

While I agree that FTL looks like time-travel, I don't think it looks
like travel into the past.  Instead it always looks like travel to and
from the future relative to any observer.  Thus there is not a chance
of creating paradoxes by combining FTL and remote control, etc.  At least
not the way it's normally imagined (remember, this is still fiction)
to work.  You don't have to use any complicated arguments to make a
pretty strong case that while the relative future may be involved, the
relative past never is.

Imagine two star systems, 10 light years apart, and that people have
FTL (assume instantaneous) travel.  Observers in system A note
"current" events in system A and ten year old events in system B.
Analogously for observers in system B.  Now someone blips from A to B.
As far as the "A" viewpoint goes, the traveller has gone into the
future (not the past) since the traveller is getting "on-line" what
will take ten years to affect those still in system A.  As far as the
"B" viewpoint goes, the traveller has come from the future (not the
past) since he can report events which will not impact B for ten
years.

Now, what happens when the traveller "blips" back from B to A?  Well,
the "A" viewpoint is that he went into the future and came back from
the future.  The "B" viewpoint is that he came from the future and
went back the future.  At no point does any modification of the
(relative) past occur.  Perhaps paradoxes can arise, but they aren't
of the "go back and kill your grandfather nature".  I would have to
have a more detailed "explanation" of FTL and the way paradoxes can
arise before I would agree, though.

P.s.: From the standpoint of the traveler, he is *always* going to the
future.  Calendar dates at *each* of his stopping points are monotonically
increasing and, of course, his local "biological" time always advances!
(substitute she for he if you prefer)

				Stu Friedberg
			{seismo, allegra}!rochester!stuart
				stuart@rochester