From: hinson@bohr.physics.purdue.edu (Jason W. Hinson)
Newsgroups: rec.arts.startrek.tech
Subject: Re: Not the Technical Manual
Date: 18 Nov 92 03:07:36 GMT
Organization: Purdue University Physics Department

news@sifon.cc.mcgill.ca writes:
<hinson@bohr.physics.purdue.edu (Jason W. Hinson) writes:
<>
<><6) CAUSALITY VIOLATION
<><
<><Jason Hinson regularly sermonizes on the net about the fact that faster
<><than light travel normally causes causality violation.  Causality is the
<><postulate that causes always preceed effects. If causality were violated
<><then events could occur spontaneously with their cause revealed only
<><after the fact. The possibility of causality violation would, of course,
<><make it difficult for one to predict future events.  That faster than
<><light travel can bring about causality violation is, of course, not
<><immediately obvious until one does a mental experiment analogous to the
<><one Einstein did with trains and lightening.
<><
<>(Stuff deleted)
<>
<><Jason Hinson points out, however, that if faster than light travel were
<><made possible by a special frame of reference then this causality
<><violation is avoided because the concepts of simultaneity and
<><instantaneity could be defined with respect to this special frame.
<>
<>(Stuff deleted)
<>
<><Unfortunately, or fortunately depending upon your point of view,
<><causality is also violated when one travels backward in time since
<><one's arrival in the past is not something that can be predicted.  In
<><addition to the time travel accomplished by the Enterprise via the
<><Slingshot Effect and by "cold starting the warp drive" (TOS:"The Naked
<><Time"), the original series allowed for time travel in "The City on the
<><Edge of Forever", "The Alternative Factor" and "All our Yesterdays".
<><The Next Generation, meanwhile, had "time vortices" in "Time Squared"
<><and "Yesterday's Enterprise" and time travellers in "Captain's Holiday",
<><"A Matter of Time" and "Time's Arrow".  It is not clear, therefore, that
<><faster than light travel on Star Trek need be such that causality
<><violation is avoided.  Let us then try to allow for faster than light
<><travel in such a way that preserves special relativity alone and thus
<><allowing for causality violation.
<>
<>You KNEW I would respond to this.
<
<Actually, I thought you'd be pleased.
<
<>As far as violating causality through FTL travel, I beleive I have a good
<>argument as to why it is not done in ST technology.  If it were, we would
<>see its effects all the time!  You get a distress call from a planet. You
<>are running out of time to get there.  All you have to do is get in the
<>right frame of reference out of warp, then enter warp, and you can get there
<>any amount of time after the destress signal was sent or even before it
<>was sent.  We do NOT see this at all.  This is why I don't think the idea
<>you mentioned about keeping the same F.O.R. you have before you enter warp
<>is correct.
<
<My idea, put simply, is that it doesn't matter what speed you're going
<at when you enter warp, you're still going to encounter the same
<physics once you do; in particular, there'd be no speed you could
<travel at that would enable you to time travel (backwards) once you
<entered warp.

OK, looks like I must sermonize some more, because you don't understand.
IF you travel FTL while keeping the same frame of reference you had 
before you went in, then IN ANOTHER frame of reference, you WILL be going
back in time.  Perhaps after reading the E-mail I sent you (the last one
which was correct), you will see that time travel is simple and hard to
avoid.         


<>
<>Finally, you seem to have a problem with me wanting a "special" frame of
<>reference as if it violates special relativity all together.           t
<
<(stuff deleted)
<
<Well I don't like special frames just as you don't like causality
<violation.  I admit it's personal taste; the fact is, if your going
<to travel at faster than light speeds then we need one or the other.


But yours (in a since) has both.  The problem is that if you have a
frame of reference in which your speed does not effect your FOR, then
you do not see the speed of light as being the same in all frames.
Both of us use this type of reference frame which occurs in warped 
space.  The difference is that yours allows many such frames, and 
this leads to the possiblity of violating causality; while mine 
insists that there be only one such FOR.

So, if you don't mind having both, then your way is OK.  I still prefer
mine.


-Jay
Xref: sparky rec.arts.startrek.tech:6448 rec.arts.startrek.current:19048