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From: js2j@mhuxt.UUCP (sonntag)
Newsgroups: net.physics
Subject: Re: Re: why FTL is illegal, in small words
Message-ID: <374@mhuxt.UUCP>
Date: Mon, 26-Nov-84 09:49:55 EST
Article-I.D.: mhuxt.374
Posted: Mon Nov 26 09:49:55 1984
Date-Received: Tue, 27-Nov-84 04:01:34 EST
References: <683@gloria.UUCP> <785@ariel.UUCP> <119@talcott.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 34


On why FTL implies time travel:
> Now supposing I take off for Alpha Centauri and arrive there in less than
> the amount of time that it takes light to get from here to Alpha Centauri.
> Then for some moving observer, I arrived before I left!  Thus I have the
> power to travel backwards in time.
> 
> This causes a whole slew of problems.  If I can travel backwards in time, I
> could, for example, go back and kill my grandfather before my father was
> conceived.  I would have to then cease to exist (as would my father).  
> But if I never existed, who killed my grandfather?

I still don't understand!  Some moving observer, who obviously doesn't   
understand relativity thinks that you arrived there before you left, and
you believe him?  Assuming for the sake of arguement that you had some
method of traveling (let's simplify things) any distance in zero time.  Please
explain how this could be used to go back in time.  I don't want to hear
about any observer who thinks that you did.

Many thanks for all who helped to explain why c is a speed limit, but I 
still don't understand why violation of this speed limit implied time travel.

Jeff Sonntag
ihnp4!mhuxt!js2j

p.s.   What do you mean?  You're my grandson from the future come here to
       test a theory?  Wait a minute.... what if I just promise not to have
       children?  Oh, you have to be sure. 

	Wait!  Put down that gun!  I'm too young to  ^#~.................


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