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*To*: Isaac Kuo <kuo@bit.csc.lsu.edu>*Subject*: Re: starship-design: FTL and time travel*From*: "Kyle R. Mcallister" <stk@sunherald.infi.net>*Date*: Sat, 30 Aug 1997 16:02:33 -0700*CC*: Starship list <starship-design@lists.uoregon.edu>*References*: <9708290057.AA17640@bit.csc.lsu.edu>*Reply-To*: "Kyle R. Mcallister" <stk@sunherald.infi.net>*Sender*: owner-starship-design

Isaac Kuo wrote: > > Kyle R. Mcallister wrote: > > >Actually, the speed of light is not constant in a vacuum, but can be > >sped up...its too in depth to post, but it happens in a casimir cavity. > >Ask Steve, he knows more. > > Actually, the speed of light is constant in a vacuum, its just that > what we normally think of as vacuum isn't really completely empty. > The casimir effect is a means by which one can "suck out" from a > normal vacuum, making it a more perfect vacuum. The speed of > light within this cavity is thus made slightly faster than that > outside, closer to its "true" speed (in a "true" vacuum). It's > potential to "increase" the speed of light is an imperceptibly > small percentage, however. It's still less than 300,000km/s. Thats what I mean. Can you tell me the difference between negative mass and imaginary mass? I couldn't find it in Spacetime Physics > > >> >Unanswered question: If I travel 1600 light years in 2 years earth time, > >> >how far back in time do I travel upon return? > > >> It depends upon how much you accelerate away (sublight) from Earth > >> before returning. > > >Lets say I navigate around the star system 1600 lightyears away for, say > >5 years, and return to earth in 2 years earthtime. Is there an equation > >for this? > > Sorry, you just don't understand. It depends upon how much you > accelerate away from Earth before returning. Ah, I see now. Is this in Spacetime Physics? > I won't go through > all the calculations, because you won't understand them. Not > without drawings of space-time diagrams, at least, which really > can't be drawn in ASCII. Jay Hinson's FAQ on relativity and FTL > does a noble attempt at it (he regularly posts it on rec.arts.sf. > startrek.tech and rec.arts.sf.science less regularly). How can I get on one of these newsgroups? > > >Question: How do we know time runs backwards in FTL? Then again, how do > >we know time runs forward here... > > The problems with FTL causing causality problems have nothing at all > to do with time "running backwards" in FTL. It only has to do with > stuff in STL frames of reference. A naive calculation of time > dilation with FTL frames of reference would show time running in > an _imaginary_ direction. Strange? Yes. But it's because this > naive use of the formula for time dilation isn't valid for FTL > frames of reference. > > Like I said before, you'd have real difficulty getting an atom, > much less an entire clock, to exist in an FTL frame of reference.

**Follow-Ups**:**Re: starship-design: FTL and time travel***From:*kuo@bit.csc.lsu.edu (Isaac Kuo)

**References**:**Re: starship-design: FTL and time travel***From:*kuo@bit.csc.lsu.edu (Isaac Kuo)

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