Re: starship-design: Re: Paradox

[kuo@bit.csc.lsu.edu (Isaac Kuo)]

Ken Wharton wrote:
>Lee writes:

>>Does anyone know of any arguments that would tend to prove or disprove
>>the case for paradoxes? I don't mean FTL in particular, just time travel
>>paradoxes.

>Ooh-- the philosophy of time travel.  I've run across three possibilities:

>A) All future time travel is ALREADY taken into account in our present,
>and is therefore self-consistent.

This possibility is more problematic than it first appears, but
according to current theory, it is possible due to the dual nature
of wave-particles.  It's a lot more like the "many worlds" scenario
than you'd think.

>B)  The second possibility is the alternate reality, where by going back in
>time the universe branches off into a "new" version of what's happening.
>This isn't quite as philisophically unweidly as A), but it does have some
>problems.

This possibility is rather easy to grasp, but the problem with it is
that by symmetry, every time you travel FTL, you are travelling into
a "new" universe.  What happenned to the old universe?  Does it
continue, with you winked out of existence?  Or does it cease to be
and you've murdered everyone you ever cared about?

>...  But at least in this case, you CAN kill your grandfather;
>you don't need to invent some physical mechanism to keep you from doing 
>whatever you want.

No you can't.  You can't kill _your_ grandfather.  You can only kill
someone a lot like your grandfather who's an inhabitant of this new (?)
universe.

>C) The third, and most philisophically pleasing possibility has been hitting
>the bookstands in the last few years, in SF like "Pastwatch" by Orson Scott
>Card and "Einstein's Bridge" by John Cramer.  In this, by travelling backwards
>in time you destroy the entire universe that exists between the time you
>leave and the time you arrive, and start creating a new one.

This isn't time travel at all, any more than perfectly reconstructing
a destroyed building.  It's the same principle, but applied on a much
larger and intricate scale.

This is actually identical to the previous possibility, except that it
specifies precisely what happenned to the old universe.
-- 
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
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