From: lwall@netlabs.com (Larry Wall)
Newsgroups: misc.writing
Subject: Re: Which way is out??
Date: 8 Apr 92 16:52:10 GMT
Organization: NetLabs, Inc.

In article <92098.140428KVJLC@ASUACAD.BITNET> KVJLC@ASUACAD.BITNET writes:
: 
:    Answer me a question, and I will lie.
:    answer me a lie, and I will question.
: ... quoted from someone

Hmm, when you say that, are you lying, or questioning?  :-)

: My question to SCI-FI, and the like, writers.
: 
:     If a person returns to the past and attempts to alter it or does;
: 
:     a.)  would the change occur before he returns to the future
:     B.)  or would the change occur after the return trip?
: 
:     If the change occurs before the return to the future, how would
: he/she return; assuming things would be different?
: 
:     or, if things don't change until the return trip, then wouldn't
: it be possible for the change to never occur?

Once you've posited a causality violation such as time travel, any and
all results are possible, depending only on the whim of the writer.  All
of the above tacks have been taken at various times by various authors.

: Some history:
: 
:     If for some reason, someone was able to return to the time when
: Abe Lincoln was killed.  Maybe a couple of minutes before, and foils
: the murder.  Lincoln lives, but does that necessary mean that destiny
: was or would now change??

Depends on whether you really believe in "destiny".  One approach to
all this is the "inertia of history" notion, that just because you
prevent Booth from doing in Lincoln doesn't mean he's not going to be
done in by someone else next week, such that the other timeline
converges back to our familiar timeline (though not necessarily
by the time that our original time traveler came from).  In some
sense this is like the Copenhagen interpretation of quantum mechanics,
in which the fact of our observation of a particular timeline causes
the waveform of possible universes to collapse into our (more or less)
single privileged timeline.

If you don't believe in "destiny", then you get divergence, which is
basically the same as the "many worlds" interpretation of quantum
mechanics, taken on a macroscopic level.  In that case you'd have to
have some way of selecting which future you wanted to go back to, maybe
like a thread that attaches you to your original timeline, and when you
go back you never get to see the fruit of your labors, since that's in
some other timeline.  Or maybe you've destroyed your original timeline,
in which case you can't go back, or can only go back to some situation
resembling your original situation in some authorially managed way.

: Is this a plot or what?   -- don't anyone say 'what'.

Sure, it's a plot.  This has been proven many times over...  :-)

[In another timeline I didn't say that.  Instead I said, "No, Booth
acted alone."  In yet another timeline I answered "It's not an entire
plot, but it's the cute idea on which base to a plot, what some might call
a 'macguffin', or what my wife calls 'half of an idea'."  Note that in
*no* timeline did I say "proved" instead of "proven".  :-)

[Glo says (when I called her to ask for the spelling of macguffin),
"To answer your basic question, the best way to find out if an idea
would make a good time travel story is to read all the time travel
stories that have already been written.  Failing that, the second best
plan is to assume that whatever idea you have has already been used by
somebody, because it probably has been.  What this means is that your
story has to have something else to offer as well."]]

Your favorite foil,
Larry Wall
lwall@netlabs.com