Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 8/28/84; site lll-crg.ARPA
Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!bellcore!decvax!genrad!panda!talcott!harvard!seismo!lll-crg!muffy
From: muffy@lll-crg.ARPA (Muffy Barkocy)
Newsgroups: net.sf-lovers
Subject: Back to the Future (spoiler)
Message-ID: <741@lll-crg.ARPA>
Date: Sun, 28-Jul-85 13:15:37 EDT
Article-I.D.: lll-crg.741
Posted: Sun Jul 28 13:15:37 1985
Date-Received: Wed, 31-Jul-85 08:23:23 EDT
Distribution: net
Organization: Lawrence Livermore Labs, CRG group
Lines: 25

First, since the original Marty, who we are following, goes
back to the changed future, I assume that Doc's time machine
does not care what time-line it came from, it just translates 
n years forward or back from its current time.

Given this assumption, Marty 1 goes back, changes the future,
then returns.  We can assume a divergence (or not, but I will)
such that there are now two time lines.  On the first one, they 
never see Marty again, since he left that time line and returned
on the other one.  On the second one, Marty 1 returns, Marty 2 
travels back.  Now we encounter the problem.  Regardless of whatever 
else happened, the two of them would travel back to approximately
the same time and place, if we carry along with the assumption that
the time machine does not leave its current time-line.  However, 
since we did *not* see Marty 2 when Marty 1 arrived, it is likely
that Doc 2 remembered seeing Marty 1 (the letter, etc) and sent
Marty 2 back to some *other* time, realizing that otherwise they
would encounter each other.  (Or, rather, that he (Doc 2) would
run into Marty 1, if he is assuming that he will make the trip
back on the second go-round.)  Eithr way, I expect that he 
would have set the clock for some other date in the past.  What
happens to Marty 2 at this point is impossible to tell.  Probably,
each one changes their future, and ends up on time-line n+1.  

					   Muffy