Subject:  a no longer so simple question
Date:  Wed, 30 Sep 1998 22:04:41 EDT
From:  "chad hadsell"

"You have confused something:  you suggest that it is not possible to travel to the future, because you would change the future.  Travel to the future is no problem.  There have been a number of sci-fi stories based on the idea that someone would 'travel to the future' by somehow being placed in some type of suspended animation and subsequently revived--Buck Rogers was one of the first of these, a pilot whose life was saved by an experimental survival system, but who was lost for five centuries, revived in the future.  That is not what we mean by traveling to the future--but in fact its effect on the future is no different.  Traveling into the future is no different from taking a vacation in Boston for a period of time, but that you don't age. It is travel to the past which causes the problem--even if that travel to the past is a misguided effort to 'correct' travel to the future.  (Caveat: if someone from the future reaches back into the past and snatches you into the future, that involves a type of travel to the past--someone from the future is interfering with the past; if you on your own initiative unaided by anyone or anything from the future travel to the future, that is not much different from Rip Van Winkle's nap--you left, the world went on without you, you came back.)"

I think that you are leaving something out here.  Travel to the future *will* effect the future, in one of two ways.  Either you stay there, thus ending your life in you "home" time and changing anything you might have done then.  Or you go back, and, knowing what you do of the future, act differently than you would have had you not time traveled.  Your explanation of future travel having no effect would only be true if all memories of the future were erased before returning to the "present".  If a "future person" travels "backward" in time, it changes his future.  this you have stated.  One of the reasons this is true is due to the information this future person gives to people of the present.  Now simply change "future person" to "returning person".

As a clearer example of this:  I go to the future. I learn that i will die in a horrible car accident.  I go back to the present.  When the night of the car accident comes around, i do not get in the car.

Thus, the future is changed.

Of course, there are always those people who believe in pre-destination, that things work out the way they are supposed to no matter what a person does....(avoiding the car accident, i stay home and am killed in an explosion of a gas main....)

just more points to ponder

--chad

Chad--

I'm afraid you are confusing things.  You are correct that if you go to the future, you will either stay there or return to the "present"--but that is where you are confused.  Once you are in the "future", it is for you the immediate "present", and returning to what you are calling the "present" is a trip into the past--the problems you connect with travel to the future do not come from the trip forward, but from the return trip, which is a trip into the past.  Seeing the future is very like going to the future and returning to the past; but merely going to the future does not in itself involve returning to the past--as you observe--and if you don't return to the past, the knowledge you gain in the future does not affect the past.

But you suggest that leaving the past and remaining in the future will change the past in that you have ended your life in the past.  But that presupposes that there was at some point a different version of the past in which you did not take the trip to the future.  This is not a necessary time line.  Consider this:  On October 1, 1998, you could jump forward to November 1, 1998.  You could instead continue your ordinary life; you could go on a vacation for a month in Boston; you could die.  If you died, you might be revived (as easily imagined as that you might travel through time) a month later.  In each of these cases, a month passes from October 1 to November 1.  In one case, you have skipped that month, and merely did not exist during that time; in the second, you were home and at work or school during much of the time; in the third, you were away from everything that was home, being in Boston; and in the fourth, you were dead for that time.  Now, you are suggesting that if you leapt into the future, you would destroy the "correct" history--but which is the correct history?  It is just as easy for the correct history to be that you ceased to exist on October 1 and returned to existence on November 1 as that you worked, went to Boston, or died and came back.  You didn't "change" history--you created the original version, in which you left time and came back--not much different from a vacation in Boston.  It is when you go backwards in time to reach what you are thinking of as the "present" that you create the altered history, in this case by injecting yourself into a timeline in which you had been absent.

Make sense?

--Mark