If one were to extrude the space-time continuum along a fifth
dimension, and define existence as the limit at infinity along this
dimension, then any time travel would be unstable and would never
persist until infinity. Whatever effect a future event had on the past
would alter time to prevent the future even from ever taking place
(this is along the extruded dimension so that is "possible" to alter
Even if the effect is only to displace a few electrons, it will change
circumstances ever so slightly. As you proceed along the extruded
dimension till infinity, circumstantial changes accumulate until at
some point the effect of those changes changes future circumstances
enough that the time travel doesn't occur. At that point the
discontinuity in space-time collapses.
This thought experiment demonstrates how there could be instabilities
in existence. Even if you discount the fifth dimension, the fact
remains that the time travel would have to have exactly the effect on
the past that produces the circumstances that led to the time travel
taking place. If even a small circumstance differs from that that time
travel cannot exist. It would be like balancing a perfect ball on the
tip of a perfectly sharp needle in a perfect gravitational field, and
having it still be there at the end of time. If the ball is 1/googol
off center, it'll eventually topple.
So it is possible, though exceedingly unlikely, that time travel could
occur. The possibility of a free will in the time loop is almost
certain to be enough of a disturbance to prevent the time loop from
While I'm on the subject, let me share a pet peeve about portrayal of
time travel in movies. For the most part I can't stand time travel in
movies. With time travel there's an inherent lack of drama (if at
first you don't succeed, you can just go back in time to prevent your
own failure). Also, the logical effects of time travel don't lend
themselves to escalation or payoff. Moviemakers deal with these
difficulties with artificial time travel rules. This allows dramatic
tension and explains the effects of time travel, but such rules
invariably cause logical inconsistencies.
Logical inconsistencies are not a deal breaker in and of themselves;
there's something called suspension of disbelief that moviemakers can
expect to a degree from the audience. But when the movie tries to
explain these articifial rules, it only creates more and more
inconsistencies. The more it tries to exlpain the rules, the more
inconsistent it gets, until the story is nothing but a confusing mess,
and that pisses me off.
Therefore, here are my rules for creating a time travel movie that
- Keep dramatic devices to a minimum.
- Whenever a plot device is used to create dramatic tension, just
use it. Don't explain it; don't talk about; and don't address
its logial flaws. Just state the rule and be done with it.
- Don't explain, talk about, or even acknowledge any issues with
time travel that aren't necessary to create drama.
Here are some movies that handled time travel well.
Back to the Future
Back to the Future's plot device was that Marty changed history,
and if he didn't change it back he'd disappear within the
week. Lots of logical loose ends here. Why didn't Marty
disappear the instant he bumped into his dad? Why does it take
week? Why does Marty go back to the "new" future? What happened
to the Marty from the new future? Does Marty have memories of
things that happened to the new Marty? If he doesn't, maybe he
slowly acquires them over a week? Does he also lose memories of
the old future over the week? Etc. Etc. Etc.
The movie handles all these questions and logical loose ends
perfectly: by ignoring them.
Another delightfully straightforward plot. The movie created
dramatic tension by ignoring the fact that Kyle's presense meant
that Sarah Connor must have survived (otherwise who would have
given him the picture so that he would volunteer to go back?). It
also ignored the issue of what the robots expected to happen if the
Terminator should succeed. Does history instantly change the moment
they send it back, and if it doesn't change it must have meant they
These questions simply weren't addressed, and it was the better for it.
Bill and Ted's Excellent Adventure
There was a pretty bad plot device ("the clock in San Dimas is
always running": Bill and Ted weren't able for some reason to
travel back in time to do their history report). That was actually
too much tension; later in the movie they got around this rule by
planning to go back in time after their report to hide things
But that's it: it was kept to a minimum. Bill and Ted never
wondered why they had to deliver their report at a certain time
according to their own watches (assuming Ted had managed to
remember to wind it), or anything else like that.
Furthermore, no attention was paid to the effect on history. Drama
over whether Napoleon got back to France wasn't necessary; there
was already enough of a story with their history report. So the
movie wisely disregarded it altogether.
And now for some movies that didn't do it well.
Back to the Future 2 and 3
These movies addressed (at some point) all those artificial rules
the first movie ignored. And the result was, well, Back to the
Future 2 and 3.
Terminator 2 and 3
These movies addressed (at some point) all those artificial
rules the first movie ignored.
T2 was all right since it was a well done movie in many other
ways. It must still be given credit for not raising the issue of
where the technology came from. But things got out of hand enough
to annoy me.
T3 it got way out of hand, and it was a big reason why it sucked so
bad, but I suspect it would have sucked even without all that time