Time travel is not only possible, it is commonplace. We are all travelers in time at the speed of exactly one second per second. Of course, we can only travel in one direction, but that is the way it should be. Time travel in another direction or at another speed, say into the future at an accelerated rate, or into the past, is not only impossible, it is so mind-numbingly frightening that only a psychopath or lawyer would ever consider it.
First of all, any time travel into the past, would destroy the concept of causality. Here’s a nutshell version of it. If you went into the past and killed your father, you would not exist in the present to go back in time and kill your father. Now that’s the great big version of the paradox of causality. But it works in any example of time travel into the past because the Heisenberg principal illustrates for us that any experiment that we can conduct automatically interferes with the result of the conclusions of that experiment.
Consider the terrifying possibility of going back just one minute. You step into the transporter at 9 a.m. and appear in the past at 8.58 a.m. There are two of you standing there. You and your past self, self2. But wait. Self 2 has not stepped through the machine yet. At 9 a.m. you watch him step through the machine. Now Self2 and Self1 appear at 8,58 a.m. And they both meet self3. And this continues forever, until there are an infinite number of selfs appearing at 8.58 a.m. Now you may want to argue that self1 walks through the machine only once, and so self 2 is the same as self1. If that were true, then they would share the same atoms, the same energy. That breaks the fundamental law of conservation of mass and energy. And the paradox would still be unsolved because self1 and self2 are self-determining agents with free will. Self1 steps through the machine, but self2 may decide differently, but self1 is already in the past. So either self1 and self2 and all the other selfs that will appear at 8.58 are real and separate, or we are automatons, robots predetermined to walk through the universe of space/time in lock with at eternal destiny, in which case God, the arbiter of destiny, would never allow such a thing.
So, what about the possibility of travel into the future, at some accelerated rate so that we might appear suddenly in the future. Well, since self 1 disappears at 8.58 and reappears at 9 a.m. then, for two minutes we have the same problem we had before. Mass and energy have been destroyed and then created. The conservation of mass has been violated, although for only a short period of time. But this is a fairly small objection, and we can, in our limited way, imagine such a blinking of matter from one space on the timeline to another. So, what is the problem? As long as the self in the future never attempts to go backward, then there should be no problem, right?
The problem now lies in the fact that we cannot conceive of a universe in which all time is laid out in advance. If the universe allows the future to exist already, then all moments of time from eternity past to eternity future exist simultaneously. And God looks down at the long string of time and sees past and present simultaneously. But if that is true, then our free will is an illusion. We may think that our decisions matter, but every one of our actions has been predetermined. In fact, so monotheistic theology would have it, God created the entire timeline in a single burst. So all our yesterdays and all our tomorrows are already in existence. God created our past-present-future all at once in the beginning. Our choices are an illusion because we are locked going through the motions of our destiny.
If you can live with that, as I can, then time travel is impossible because we simply have no free will to somehow change the timeline that God has already decreed. On the other had, if you do not believe that the future exists yet and is waiting to exist when we make decisions, then there is no “place” to travel to. We can look into the past by looking in a telescope and seeing a location separated us by light years. We see the sun, for instance as it existed four minutes ago when the light from the sun started its journey to earth. So either the future is locked away from us by cruel destiny, or it does not exist yet.
Now this completely ignores the tremendously delicate time-space fantasms created by modern physics. Physics is now so riddled with paradoxes that it is virtually impossible to rationally explain the fundamentals of string theory or particle accelertion without using language that was once reserved for metaphysics. Now physicists use the language of religion. Stephen Hawkins’ discussion of the creation of the universe in his seminal work, A Brief History of Time, sounds very close to agreeing with Genesis. And modern physics seems to agree that nothing is real except as it is observed by some intelligence outside of the matrix of our dimensions.
So, I think I shall be satisfied with my own limited form of time travel, one second per second into the future, and enjoy the scenery as it passes by.