Time Travel

Today I watched a show on the History Channel called UNIVERSE. In that show, scientists - supposedly intelligent, educated people - were discussing the probability of time travel.

I guess a good education cannot instill common sense, because here's what I figured out a long time ago.

Let us assume time travel eventually exists. Sooner or later, someone will abuse it, and use it to change history. That is as certain as the fact that, eventually, someone will gain control of, and abuse, nuclear material. It is human nature.

So, let us assume that Joe Blow, in 2145, returns to the past, to 1932, and assassinates Hitler. At the precise instant he does so, he changes the entire future from that point on. The change is instant - it must be, because the previous circumstances no longer exist.

So, in the "new" year of 2145, Joe Blow cannot go back in time to kill Hitler, because Hitler never rose to power, and was never a problem. But if Joe cannot go back and kill Hitler, Hitler would then survive and rise to power.

This would, at best, create an unbreakable time loop. And here is why that is not possible, either. The only events that changed were "local" events - local to a specific period, on one tiny planet in the universe. It simply defies logic and science for such an event to create a loop that the entire universe would be caught up into. There is no logic or scientific data that indicates that time on Earth is separate from time elsewhere, and that time on Earth cannot affect time on Mars, for example. Because a change in our history - and future - could change any future that includes travel to, or colonization of Mars, so time is therefore not separate. Any loop created on Earth would ultimately affect the entire universe.

Now, here is my "proof" that such is not possible: it has not occured. If time travel ever becomes possible, future citizens would already have traveled back in time. They would already have visited. And changes would already have been made, creating a loop.

Of course, I could be wrong - maybe such a loop has already been created. That would, after all, account for all those instances of deja-vu.