Okay...I saw this thread and wanted to chime in with my thoughts.
If time travel to the future were possible, that would mean "fate" does exist. That we are following a life path pre-determined by some higher power. That no matter what we do, even me typing this response, it has been scripted and we cannot change it. Whenever I think this, I think of the line from "The Matrix" when Neo is asked if he believes in fate. His response was "I don't like the idea of not being in control of my life." Or something to that effect. But, this could explain that if time travel to the past were possible, how the present is the way it is without erratically changing....that if we could go back in time, if we were to somehow alter what happened then, it could impact the way things are in the present.
Now, if "fate" does not exist and we truly are in control of things then consider these:
- If we could travel back in time, we could alter courses of events...which would be constantly, chaotically altering the present (exteme examples: a wastebasket may be under your desk one minute, then just gone the next....somebody could be walking down the street one minute, then suddenly vanish in thin air as if they were never conceived...)
- If we could travel to the future, then it would be a sort of "blank canvas". There would be nothing when we arrive there. Absolutely nothing. Because who would know what would happen in the future if the present is constantly changing?
Some weird food for thought. I think time travel would just upset the universe in general.