"Time travel" isn't possible. Even though Einstein's theories allow for the possibility of time travel, hear me out here... 1. The math: Math can allow for situations that work theoretically, but which fail in reality. Think of Pi. It has an infinite, non-repeating, string of numbers after the decimal, right? (3.14.......) So you should theoretically be able to break a circle down into segments infinitely; but in reality, once you get down to planck size (the smallest unit of measurement possible), there would be a finite number of segments that the circle could be broken down into. So, just because math says that something is theoretically possible, it doesn't mean it's possible in reality. 2. Traveling at a faster speed, or being in different gravity, than someone else, theoretically changes your time, relative to that other person. The astronaut that has spent the most time in the International Space Station (I forget his name), has traveled at such high speeds, and for so long, that theoretically, his time should different than ours. His time should've moved slower than ours by a fraction of a second. Therefore, putting our time, relatively, a fraction of a second ahead of his. If time travel was possible, why hasn't he disappeared, a fraction of a second into the future? I propose that Einstein's theory of special relativity is correct, but most scientists just interpret it wrong. I believe that time can be relative, due to speed or gravity, but that your relative time wouldn't move you into the future, or the past. I'm saying that, if scientists built a time machine, we would see the person inside of it aging either faster, or slower, relative to us outside of it; but they wouldn't disappear into some time ahead, or behind us. Their time would only be relative. There are no slices, or frames, of time; like frames of a movie, where a time machine would take them back to whichever frame of time that you set it for. Where they'd be in a different time, where we can't see them. Rather, they'd stay right there in the same place, they'd only age faster, or slower, than those of us outside of the "time machine". So, it'd be more like a "time manipulation" machine, instead of a "time travel" machine.