The Voyager

Here is a little clip of how time travel can occur. In this case traveling to the future. Traveling back in time is another issue all together since you may need a black hole (hard to get there or get away alive if fallen into it) or a time machine. A time machine that can only work from the day and time is turned ON and left ON. This time machine, would have to use many laser cannons on a spiral to simulate a black hole and warp time. Therefore, you can’t go back before the machine is turned on. Still, this is just a theory and has not been proven yet.

Time Travel: Einstein’s big idea