For the longest time, physicists had to contend with strictly guided Newtonian physics that suggested all time was linear and gave the troubling idea of predestination. But then as Einstein tested his theories of the universe in the brilliant display of atomic power, we discovered that time was not linear as had been once proposed, but was in fact very relative given the movement of an object. Hence, time travel was not only suggested, it was promised.
Unfortunately, it is also not easy. As we pick up speed, we are actually slowing time down. A year for us as we travel at close to the speed of light could be ten or twenty years on Earth. But by the same respect, if we were to travel faster than the speed of light, we would eventually be able to travel back in time. Of course this promise also came with a very important disclaimer. We simply cannot travel faster than the speed of light with our current understanding of physics. It’s this exact same disclaimer that results in us being unable to suddenly jump to another dimension.
But there are other places in the universe where physics gets very strange. Black Holes, for one, seem to have an effect on light and could in theory even have an effect on time. But traveling to a black hole without protection beyond what we currently understand could result in being completely atomized and ripped into strands a hundred trillion miles long. And of course this isn’t very promising at all if you want to see dinosaurs or watch Shakespeare’s debut.
So will we ever be able to hop in a ship and travel faster than the speed of light without subjecting ourselves to the dangers of black holes? Or will we develop a ship capable of traveling into the heart of a black hole without being crushed and ripped to shreds? There have been dozens of other solutions, including the now famous Tipler Cylinder, but each has its own problems. Problems on the scale of the Tipler Cylinder require that a time machine would have to be infinitely long in either direction and spin incredibly fast in order to travel back in time. Such an endeavor would take an infinitely long period of time and require an infinite amount of energy to spin. It would be easier to just reverse the process of everything in the universe to achieve backwards time travel, in other words.
Of course in the meantime, we may develop devices that find a workaround system. If not traveling backwards through the whole universe, perhaps it would be possible to travel backwards in time on Earth. You may be surprised, but there actually have been several time travelers that have come from our past into the future. Russian cosmonaut Sergei Adveyev holds the current world record for time travel, having traveled almost a quarter of a second into the future. Of course this time wasn’t exactly noticed by Adveyev, and he was able to do it merely by orbiting Earth for long enough.
So if you want to travel into the future, it might be possible if you move fast enough in space. But if you want to come back to this moment? Use it well, as you will never get it back. That is, unless science discovers a new way of looking at the universe.