Ah, where would sci-fi be without time travel? Well for one thing, there would be around fifty fewer episodes of the various Star Trek series, and no Doctor Who. Damn.
Time travel into the future and past has been around for a very long time, but the idea of using a machine to travel through time can be credited to H.G. Wells
Stories about time travel usually have people visit historical moments, or go to important events in their own lives. A constant theme in stories with backwards time travel is the idea of changing the past – that a time traveler could create a new history by going back and doing something differently.
Is it possible?
Well, going into the future, sure, that’s possible. You could travel close to the speed of light for a few years, and come back to Earth to find everyone you know a lot older than you. As for getting into the past, that’s impossible – so far.
There are solutions for many physical equations that work regardless of which direction time is going, which seems to imply that the universe could allow you to go back in time.
If something were to go faster than the speed of light, it would effectively arrive at its destination before it left.
However, no experiment has yet shown anything go faster than light, or go back in time. Scientists who study this aren’t sure how to get something back in time if it is possible, and how cause-and-effect paradoxes (like killing your parent before you are born) would be accounted for. It might just be that there is an undiscovered law of physics that either prevents backward time travel completely, or that prevents you from changing anything.