Everyone has something about their past that they want to change. People wish that they had a time machine that they could use to go back in time and change everything, at least after seeing movies that do display time travel.
However before we even think of changing our past we need to understand time and time travel. Time is an illusion, it is relative, i.e, it varies from person to person depending on the speed that the person is travelling at. Einstein’s theory of special relativity says that time slows down or speeds up depending on how fast you move relative to something else. Approaching the speed of light, a person inside a spaceship would age much slower than his twin at home.
Moreover time is a 4-D fabric rather than just a quantity you measure on your clock.
The theory of relativity provides with equations that could make time travel possible but the conditions required to do this are almost impossible for one you would need to travel faster than the speed of light (300000 km/s) and be able to withstand various conditions such as extreme heat and possible explosions along the way. However, unfortunately even if we did reached speeds equal to the speed of light then we would have infinite mass this contradicts the entire supposition in the first instance, nothing with infinite mass can move at all let alone move at the speed of light. Again, if we were able to move the infinitely massed object then the force or energy required to do so would be again quite literally infinite.
So as much as movies try to convince us that time travel is possible it is very unlikely that we are going to achieve it anytime soon, perhaps sometime in the future.
Oh wait that is a paradox in itself if time travel was possible in the future then people were sure to visit our time at some point and it is very difficult to think that we could not have recognized our future race, because *hopefully* things are different, say a 100 years from now.
So it is most unlikely that time travel is going to be ever possible. But that should not stop you from trying to built a time machine because if you do so you will change the entire timeline, quite literally, of human history.