However, let us not jump to conclusions and explore the question of whether time travel is possible, by going deeper into the subject. To answer the question of whether time travel is possible, one must explore the very nature of time. So, let us question first what time is and what are the things that make time travel only a matter of fiction.
The concept of time dilation in special relativity tells us, that time slows down for an object as it speeds up. The faster you move, the slower time changes for you! It is a fact which has been verified through experiments.
Let us try to see what theoretical physics, which is the only subject which can give us a realistic answer, says about both these cases of time travel theory.
This phenomenon has been observed in case of a particle called a Muon, which lasts longer (than the time in which it should have decayed if stationary) when it is traveling close to the speed of light. So in a way, it has lived longer and traveled into the future! So, time travel into the future is theoretically possible!
Same is not the case with traveling backward in time. A major roadblock is the second law of thermodynamics about entropy. The disorder in the universe, termed as entropy, always goes on increasing.
There are speculations about time travel backwards possible through a concept called a wormhole. It arises out of general theory of relativity, which tells us that gravity is not a force but a manifestation of curvature of space time! Matter bends space time around it!
Theoretically, this black hole could be one mouth of a worm hole, which connects two regions of space time with a passage and it is a mathematical solution of Einstein's equations of general relativity. However, there is no way one can verify the truth of this statement, as mere mathematical validity doesn't mean that it could exist!
Hope the scientific viewpoint about the possibility of time travel is clear for you, by now. Traveling back in time is simply unrealistic! So, if anybody asks you about whether time travel possible, you know what to say!