Time travel has been one of the most attractive topics in science fictions. But it is not just a matter of stories.
It could happen in all probability. Scientists all over the world are talking about it and many researchers are working in this direction.
Understanding the idea
Actually speaking all of us are traveling through time. Yes. Everything is changing over time. Even we are changing. We witness and experience all these and it is nothing but our travel in time, but at the speed of 1 hour per hour and towards future.
The challenge is to travel in time at some speed of more than 1 hour per hour, either in future or in the past. Amazingly, it is theoretically possible. But how. Let us see.
Slowing of Time
The world-fame theoretical physicist Albert Einstein tells in his Special Theory of Relativity that if one could travel in the space at some speed very near to that of light, time will run slower for that person. But how much slow? It depends on upon the speed of that fellow. If this speed is pretty close to that of light, the slowing down of time would be substantially high.
This is how you could travel to future
Suppose you board a spaceship and fly at the speed of 99.5% of that of light. You leave the planet earth at the age of 15 years. You travel for the next five years in the space.Suppose you started in 2016. In the space, for you, just five years passed. So your age would be just 20. A young fellow. But what about your classmates. Surprisingly they would be of the age around 65 years. So 50 years passed on the earth while just 5 years passed for you in the space. See the point now. It means you would be coming back to the earth in the year 2066. It means that you traveled through 50 years in future just in 5 years!
All this is based on the Special Theory of Relativity and this theory is accepted by the scientist all over the world. It has been tested in strict experiments. So far no contradictions found regarding this theory.
Let us see a practical example of time travel. A Russian cosmonaut and mechanical engineer Sergei Krikalev spent the longest amount of time in space and that is 803 days, 9 hours, 39 minutes. He was on the International Space Station,ISS, that travels at a speed nearly 7.66 km/s. When the cosmonaut came back to the earth, he actually came in a future time of 0.02 seconds ahead. Same goes for other astronauts. But the amount of time travel is significantly small.
Paradox of Past Travel
Many scientists believe that travel to the past also is possible. But how? A much-discussed paradox about this idea is there. Suppose you travel back in time and somehow manage your parents not to meet. Then what would happen? Actually, you would prevent yourself from being born. The point is that if you are not born, how could you travel to the past?
In his General Theory of Relativity, Einstein stated that time and space are not two different things. Rather they are just two aspects of a single thing called space-time. He stated that near objects in the gravitational field, this space-time bends. It means, some sort of time travel in possible near objects with heavy gravitational pull, like black holes.
The idea of wormholes is also very much used in the fictions. Scientists believe in it. A wormhole is a shortcut to travel in space-time. A long distance could be covered through a shortcut and that reduces time and distance. But the wormholes could collapse quickly, they are filled with radiation and there is a danger of exotic matter. And also, the dimension of a wormhole is predicted to be of the order of 10-33 and it is not possible for us to enter it.
Future will tell
Many scientists believe that in coming days time travel to future would be possible. But we need to develop a high-end technology. The requirement of energy for such travels would be tremendously high and that is another big question how to get that.But enthusiasts state that in future we would be capable to traverse thousands of years in a single year only. Though many state that travel to future is easier than travel to past.
Only time would show what is possible. Till then let the scientists ponder and the storytellers do their business!