Time is not just what we human beings think of by just looking at our watches, it is much more. Time, according to physics theories, is a scalar quantity and is linear in nature. That is, it is only possible to go in the future and not the past. Time is considered irreversible, that means, what is gone is gone, it can never come back. But imagine a world where you could travel back through time, maybe you would just wanna tell your grandmother not to marry, so your dad wouldn’t have come and so not you. But if you didn’t exist, then who was it who travelled back through time and told your grandmother not to marry? Isn’t this a bit confusing.
The famous physicist Albert Einstein said that time is relative in nature, that is, time changes with the speed of any object. Earlier time travel was thought of as just science fiction, but after Einstein’s general theory of relativity that allows for the possibility that we could warp space time so much that you could go off in a rocket and return before you set out. Albert Einstein’s theory of special relativity proposed that speed of light in space is independent of any kind of motion of observers. It is a fact that, the faster you travel in space the slower you travel in time. So, if you build a time machine that could match the speed of light in space and could make you travel faster than time, then finally you would reach earth to find that all your colleagues have grown very very old to appreciate your discovery.
This phenomenon is known as time dilation. Apollo 10 which was launched on May 18, 1969, was the fourth piloted mission in the United Space Apollo Space Program and it had a speed of around eleven thousand meters per second and speed required to travel through time is somewhat around 299 million meters per second. So this is a great news for all those keen for time travelling that they don’t have to confront time dilation.
According to Einstein time is the fourth dimension and together with the three dimensions of space it is fused in a single four dimensional continuum. Time is constantly moving forwards and we are also moving forwards along with the time, so basically we travel with time every day. But then there is another discovery for those who really want to travel to their future, it is wormholes. A wormhole also known as Einstein-Rosen Bridge are basically theoretical tunnels that are linked to two different places at two different times. This may be taken as a shortcut to go to another universe at a different timeline.
Wormholes can be imagined as a giant tunnel above the earth, passing through which will lead us to another planet at a totally different timeline and theoretically, if we join the two ends of the wormhole then we could possibly travel to future and then come back to our past in no time.