Is the Time Machine hypothetical or theoretically possible?

Time travel or a time machine has always attracted many scientists and physicists. It has been man's wildest imagination. Time machine is a topic that fantasizes each one of us. Who doesn't want to travel in future or go back in time and alter his/her past? Many sci-fi novels and movies are based on time machines.  A lot of research has been done on this topic and many theories have been proposed for time travel. But it still remains a question whether a time machine is hypothetical or theoretically possible?

"Time travel was once considered a scientific heresy," writes Professor Stephen Hawking in the Daily Mail. "I used to avoid talking about it for fear of being labelled as a crank." However, these days he's far less cautious, admitting he believes human will one day figure out how to travel into the future. Time travel can either be in past or future and they both have different theories and concepts.  It is always said that travelling in past is not possible whereas travelling in future is feasible.

We live in a three dimensional world. Everything has a length, width and height. But there exists another dimension - the fourth dimension which is time. For ordinary people it is hard to imagine time as a fourth dimension but physicists look at time as fourth dimension. In order to travel forward or backward in time we require a device and i.e. a time machine. A time machine will travel through this fourth dimension. In movies or novels, a time machine is usually depicted as a huge machine having lots of control panels. A machine that would vibrate so fast as soon as it is switched on. The machine creates a path through fourth dimension.

As mentioned above, travelling back in time is not possible as it is more complicated than travelling in future. Travelling back in time is explained by classical example- the grandfather paradox, in which a time traveller goes into the past murders his grandparents and thus prevents the time traveller from being born. Lloyd has conducted quantum mechanical experiments in the last few years that suggest timelines remain self-consistent. The tests served as "the moral equivalent of sending a photon a few billionths of a second backwards in time and try to kill its former self," Lloyd said.

The concept suggested here is that time travel is not impossible if we talk about travelling in future. Time is like a river that flows at different speeds at different places. And this makes time travel possible. Albert Einstein proposed this idea over 100 years ago. He suggested that there should be areas where time slows down and others where time speeds up. And this phenomenon can be observed in space. There are few possible ways about how we can build a time machine or what can serve as a time machine. One option is a wormhole. The concept of wormholes was suggested by Einstein along with physicist Nathan Rosen in 1935. But till date, no wormhole has been discovered. A wormhole is theoretical tunnel or a shortcut that links two places in space-time. We can enter a wormhole from one end and exit from the other end into a new galaxy or remain in the same galaxy but at a different place. But since wormholes are yet to be discovered, their usage remains theoretical but impractical.

Another way to build a time machine is to build a spaceship that travels with the speed of light. Though achieving speed of light is not possible, let's assume it is quite near to the speed of light. Now time starts to flow slowly on board relative to the rest of the world. If we assume that a child is running forward on the spaceship, the speed of the child will add to that of the spaceship. Now one may think that due to this addition of speed, the speed of light may be exceeded. But this will never happen because the time will slow down to compensate any increase in speed. The time will always slow down to protect the speed limit. If the spaceship orbited around the earth for about 100 years, then 100 years would have passed on Earth. But on board, only one week would have passed because the time inside the spaceship has slowed down that much. When the passengers would come out of spaceship they would see an entirely new earth.

Now the question arises whether such a spaceship is possible to build or not? Well, the answer is no. Such a ship is impossible to be build. It is not practically possible but theoretically it can be achieved. Building a time machine is not a hypothetical thought. It may be practically impossible but theoretically it can be achieved. A Swiss organization, CERN, has developed an accelerator that accelerates particles to nearly speed of light. Although it never reaches the exact speed of light but it is quite near to that. The particles in the accelerator experiences time travel. Since the speed is very high, the time is slowed down. The short lived particles usually disintegrate after 25 billionth of a second, last about 30 times longer in the accelerator.

In theory, a time machine is not a farfetched dream. Considering a time machine as a hypothetical device is not justified. We all are waiting for the day when we can actually travel in time and explore the fourth dimension. Travelling in time, if possible, will be a dream comes true for many physicists and scientists.

"Time travel used to be thought of as just science fiction, but Einstein's general theory of relativity 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."- Stephen Hawking.