Till now we have seen the time travel phenomenon is science fiction movies and TV shows like Dr.who. The characters in these science fictions use some kind of time machines, enter the time, date and place and whoooop!, they are gone. It would be so good if it could be that simple. We would have gone back to the past and stopped all the terrible things from happening. Sounds nice, right? However this is far more complex than it sounds.
Question: If time travel is possible then why has no one come to us from the future?
Answer: According to a theory, even if someone is able to make a time machine, it is not possible to travel back to the time before the time machine has been started. The Time travel to the past with this time machine would only be limited to the time it has been started.
One of the things that makes time travel complex is a paradox known as the Grandfathers paradox. According to this paradox if a person goes to the past and meet his grandfather before his marriage and kills him or stops him from marrying by any possible way, this would mean that he would not have produced any children and thus the person killing his grandfather would not have been born. So if a person has not been born at all then how can he go to the past and kill his grandfather. This creates a complex paradox which seems kind of unsolvable.
Let’s take another example. Think of an event you want to change in your past. Your uncle gave you a nice little time machine as your birthday gift and you went 5 years back in time to stop that embarrassing event before it happens. So you stopped it, but if such an event never happens(as the future you has already stopped it) it means that you(past you) will never know about it. Thus, you will not feel the need to go to the past to change that event. And if you do not go back to change it, this will create a self contradicting loop.
A POSSIBLE SOLUTION
Physicists have been searching a solution for this paradox from a long time. One theory is that for each choice we have in life, multiple parallel universes are formed based on our choices. So if you go back in time and change something, the change occurs in another universe and thus your present will not be affected.
However the idea of parallel universe(or universes) is complicated itself. To understand the idea of parallel universe better, imagine your friends set you up for a blind date. You have two choices; either you can feel shy and ditch your date or you buckle up and go on a date. According to the theory of parallel universe you might be doing both of the above choices but in different universes. These universes would be exactly the same as this one but would be formed by each choice you face in your life. Which basically leads to two contradicting statements:
- If each choice in a persons life forms a new universe in a new dimension, it would ultimately mean that there are infinite amount of universes or dimensions.
- If the change you want to make in your past would not affect your present(as it would only affect the parallel universe), it means you have gone to another universe(or dimension). So it would not be called time travel technically. It would be more like travelling between universes or dimensions. And if you cannot affect the present by altering the past, why would you even bother doing it. So it clears the whole purpose of time travelling.
Now, these were the complexities of travelling back in time. Travelling forward in time might not be that much complex.
If all the paradoxes are ignored somehow, how can we travel in time?
Theoretically, there are two ways to travel in time.
- Travel faster than the speed of light. It has been theoretically proved that if a person can travel faster than the speed of light then he can reach hundreds of years ahead without much increase in his age.
- Worm holes are the practical way to travel in time. According to scientists and researches worm holes are very minute gateways to different time zones, which if accessible can make time travelling a real possibility.