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Grandfather Paradox


Move back in time..?

Have you ever wondered how can we achieve time travel to the past? In the light series part 2 we talked about time dilation, which sort of let you move forward in time when you are moving close to light speed. But what about time travel to the past? One of the problems that will arise with travelling back in time, is the famous grandfather paradox.

So imagine you invented a time travel machine that helps you move back in time. What if you move to the time when your grandfather was still a child and you killed him? Then your mother or father wouldn’t have been born, and you wouldn’t have been born. So you wouldn’t have been able to go back in time to kill your grandfather in the first place. This closed loop seems to suggest that time travelling into the past is impossible because there’s a possibility that both different events are happening in parallel.

One simple explanation is the principle of Novikov self- consistency. This theory contends that the probability of an event that can cause a paradox or any change to the past is zero. If you are born, then the event of you going back in time to kill your grandfather will never exist. If you did go back in time, you won’t be able to kill you grandfather or do anything that can alter the past.

So what’s happened happened? That’s boring. There’s another possible theory: parallel universe. When you travel back in time, you’re travelling to the past of a parallel universe, and you can kill your grandfather and you can exist at the same time. The past that you altered is the other parallel universe, therefore your grandfather is pretty much still alive in your universe, but not in the other.


Keywords

  • Closed Loop: An automatic control system in which an operation, process, or mechanism is regulated by feedback.

  • Parallel Universe: A parallel universe, also known as a parallel dimension, alternate universe, or alternate reality, is a hypothetical self-contained plane of existence, co-existing with one’s own. The sum of all potential parallel universes that constitute reality is often called a “multiverse”.


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References

https://en.wikipedia.org/wiki/Parallel_universes_in_fiction
https://www.space.com/grandfather-paradox.html
https://www.youtube.com/watch?v=XayNKY944lY
https://en.wikipedia.org/wiki/Novikov_self-consistency_principle