Everyone in their life has wondered about the past. How were the pyramids made? How did dinosaurs look? What was the world like thousands of years ago? We may never get definite answers to these questions, but is there even a small chance that we could experience all this by travelling back in time?
In my previous article, I discussed how it would be possible to travel into the future, but travelling into the past is a whole different matter. Firstly, unlike time travel to the future, we do not have any theories about how we can accomplish it. Thermodynamics tells us that time is an arrow, and it constantly keeps moving forward. However, Einstein’s theory of relativity added something more– time is relative. This means that to each observer, time passes differently. Other scientists speculate that if you keep moving forward through time, you will eventually come back to where you started, like a circle. This is also clear in a lot of scenarios where patterns throughout history tend to repeat themselves. Examples of such recurrence are evident throughout history, such as famous wars, natural disasters, and the rise and fall of empires, all occurring every fixed number of years.
The more interesting side of this coin are the paradoxes – statements or problems that either appear to produce two entirely contradictory outcomes, or provide proof for something that goes against what we intuitively expect. The most famous of the paradoxes is the Grandfather Paradox, wherein a time traveller goes back in time, and accidentally kills his own grandfather. As you would have probably guessed, it is very difficult to ascertain what would happen after this. Would the time traveller simply vanish, or would something stop his grandfather from dying? According to some theories, this entire conundrum ties in with the hypothesis of a larger multiverse. The moment the time traveller’s grandfather dies, the arrow of time splits, and forms a new reality, but the time traveller continues to exist.
All of this is currently unproven, only proven in theories that could be wrong. With more research done in these fields, hopefully we can find some proof that such phenomena like time travel can be possible.
The original and subsequent arrow of time from the perspective of the time traveller
Part 2 of 2.
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