Time Travel and Philosophy

What if tomorrow, you woke up in the past? What if, when you went outside, the only vehicles you saw were horse-drawn carts? In fact, the only roads that are paved and only appear when you get closer to the town. The town itself has a main drag including, yes, a vintage barber shop. And a barber shop pole. You have woken up in the past.

What if, during your time in the past, you killed somebody? And that somebody turned out to be none other than your great-grandfather? This is of course one of the most simple and famous paradoxes of time travel. This one in particular is explored in the Back to the Future  movies (highly recommended). Also in the science fiction short story called The Sound of Thunder. For those uncultured among us, I’ll summarise as quick as I can:

  • Guys in the future invent a time machine.
  • They go back in time to hunt a Tyrannosaurus Rex.
  • One of the crew accidentally crush a butterfly.
  • This single event has repercussions which drastically affect their present.

This is of course known as the butterfly effect. The effect of every action possibly having severe consequences in the future is known as the Grandfather Paradox. The impossibility lies in the fact that if one kills their own ancestor, they will never be born. If this is the case, then how could they even travel back in time in the first place? The simple and most obvious solution to this paradox is that the universe would prevent such impossibilities would occur. That is, time travel is not possible. The second possibility is that of parallel universes. This concept is pretty difficult to explain; it’s a bit of a mindblow. The basic idea is that if you alter anything in the past, a separate universe is instantly created in which the effects of changing the past can be seen. This in itself creates even more paradoxes (paradi?). When the time traveller returns to the present, which present will he be in? The affected one or the original universe?

grandfather_paradox

grandfather_paradox2

This opens up some really cool possibilities. Do parallel universes already exist? If so, how many are there? Do we live in a parallel universe, or the ‘original’? How different are parallel universes?

My own personal opinion is that if you could manage to travel back in time, you wouldn’t be able to change anything. You would be much like a ghost, not a part of the physical reality of your environment. You can perceive the past, but you cannot edit it. Kind of like viewing a ‘read only’ version of the past universe. This opens up the possibility that time travellers are already among us. The popular theory that if time travel were possible, we would know about it because of contact from people from the future becomes irrelevant, because we wouldn’t know that they’re here.

Another huge paradox – is it possible for there to be two of yourself in the universe at the same time? What if you were to visit yourself? This paradox is far more philosophical. Physically it is possible for one set of billions of atoms to be identically arranged to another billion atoms, although the chances of that occurring are slim. The essence of a person is a little more complicated. This is the part of you that defines you as being you. And for you to be truly you, there can only be one of you. I’ll try to explain. When somebody describes your location, they say you are over there, and point to the spot. You cannot be over here while you are over there. This is called the principle of noncontradiction. Two contradictory facts cannot both be true at the same time. For the same reason, you cannot describe a person as being one thing and another. For this to be true, there can not be two identical versions of you on earth at the same time. I hope I explained that concept well enough to be understood. It’s scarily complicated.

Another point to consider is the location of the past. I mean, if you’re going to travel to the past, you need to have somewhere to travel to. Where is the past? Only the present moment in time exists, the future does not yet exist, and the past no longer exists. Or does it? Is the past stored in some way in the nature of the universe? One suggestion I would have is to reverse everything that has ever been done to travel into the past. If we as humans could somehow find that all subatomic particles have within them a record of where they have been relative to each other, and how they have reacted with each other, we may also find a way to trace back this path through history, to reverse all of time. The only problem with this is, it may not be selective. You may not be able to reverse just some of the universe, or everything excluding the time machine itself. The most likely case would be the reversal of the entire universe, including the invention of the time machine, and the memories of the person who invented it. Life up until that point would simply be relived by everybody on earth. For all we know, it may have already happened. We can’t tell. It’s a very difficult concept to explain well, and I think I did a pretty terrible job.

spacetime-time

But I think we’re a long way ahead of ourselves. These are all paradoxes which all point towards one simple fact – time is a dimension which can only be measured at a constant rate, which is pre-defined. The closest humans have come to postulating time travel is wrapped up in Einstein’s theory of relativity. Even so, it would require something to be able travel faster than the speed of light. As far as we know, that’s also impossible.

So, time travel. It would be absolutely awesome if it were developed. But it might also wreck some sort of fundamental aspect of the universe. Then we would have nowhere to live.

If you want something extra on time travel, check this video out. VSauce is probably one of the best Youtube channels when it comes to explaining heavy science.

Spread the word! –> http://wp.me/p3hnhE-6

Stay cool,

h

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15 thoughts on “Time Travel and Philosophy

  1. Mate, top blog. Love the use of follow-up video, and I shall stay cool. Next blog should be on: Were any of the super-genius ancient civilizations, such as the Ancient Egyptians (who managed to create multiple kilometer long tunnels into the earth in near perfect rectangles) influenced by alien technology, or perhaps a civilization from thousands and thousands of years ago perhaps more advanced then our own? I look forward to you researching this for me, and what cool title you come up with.

  2. Have you heard how Stephen Hawking proved time travel to be non-existent?

    He made a time-travelers party and sent a message into the future through the internet and leaving people fliers and whatever. Nobody turned up. So, the only two possibilities are, is that the notes never ever got that far into the future, or time travel was never invented.

    • Interesting proposition. The article that I have written focuses mainly on travelling to the past, and I left travelling to the future completely out of the equation. Does Mr Hawking have anything to say about travelling to the past?

    • Another possibility is that Stephen Hawking didn’t set up a time machine to receive the time travelers who would have otherwise attended his party. Time travel might be possible, but only to times and locations where time machines are set up to send and receive time travelers.

      • So, as a conclusion of that, time travel by people from the future to the present is not yet possible, because we don’t have the technology to receive them?

        Would that also mean that, at this present moment in time, time travel to the past is not possible, until we invent a time machine? And then we could only travel back in time to the point when the time machine was created.

      • It depends on whether a time travel device is needed to receive a time traveler at their destination time and place. If it is, then I don’t see how time travel to any point in time before the time travel device is created will be possible.

        If a device can be made that will project a time traveler through time without the need for another device on the receiving end, then I could see it being possible to travel to the past before a time travel device is invented.

        My main point is that the fact that no time travelers showed up for Hawking’s party is not proof that time travel is impossible.

      • Sorry for the late reply, I’ve been ill recently. I have no reason to doubt that certain kinds of particles could be accelerated faster than the speed of light. I’m willing to believe in tachyons. But I don’t believe the existence of such particles makes it any less likely that time travel for humans would require a time travel device. I sort of look at time travel for humans as requiring a device to reconstruct the human from the time traveling particles, even if those particles themselves didn’t need a device to travel to their destination.

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