• Question: Is it possible to do time travel? If it is, then would the thing you do affect the future?

    Asked by anonymous to Steve, Emma, Christian, Bose, Alice on 9 Mar 2016. This question was also asked by junjie, EJH.13.
    • Photo: Emma Dean

      Emma Dean answered on 9 Mar 2016:

      If you can travel faster than the speed of light then you can time travel. The problem is the universe has a speed limit, and that happens to be the speed of light in a vacuum. Another way we might be able to time travel is through black holes, but no-one knows what actually happens inside a black hole. If we could time travel, we could only travel as far back as in time to when the time travel machine was invented.

      If you were to travel back in time, your actions would almost certainly change the future. That’s because everything we do has a knock-on effect. Even what seems like the tiniest thing, could have huge consequences. This is known as the ‘butterfly effect’. This theory says, that a flutter of a butterfly’s wings can cause a hurricane on the otherside of the world.

    • Photo: Alice Harpole

      Alice Harpole answered on 9 Mar 2016:

      Possibly. There is a (highly hypothetical!) type of black hole called a wormhole, which would connect one point in spacetime to another point in spacetime. This second point could another point in time, on the opposite side of the universe, or maybe in a different universe entirely. So, if we found or somehow created one of these wormholes, it may be that we could use it to travel into the future.

    • Photo: Steve Marsden

      Steve Marsden answered on 9 Mar 2016:

      There are a couple of theories that suggest that time travel may be possible, through the use of wormholes, or faster than light travel.

      There are also a couple of theories which detail how time travel may behave. My favourite of these is the Novikov self consistency principle. The concept of this states that everything is self consistent, and there aren’t multiple time lines caused by the time travel. This is the method of time travel used in The Prisoner of Azkaban and The Time Traveller’s Wife.

      There’s a couple of really interesting thought experiments on the subject of paradoxes in the Novikov framework that you should look up if you’re interested in time travel. They essentially state that paradoxes couldn’t exist, and that something would happen to stop the paradox forming.

      In this manner, it would not be possible to affect known history (but unknown history would be fair game).