• Question: Is it physically possible to travel back in time?

    Asked by aimeej to Andrew, Daniel, Hayley, Natalia, Peta on 18 Nov 2011. This question was also asked by justcallmex.
    • Photo: Andrew Cairns

      Andrew Cairns answered on 13 Nov 2011:

      Theoretically yes, along with walking through a brick wall a lot of things can be proved through theories such as Einstein’s general relativity or Heisenberg’s uncertainty principle. In reality, however, I believe it is practically impossible and many further considerations have to be taken into account.

      Also thinking about the philosophical consequences of going back in time gives me a sore head.

    • Photo: Daniel Scully

      Daniel Scully answered on 14 Nov 2011:

      Probably not.

      The best evidence that time travel is impossible is the lack of reports of anyone having met someone from the future.
      Of course this isn’t proof, they may have some rule that prevents them telling people.

      Also, the ability to create paradoxes (for example killing your mother before you were born) might in fact prevent you from travelling back through time (physics has a knack for not allowing paradoxes to occur).

      Theoretically there have been some solutions to Einstein’s General Relativity which might allow time travel, essentially by making a wormhole. Unfortunately this solution might not be allowed, and even if it was it would require impossible amounts of energy to make and the wormhole would be too narrow for anyone to pass through.

      Travelling forward in time doesn’t have anywhere near as many problems though…

      And travelling slower through time than other people is definitely possible… but you need to travel close to the speed of light to do that, which is difficult.

    • Photo: Peta Foster

      Peta Foster answered on 15 Nov 2011:

      Hmmm a tricky question… we all currently travel through time at the rate of 1second/second you could speed up your progression into the future by travelling at very high speeds and thus when you had done so, say on a ultra-fast plane, and then landed back on earth… if you had a twin, who had remained on earth, your twin would be older than you now.

      Travelling backwards is potentially what they call paradoxical. You could travel back in time and kill your own grandfather when he was a boy for example which would mean you would never have been born to get into the time machine. However i am not sure about this argument myself being a fundamental limit and there have been a number of philosophers who have suggested that this reasoning does not actually make sense even though it seems to and my gut reaction is inclined to agree.

      Then there is the argument that we have had no global agreement of people having come back from the future… however getting reports of such things to be taken serious would be somewhat of an achievement considering we still have people who do not believe in global warming where there is lots of evidence so i do not feel that is a conclusive argument.

      Some physicist talk about positrons being the anti-matter brother of the electron which happens to travel backwards in time… if this was the case then backwards travel would be possible… you’d just have to be a positron. 🙂

      Then there is the theory that if you hold a concept of universal time and if space is curved near a very massive object then it could introduce a feature such as a wormhole in space-time which could transport you through time… potentially backwards but you would also not be in anywhere near the same space and probably not in a healthy state afterwards either 😛

      I think it is fair to say that it is highly highly unlikely that it would ever be possible for us humans to travel backwards through time while being in the same location and remaining intact 😀

      I hope this helps.

    • Photo: Natalia Parzyk

      Natalia Parzyk answered on 18 Nov 2011:

      If your iterested in that time – travel and stuff like that few years ago I’ve read a book by
      Michio Kaku: ‘Hyperspace. A Scientific Odyssey through Parallel Universes, Time Warps and the Tenth Dimension’
      (maybe you can find it on your local library?)

      It’s written at non – scientific way, so should be ok to read for you (at least it worth to try and do not give up when you don’t understand some pieces- it has some pictures to explain some concepts)

Comments

  • Photo: whitejack

    whitejack commented on :

    Good question aimee 🙂

  • Photo: Daniel

    Daniel commented on :

    I should probably clarify my point about paradoxes…

    You can’t create a paradox, by definition… so either you can’t kill your grandfather or time travel works such that doing so doesn’t create a paradox.

    In physics sometimes you can try and calculate the chance of something which is impossible happening… when you do the different parts of your calculation end up cancelling each other out and you get 0 chance.

    So if killing your grandfather is impossible… then physics won’t allow it.