• Question: do you think that someday, humans will be able to invent a real time machine?

    Asked by 07quiambaoj to Alastair, Emma, Hywel, Keith, Vicki on 18 Jun 2010 in Categories: .
    • Photo: Keith Brain

      Keith Brain answered on 18 Jun 2010:

      I can’t see us going back in time … because if someone did, then I think we would know about it. Also, it creates a really big problem with causality – the idea that the events in the present are determined by things that occurred in the past. If the “cause” of something can occur after an event, then that can lead to contradictions.

      However, travelling into the future is already possible (if you have a big enough engine – Hywel – help us out!). All you need to do it build a space ship, accelerate off into space at as close to the speed of light as possible (say 99.9999% of the speed of light), hang about for a while on your space ship, then come back to earth – remembering to slow down before you crash right through it!. You’ll then be “in the future”, at least as far as anyone on earth is concerned. The one problem is that you then can’t go back in time. This effect is called “time dilation” and is a consequence of Einstein’s Special Theory of Relativity; and he didn’t even with a Nobel prize for that discovery.

      Why hasn’t anyone done this? Because its really hard to get anything the size of a person that close to the speed of light.

      PS: Quick calculation spending 1 year at 99.9999% of the speed of light (as time appears to pass to you in your space ship), then returning to earth, will mean that …

      Number of years passed on earth = 1/SQRT(1-0.999999^2)= 707 years. Travelling faster will mean that you’re even further into the future, but you can’t end up going faster than the speed of light … damn that Einstein!

    • Photo: Vicki Stevenson

      Vicki Stevenson answered on 18 Jun 2010:

      I wouldn’t rule it out – a couple of centuries the idea of getting to the moon would have been definite science fiction and now that’s been achieved.
      Some people think that a time machine will need a receiver and a transmitter, so it won’t be possible for people to travel further back in time than the machine gets invented – which could be why we’ve never met a time traveller yet.

    • Photo: Alastair Sloan

      Alastair Sloan answered on 18 Jun 2010:

      I don’t think so – time travel is still sci-fi. The reason is you would have to travel as fast as or faster than the speed of light and in doing that you could only go forward in time. In theory it is possible and I may be wrong but I think at an atomic level it has been proved. There’s also good old Einsteins theory of relativity to take into account. Guys help me out here !!!

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