• Question: How is time travel feasible? (Hypothetically) What do we need to go to the future? What about past?

    Asked by sanban to Chris, Dave, David, Jack on 26 Jun 2013.
    • Photo: Chris Mansell

      Chris Mansell answered on 26 Jun 2013:

      A guy called Kurt Godel (who is worth looking up if you get the chance) solved Einstein’s general relativity equations in a rotating universe. The solution said the universe should have closed time like curves, which basically means time travel would be possible in such a universe.

    • Photo: Jack Miller

      Jack Miller answered on 26 Jun 2013:

      As Chris says timetravel is permitted mathematically by the presence of closed timelike curves. However, I think Hawking’s onto something here: http://en.wikipedia.org/wiki/Chronology_protection_conjecture.

    • Photo: David Freeborn

      David Freeborn answered on 27 Jun 2013:

      Hi Sanban,

      Chris and Jack answered this pretty well, but there’s a tiny bit more to say.

      In our Universe, given its geometry, time travel might be feasible, but it would be very difficult to achieve.

      Essentially, the only way to time-travel would be for time to curve back on itself. The one plausible way to do this might be through a worm-hole, where two black holes join end-to-end. That’s extremely unlikely to happen, and would require the geometry of time in our Universe to be a bit weird (it’s probably not like this, but there’s a small chance it might be). Something like this:

      Obviously, the capacity for time travel would be very limited, and it would only go between two fixed points in space and time, even if it were viable.