• Question: Do you think time travel is possible?

    Asked by to Roberto on 23 Jun 2014. This question was also asked by .
    • Photo: Roberto Trotta

      Roberto Trotta answered on 23 Jun 2014:

      We don’t know of any way, even in theory, that could make time travel happen.

      The problem with time travel is something we call “causality” — it means that causes have to come BEFORE their effect, or nothing would make any sense in the universe.

      But with time travel, you could travel back in time and make a mess of this causality business! Imagine the problems: you could travel back in time, and kill your grand-dad (hopefully nobody would want to do this, but just as an example), before he meets your grand-ma. Hence your dad would not be born, and you could not be born. So if you are not born, how can you go back in time and kill anybody in the first place?!

      So you see why we think that time travel is fundamentally impossible. Plus, if time travel ever becomes possible in the future, you would expect to see tons of time-tourist coming back to today and visit us from the future. But we don’t see any, so this probably means it will never be possible.

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