• Question: What is relativity?

    Asked by Bucky to Craig, Flavia, Giuditta, Jack, Sheona on 9 Nov 2015.
    • Photo: Jack Carlyle

      Jack Carlyle answered on 9 Nov 2015:

      Put simply, relativity just means “compared to something else”. Let me try to explain…

      Imagine you are on a really, really long bus, which is driving down the road at 30 miles per hour. Then imagine you walk from the back to the front of the bus at 2 miles per hour. That means you are moving at 32 miles per hour “relative” to the outside world, but you are moving at 2 miles per hour “relative” to the bus!

      Einstein has developed this idea into a much more complicated concept which is to do with all sorts of crazy things like changing the speed of time, but I don’t think I could answer that here…!

    • Photo: Giuditta Perversi

      Giuditta Perversi answered on 9 Nov 2015:

      OMG we are getting to the really hard questions here!

      Jack already gave a nice answer, as it’s to be expected from an astrophysicist 😛 Let’s see how can I manage to make a chemist grasp on relativity look light.

      Basically, with “Relativity” we talk about a specific theory that is used to describe your “everything”. If you don’t use relativity, you just look at your system from above, just like a table for billiard filled with moving balls, you get the table as “still” and the balls are moving. With relativity, you can say “ok, who cares about the table, just look how the balls move in comparison to each other”.
      This is particularly useful when you try to deal with the Universe as a whole because you have incredibly big object, or incredibly fast objects, or stuff like that.

      If it sounds complicated it’s because it’s REALLY complicated.
      However, it can be important for your everyday life. For example the GPS in your smartphone needs to communicate with a satellite that it’s in orbit around the Earth, when your smarphone sends the signal with the request it would not receive an answer if you didn’t apply the relativity theory. I know it’s weird to read it, but basically it’s like the time flows faster for the satellite than for your smartphone!

      It’s a really broad and interesting questions, sorry if the answer is messy!

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