• Question: What is Gravity?

    Asked by MyNameIsn'tAlaae to Daniel, Hannah, Maggie, Ry, Scott on 13 Nov 2017.
    • Photo: Hannah Middleton

      Hannah Middleton answered on 13 Nov 2017:

      Gravity is a curvature of space and time!

      A hundred years age a physicist called Albert Einstein came up with a theory to explain gravity. He thought of space as a stretched out fabric sheet. If there is no mass around, the fabric (and space) is just flat and empty. But if you imaging placing a heavy ball on the fabric, it will curve (like if you put a bowling ball on a trampoline). How much the fabric curves depends on how much mass there is, the heavier the mass, the more it curves space.

      Then if you place a ping pong ball on the fabric, it will roll towards the heavy ball as it follows the slope of the fabric. This is how we can think of gravity – objects get attracted to each other because they are following the curvature of space.

      This is how the planets orbits the Sun. The Earth is following the curvature of space around the Sun, a bit like those funnel things that you can roll coins into!

      Here’s a clip of us making our own solar system with a fabric sheet!

    • Photo: Scott Melville

      Scott Melville answered on 13 Nov 2017:

      I love Hannah’s video! So cool!
      The answer to this question depends a bit on which approximations you’re allowed to make.
      If you’re going really slow and are really big:
      gravity is a force which pulls two masses together, and is given by Newton’s laws,
      If you’re going pretty fast and are really big:
      gravity is like a curvature of space and time, described more accurately by Einstein’s equations,
      If you’re going really slow and are really small:
      then quantum mechanics becomes important, and you can try to solve Schroedinger’s equation for atoms being tickled by some Newtonian forces,
      If you’re going really fast and are really small:
      then we have absolutely no idea – all hope is lost – this is ‘quantum gravity’ territory 😛 (some people think it’s where string theory comes in, but who knows?!)

    • Photo: Maggie Lieu

      Maggie Lieu answered on 13 Nov 2017:

      gravity is the force between any two objects with mass. For example the force between us and the Earth.

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