• Question: If gravity is a measurable force, what's the opposite of it?

    Asked by maddy2468 to Claire, Kate, Matt, Rob, Sam on 24 Jun 2013.
    • Photo: Kate Husband

      Kate Husband answered on 24 Jun 2013:

      There is no opposite to gravity – it is always attractive. It’s actually a very weak force but we feel its affects strongly because it adds up.

    • Photo: Sam Geen

      Sam Geen answered on 24 Jun 2013:

      Unlike electricity and magnetism, there’s no anti-gravity force. If you mean Newton’s 3rd Law, the “reaction” force from my body being pulled down by gravity is the electromagnetic force on the chair’s molecules pushing my bum to stop it falling through the chair.

    • Photo: Claire Lee

      Claire Lee answered on 24 Jun 2013:

      The thing about gravity is that it is a very “different” sort of force than the other ones we’re used to. Those forces (like the nuclear forces, electricity and magnetism) act on particles. Gravity is a bit different – in fact, our latest interpretation of what gravity really is, says that gravity is something that happens to space (spacetime).

      Read my explanation here of what I mean by that: /speedj13-zone/2013/06/24/what-is-general-relativity/

      So you see, when you think of gravity instead as the “shape” of spacetime, then it doesn’t really make sense to have something that’s the opposite of a shape 🙂

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