• Question: What is gravity?

    Asked by Bethyboo to Alice, Bose, Christian, Emma, Steve on 17 Mar 2016. This question was also asked by :-) :-) :-) :-) :-) :-) :.
    • Photo: Benjamin Bose

      Benjamin Bose answered on 17 Mar 2016:

      Simply put: Gravity is a force of nature which works to pull masses and energy together.

      In a deeper sense: all things would move along straight lines if there was no gravity. Because of gravity, the straight paths of things no longer look like straight paths because spacetime becomes curved, so it appears as though there is an attractive force.

    • Photo: Steve Marsden

      Steve Marsden answered on 17 Mar 2016:

      According to Einstein’s general relativity, gravity is a result of a curved space-time. That is to say, that any body of mass causes space to bend. An object attempting to move in a straight line would then appear to move in a curve. In this respect, gravity is unlike all other forces.

      This principle only works on the scale of planets, stars, galaxies etc. When you consider atoms, or subatomic particles, this breaks down. Essentially the maths required by allowing space to bend makes the Standard Model (the theory of particles) completely unworkable. So when we get down to the fundamental bits that make up the universe, we don’t know how gravity behaves, or what makes it up.

    • Photo: Emma Dean

      Emma Dean answered on 17 Mar 2016:

      Gravity is very interesting because we know very little about it. We know know it is an attractive force. It travels at the speed of light. We experience it everywhere all of the time.

      Einstein’s idea of gravity was that massive objects in the universe like planets, stars and black holes, all bend spacetime. Kind of like how a bowling ball bends the fabric on a trampoline. If you roll a marble from one side of the trampoline to the other, it would dip in towards the bowling ball as it passes. It might even start circling the bowling. You could then say the marble is attracted towards the bowling ball, like earth is to the sun. Gravity is what we call this bending of spacetime. The stronger the bending, the stronger the gravity.

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