I never really ‘got’ gravity at school. I knew gravity was what made apples fall to the ground and planets loop around the Sun, but I could never satisfactorily get my head around how it actually worked. It wasn’t until university, when I walked into a classroom with nylon stretched out between some tables like a badly made trampoline, that I really understood. The nylon, my friend explained, was space-time, the fabric of the Universe. The weight in the centre, stretching the fabric towards the floor, was the Sun. This was what huge objects like stars did to space-time: they warped it, only in three dimensions rather than just two. Throw some marbles in and they became recognisable as small planets orbiting a large sun. Throw in dozens, and you soon saw why solar systems tend to orbit stars in one direction. Physicists will be familiar with the demonstration I’m talking about, but luckily for everyone else, I recently came across a much better recreation of it on YouTube – search for ‘gravity visualized’ (they’re American) to see it for yourself.
My point is, gravity is an elusive concept. The nylon analogy demonstrates Einstein’s take on gravity, the General Theory of Relativity, but unfortunately these neat, simple ‘rules’ can’t be reconciled with quantum mechanics, the other cornerstone of modern physics. It also leaves us with some big questions about the way our Universe works, such as why it seems to be expanding at an ever increasing speed. But one theoretical physicist, Erik Verlinde thinks he might have a solution – and it’s one that could rewrite the laws of physics as we know them. Turn to p40 to find out more…
Enjoy the issue!