Question: I read that string theory attempts to model gravitation, electromagnetism, strong nuclear force and weak nuclear force in one theory. Is that true? And if so, how does it all come under one theory?

Francesca Day answered on 12 Mar 2014:

Yes, this is true! String theory tries to explain everything by modelling all the different particles as different patterns of vibration on tiny strings. The four different forces are caused by the way these vibrations interact with each other.

Sadly, things aren’t quite as easy as that though! For example, it looks to us humans like the world has 3 space dimensions plus time. (Physicists tend to think of time as the 4th dimension.) But string theory requires 6 extra dimensions to work properly!

If string theory is true, where are these extra dimensions? One theory is that they are squashed into a tiny space so we can’t see them. So every time you move your hand, for example, you could be circling 6 extra dimensions many, many times!