“Well, if we take all the objects in our daily experience – your body, the chair you’re sitting in, the air you’re breathing, the walls around us, throw in the planets, throw in the stars – all of that, it’s made of atoms, which we do understand, but all of that atomic matter only adds up to 5% per cent of the universe - 5%! So it’s the other 95% that we have to understand. And that’s where dark matter and dark energy come in.

“When these things go through you – and there are billions going through you every second – you don’t notice it because this weak nuclear force is really weak, so really not much is happening.”

So how do you set about looking for something that you have no hope of seeing?

“A nice analogy for the dark matter might be something like the wind. We don’t see it directly, it’s invisible, and yet we’re very sure that it’s there because it makes the leaves rustle around. So the same thing is true with the dark matter. We see that it pulls things around… it’s matter, which means it feels gravity. It clumps together and it pulls on things. So that’s how we know that it’s there, although we don’t know yet exactly what it’s made of.”