I have been sent a link to a marvellous song about String Theory. Danke! You HAVE to see this: it's awesome.
http://www.youtube.com/watch?v=2rjbtsX7twc String theory is now an attempt to have a theory of quantum gravity. In other words, to have gravity work on very small scales where the world is inherently lumpy. So you'd think that lumps would be particles. But mathematically a particle is no dimensions. It takes up no space! This leads to problems with the maths because when you divide by zero space, the answer is infinity. The quantum theory of light, Quantum Electrodynamics (QED) for which Feynman, Schwinger and Tomonaga received the Nobel Prize, got round the problem by a technique of effectively cancelling infinities on either side of the equation. This is usually very dodgy but it worked perfectly in this case. The technique is called renormalisation. It doesn't work for quantum gravity. To get round the problem it was suggested that we should give the quantum particles a dimension. Hence they are strings because a line has only one dimension. Your computer screen has two dimensions. It gets round the infinities problem but is controversial because many people say that it is not possible to prove it experimentally.
I had a chance to consider gravity more intimately on Saturday afternoon when I came face to face with Broad Stand, one of the most notorious features in the Lake District. This small cliff blocks the way between Scafell Pike and Scafell. You go in through the narrow cleft in the rock (see detail in the bottom photo). That's as far as I dared. The way forward sees you out over a long drop and many people have been seriously hurt falling. Discretion proved the better part of valour. String theory might explain gravity but it won't stop you falling. It didn't stop Samuel Taylor Coleridge, one of my favourite poets, from falling down over 200 years ago, but he survived to write about it. You have been warned!
