My wife surprised me this morning by striking up a conversation about String Theory causing me to pause over my Marmite on toast. Unlike the Mrs I'm one of those people who'd tick the box marked "don't know" when as asked about this, but she enlightened me about particle physics and even managed to mention Deepak Chopra, although I'm not sure how he got in there. Apparently those with the word ‘physics’ in their job title are fascinated by the idea of a Unified Theory, something that can explain life, the universe and everything. They originally reckoned Newton had sussed it, as his ideas seemed to explain stuff that was very big like planets and small like apples. As Newtonian physics became inadequate it spawned two new ideas, the General Relativity Theory and Quantum Mechanics that unfortunately are incompatible when one is used to explain the other, a bit of a problem if you’re looking for a single theory of everything. Then in the mid-eighties something called String Theory emerged as a possible way to explain things that happen at very small scales where neither quantum mechanics nor gravity can be ignored. But what is it? At something called the Planck Scale which is about 10^-33 centimetres, or about a millionth of a billionth of a billionth of a billionth of a centimetre, the different particles we learned about at school are replaced by one fundamental building block or a ‘string’. These can be closed in a loop or open like…well a string. Now this gets a bit freaky so stay with me. As the string moves through time it traces out a sheet or tube depending on whether it’s opened or closed. In addition it is free to vibrate and the different ‘notes’ these vibrations create represent the different particle types, one note makes the string appear like an electron another a photon or even a graviton. And it's the graviton that gets the physicists excited because now they have a way of understanding of how large celestial objects interact along with tiny stuff like atoms. They are however still some way from connecting all this things together to everyones satisfication, I for one won't be happy until it explains why some people don't like Marmite and others do.