So are the known laws of physics exactly the same for matter and anti-matter? The answer is no. In the 1960s, physicists first noticed that the decays of obscure particles called neutral kaons were very slightly different for the matter and anti-matter versions. Makoto Kobayashi and Toshihide Maskawa realised that they could explain this based on the "mixing" of different kinds of quarks by different interactions, but only if there existed two new kinds of quarks. These two new kinds of quarks were subsequently discovered, and decades of experiments on the decays of mesons have shown that the mixing of quarks is just as Kobayashi and Maskawa predicted (hence their award of the 2008 Nobel Prize for Physics). But the surprise is that the differences between matter and anti-matter explained by Kobayashi and Maskawa would produce something like one-trillionth of the amount of matter we see around us, leading to an exciting conclusion - since the known laws of physics did not produce the matter we see, there must be entirely new laws of physics which are different for matter and anti-matter (or for time running forwards or back).

So what are these new fundamental laws of physics? Unfortunately, the evidence that they exist is compelling but completely non-specific, so there is very little theoretical guidance on where to search. The new Large Hadron Collider at Cern, Europe's particle physics laboratory, is one potentially fruitful hunting ground. One of the big experiments on the LHC, which is called LHCb, will continue the study of meson decays searching for deviations from predictions based on the work of Kobayashi and Maskawa that could signal new CP-violating physics. The big general purpose detectors, Atlas and CMS, will search for any other new physics, most versions of which could produce CP violation.

I have put my money on two other horses. The first has to do with the properties of the enigmatic neutrinos, the ghosts of particle physics. Neutrinos are actually quite common. They are produced in huge numbers by the thermonuclear reactions that power the sun (there are 67 billion of them travelling through every square centimetre of your body every second), but they interact so weakly with normal matter that the neutrinos from the sun pass effortlessly through the Earth. Despite their ghostly nature, these solar neutrinos have now been detected many times, and so have neutrinos from reactors, accelerators, radioactive sources, cosmic-ray interactions in the atmosphere and even a supernova. Experiments have now shown that the same sort of mixing seen in quarks also takes place in neutrinos, where we call it neutrino oscillations. Neutrino oscillations could also violate CP, but to confirm that will require far more precise measurements than we have been able to make up to now. I am therefore part of an ambitious new experiment called T2K, which is building a beam of neutrinos using a new accelerator at Tokai on the east coast of Japan. The beam will be measured there, and then fired 295 kilometres through the ground to the vast Super Kamiokande neutrino detector under a mountain near the west coast of Japan. By looking at changes in the neutrino beam as it oscillates we can make the first tentative steps towards measuring CP violation in neutrinos, which could be the signpost of the physics that led to the excess of matter in the universe.