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Other interesting talks I saw yesterday involved dark matter and GR.

In this dark matter session I saw a talk on Noble liquid dark matter detectors and axion detection. The talk on Noble liquid dark matter detectors was by Richard Gaitskell of Brown University. This man is the most English man ever! He puts Hugh Grant to shame. The talk was littered with many utterances of "Damn!" and general foppish bumbling, in the endearingly charming way that only a true Englishman can pull off. It was an entertaining talk describing the how you can look for neutron recoils caused by WIMPs (a term for a variety of dark matter candidates) within various Noble gas detectors. The other talk in this session that I saw was about axion detection by Dave Tanner of the University of Florida (who some of us at Glasgow, and within the gravitational wave community will know). The axion is another dark matter candidate. It was proposed as a solution to the CP problem in various weak interactions (you expect interactions to be symmetric i.e. if you take a reaction and mirror it [swap the charges, parities and directions of the particles involved] then you expect things to look the same, but there are certain interaction involving the weak force where charge conjugation and parity are not symmetric [imagine walking towards a mirror, but your reflection moves away from the mirror - that would be a strongly broken symmetry]). You can't detect the axion itself, but it will decay into two photons although with a decay time much greater than the age of the universe. If you want to try and detect this decay you have to induce the decay. The talk was about the axion detector ADMX, which aims to detect axions forming a cold dark matter halo around the Milky Way. It does this by using a microwave cavity to try and induce the axions to decay. One of the most interesting ideas talked about was a future plan to generate and detect axions using optical cavities within large magnetic fields. You create axions from the photon field on one side of a wall, this axions flow through the wall and are then converted back to photons on the other side - you essentially are "shining light through a wall"! It was very interesting.

The final talk I saw yesterday was a nice historical perspective on the development and use of General Relativity. It was a very entertaining talk, with lots of anecdotes, which showed that even the great minds who worked on the foundations of GR could make mistakes.

Later today I give my own talk, so I should give it a run through at some time to make sure I can stay on time (I've only got 10 minutes).