Sunday, April 15, 2007

Science report

In a shock to all my loyal reader's I'm going to talk about science and comment on some of the talks I've seen here at the APS meeting. Yesterday afternoon I went to a talk given by Geoff Burbidge of Burbidge, Burbidge, Fowler and Hoyle (or B2FH as it is commonly referred to in the astronomy community) fame - this was one of the seminal works on stellar nucleosynthesis i.e. the creation of heavy elements within stars. The paper was published in 1957 so Burbidge was giving a lecture in a session dedicated to the anniversary of it. As you'll probably gather from the paper being 50 years old Burbidge himself is getting on a bit. He's originally English, but has lived in the US for many years and has an accent that fluctuates between the two as he talks. The start of his talk was a good historical perspective of his field, which is always interesting to here from one of the people who was around at it's very start. However, for the majority of the talk he moved onto discussing his many problems with current cosmology. You see he is one is the dwindling minority (a fact he indeed joked about) who, like his more famous co-author Fred Hoyle, still hold onto some form of a steady state universe. Part of his theory relies on the CMB being explained by the synthesis of Helium from Hydrogen, rather than from the hot fireball Big Bang model. Although he makes his points well, some of his conclusions do seem to be rather clutching at straws to hold onto a model that pretty much all evidence points against. It was a very entertaining talk in all.

Today I have seen some very nice talks on the proposed Dark energy missions SNAP, Destiny and ADEPT. The first talk was by Saul Perlmutter, the lead author on the original Supernova cosmological acceleration results (supernova observations seemed to show that the universe is currently undergoing an accelerating expansion caused by an as yet unknown dark energy). He gave a very nice, and understandable, overview of the scientific objectives of SNAP (Supernova Acceleration Probe). Another of the talks was by Daniel Eisenstein of the University of Arizona describing the science objectives of ADEPT, which goes about the dark energy problem in a rather difference way that the supernova observations. This is instead looking for Baryon Acoustic Oscillations (BAO). This requires looking at the large scale distribution in space of galaxies at different redshifts. Now my knowledge of BAOs was very limited before this talk, but it was all very well explained and I came out feeling quite well informed on the subject. It basically says that there should be a naturally preferred distance scale between galaxies set down by the speed of sound propagation, and therefore matter density propagation, in the early universe. You look for these preferred scales by looking at the distribution of galaxies, and indeed they are seen. I shouldn't be too enthusiastic about these missions though as they're in direct competition against the gravitational wave mission LISA for being the first Beyond Einstein mission to be funded - of course it would be nice if they could all be done.

I also saw a talk this morning by a promising young physicist by the name of Jennifer Watson, of the University of Edinburgh, but currently working at SLAC. I learned all about the B → k*ll decay process and how you can distinguish it from the charmonium decay. Fascinating stuff ;)

More news tomorrow maybe.