Tuesday, May 5, 2009

Report from the 'April meeting'

Scientific conferences have personalities. They shift locations and take on the color of the locale, but the canvass of a given conference is the same. I write this from a hotel room in Denver, CO, site of my society's annual meeting. It does not matter that it is in Denver, or that it's May, it is still the 'April meeting'.  The April Meeting is not a cozy specialized meeting, nor is it a zoo that the largest meetings become. It covers just the subjects of particle physics, nuclear physics and astrophysics. So it is a chimera of the small and the large, the specialized and the very broad.

There is the same rhythm of expansive plenary talks in darkened ballrooms, and frenzied cryptic parallel session talks in small rooms which either are empty or overfull. There are talks on science and society. There are all the organizational meetings. There are the booths and posters. Yet at 1400 people it feels sparse.

The most exciting results this year are from the Fermi Gamma-ray Space Telescope (formerly called GLAST). Launched in June 2008, it is already changing our view of the high-energy sky. Its main instrument, the Large Area Telescope, or LAT, has made a precise measurement of ultra-high energy electrons and positrons. A previous experiment had shown indications of an excess in number of particles detected, which was hard to explain with known physics. LAT has shown that that "bump" was likely just a statistical fluctuation. Alas, this is what usually happens--most coincidences are actually just coincidences. LAT also showed that there is some new source of high-energy positrons out there, which will surely launch a thousand papers.

Fun anecdote: One of the talks was given by a senior physicist  (he received the Nobel prize for work done in 1964). He admitted that he had a habit of showing data before the large collaboration of which he is a part was ready to release it. After his talk, someone asked a question about the composition of the cosmic rays his collaboration had detected. He excitedly jumped to a slide he'd prepared because he "knew someone would ask that question". He explained that the collaboration would release the data soon, after further analysis, but he'd show the figure now. When the figure popped up there was a big "X" in place of the plot. He was astonished and confused and wondered aloud how it could have happened. Then one of his collaborators raised her hand and admitted to have hacked into his talk. She said, "we knew you might show this but we're not ready to release it yet".   He laughed at being thwarted.

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