Posts Tagged ‘cosmology’

Neutrinos, Antarctica, and People

Sunday, March 28th, 2010

Another highlight from the Moriond conference: Abby Veiregg gave a presentation on the ANITA experiment. ANITA is basically a set of radio antennas put on a balloon that circles the Antarctic for several weeks at a time.  The experiment is looking for evidence of extremely high-energy cosmic ray neutrinos. When these high-energy neutrinos graze the Antarctic ice, they are traveling faster than light can travel in the ice, which produces the analogue of the shock wave a supersonic aircraft makes. This electromagnetic shock wave, called Cherenkov radiation, includes some radio waves that can be detected by ANITA. Unfortunately this round of the experiment was not sensitive enough to see any neutrinos; an upgraded version is currently being built. One of the reasons that the experimentalists had a difficult time is that there was a lot of radio wave background from human sources. Apparently there are scientists all over Antarctica!

Radio waves detected by the ANITA experiment provide a "heat" map of Antarctica.

Radio waves detected by the ANITA experiment provide a "heat" map of Antarctica.

The dark blue region is the area scanned by ANITA, the other colored areas represent places where radio waves were found.

Cosmic Landscape

Wednesday, October 18th, 2006

Lenny Susskind

Lenny Susskind

Leonard Susskind of Stanford gave a HEFTI public lecture, based on his book The Cosmic Landscape: String Theory and the Illusion of Intelligent Design at UC Davis on Oct 17.  About 400 people got an entertaining look at the “landscape” of universes allowed by string theory and how it might explain some of the apparent fine-tunings in nature that make life possible. “Lenny” (as he is affectionately known to almost all) was in high form, but also showed how he could be gentle with his critics.

New Axion Analysis

Monday, November 28th, 2005

photon-axion mixing

A cartoon of photons leaving a supernova, partially converting to axions, and the axions passing through the Earth.

There is a new analysis by Yong-Seon Song and Wayne Hu of photon-axion oscillations using data from Type IA supernovae, the Wilkinson Microwave Anisotropy Probe, and baryon oscillations in the density power spectrum seen by Sloan Digital Sky Survey.  They find that while photon-axion oscillations cannot explain supernova dimming in the absence of dark energy, photon-axion oscillations with dark energy are preferred by the data over a cosmological constant. For more background on photon-axion oscillations click here.