Experimental gravity with LIGO - Sam Waldman - Special Seminar

Tue, Mar 1, 2011, 1:30 pm to 3:30 pm
Jadwin 303
The direct detection of gravitational waves (GWs) offers a revolutionary new probe of the most energetic processes in the universe and a test of general relativity in new regimes. The 4 km long LIGO interferometers have demonstrated the sub-attometer displacement sensitivity (< 10^{-18} m/ Hz^{1/2}) and continuous operation (> 75\% duty factor) needed to detect GWs out beyond the Virgo cluster, but none have yet been seen. Starting in 2008, we began construction of a 2nd generation of interferometers, Advanced LIGO, to increase the detector sensitivity and bandwidth by more than an order of magnitude. In this talk I will review the next five years of physics challenges and experiments involved in building and commissioning Advanced LIGO. We will discuss our plans to commission active seismic isolation systems with picometer displacement noise, low-loss passive isolation systems with mechanical quality factors >10^7, and Michelson interferometers with 750 kW of stored power. Together, these systems form a detector capable of detecting the 2x10^{-20} m GW signal from two black holes coalescing 6 billion light years away. We expect Advanced LIGO to detect the most powerful sources -- the merger of two compact objects such as neutron stars and black holes -- with rates from a few to many per year. The GW waveform, together with electromagnetic observations, will allow tests of the physics of black holes and general relativity. As the Advanced LIGO program continues, we will continue to improve the interferometer sensitivity using techniques from integrated photonics, material science, and quantum measurement.