Speaker:
　  Prof. Anthony C. S. Readhead
Affiliation：
　  Director, OwensValley Radio Observatory (Caltech)
Time: 
　  3:00PM, March 15 (Monday)
Location: 
　　middle conf. room, 3rd floor
Abstract：
　  The Cosmic Microwave Background Radiation (CMBR) has proven to be an extremely productive arena for the study of cosmology. In my talk I will describe early CMBR work at the Owens Valley Radio Observatory, which demonstrated that most of the matter in the universe is non-baryonic cold dark matter, and I will then describe observations with the Cosmic Background Imager (CBI) in Chile, which was the first instrument to detect anisotropy in the CMBR on mass scales from galaxy clusters to superclusters, revealing, for the first time, the seeds that gave rise to all the structure we see in the universe today. In addition the CBI provided ensitive measurements of the E-mode polarization that demonstrated convincingly that the anisotropy in the CMBR was caused by acoustic waves. Following the detection and delineation of the E-mode polarization, the "Holy Grail"  of CMBR observations has become the detection of large scale B-mode  polarization caused by the interaction of primordial gravitational waves with the CMBR. If detected, such B-mode polarization would show that an inflationary epoch did actually occur in the very early universe.  It would reveal the energy scale of inflation and push the clock back to an era ~10^-35 seconds after the Big Bang. However, these B-mode signals are extremely weak and sensitivity of 10^-8 Kelvin is needed to search for them. This daunting challenge is being met by the QUIET project, which is now operating in Chile will be described in detail.