The theory of inflation, which posits that the Universe expanded exponentially very early in its history, is by now widely accepted as part of the standard cosmological paradigm. Within the last 15 years it has become widely recognized that, in addition to seeding scalar, matter density perturbations in the Universe, inflation will also produce a background of gravity waves (tensor perturbations) that imprint a curl component into the polarization pattern of the Cosmic Microwave Background (CMB) at the time of recombination. The detection of this so-called B-mode pattern would both constitute robust, "smoking gun" evidence for inflation and offer a probe of the physics responsible for it. In this talk I will discuss the recent, high-significance detection of B-mode polarization by the BICEP2 experiment, a microwave polarimeter that observed at the South Pole from 2010-2012 and that was specifically designed to measure the inflationary signal. I will discuss the instrument, analysis and results, and review the status of other experiments, such as the Keck Array and BICEP3, that are currently poised to measure this signal in more detail.
Argonne Physics Division Seminar Schedule