Events at Physics
Events on Thursday, March 3rd, 2011
- R. G. Herb Condensed Matter Seminar
- Universal energy fluctuations in driven thermally isolated systems
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Anatoli Polkovnikov, Boston University
- Abstract: In this talk I will present two stories of emergent uiversality in thermally isolated driven systems. In the first I will show how unitary dynamics constraints energy distribution in a repeatedly driven thermally isolated system (microwave setup). I will present generalized fluctuation relations and will show that they imply a dynamical phase transition between canonical like and wide regimes. In the second part of the talk, if time permits, I will discuss universal scaling of energy, entropy and defect generation for quench dynamics through quantum critical points. In particular, I will show how quantum Kibble-Zurek and other related scalings follow from the adiabatic perturbation theory.
- Host: Maxim Vavilov
- Astronomy Colloquium
- The missing baryons around galaxies and galaxy clusters
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Joel Bregman, University of Michigan
- Abstract: The baryon content is composed of the sum of stars and the gaseous <br>
components, which can be measured in potential wells from the richest clusters to the poorest galaxies. For the richest clusters of galaxies, most of the baryons are accounted for in that the baryon fraction approaches the cosmological value, within theoretical expectations. Progressing toward shallower potential wells, the baryon fraction decreases slowly until temperatures of about 1E6 K, below which the baryon fraction decreases quickly. This trend of decreasing baryon content continues through galaxies, where the Milky Way is missing about 75% of its baryons and the typical (lower mass) galaxy is missing 90% of <br>
its baryons. The missing baryons do not surround the galaxies as hot halos and we argue that the material never fell into these galaxies, having been pre-heated by an early population of supernovae. Furthermore, we show that the heating and metallicity contributions from this early population of stars may be largely independent of galaxies as well.
- Host: Bart Wakker
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Neutrinos and the Future of the Standard Model
- Time: 4:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Dan Dwyer, Caltech
- Abstract: For over 30 years the Standard Model has served as our template for interpreting the world of particle physics. Recent results from neutrino experiments have shown that we must modify this long-standing theory. Current and future experiments will be discussed, with special attention on the KamLAND and Daya Bay neutrino oscillation experiments. The necessary changes for the Standard Model have consequences for the current set of fundamental particles, the nature of dark matter, and the matter-antimatter asymmetry of the universe.