Events at Physics |
Events on Thursday, March 12th, 2009
- R. G. Herb Condensed Matter Seminar
- Coulomb Correlations and the Wigner-Mott Scenario for the 2D-MIT
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Vladimir Dobrosavljevic, Florida State University
- Abstract: Significant experimental advances over the past ten years have provided beautiful and convincing evidence for the existence of a sharp metal-insulator transition (MIT) in the two-dimensional 2D electron gases (2DEG). The best evidence for a sharp MIT is found in the cleanest samples, suggesting that key experimental features can all be understood by deliberately disregarding disorder, and focusing on interaction effects alone: viewing the quantum melting of a Wigner crystal as the fundamental mechanism for the MIT in a sufficiently clean 2DEG. A theory describing this phenomenon will be presented, which provides a natural explanation of several puzzling experimental features, including the large effective mass enhancement, the large resistivity drop on the metallic side, and the giant magneto-resistance in presence of a parallel magnetic field.
- Host: Robert Joynt
- Whitford Lecture
- A brief History of Cosmic Expansion and Acceleration
- Time: 3:30 pm
- Place: 2103 Chamberlin Hall
- Speaker: Adam Riess, JHU and STSci
- Abstract: <br>
The expansion rate and its evolution must be empirically determined for our Universe to reveal its composition, scale, age, and fate. In 1998, high-redshift SNe Ia provided the first and only direct evidence for an accelerating Universe and the existence of dark energy. To identify the nature of dark energy we seek to improve on past and present measurements of the recent history of cosmic expansion. Today's keystones of expansion are distant type Ia supernovae and Cepheid variables in their hosts. I will report on new calibrations of the Hubble diagram of SNe Ia with new SN Ia and Cepheid data and an extension of its reach to <br>
z > 1 when cosmic expansion was still decelerating. These measurements are providing new clues about the nature of the mysterious dark energy.<br>
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- Host: Professor Richard Townsend
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- New Results from the Pierre Auger Observatory
- Time: 4:00 pm
- Place: 4274 Chamberlin
- Speaker: Segev BenZvi, University of Wisconsin - Madison
- Host: Stefan Westerhoff