Events at Physics |
Events During the Week of September 12th through September 19th, 2010
Monday, September 13th, 2010
- No events scheduled
Tuesday, September 14th, 2010
- Chaos & Complex Systems Seminar
- Designing Climate Change Solutions
- Time: 12:05 pm
- Place: 4274 Chamberlin Hall
- Speaker: Tracey Holloway, UW Department of Atmospheric and Oceanic Sciences
- Abstract: Climate change is affected by almost every sector of the economy and society (transportation, electricity, consumption, food, agriculture, land use, manufacturing, etc.). Similarly, the impacts of climate change affect these same systems (extreme weather, seasonal shifts, agricultural vulnerability, infrastructure, public health, coastal areas, etc.). So, the options for mitigating - reducing emissions of CO2 and other greenhouse gases - or adapting - reducing vulnerability of systems - are almost limitless. For the third year in a row, the SAGE (the Center for Sustainability and the Global Environment in the Nelson Institute) hosts the largest student environmental innovation competition in the world: the Climate Leadership Challenge (CLC). The CLC focuses on innovative, scaleable solutions to climate change. In 2011, the CLC will again be awarding a $50,000 grand prize to a student team interested in advancing a climate solution. This talk will discuss climate change mitigation and adaptation broadly, success stories, and opportunities for students to compete this year.
- Special Astronomy Colloquium Talk
- The Transiting Extrasolar Planets - A vehicle to learn new features about extrasolar systems
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall Same Location
- Speaker: Tsevi Mazeh, Tel Aviv University
- Abstract: About 100 of the known extrasolar planets eclipse their parent star once every orbital period. The detection of these transiting planets in the last few years allowed the derivation of the planetary masses and radii, some of the parent star obliquity and sometimes even the planetary temperatures and atmospherical features. The talk will review the detection and study of the presently known transiting planets, and will point out how the new systems are different from our own solar system.
The new era of studying transiting planets from space by CoRoT and Kepler allows detection of minute modulations, with amplitudes of the order of 10's ppm (parts per million). I will discuss a recent detection of the ellipsoidal and the relativistic beaming effects in the lightcurve of CoRoT-3.
- Host: Robert Mathieu
Wednesday, September 15th, 2010
- No events scheduled
Thursday, September 16th, 2010
- R. G. Herb Condensed Matter Seminar
- A Macroscopic Mechanical Resonator Driven by Mesoscopic Electrical Backaction
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Alex Rimberg, Dartmouth College
- Abstract: We have recently discovered that the driven classical dynamics of a macroscopic mechanical object can be dominated by the quantum statistical fluctuations of tunneling electrons, i.e., by shot noise. Furthermore, coupling between the object and the electrons modifies the electron-electron correlations, resulting in strongly super- and sub-Poissonian current noise. In particular, we have found that a GaAs-based quantum point contact (QPC) can be viewed as a macroscopic mechanical oscillator (a normal mode of the host crystal) whose position is continuously monitored by a mesoscopic electrical detector (the QPC). Furthermore, electrons tunneling through the QPC cause the host crystal to vibrate by means of quantum mechanical backaction. This effect is similar to Brownian motion, in which the motion of a grain of pollen in water is determined by the classical equilibrium statistical fluctuation of molecules. In our case, however, the motion of the oscillator is determined by the quantum non-equilibrium statistical fluctuations of tunneling electrons. Furthermore, the size disparity between the oscillator (a semiconducting chip containing 10^20 atoms) and the source of the fluctuations driving them (fundamental subatomic particles) is truly extreme, and provides a dramatic example of interaction between the quantum and classical worlds.
- Host: Mark Eriksson
- Astronomy Colloquium
- Finding Dark Galaxies From Their Tidal Imprints
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall Same Location
- Speaker: Sukanya Chakrabarti, UC Berkeley
- Abstract: Characterizing the ubiquitous dark matter in the universe has proven to be one of the most challenging problems in modern astrophysics. If the dynamical impact of dark-matter dominated dwarf galaxies on the outskirts of galactic disks can be deciphered, we may be able to infer and characterize cold dark matter sub-structure in a fundamentally new way. I show how one can analyze observed disturbances in the outer gas disks of spiral galaxies to quantitatively characterize galactic companions without requiring knowledge of their optical light. This method, which I call "Tidal Analysis", allows one to determine the mass and relative position (in radius and azimuth) of galactic companions from analysis of observed disturbances in gas disks. I will first demonstrate the validity of this method by applying it to local spirals with known optical companions to provide a proof of principle. I will then review my earlier work on the Milky Way that prompted the development of this method. Specifically, analysis of observed disturbances on the outskirts of the Milky Way disk favor a 1:100 mass ratio perturber with a close pericentric approach. I will conclude by discussing ongoing work on developing scaling relations between observed HI maps and satellite mass, and our plans for the near-future which include testing the Tidal Analysis method on large samples to determine its statistical viability.
- Host: Bob Benjamin/Barb Whitney
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Precision Gravity and Effective Field Theories
- Time: 4:00 pm
- Place: 4274 Chamberlin
- Speaker: Andreas Ross, University of Wisconsin at Madison/Argonne National Laboratory
- Abstract: The effective field theory description yields a systematic treatment of gravitational bound states such as binary systems. Gravitational waves emitted from binaries are one of the prime event candidates at direct detection experiments such as LIGO, VIRGO etc. Due to the multiple scales involved in the binary problem, an effective field theory treatment yields many advantages in perturbative calculations. My talk will review the setup of the effective field theory framework and report on recent progress in gravitational wave phenomenology.
- Host: Michael Ramsey-Musolf
- Graduate Introductory Seminar
- Biophysics Seminar
- Time: 5:30 pm - 6:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Coppersmith, Gilbert
Friday, September 17th, 2010
- Physics Department Colloquium
- Big Bang Nucleosynthesis as a Probe of Cosmology and Particle Physics
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Gary Steigman, Ohio State
- Abstract: Briefly, during its early evolution, the Universe was a cosmic nuclear reactor. The expansion and cooling of the Universe limited this epoch to the first few minutes, allowing time for the synthesis in astrophysically interesting abundances of only the lightest nuclides: D, 3He, 4He, 7Li. For big bang nucleosynthesis (BBN) in the standard models of cosmology and particle physics (SBBN), the SBBN-predicted abundances only depend on the baryon density parameter, the ratio (by number) of baryons (nucleons) to photons. The predicted and observed abundances of the relic light elements are reviewed, testing the internal consistency of SBBN. The consistency of BBN is further explored by comparing the values of the cosmological parameters inferred from primordial nucleosynthesis for models with non-standard early Universe expansion rates with those derived from studies of the cosmic background radiation, which provides a snapshot of the Universe some 400 thousand years after BBN has ended.
- Host: Ramsey-Musolf