Events at Physics |
Events During the Week of March 13th through March 20th, 2016
Monday, March 14th, 2016
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Magnetic pumping of the solar wind, and new results from the Terrestrial Reconnection Experiment (TREX)
- Time: 12:00 pm - 1:00 pm
- Place: 1153 Mechanical Engineering
- Speaker: Jan Egedal, UW Madison
- Abstract: The transport of matter and radiation in the solar wind and terrestrial magnetosphere is a complicated problem involving competing processes of charged particles interacting with electric and magnetic fields in a turbulent medium. Given the rapid expansion of the solarwind, it would be expected that superthermal electrons originating in the corona would cool rapidly as a function of distance to the Sun. However, this is not observed, and various models have been proposed as plausible candidates for heating the solar wind as it super-sonically streams away from the sun. Here we investigate magnetic pumping as a possible heating source. The mechanism allows energy to be transferred to the particles directly from the largest scales of the solar wind turbulence. Guided by kinetic simulations a theory is derived for magnetic pumping, expressed through a generalization of the Parker Equation to capture the role of the pressure anisotropy during the pumping process. In the talk I will also discuss the latest results from the Terrestrial Reconnection Experiment. These results include the formation of collisionless reconnection layers, strongly modulated by the plasmoid instability.
- Host: UW Madison
Tuesday, March 15th, 2016
- Chaos & Complex Systems Seminar
- Coping with climate change and environmental degradation science, universities, and a great American challenge
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin Hall (refreshments will be served)
- Speaker: Bernard Z. Friedlander and Noah M. Friedlander, University of Hartford
- Abstract: Under pressures of Climate Change, national political stasis, and other potent factors, American universities, colleges, and schools face harsh challenges unlike any our professions have ever encountered. This is due largely to profound contradictions between national needs in our changing society and pressures within and between our varied and competing American sub-cultures. This presentation views the issues in four major categories: Evidence: facts about suppressive forces affecting science, academia, and education. Limited Time: an urgently critical factor. Suppressive Impacts: Climate Change and Environmental Degradation as force multipliers. Prescription: NEW WAYS TO EXPAND AN AGENDA FOR POSITIVE CHANGE.
- Host: Clint Sprott
- Theory Seminar (High Energy/Cosmology)
- Galaxy-galaxy lensing for cosmology in the Dark Energy Survey
- Time: 3:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Juliana Kwan, University of Pennsylvania
- Abstract: The Dark Energy Survey (DES) is an ongoing photometric survey that
will cover 5000 sq deg of the Southern sky over five years with the
aim of determining the origin of cosmic acceleration. Two of the key
probes involved in achieving this goal are the large scale clustering
of galaxies and weak gravitational lensing, which are more powerful
when taken in combination, since the dependence on galaxy bias can be
broken in both probes. Using the red galaxies identified in the Science
Verification area in DES, we have measured the angular clustering and
tangential shear from galaxy-galaxy lensing using red sequence
selected galaxies. In this talk, I will present constraints on the
dark energy equation of state and the amplitude of clustering from a
joint analysis of these probes. - Host: Amol Upadhye
Wednesday, March 16th, 2016
- Department Meeting
- Time: 12:15 pm
- Place: 5310 Chamberlin Hall
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- New results from RENO
- Time: 2:00 pm - 3:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Seon-Hee Seo, Seoul National University
- Abstract: RENO (Reactor Experiment for Neutrino Oscillation) is designed to measure the neutrino mixing angle theta_13 and the effective mass squared difference |dm^2_ee| using electron anti-neutrinos from six reactors at Hanbit nuclear power plant in S. Korea. RENO has been taking data since August 2011 using two identical detectors at near and far sites. The unprecedented measurement of the theta_13 by RENO was made in 2012 with 4.9 sigma significance using 220 live days of data.
In this talk we present the updated sin^2(2q13) value and first measurement on |dm^2_ee| based on a spectral shape analysis using 500 live days of data. And they are sin^2 (2theta_13) = 0.082 +- 0.009(stat.) +- 0.006 (syst.) and |dm^2_ee| = 2.62 +0.21 -0.23 (stat.) +0.12 -0.13(syst.) (X 10^-3 eV^2. The systematic uncertainty of sin^2(2q13) has improved mainly due to the better estimation of the Li9/He8 background and the reduction of its uncertainty. The 5 MeV excess of the electron anti-neutrino events is also discussed.
- Host: Albrecht Karle
Thursday, March 17th, 2016
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm - 1:15 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
http://cmb.physics.wisc.edu/journal/index.html
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Amol Upadhye (aupadhye@wisc.edu). - Host: Amol Upadhye
- Astronomy Colloquium
- The Role of Dwarf-Dwarf Galaxy Interactions in Galaxy Assembly
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall, Coffee and cookies at 3:30 PM, Talk at 3:45 PM
- Speaker: Sabrina Stierwalt, NRAO
- Abstract: Massive galaxy mergers are an important mode of galaxy evolution and are observed to inspire intense starbursts, the growth of AGN,and significant rearranging of the galaxies' gas and dust. However, despite the fact that the majority of mergers at all epochs occur among low mass galaxies, whether these effects occur in the shallow gravitational potential wells of dwarf galaxies remains mostly uncharted territory. Mergers at low redshift in particular offer a high resolution look at a process that set the stage for galaxy assembly at earlier epochs when such low metallicity mergers were more frequent. I will present initial results and future plans for TiNy Titans, the first systematic study of a sample of interacting dwarf galaxies and the mechanisms governing their star formation and subsequent processing of the ISM. We find multi-wavelength evidence based on star formation rates, gas and dust content that mergers proceed substantially differently at low masses. Our survey further uncovers galaxy groups with only low-mass members, a discovery that appears to contradict predictions of structure formation from hydrodynamic cosmological simulations.
- Host: Snezana Stanimirovic
- Physics Department Colloquium
- From Bell's inequalities to quantum information: a new quantum revolution
- Time: 4:00 pm - 5:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:45 pm)
- Speaker: Alain Aspect, CNRS, Institut d’Optique
- Abstract: In 1935, with co-authors Podolsky and Rosen, Einstein discovered an intriguing quantum situation, in which particles in a pair are so strongly correlated that Schrödinger called them “entangled”. By analyzing that situation, Einstein concluded that the quantum formalism is incomplete. Niels Bohr immediately opposed that conclusion, and the debate lasted until the death of these two giants of physics.
Thirty years later, John Stuart Bell discovered that it is possible to settle the debate experimentally, by testing the famous "Bell's inequalities", and to show directly that the revolutionary concept of entanglement is indeed a reality. A long series of experiments closer and closer to the ideal scheme proposed by Bell has confirmed that entanglement is indeed "a great quantum mystery", to use the words of Feynman.
Based on that concept, a new field of research has emerged, quantum information, where one uses quantum bits, the so-called “qubits”, to encode the information and process it. Entanglement between qubits enables conceptually new methods for processing and transmitting information. Large-scale practical implementation of such concepts might revolutionize our society, as did the laser, the transistor and integrated circuits, some of the most striking fruits of the first quantum revolution, which began with the 20th century. To cite only the simplest example of these new concepts, quantum cryptography allows one to guarantee an absolute privacy of communications, based on the most fundamental laws of quantum mechanics.
- Host: Thad Walker
Friday, March 18th, 2016
- Informal meeting with Fleming Crim
- Time: 10:30 am - 10:00 am
- Place: 4274 Chamberlin Hall
- Speaker: Fleming Crim, NSF
- Abstract: Assistant Director of the NSF Math and Physical (MPS) will be here to have an informal discussion about trends at NSF.
- Host: Albrecht Karle
- Atomic Physics Seminar
- Atomic Hong-Ou-Mandel effect: a mile-stone in Quantum Atom Optics
- Time: 11:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Alain Aspect, Institut d’Optique
- Abstract: Atomic Hong-Ou-Mandel effect: a mile-stone in Quantum Atom Optics
- Host: Walker
- Physics Department Colloquium
- Gene Surfing and Survival of the Luckiest
- Time: 3:30 pm - 4:30 pm
- Place: 2241 Chamberlin Hall (coffee at 3:15 pm)
- Speaker: David Nelson, Harvard University
- Abstract: It is widely appreciated that population waves have played a crucial role in the evolutionary history of many species. In parallel with Fokker-Planck descriptions of stochastic processes in physics, population geneticists have developed methods for understanding mutations, genetic drift and selective advantage in such situations. Provided number fluctuations at the frontier are taken into account, neutral genetic markers can be used to infer information about growth, ancestral population size and colonization pathways. Neutral mutations optimally positioned at the front of a growing population wave can increase their abundance via a "surfing" phenomenon. Experimental and theoretical studies of this effect will be presented, as well as recent attempts to extend statistical dynamics ideas to microorganisms cooperating and competing in the turbulent environment of the ocean.
- Host: Pupa Gilbert