Fall 2013 - Hamilton Colloquium Series
4:30 PM Jadwin A10
Thursday, September 19, 2013
Justin C. Kasper, University of Michigan; Smithsonian Astrophysical Observatory
"Sending a spacecraft to the Sun"
For centuries solar eclipses have provided brief glimpses of the solar corona, a remarkably structured atmosphere that surrounds the Sun and spreads into the solar system. Today, the Sun and the corona are tracked continuously by observatories on Earth and in space. We know much more about solar activity and the impact space weather can have on society than ever before, but we have not been able to answer fundamental questions about the Sun. Why is the corona millions of degrees hotter than the visible surface of the Sun? How does the corona drive a supersonic solar wind? How are solar flares and eruptions able to produce storms of radiation? It has long been recognized that the only way to unambiguously answer these questions is to send an instrumented probe close to the Sun. In 2018 we will finally embark on this journey with the Solar Probe Plus spacecraft, a NASA mission that will repeatedly plunge through the corona to obtain the first direct samples of the Sun. The mission will be reviewed, with a focus on the physics of the solar corona and the design of plasma instruments capable of both making the necessary measurements and of surviving the solar encounters.
Host: Amitava Bhattacharjee, Department of Astrophysical Sciences; PPPL
Thursday, September 26, 2013
Andrei Bernevig, Princeton University
"Topological States of Matter"
Thursday, October 10, 2013
Will Happer, Princeton University
"Why Has There Been No Global Warming For The Past Decade?"
The temperature of the Earth's surface has not changed by more than 0.1 C since the year 2000, and it may even have cooled slightly. Most computer models predicted that the increase of CO2, from about 370 to 400 ppm during that period, should have caused a warming of around 0.3 C. There are many possible reasons for the failure of the models, but one may be insufficient careful attention to important, and often neglected details of how CO2 molecules really absorb and emit radiation in the Earth's atmosphere. Some of the physics in question is related to early work by Princeton's Robert Dicke on collisional line narrowing.
Host: Lyman Page, Princeton University
Thursday, October 17, 2013
Risa Wechsler, Kavli Institute, Stanford University
"Dark Matter Insights from Cosmological Structure Formation"
There is now overwhelming evidence that more than eighty percent of the mass in the Universe is dark matter. This provides a clear indication for the existence of a particle or particles beyond the standard model, but we have yet to determine the nature of this particle. Models of dark matter make specific predictions for the formation of cosmological structure on a wide range of scales, from the shapes of and substructures within galaxies to the distribution of matter over cosmological distances. I will outline how theoretical predictions, simulations, and observations of cosmological structure formation shed light on the distribution and particle nature of dark matter. This includes both how they inform our understanding and interpretation of limits and signals from dark matter, direct and indirect detection experiments, and how astrophysical measurements can complement these studies.
Host: Mariangela Lisanti, Princeton University
Thursday, October 24, 2013
Shiraz Minwalla, Tata Institute of Fundamental Research - Mumbai, India
"The Fluid Gravity Correspondence"
Thursday, November 7, 2013
Sarah Eno, University of Maryland
"The LHC: Beyond the Standard Model"
The Higgs was postulated, during the 1970s, to be the source of electroweak symmetry breaking in the standard model. For my entire professional career, the search for the Higgs boson has been the highest priority goal for the field of experimental high energy physics. The Large Hadron Collider was designed with its discovery in mind, and the observation of a new boson during the 2012 run is the culmination of the work of many people. However, the data provided by the Large Hadron Collider can also be used to investigate newer questions, inspired both by results from cosmology and from the remaining mysteries of the standard model. In this talk, I will briefly review the Higgs results, but then will emphasize what we have learned from the LHC about dark matter and theories of physics beyond the standard model. I will also talk about plans for future LHC runs, and what we might learn from their data.
Host: Dan Marlow, Princeton University
Thursday, November 14, 2013
Cristiano Galbiati, Princeton University
"What about dark matter?"
I will discuss the status of direct dark matter searches and the prospects for the DarkSide program.
Thursday, November 21, 2013
Joseph Polchinski, Kavli Institute for Theoretical Physics (KITP), University of California, Santa Barbara
"The Black Hole Information Paradox: Alive and Kicking"
Thought experiments have played an important role in figuring out the laws of physics. For the unification of quantum mechanics and gravity, where the phenomena take place in extreme regimes, they are even more crucial. Hawking's 1976 paper "Breakdown of Predictability in Gravitational Collapse" presented one of the great thought experiments in the history of physics, arguing that black holes destroy information in a way that requires a modification of the laws of quantum mechanics. Skeptics for years failed to poke holes in Hawking's argument, but concluded that if quantum mechanics is to be saved, then our understanding of space time must break down in a radical way. For a time it seemed that Maldacena's discovery of gauge/gravity duality had resolved the issue, but the recent firewall argument has opened many new questions.
Host: Herman Verlinde, Princeton University
Thursday, December 5, 2013
Emilia Morosan, Rice University
(title to be announced)