Physics Colloquia

September, 09/26/2016
Events and times subject to change

September 29, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Andrea Ghez

Our Galactic Center: A Laboratory for Exploring the Physics & Astrophysics of Black Holes

The proximity of our Galaxy's center presents a unique opportunity to study a galactic nucleus with orders of magnitude higher spatial resolution than can be brought to bear on any other galaxy. After more than a decade of diffraction-limited imaging on large ground-based telescopes, the case for a supermassive black hole at the Galactic center has gone from a possibility to a certainty, thanks to measurements of individual stellar orbits. The rapidity with which these stars move on small-scale orbits indicates a source of tremendous gravity and provides the best evidence that supermassive black holes, which confront and challenge our knowledge of fundamental physics, do exist in the Universe. This work was made possible through the use of speckle imaging techniques, which corrects for the blurring effects of the earth's atmosphere in post-processing and allowed the first diffraction-limited images to be produced with these large ground-based telescopes. Further progress in high-angular resolution imaging techniques on large, ground- based telescopes has resulted the more sophisticated technology of adaptive optics, which corrects for these effects in real time. This has increased the power of imaging by an order of magnitude and permitted spectroscopic study at high resolution on these telescopes for the first time. With adaptive optics, high resolution studies of the Galactic center have shown that what happens near a supermassive back hole is quite different than what theoretical models have predicted, which changes many of our notions on how galaxies form and evolve over time. By continuing to push on the cutting-edge of high-resolution technology, we will be able to capture the orbital motions of stars with sufficient precision to test Einstein’s General theory of Relativity as well as theories of galaxy formation and evolution - all in regimes that have never been probed before.


September 29, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Andrea Ghez
UCLA

Our Galactic Center: A Laboratory for Exploring the Physics & Astrophysics of Bla

The proximity of our Galaxy's center presents a unique opportunity to study a galactic nucleus with orders of magnitude higher spatial resolution than can be brought to bear on any other galaxy. After more than a decade of diffraction-limited imaging on large ground-based telescopes, the case for a supermassive black hole at the Galactic center has gone from a possibility to a certainty, thanks to measurements of individual stellar orbits. The rapidity with which these stars move on small-scale orbits indicates a source of tremendous gravity and provides the best evidence that supermassive black holes, which confront and challenge our knowledge of fundamental physics, do exist in the Universe. This work was made possible through the use of speckle imaging techniques, which corrects for the blurring effects of the earth's atmosphere in post-processing and allowed the first diffraction-limited images to be produced with these large ground-based telescopes. Further progress in high-angular resolution imaging techniques on large, ground- based telescopes has resulted the more sophisticated technology of adaptive optics, which corrects for these effects in real time. This has increased the power of imaging by an order of magnitude and permitted spectroscopic study at high resolution on these telescopes for the first time. With adaptive optics, high resolution studies of the Galactic center have shown that what happens near a supermassive back hole is quite different than what theoretical models have predicted, which changes many of our notions on how galaxies form and evolve over time. By continuing to push on the cutting-edge of high-resolution technology, we will be able to capture the orbital motions of stars with sufficient precision to test Einstein’s General theory of Relativity as well as theories of galaxy formation and evolution - all in regimes that have never been probed before.


October 6, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Lisa Manning
Syracuse University

Glassy and Heterogeneous Dynamics in Biological Tissues

Biological tissues involved in important processes such as embryonic development, lung function, wound healing, and cancer progression have recently been shown to be close to a liquid-to-solid transition. In many non-biological materials, a disordered liquid-to-solid transition occurs when the temperature decreases or the packing density increases past a critical threshold. Over the past 20 years physicists have made great progress in understanding the universal nature of these glass and jamming transitions. However, existing theories cannot explain observations of jamming transitions in confluent biological tissues, where there are no gaps between cells and the packing density is always unity. I will discuss a new theoretical framework for rates of cell migration in biological tissues, and show that this model predicts a novel type of critical rigidity transition, which takes place at constant packing density and depends only on single cell properties. Next, we take into account the fact that cells are motile and tend to move persistently, and develop a phase diagram that includes cell speed and persistence. I will discuss how our a priori theoretical predictions with no fit parameters are precisely realized in cell cultures from human patients with asthma, and discuss how these ideas might also be applied in heterogeneous cell populations to understand processes in embryonic development and cancer progression.


October 27, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Mehran Kardar
MIT

TBA



November 3, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Monica Olvera de la Cruz
Northwestern University

TBA



November 10, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Brian Maple
UCSD

TBA



November 17, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Eliezer Rabinovici
Racah Institute of Physics

TBA



December 1, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Adam Riess
Space Telscope Science Institute

TBA



December 8, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Rob Phillips
Caltech

TBA



December 15, 2016 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Jenny Hoffman
Harvard University

TBA



January 26, 2017 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Jane Kondev

TBA



February 16, 2017 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Eric Siggia
Rockefeller University

TBA



February 23, 2017 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


David Huse
Princeton University

TBA



April 27, 2017 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Daniel Whiteson
University of California, Irvine

TBA



May 4, 2017 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Eva Halkiadakis
Rutgers University

TBA