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Past years' colloquia

Archive of videos - Fall 2012

Archive of videos - Spring 2013

Archive of videos - Fall 2013

Archive of videos - Spring 2014

Current videos - Fall 2014

Eisenbud Lecture Series in Mathematics and Physics

Berko Symposium

All colloquium videos are under copyright and may not be reproduced, in part or in total, without written permission of the speaker and of the Physics Department.

Department Colloquia

Martin Weiner Lecture Series
Department of Physics Colloquium
4:00 pm, Abelson 131
Refreshments at 3:30pm outside Abelson 131

Fall 2014 Colloquia

Tuesday, September 2

Enectali Figueroa-Feliciano, MIT
What's the Matter with the Universe?

Abstract: Dark matter makes up 85% of the mass of the Universe, yet we know very little about what it is. We hunt for dark matter in an old iron mine half a mile underground using detectors operating only thousandths of a degree above absolute zero. I will present results from two experiments by the Cryogenic Dark Matter Search (CDMS) collaboration that are focused on light mass (< 10 GeV) dark matter, and discuss the future reach of this technology. Although the composition of the other 15% of the mass in the Universe is understood, plenty of questions about its origin and evolution remain. I will also introduce the Micro-X sounding rocket, a high-spectral resolution x-ray telescope which will study supernova remnants, the fascinating relics of stars whose explosive deaths gave birth to most of the atoms that form our planet.

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Tuesday, September 9

Matthew Headrick, Brandeis University
Quantum entanglement and the geometry of spacetime

Abstract: Recent developments have led to the discovery of a beautiful and surprising connection between the geometry of spacetime in quantum gravity and entanglement in quantum field theories. This discovery offers a new perspective on old puzzles concerning black holes, and may lead to a profoundly new way of thinking the emergence of spacetime from fundamental quantum-mechanical building blocks. I will describe these developments, explaining along the way the necessary background in general relativity, quantum field theory, and quantum information theory.

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Tuesday, September 16

Jeffrey J. Fredberg, Harvard School of Public Health
Collective migration and cell jamming

Abstract:  Our traditional physical picture holds with the intuitive notion that each individual cell comprising the cellular collective senses signals or gradients and then mobilizes physical forces in response. Those forces, in turn, drive local cellular motions from which collective cellular migrations emerge. Although it does not account for spontaneous noisy fluctuations that can be quite large, the tacit assumption has been one of linear causality in which systematic local motions, on average, are the shadow of local forces, and these local forces are the shadow of the local signals. New lines of evidence now suggest a rather different physical picture in which dominant mechanical events may not be local, the cascade of mechanical causality may be not so linear, and, surprisingly, the fluctuations may not be noise as much as they are an essential feature of mechanism. Here we argue for a novel synthesis in which fluctuations and non-local cooperative events that typify the cellular collective might be illuminated by the unifying concept of cell jamming. Jamming has the potential to pull together diverse factors that are already known to contribute but previously had been considered for the most part as acting separately and independently. These include cellular crowding, intercellular force transmission, cadherin-dependent cell-cell adhesion, integrin-dependent cell-substrate adhesion, myosin-dependent motile force and contractility, actin-dependent deformability, proliferation, compression and stretch.

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Tuesday, September 23

No colloquium. Brandeis Thursday.
Tuesday,  September 30

Mehran Kardar, MIT
Levitation by Casimir forces in and out of equilibrium

Abstract:  A generalization of Earnshaw's theorem constrains the possibility of levitation by Casimir forces in equilibrium. The scattering formalism, which forms the basis of this proof, can be used to study fluctuation-induced forces for different materials, diverse geometries, both in and out of equilibrium. In the off-equilibrium context, I shall discuss non-classical heat transfer, and some manifestations of the dynamical Casimir effect.

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Tuesday, October 7

Christopher Rycroft, Harvard University 
Modeling the toughness of metallic glasses

Abstract: Metallic glasses are a new type of alloy whose atoms form an amorphous structure in contrast to most metals. They have many favorable properties such as excellent wear resistance and high tensile strength, but are prone to breakage in some circumstances, depending on their method of preparation. The talk will describe the development of a quasi-static projection method within an Eulerian finite-difference framework, for simulating a new physical model of a metallic glass. The simulations are capable of resolving the multiple timescales that are involved, and provide an explanation of the experimentally observed differences in breakage strength.

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Tuesday, October 14

Dam Thanh Son, University of Chicago
Hydrodynamics and quantum anomalies

Abstract: Hydrodynamics is the theory describing collective behaviors of fluids and gases. It has a very long history and is usually considered to belong to the realm of classical physics. In recent years, it has been found that, in many cases, hydrodynamics can manifest a purely quantum effect --- anomalies. We will see how this  new appreciation of the interplay between quantum and classical physics has emerged, unexpectedly, through the idea of gauge/gravity duality, which originates in modern string theory. I will briefly mention the possible relevance of the new findings to the physics of the quark gluon plasma.

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Tuesday, October 21

Matthew Reece, Harvard University
After the Higgs: What's Next for Particle Physics?

Abstract:  The Large Hadron Collider's discovery of the Higgs boson in 2012 placed the capstone on the Standard Model of particle physics. In many ways, the theory is complete. Still, we have important unanswered questions. What is dark matter? Why is there more matter than antimatter? Do we live in a fine-tuned universe? I will discuss how the upcoming LHC run at higher energy, terrestrial and astrophysical experiments probing the nature of dark matter, and possible future high precision or high energy collider experiments could help us find answers to these questions.

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Tuesday, October 28

Raymond Brock, Michigan State
That Spin 0 Boson Changes Everything--The Future of the Energy Frontier in Particle Physics

Abstract: The "Higgs Boson" discovery requires us to think differently about planning for the future of Particle Physics. While the decades-long confirmation of the Standard Model itself an historic episode, as a dynamical model of nature it is unhelpful as a clear guide to the future. I’ll review the features of the Standard Model that make it superb, I’ll point out why it’s frustrating, and I’ll describe the hints that motivate us in the coming decades.

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Tuesday, November 4

Parthasarathi Majumdar, Ramakrishna Mission Vivekanandan University
The Quantum and the Continuum: Einstein's dichotomous legacies

Abstract: This talk begins with a summary of some of Einstein’s seminal contributions in the quantum domain, like Brownian motion and the Light Quantum Hypothesis, as well as on the spacetime continuum enshrined in the theories of special and general relativity. We then attempt to point to a possible dichotomy in his thinking about these two apparently disparate aspects of physics, which must have been noticed by him, but was not much discussed by him in the public domain. One may speculate that this may have had something to do with his well-known distaste for the probability interpretation of quantum mechanics as a fundamental interpretation. We argue that theorems ensuing from Einstein’s general relativity theory itself contain the seeds of a dramatic modification of our ideas of the Einsteinian spacetime continuum, thus underlining the dichotomy even more strongly. We then survey one modern attempt to resolve the dichotomy, at least partly, by bringing into the spacetime continuum, aspects of quantum mechanics with its underlying statistical interpretation, an approach which Einstein may not have thoroughly enjoyed, but which seems to work so far, with good prospects for the future.

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Tuesday, November 11

Seth Fraden, Brandeis University
Testing Turing's Theory of Morphogenesis

Abstract:  A single fertilized egg first divides into two identical cells and then repeats that process producing hundreds more identical cells. Yet cells in mature animals are not identical; we have a head and tail, eyes and ears. In 1952 Alan Turing offered the first theory explaining cellular differentiation in his seminal paper, The Chemical Basis of Morphogenesis. Turing’s genius was the creation of a minimal model that raised very specific questions and has guided development biology even to this day.  It turns out that biology does development somewhat differently than Turing envisioned. This raises the question as to whether or not any system exists in which Turing’s vision is realized. I’ll describe Turing’s model and an experimental system developed at Brandeis that is ideally suited for testing Turing's ideas in synthetic “cells” consisting of microfluidically produced emulsions. The Turing model is regarded as a metaphor for morphogenesis in biology; useful for a conceptual framework and to guide modeling, but not for prediction. In this chemical system,  we quantitatively assess the extent to which the Turing model explains both pattern formation and temporal synchronization of chemical oscillators.  I’ll describe my lab’s recent demonstration that chemical morphogenesis drives physical differentiation in synthetic cells and speculate on what technologies the future holds.

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Tuesday, November 18

Ian Hutchinson, MIT
Physics of Fusion Energy; What we know and what we don't know

Abstract: This talk will present an overview of the plasma physics that;determines whether or not we can make fusion, the energy sourse of the stars, a practical reality on the terrestrial scale. The main focus is on magnetic plasma confinement, in which we now know a very great deal;in a range of physics fields including MagnetoHydrodynamics, plasma collisionless heating and sustainment, cross-field transport, and the plasma boundary and materials interactions. There are several grand physics challenges that remain to be solved, and even more engineering challenges.

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Tuesday, November 25

No colloquium. Thanksgiving week.

Tuesday, December 2

Eisenbud Lectures in Mathematics and Physics
Peter Sarnak, Inste. for Advanced Study and Princeton University
Randomness in number theory and geometry 

Abstract: The behavior of many arithmetic and geometric objects, from the zeros of zeta functions to the the topologies of random real algebraic varieties are apparently dictated by models from statistical physics. We will review some of these and highlight the basic conjectures and some of what is known towards them .

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Wednesday, December 3

Eisenbud Lectures in Mathematics and Physics, Lecture II
Peter Sarnak, Inste. for Advanced Study and Princeton University
Nodal domains for Maass (modular) forms 

Abstract: The eigenstates of the quantization of a classically chaotic hamiltonian are expected to behave like random monochromatic waves .We discuss this in the context of the eigenfunctions on the modular surface -- i.e "Maass Forms ", and especially what can be proved about their nodal domains.

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Thursday, December 4

Eisenbud Lectures in Mathematics and Physics, Lecture III
Peter Sarnak, Inste. for Advanced Study and Princeton University
Families of zeta functions, their symmetries and applications

Abstract: The local statistical laws for the distribution of the zeros of the Riemann Zeta function and more generally of families of zeta functions ,follow  one of 4 of the 10 universal random matrix ensembles. We review some this phenomenon ,especially in connection with applications.

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Spring 2015 Colloquia

Tuesday, January 13

No colloquium.

Tuesday, January 20

No colloquium.

Tuesday, January 27
CANCELED due to inclement weather (to be rescheduled)

Karen Kasza, Sloan-Kettering Institute
Spatiotemporal control of the active forces that shape living tissues

Abstract: Spatiotemporal control of the active forces that shape living tissuesThe ability of living tissues to physically change shape, move, and grow is essential to fundamental biological processes during development, wound healing, and in disease. Macroscopic changes in tissue shape are often accomplished by the local rearrangements of cells within tissues. These rearrangements are actively driven by forces generated in the actin-myosin cytoskeleton. During embryonic development, these forces are patterned to bias or orient cell rearrangements, resulting in changes in tissue shape and structure that build functional tissues. I use the fruit fly embryo as a model system, where polarized patterns of myosin activity are required for oriented cell rearrangements that drive rapid tissue elongation along the head-to-tail axis. To uncover mechanisms of how active, myosin-generated forces drive cell rearrangement, I quantify how perturbing myosin activity alters rearrangement number, speed, and orientation. For example, to study how myosin activity levels influence rearrangement, I generated myosin variants that mimic the active, phosphorylated state of myosin. These variants accelerate rearrangement but, surprisingly, also alter the spatial pattern of forces and result in reduced tissue elongation. These studies reveal that the levels and patterns of forces are controlled by the same cue and suggest a trade-off between the speed and orientational precision of cell rearrangement. Finally, I will discuss how higher-order, collective cell rearrangements are influenced by perturbations to myosin activity.

Tuesday, February 3

Dustin Kleckner, University of Chicago

Tuesday, February 10

Scott Forth, Rockefeller University

Thursday, February 12    
Special colloquium, 1pm in Abelson 131

Wylie Ahmed, Institute Curie

Tuesday, February 17
Special colloquium

Al Sanchez, Harvard University

Tuesday, February 24

Xuefeng Wang, University of Illinois, Urbana-Champagne

Thursday, February 26
Special Colloquium, 1pm in Abelson 131
Benjamin Rogers, Harvard University

Tuesday, March 3

No colloquium. APS Meeting.

Tuesday, March 10

Markus Deserno, Carnegie Mellon Physics

Tuesday, March 17

Robert J. Wood, Harvard University

Tuesday, March 24

Tuesday, March 31

Daniel Prober, Yale University

Tuesday, April 7

No colloquium. Passover/Spring Recess.

Tuesday, April 14

Paul Townsend, Cambridge University

Tuesday, April 21

Tuesday, April 28

No colloquium. Brandeis Friday.