Colloquium Archives (before June 2017)

More recent colloquia are posted on the Physics & Astronomy Colloquia page.

Professor Robert L. Lysak, Uni. of Minnesota

Title: Alfvén Waves and Auroral Particle Acceleration (Video)

Abstract: Electrodynamic coupling between the magnetosphere and ionosphere is accomplished by means of the passage of Alfvén waves between these regions. These waves can be accompanied by parallel electric fields when the perpendicular scale size becomes small. There are two main regimes of this acceleration. At lower altitudes where the plasma is cold, electron inertial effects becomes important and can lead to the bulk acceleration of the cold plasma. At higher altitudes, the primary particle acceleration mechanism is Landau damping, which preferentially accelerates electrons with velocities near the Alfvén wave phase velocity. These mechanisms are favored in regions where there are sharp plasma gradients, such as at the plasma sheet boundary layer or on the edges of the auroral density cavity, since phase mixing is an efficient mechanism for reducing the perpendicular wavelength.

Jim Burch, Space Science & Engineering, Southwest Research Institute

Title: "Solar Wind Interactions with the Earth and Comets"  (Video)

Abstract: In addition to being our home in space, the Earth’s magnetosphere, by virtue of its interaction with the solar wind, exhibits a wide variety of dynamic space plasma phenomena. It is an interesting and important place; but there are numerous magnetospheres in the solar system, and no two are even remotely alike. Therefore, there are opportunities for significant discoveries in making old measurements in new places as well as in making new measurements in old places.

Professor V.P. Nair, City College of CUNY

Title: Liquid Helium and QCD: Feynman’s Last Problem 30+ Years Later  (video)

Abstract:  In 1954, Feynman gave a beautiful analysis of superfluid Helium using general properties of wave functions and of the space of particle configurations. In the 1970s, with the emergence of QCD, the question of quark confinement and the generation of a mass gap was recognized as an important question about the nonperturbative behavior of nonabelian gauge theories. QCD in two spatial dimensions would provide the simplest case of  a nontrivial gauge theory which could exhibit confinement and mass gap. In 1981, Feynman tried to use a set of arguments similar to what he had developed for superfluidity to argue for the existence of a mass gap for these theories. Did he succeed? If so, to what extent?

Professor Adolfo del Campo, Department of Physics, UMass Boston, USA

Title:  "Shortcuts to Adiabaticity in Many-Body Systems"   (video)

Abstract:  Quantum adiabatic processes -that keep constant the populations in the instantaneous eigenbasis of a time-dependent Hamiltonian- are very useful to prepare and manipulate states, but take typically a long time. This is often problematic because decoherence and noise may spoil the desired final state, or because some applications require many repetitions. ”Shortcuts to adiabaticity” are alternative fast processes that mimic adiabatic dynamics without the requirement of slow driving.

This talk is a "tapas selection", reviewing recent advances in the design of shortcuts to adiabaticity in many-body systems.

Priyamvada Natarajan, Professor of Astronomy & Physics, Chairman Women Faculty Forum, Yale University

Title:  "Tracing the Growth of Black Holes in the Universe" (video)

Abstract:  Supermassive black holes appear to be ubiquitous in the nearby universe,
almost every galaxy in our neighborhood appears to host one. Bright luminous quasars powered by supermassive black holes also appear to be in place when the universe was barely a Gigayear old. I will discuss our current understanding of how and when these black holes formed, grew and evolved from early black hole seeds.