Swarthmore College Department of Physics and Astronomy

Relaxation, self-organization, and turbulence in plasmas

Tim Gray, Department of Physics and Astronomy, Swarthmore College

Fri, Sept. 17, 2010, 12:45 PM

Large scale structures can spontaneously emerge from turbulent systems in a process called self-organization. Many systems in nature exhibit this behavior and plasmas are no exception. Recent results in plasma turbulence, self-organization, and relaxation from the Swarthmore Spheromak Experiment will be presented.

(Nearly) Invisible Galaxies

Beth Willman, Department of Astronomy, Haverford College

Fri, Oct. 22, 2010, 12:45 PM

In the past five years, more than two dozen dwarf galaxies have been discovered around the Milky Way and M31. Many of these discoveries are 100 times less luminous than any galaxy previously known and a million times less luminous than the Milky Way itself. These objects have made astronomers question the very meaning of the word "galaxy". The advent of wide-field, digital surveys (in particular the Sloan Digital Sky Survey) facilitated these discoveries, and hint at a much larger population that will be revealed in imminent and future imaging datasets. These dwarfs have emerged as the most dark matter dominated and most metal-poor galaxies known. As such, they are changing our understanding of galaxy formation at the lowest luminosities and are currently our most direct tracers of the properties of dark matter on small scales. This talk will highlight new and on-going studies of and searches for the very least luminous companions to the Milky Way - those with less than 1000 times the luminosity of the Sun.

Radiative properties of astrophysical matter: a quest to reproduce astrophysical conditions on earth

Jim Bailey, Sandia National Laboratories

Fri, Oct. 29, 2010, 12:45 PM

Creating stellar interior matter, the extreme radiation near an accretion powered object, and surrogate white dwarf atmospheres are becoming possible with the advent of megaJoule class laboratory facilities. One example is Z, the world's largest pulsed power generator. Z delivers approximately 20 TW electrical power to cm-scale experiments, a power that for a few nanoseconds exceeds the combined capacity of all the world's power plants. The three research topics mentioned above share the feature that ten years ago they were impossible to execute. This talk will describe research at the Z facility demonstrating that all three are now within reach. Significant challenges remain, but as these topics advance toward mature realization, we are motivated to ask: What additional astrophysical research might benefit from newly feasible laboratory measurements?

Pre-colloquium talk by David Cohen on Wednesday, Oct. 27, 2010, 4:30PM in Cunniff

Pencil + Tape = Topological Quantum Computation? - The New Two-Dimensional Universe of Graphene

Paul Cadden-Zimansky, Department of Physics & Astronomy, Columbia University

Fri, Dec. 3, 2010, 12:45 PM

From its isolation in 2004 to this year's Nobel Prize, the impressive material properties of graphene have been widely touted: it's a single atom thick, stronger than steel, a better conductor than copper, and more transparent than glass. But what has intrigued many condensed matter physicists is the unusual charge carriers that can exist in graphene, particularly when it is subjected to high magnetic fields. These "particles" that inhabit graphene's two-dimensional universe can be relativistic, have fractional charge or multiple spins, and may even obey new types of quantum statistics. This talk will present recent experiments demonstrating some of these properties, and explain why the topological nature of these high-field carriers make them a potential building block for quantum computation.