New York University
Department of Physics
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Physics Colloquia

November, 11/23/2009
Events and times subject to change

December 3, 2009 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


James Carpenter

TBA



December 10, 2009 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Sal Torquato
Princeton University

From Unusual Ground States to Packing Problems

Ground-state problems naturally arise in many fields, including physics, biology, materials science, and mathematics. A classical ground-state configuration of a system of interacting particles is one that minimizes the system potential energy. In the laboratory, for example, such states can be produced by slowly cooling a liquid to a temperature of absolute zero, and usually the ground states are close-packed crystal structures. I will describe isotropic interactions with unusual crystal ground states in three dimensions (e.g., diamond lattice) as well as disordered ground states, a counterintuitive phenomenon. I then will discuss the problem of determining the densest packings of particles in Euclidean spaces, which are closely related to ground-state problems. We provide the putative exponential improvement on Minkowski's 100-year-old lower bound on the maximal packing density of spheres in high dimensions. This suggests that disordered (rather than ordered) sphere packings may be the densest for sufficiently large dimension, implying the existence of disordered ground states for some continuous potentials. Finally, I will describe a recent Kepler-like conjecture for the maximal-density packings of a majority of the Platonic and Archimedean solids.


February 4, 2010 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Matias Zaldarriaga
IAS

TBA



February 25, 2010 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Jerry Gollub
Haverford College

TBA



March 4, 2010 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Adam Burrows
Princeton University

TBA



March 11, 2010 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Janet Conrad
MIT

TBA



April 1, 2010 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Jennifer Lewis
University of Illinois at Urbana-Champaign

TBA



April 8, 2010 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Meg Urry
Yale University

TBA



April 22, 2010 Thursday 4:00 PM 
Meyer 122
Physics Colloquia (colloquia)


Alex Filippenko
UC Berkeley

TBA