Events Archive

Sep
29
2014
Puzzles of the glass transition and why it is still interesting
For thousands of years people are using glass transition process and glasses in their everyday life. For hundreds of years researchers are studying the glass transition phenomenon. However, understanding the microscopic mechanism underlying the tremendous slowing down of structural relaxation remains one of the main challenges in the current condensed matter...
Sep
25
2014
2014 Stelson Lecture: How quantum theory and statistical mechanics gave a polynomial of knots
We will see how a result in von Neumann algebras (a theory developed by von Neumann to give the mathematical framework for quantum physics) gave rise, rather serendipitously, to an elementary but very useful invariant in the theory of ordinary knots in three dimensional space. Then we'll look at some subsequent developments of the theory, and talk about a thorny problem which remains open.
Sep
22
2014
Walter Kohn and the Creation of Density Functional Theory
The theoretical physicist Walter Kohn was awarded one-half the 1998 Nobel Prize for Chemistry for his mid-1960's creation of an approach to the many-particle problem in quantum mechanics called density functional theory (DFT). DFT establishes that the ground state charge density provides a complete description of ALL the properties of any atom, molecule, or solid. This was a breakthrough (both conceptually and computationally) because it had been presumed previously that the vastly more complicated many-electron wave function was essential for this purpose. In this talk, I present a biographical sketch of Kohn's unusual educational experiences and the events...
Sep
22
2014
Polaritons in Quantum Optomechanics
The concept of polariton is ubiquitous in the context of radiation-matter interaction. It refers to a generic quasi-particle resulting from the mixing of light with some kind of material excitation (e.g. a plasmon, phonon, or exciton). Cavity optomechanics offers an ideal system to study the coupling between trapped photons and the oscillations of a mechanical resonator. We can thus describe the coherent dynamics in terms of polaritonic excitations. The role of...
Sep
18
2014
The XENON1T Dark Matter Detector
The nature of dark matter remains one of the most fascinating yet unsolved problems in modern science. A large compelling body of evidence supports the theory that almost 27% of the mass-energy density of the universe is made of cold dark matter. The XENON Project aims at the direct detection of dark matter in the form of Weakly Interacting Massive Particles (WIMPs) via nuclear recoils in a LXe Dual-phase Time Projection Chamber. The third phase of the project XENON1T, a ton scale LXe dark matter detector is currently under construction at the Laboratori Nazionali del Gran Sasso in Italy and...
Sep
18
2014
Thinking Beyond The Phonon Gas Model
Understanding the thermal conductivity of bulk crystalline solids is essentially a solved problem and it is well described by the phonon gas model (PGM). The PGM treats individual phonons (e.g., quanta of lattice vibration energy) as gas molecules that carry energy at a certain speed for some averaged distance, termed the mean free path (MFP). This model does an excellent job at explaining the thermal conductivity of crystalline solids and due to advancements in modeling over the last decade, one can now calculate phonon energies, velocities...
Sep
16
2014
Looking Inside (and Under) Theropod Dinosaur Locomotion
Striding bipedalism evolved over 230 million years ago in the ancestors of dinosaurs. Predatory dinosaurs (Theropoda) gave rise to tyrannosaurs and velociraptors, but also to birds, which survived the end-Cretaceous extinction. Fossilized skeletons and trackways offer unique, if static, evidence of ancient species. We seek to integrate data from living avians with the fossil record to understand theropods as living, moving organisms, as well as broader patterns of locomotor evolution along this lineage. I will first present a...
Sep
15
2014
Hydrodynamics and Quantum Anomalies
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...
Sep
08
2014
The Nuclear Spectroscopic Telescope Array (NuSTAR) High-Energy X-ray Mission: Bringing the High Energy Universe into Focus
The Nuclear Spectroscopic Telescope Array, the first focusing high-energy X-ray (3 – 79 keV) telescope in orbit, extends sensitive X-ray observations above the band pass where Chandra and XMM-Newton operate. With an unprecedented combination of sensitivity, spectral and imaging resolution above 10 keV, NuSTAR is advancing our understanding of black holes, neutron stars, and supernova remnants. I will describe the mission, and present science highlights from the two-year baseline mission.
Sep
05
2014
Gravitational waves and the physics of compact objects: from gamma-ray bursts to I-Love-Q
Coalescing binaries are among the most promising sources of gravitational waves for the advanced generation of ground based interferometers. Moreover they have been suggested as a possible progenitors of short gamma-ray bursts. The gravitational signal emitted in the late inspiral of such systems encodes the deformability properties of the neutron star, which depend on the behavior of matter in the stellar interior. In this talk I will discuss how the detection of this signal can be used to extract information on the neutron star equation of state, and on the physics of the surrounding environment.

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