Colloquium

Displaying 337 - 348 of 609

The Sherrington-Kirkpatrick model and its diluted version

Dmitry Panchenko Texas A&M University
February 20, 2014

PIRSA:14020151
Mathematical physics
Non equilibrium thermodynamic of gravitational screens

Laurent Freidel Perimeter Institute for Theoretical Physics
February 19, 2014

PIRSA:14020144
Quantum Gravity

Mathematical physics
The National Ignition Facility (NIF):Pathway to Energy Security and Physics of the Cosmos

Edward Moses Lawrence Livermore National Laboratory
February 05, 2014

PIRSA:14020098
Cosmology
Time, Dynamics, Chaos, and the Brain

Dean Buonomano University of California, Los Angeles

January 29, 2014

PIRSA:13010117
Beyond the Standard Paradigm

Paul Langacker Institute for Advanced Study (IAS)
January 15, 2014

PIRSA:13010116
Particle Physics
Partially Massless Gravity
December 11, 2013

PIRSA:13120005
Cosmology
The Galactic Real Estate Market: The Physics and Chemistry of Habitability

Penelope Boston National Cave and Karst Research Institute

December 04, 2013

PIRSA:13120044
Insightful supersymmetry

Erich Poppitz University of Toronto
November 27, 2013

PIRSA:13110061
Particle Physics
Light and matter: towards macroscopic quantum systems

Jacob Taylor Office of Science and Technology Policy
November 20, 2013

PIRSA:13110060
Quantum Information
Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

Natalia Toro Stanford University
November 13, 2013

PIRSA:13110047
Particle Physics
Fractional statistics in two-dimensions: Anyon there?

Smitha Vishveshwara University of Illinois Urbana-Champaign
November 06, 2013

PIRSA:13110062
Mathematical physics
Gravity and the Search for New Physics with Cosmology

Kris Sigurdson University of British Columbia
October 30, 2013

PIRSA:13100098
Particle Physics

The Sherrington-Kirkpatrick model and its diluted version

Dmitry Panchenko Texas A&M University
February 20, 2014

PIRSA:14020151
Mathematical physics
I will talk about two types of random processes -- the classical Sherrington-Kirkpatrick (SK) model of spin glasses and its diluted version. One of the main motivations in these models is to find a formula for the maximum of the process, or the free energy, in the limit when the size of the system is getting large. The answer depends on understanding the structure of the Gibbs measure in a certain sense, and this structure is expected to be described by the so called Parisi solution in the SK model and Mézard-Parisi solution in the diluted SK model. I will explain what these are and mention some results in this direction.
Non equilibrium thermodynamic of gravitational screens

Laurent Freidel Perimeter Institute for Theoretical Physics
February 19, 2014

PIRSA:14020144
Quantum Gravity

Mathematical physics
In this talk I will review the evidence for a mysterious and deep relationship between gravitational dynamics and thermodynamics. I will show how we can extend this connection to non equilibrium thermodynamics. Using the fact that the gravitational equations are fundamentally holographic, we express them in a way that shows a deep connection between gravity and the dynamics of viscous bubbles. We will explore some aspects of this surprising correspondence.
The National Ignition Facility (NIF):Pathway to Energy Security and Physics of the Cosmos

Edward Moses Lawrence Livermore National Laboratory
February 05, 2014

PIRSA:14020098
Cosmology
NIF is the world's most energetic laser system capable of producing over 1.8 MJ and 500 TW of ultraviolet light, about 100 times more than any other operating laser of its kind. This talk describes the unprecedented experimental capabilities of NIF, its role in fundamental science, the pathway to achieving fusion ignition and energy security missions, and the status of progress in these areas.
Time, Dynamics, Chaos, and the Brain

Dean Buonomano University of California, Los Angeles

January 29, 2014

PIRSA:13010117

Time poses a fundamental problem in neuroscience, in part, because at its core the brain is a prediction machine: the brain evolved to allow animals to anticipate, adapt, and prepare for future events. To accomplish this function the brain tells time on scales spanning 12 orders of magnitude. In contrast to most man made clocks that share a very simply underlying principle-counting the "tics" of an oscillator-evolution has devised many different solutions to the problem of telling time. On the scale of milliseconds and seconds experimental and computational evidence suggests that the brain relies on neural dynamics to tell time. For this strategy to work two conditions have to be met: the states of the neural network must evolve in a nonrepeating pattern over the relevant interval, and the sequence of states must be reproducible every time the system is reengaged. Recurrently connected networks of neurons can generate rich dynamics, but a long standing challenge is that the regimes that create computationally powerful dynamics are chaotic-and thus cannot generate reproducible patterns. We have recently demonstrated that by tuning the weights (the coupling coefficients) between the units of artificial neural networks it is possible to generate locally stable trajectories embedded within chaotic attractors. These stable patterns function as "dynamic attractors" and can be used to encode and tell time. They also exhibit a novel feature characteristic of biological systems: the ability to autonomously "return" to the pattern being generated in the face of perturbations.
Beyond the Standard Paradigm

Paul Langacker Institute for Advanced Study (IAS)
January 15, 2014

PIRSA:13010116
Particle Physics
I reexamine the current situation in particle and neutrino physics from a top-down perspective, discussing such underlying issues as uniqueness versus environment, minimality versus remnants, and naturalness versus tuning.
Partially Massless Gravity
December 11, 2013

PIRSA:13120005
Cosmology
On de Sitter space, there exists a special value for the mass of a graviton for which the linear theory propagates 4 rather than 5 degrees of freedom. If a fully non-linear version of the theory exists and can be coupled to known matter, it would have interesting properties and could solve the cosmological constant problem. I will describe evidence for and obstructions to the existence of such a theory.
The Galactic Real Estate Market: The Physics and Chemistry of Habitability

Penelope Boston National Cave and Karst Research Institute

December 04, 2013

PIRSA:13120044

Exoplanets, planets circling distant stars, are proving to be an extraordinary source of new thinking about the potential for life beyond Earth. Until recently, we have assumed that our Solar System and its planets were probably representative of such systems elsewhere. But the amazing array of very odd exoplanets that are being uncovered have stimulated a renaissance of thought on the subject of potential homes for life in the universe. Combined with work on extreme lifeforms here on Earth and intensive study of Mars and several other planets and moons in our system, new paradigms for life search missions are emerging. Science fiction has long drawn from and extrapolated out from science, but the cross-fertilization has gone both ways. Some of the more outrageous planets incorporated into fiction in the past may not be so outrageous after all. I will discuss what we think we know about exoplanets so far, how they are detected, how we are beginning to characterize their environments, and ideas about what this means for our search for living neighbors in our galaxy, whether they be microbes or folks we can actually chat with some day.
Insightful supersymmetry

Erich Poppitz University of Toronto
November 27, 2013

PIRSA:13110061
Particle Physics
It has recently been realized that some studies of supersymmetric gauge theories, when properly interpreted, lead to insights whose importance transcends supersymmetry. I will illustrate the insightful nature of supersymmetry by two examples having to do with the microscopic description of the thermal deconfinement transition, in non-supersymmetric pure Yang-Mills theory and in QCD with adjoint fermions. A host of strange ``topological" molecules will be seen to be the major players in the confinement-deconfinement dynamics. Interesting connections between topology, ``condensed-matter" gases of electric and magnetic charges, and attempts to interpret the divergent perturbation series will emerge. Much of the presentation will be aimed at non-experts.
Light and matter: towards macroscopic quantum systems

Jacob Taylor Office of Science and Technology Policy
November 20, 2013

PIRSA:13110060
Quantum Information
Advances in quantum engineering and material science are enabling new approaches for building systems that behave quantum mechanically on long time scales and large length scales. I will discuss how microwave and optical technologies in particular are leading to new domains of many-body physics, both classical and quantum, using photons and phonons as the constituent particles. Furthermore, I will highlight practical consequences of these advances, including improved force and acceleration sensing, efficient signal transduction, and topologically robust photonic circuits. Finally, I will consider how such large quantum systems may help us measure and constrain theories of quantum gravity and gravity-induced decoherence.
Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

Natalia Toro Stanford University
November 13, 2013

PIRSA:13110047
Particle Physics
The success of gauge theory descriptions of Nature follows simply, in hindsight, from Lorentz symmetry, quantum mechanics, and the existence of interacting massless particles with spin. Yet, remarkably, the most generic type of massless particle spin has never been seriously examined: Wigner's so-called "continuous spin" particles (CSPs), which have a tower of polarization states carrying all integer or half-integer helicities that mix under boosts. I will explain recent progress in understanding these particles on two fronts: simple scattering amplitudes and a free quantum field theory. The scattering amplitudes give two remarkable insights into CSP physics. First, Lorentz symmetry protects CSP interactions from the dysfunction one might expect in a theory with infinitely many polarization states: divergent cross-sections and problematic thermodynamics. Second, and most intriguingly, CSP interactions approach those of ordinary scalars or helicity-1 or 2 gauge bosons in a high-energy "correspondence" regime. While a full interacting theory of CSPs remains elusive, these results suggest that any such theory would extend Maxwell electrodynamics and/or general relativity in a viable and testable way.
Fractional statistics in two-dimensions: Anyon there?

Smitha Vishveshwara University of Illinois Urbana-Champaign
November 06, 2013

PIRSA:13110062
Mathematical physics
A fascinating aspect of the two dimensional world is the possible existence of anyons, particles which obey 'fractional' statistics different from fermionic and bosonic statistics. In this colloquium, following an introduction to fractional particles in the context of quantum Hall systems, some of the tantalizing experiments for detecting the fractional charge of these particles will be described. Probes of fractional statistics in these systems will be discussed, drawing from analogies with the bosonic behavior of light studied by Hanbury Brown and Twiss in the 1950's as well as in the more recent beam-splitter settings in quantum optics. Finally, the exciting prospect of detecting fractional statistics in the context of superconductors will be explored.
Gravity and the Search for New Physics with Cosmology

Kris Sigurdson University of British Columbia
October 30, 2013

PIRSA:13100098
Particle Physics
Despite its feeble in strength, gravity plays a pivotal role in shaping our Universe and the things in it. Ever since Newton formulated his universal law of gravitation the recognition that all things gravitate has been nearly sacrosanct. Repeatedly, apparent gravitational anomalies have either foretold the existence of new physics or a misunderstanding of gravity itself, from the existence of nuclear forces to Einstein's general relativity. Eighty years ago gravity betrayed the existence of dark matter, and fifteen years ago gravity demanded dark energy from reluctant cosmologists. I will discuss how gravity enables modern cosmology to explore the echoes of the invisible universe, even if it is impossible or difficult to directly see the invisible universe. In particular, I will show how gravity enables us to put surprisingly severe constraints on the coupling of dark matter to new light particles and search for secret interactions between Fermi's elusive neutrinos. The physics and cosmic history of the invisible universe are writ large across the cosmos itself, and gravity is our tried and trusted messenger.

Title	Speaker(s)	Date	Talk Type	Info
The Sherrington-Kirkpatrick model and its diluted version	Dmitry Panchenko	2014-02-20	Scientific Series	View details
Non equilibrium thermodynamic of gravitational screens	Laurent Freidel	2014-02-19	Scientific Series	View details
The National Ignition Facility (NIF):Pathway to Energy Security and Physics of the Cosmos	Edward Moses	2014-02-05	Scientific Series	View details
Time, Dynamics, Chaos, and the Brain	Dean Buonomano	2014-01-29	Scientific Series	View details
Beyond the Standard Paradigm	Paul Langacker	2014-01-15	Scientific Series	View details
Partially Massless Gravity		2013-12-11	Scientific Series	View details
The Galactic Real Estate Market: The Physics and Chemistry of Habitability	Penelope Boston	2013-12-04	Scientific Series	View details
Insightful supersymmetry	Erich Poppitz	2013-11-27	Scientific Series	View details
Light and matter: towards macroscopic quantum systems	Jacob Taylor	2013-11-20	Scientific Series	View details
Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle	Natalia Toro	2013-11-13	Scientific Series	View details
Fractional statistics in two-dimensions: Anyon there?	Smitha Vishveshwara	2013-11-06	Scientific Series	View details
Gravity and the Search for New Physics with Cosmology	Kris Sigurdson	2013-10-30	Scientific Series	View details

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