# Colloquium

This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.

## Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

## The Sherrington-Kirkpatrick model and its diluted version

Thursday Feb 20, 2014
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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.

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## Non equilibrium thermodynamic of gravitational screens

Wednesday Feb 19, 2014
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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.

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

Wednesday Feb 05, 2014
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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.

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## Time, Dynamics, Chaos, and the Brain

Wednesday Jan 29, 2014
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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.

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Wednesday Jan 15, 2014
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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.

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## Partially Massless Gravity

Wednesday Dec 11, 2013

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.

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## The Galactic Real Estate Market: The Physics and Chemistry of Habitability

Wednesday Dec 04, 2013
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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.

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## Insightful supersymmetry

Wednesday Nov 27, 2013
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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

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## Light and matter: towards macroscopic quantum systems

Wednesday Nov 20, 2013
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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.

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## Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

Wednesday Nov 13, 2013
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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.

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## RECENT PUBLIC LECTURE

### Janna Levin: Black Hole Blues and Other Songs from Outer Space

Speaker: Janna Levin