Colloquium

607 talks

S001

Collection TypeSeries

SubjectPhysics

Source RepositoryPIRSA

Displaying 337 - 348 of 607

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
Astrophysics
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
High Energy Physics
Partially Massless Gravity
December 11, 2013

PIRSA:13120005
Astrophysics
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
High Energy Physics
Light and matter: towards macroscopic quantum systems

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

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

Natalia Toro Stanford University
November 13, 2013

PIRSA:13110047
High Energy 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
High Energy Physics
The Stokes groupoids

Marco Gualtieri University of Toronto

October 23, 2013

PIRSA:13100110
Simulating Hamiltonian evolution with quantum computers

Richard Cleve Institute for Quantum Computing (IQC)
October 16, 2013

PIRSA:13100097
Quantum 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
Astrophysics
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
High Energy 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
Astrophysics
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
High Energy 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 Physics
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
High Energy 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
High Energy 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.
The Stokes groupoids

Marco Gualtieri University of Toronto

October 23, 2013

PIRSA:13100110

Ordinary differential equations become much less ordinary when they are allowed to have singularities. Solving them naively in formal power series, one often obtains divergent series, just as in the perturbation series for physical observables in quantum field theory. The asymptotic interpretation of this divergent series exhibits the famous Stokes phenomenon, an essential ingredient in any full description of the solutions to the system. I will explain a new viewpoint on singular ODE which illuminates the geometric meaning of the phenomena described above, and which can be applied to the problem of resummation of formal power series. This viewpoint uses a very basic but underused tool in differential geometry: Lie groupoids. A Lie groupoid is as natural and essential an object as a Lie group; I shall explain how to build examples of them and how to use them to solve singular differential equations.
Simulating Hamiltonian evolution with quantum computers

Richard Cleve Institute for Quantum Computing (IQC)
October 16, 2013

PIRSA:13100097
Quantum Physics
In 1982, Richard Feynman proposed the concept of a quantum computer as a means of simulating physical systems that evolve according to the Schrödinger equation. I will explain various quantum algorithms that have been proposed for this simulation problem, including my recent work (jointly with Dominic Berry and Rolando Somma) that significantly improves the running time as a function of the precision of the output data.

Title	Speaker(s)	Date	Talk Type	Info
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
The Stokes groupoids	Marco Gualtieri	2013-10-23	Scientific Series	View details
Simulating Hamiltonian evolution with quantum computers	Richard Cleve	2013-10-16	Scientific Series	View details

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Format results

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

Time, Dynamics, Chaos, and the Brain

Beyond the Standard Paradigm

Partially Massless Gravity

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

Insightful supersymmetry

Light and matter: towards macroscopic quantum systems

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

Fractional statistics in two-dimensions: Anyon there?

Gravity and the Search for New Physics with Cosmology

The Stokes groupoids

Simulating Hamiltonian evolution with quantum computers

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

Time, Dynamics, Chaos, and the Brain

Beyond the Standard Paradigm

Partially Massless Gravity

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

Insightful supersymmetry

Light and matter: towards macroscopic quantum systems

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

Fractional statistics in two-dimensions: Anyon there?

Gravity and the Search for New Physics with Cosmology

The Stokes groupoids

Simulating Hamiltonian evolution with quantum computers