Colloquium

Displaying 373 - 384 of 601

Beyond Massive Gravity

Rachel Rosen
Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Cosmology
The Evolution of Quasars with Cosmic Time

Michael Strauss
Princeton University

February 20, 2013

PIRSA:13020120
Prospects for GW transients in early Advanced LIGO and Virgo science runs

Gabriela Gonzalez
Louisiana State University
February 06, 2013

PIRSA:13020124
Strong Gravity
Hidden Structure in Linguistics: The Organization of Sound Systems

Elan Dresher

January 30, 2013

PIRSA:13010017
What is motion? What is time?

Flavio Mercati
University of Naples Federico II
January 23, 2013

PIRSA:13010003
Quantum Gravity
Einstein's gravity versus String Gravity

Barton Zwiebach
Massachusetts Institute of Technology (MIT) - Department of Physics
January 16, 2013

PIRSA:13010103
Quantum Fields and Strings
Adventures with Monte Carlo Simulations of the Self-Avoiding Walk

Esaias Janse van Rensburg
York University

December 12, 2012

PIRSA:12120025
Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons

Steve Girvin
Yale University
November 28, 2012

PIRSA:12110041
Condensed Matter
Quantum Signatures of Chaos

Shohini Ghose
Wilfrid Laurier University

November 21, 2012

PIRSA:12110072
Massive gravitons, the cosmological constant and new directions in gravity
November 14, 2012

PIRSA:12110061
Cosmology
An introduction to quantum channels and their capacities

Graeme Smith
Institute for Quantum Computing (IQC)
November 07, 2012

PIRSA:12110066
Quantum Information
Astrophysical shear-driven turbulence

Jeremy Goodman
Princeton University

October 17, 2012

PIRSA:12100043

Beyond Massive Gravity

Rachel Rosen
Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Cosmology
In the last few years there has been a burst of progress in the field of massive gravity. The construction of consistent theories in which the graviton has a small mass has in turn led to the development a new family of compelling, consistent low-energy modifications of General Relativity. These theories improve our understanding of the interplay between gravity and particle physics and provide new approaches to solving the cosmological constant problem. In this talk I will review these recent developments. I will discuss the search among these new theories for a symmetry that has the potential to address the cosmological constant problem.
The Evolution of Quasars with Cosmic Time

Michael Strauss
Princeton University

February 20, 2013

PIRSA:13020120

While the luminosity and mass distributions of quasars has evolved dramatically with cosmic time, the physical properties of quasars of a given luminosity are remarkably independent of redshift. I will describe recent results on the spectra of luminous quasars, the dark matter halos in which they sit, and the intergalactic medium of their host galaxies, that are essentially indistinguishable from moderate redshifts to z>6. The one property apparently unique to the highest-redshift quasars is that some small fraction show evidence for having very little infrared excess from hot dust. Dust obscuration is another theme in quasar studies; an appreciable fraction of the growth of black holes may be hidden at optical wavelengths by dust. I will describe searches for obscured quasars at high redshift and low, and studies of their demographics and physical properties.
Prospects for GW transients in early Advanced LIGO and Virgo science runs

Gabriela Gonzalez
Louisiana State University
February 06, 2013

PIRSA:13020124
Strong Gravity
Advanced LIGO (aLIGO) and Advanced Virgo (AdV) are kilometer-scale gravitational wave (GW) detectors that are expected to yield the first direct observations of gravitational waves. I will describe the currently projected schedule, sensitivity, and sky localization accuracy for the GW detector network in the next decade.
Hidden Structure in Linguistics: The Organization of Sound Systems

Elan Dresher

January 30, 2013

PIRSA:13010017

I will discuss some basic notions in the theory of phonology (sound systems in language). The sounds of a language are generally assumed to be composed of smaller constituents, called features. The features that make up a sound cannot be directly obtained from its pronunciation, but rather must be inferred from the system of contrasts that are at play in a particular language. How to determine which features are contrastive presents a logical and empirical puzzle that may be interesting to students of physics, who are accustomed to explaining observable events in terms of hidden structures that cannot be directly observed.
What is motion? What is time?

Flavio Mercati
University of Naples Federico II
January 23, 2013

PIRSA:13010003
Quantum Gravity
I give an account of the Machian approach to dynamics, from Mach's critique of Newton to the work of Barbour, Bertotti, York and O'Murchadha, which culminated in the theory of Shape Dynamics, a new and original way of thinking about General Relativity. I conclude commenting on the present research lines in Shape Dynamics, and the opportunity it offers to solve the problem of time in quantum gravity.

Support for this colloquium is provided by The Templeton Frontiers Program.
Einstein's gravity versus String Gravity

Barton Zwiebach
Massachusetts Institute of Technology (MIT) - Department of Physics
January 16, 2013

PIRSA:13010103
Quantum Fields and Strings
Gravity in string theory is a generalized version of Einstein's theory with some universal features that call for a reformulation of the key geometrical concepts. In addition to the metric tensor, for example, string theory contains an antisymmetric tensor and a dilaton that allow for extra symmetries. A new branch of mathematics, Generalized Geometry, suggests a framework that finds a realization in the recent Double Field Theory formulation of string gravity. I will describe the main ideas, the progress, and the mysteries that remain in the search for a proper description of string gravitation.
Adventures with Monte Carlo Simulations of the Self-Avoiding Walk

Esaias Janse van Rensburg
York University

December 12, 2012

PIRSA:12120025

The Rosenbluth Method is a classical kinetic growth Monte Carlo algorithm for growing a self-avoiding walk by appending steps to its endpoint. This algorithm can be generalised by the implementation of more general elementary moves (for example, BFACF elementary moves) to realise kinetic growth algorithms for lattice polygons. This generalises the counting principle that underlies the Rosenbluth method and the result is a widely applicable class of algorithms which may be used for microcanonical sampling in discrete models. In addition to self-avoiding walks, several applications of kinetic growth and canonical Monte Carlo algorithms will be presented, including the sampling of trivial words in abstract groups, as well as knotted lattice polygons and discrete lattice spin systems such as the Potts model. This is work was done in collaboration with Andrew Rechnitzer of the Mathematics Department at the University of British Columbia.
Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons

Steve Girvin
Yale University
November 28, 2012

PIRSA:12110041
Condensed Matter
A revolution is underway in the construction of ‘artificial atoms’ out of superconducting electrical circuits. These macroscopic ‘atoms’ have quantized energy levels and can emit and absorb quanta of light (in this case microwave photons), just like ordinary atoms. Unlike ‘real’ atoms, the properties of these artificial atoms can be engineered to suit various particular applications, and they can be connected together by wires to form quantum ‘computer chips.’ This so-called ‘circuit QED’ architecture has given us the ability to do non-linear quantum optics in electrical circuits at the single photon level. It is now possible to entangle multiple qubits, count individual microwave photons, create large ‘Schrödinger cat’ photon states and perform quantum feedback. This talk will present an elementary introduction to the field.
Quantum Signatures of Chaos

Shohini Ghose
Wilfrid Laurier University

November 21, 2012

PIRSA:12110072
Massive gravitons, the cosmological constant and new directions in gravity
November 14, 2012

PIRSA:12110061
Cosmology
The solutions to the cosmological constant problems may involve modifying the very long-range dynamics of gravity by adding new degrees of freedom. As an example of a conservative and minimal such modification, we consider the possibility that the graviton has a very small mass. Massive gravity has received renewed interest due to recent advances which have resolved its traditional problems. This kind of modification has some peculiar and unexpected features, and it points us towards a universe which looks quite unfamiliar.
Support for this colloquium is provided by The Templeton Frontiers Program.
An introduction to quantum channels and their capacities

Graeme Smith
Institute for Quantum Computing (IQC)
November 07, 2012

PIRSA:12110066
Quantum Information
A quantum communication channel can be put to many uses: it can transmit classical information, private classical information, or quantum information. It can be used alone, with shared entanglement, or together with other channels. For each of these settings there is a capacity that quantifies a channel's fundamental potential for communication. In this introductory talk, I will discuss what we known about the various capacities of a quantum channel, including a discussion of synergies between different channels and related additivity questions.
Astrophysical shear-driven turbulence

Jeremy Goodman
Princeton University

October 17, 2012

PIRSA:12100043

Astronomical hydrodynamics is usually almost ideal in the sense that the Reynolds number (Re) is enormous and any effective viscosity must be due to shocks or turbulence. Astronomical magnetohydrodynamics (MHD) is often also nearly ideal, so that magnetic fields and plasma are well coupled. In particular, dissipation of orbital energy in accretion disks around black holes is readily explained by MHD turbulence. On the other hand, the planet-bearing disks around protostars are magnetically far from ideal because of very low fractional ionization. MHD turbulence is at best marginal in these disks, yet accretion is observed. The Reynolds numbers based on orbital-velocity gradients are enormous, so by analogy with high-Re terrestrial flows, one might expect hydrodynamic (i.e., unmagnetized) turbulence. Direct numerical simulations indicate that such turbulence is somehow suppressed by keplerian rotation, though the mechanism is
unclear and the simulations are limited in Re. Recently, a few groups have studied the question via Taylor-Couette experiments at somewhat higher Re, obtaining conflicting results. Complicating and enriching this debate is the recent discovery that turbulence tends to have a finite lifetime in shear flows that admit a formally linearly stable laminar solution: this includes flow in smooth pipes and probably also unmagnetized keplerian disks. Some suggestions will be offered as to how these open questions might be resolved.

Title	Speaker(s)	Date	Talk Type	Info
Beyond Massive Gravity	Rachel Rosen	2013-02-25	Scientific Series	View details
The Evolution of Quasars with Cosmic Time	Michael Strauss	2013-02-20	Scientific Series	View details
Prospects for GW transients in early Advanced LIGO and Virgo science runs	Gabriela Gonzalez	2013-02-06	Scientific Series	View details
Hidden Structure in Linguistics: The Organization of Sound Systems	Elan Dresher	2013-01-30	Scientific Series	View details
What is motion? What is time?	Flavio Mercati	2013-01-23	Scientific Series	View details
Einstein's gravity versus String Gravity	Barton Zwiebach	2013-01-16	Scientific Series	View details
Adventures with Monte Carlo Simulations of the Self-Avoiding Walk	Esaias Janse van Rensburg	2012-12-12	Scientific Series	View details
Wiring up Quantum Systems: Fun with Artificial Atoms and Microwave Photons	Steve Girvin	2012-11-28	Scientific Series	View details
Quantum Signatures of Chaos	Shohini Ghose	2012-11-21	Scientific Series	View details
Massive gravitons, the cosmological constant and new directions in gravity		2012-11-14	Scientific Series	View details
An introduction to quantum channels and their capacities	Graeme Smith	2012-11-07	Scientific Series	View details
Astrophysical shear-driven turbulence	Jeremy Goodman	2012-10-17	Scientific Series	View details

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