Colloquium

607 talks

S001

Collection TypeSeries

SubjectPhysics

Source RepositoryPIRSA

Displaying 373 - 384 of 607

Frustrated Magnets and Quantum Spin Liquids

Steven White University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
The Higgs confronts 3 universes at the LHC

Markus Luty University of California, Davis
March 13, 2013

PIRSA:13030095
High Energy Physics
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Astrophysics
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
High Energy Physics
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Astrophysics
Quantum Gravity as Random Geometry

Vincent Rivasseau University of Paris-Saclay
February 27, 2013

PIRSA:13020132
General Relativity & Quantum Cosmology
Beyond Massive Gravity

Rachel Rosen Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Astrophysics
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
General Relativity & Quantum Cosmology
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
General Relativity & Quantum Cosmology
Einstein's gravity versus String Gravity

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

PIRSA:13010103
High Energy Physics

Frustrated Magnets and Quantum Spin Liquids

Steven White University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
A quantum spin liquid is a solid whose atoms have magnetic moments but, because of quantum fluctuations, these moments fluctuate like a liquid even at zero temperature. Two dimensional spin liquids have been suggested as a way to produce high temperature superconductivity, and to build quantum computers. Just as helium is the only element which is a liquid at zero temperature, 2D spin liquids have been extremely difficult to find, despite decades of effort, raising the question, do realistic spin liquids even exist?
Recently, apparent spin liquids have been found experimentally, stimulating theoretical work to find simple model Hamiltonians of frustrated spin systems that have spin liquid ground states.

In this talk, I will give a broad overview of spin liquids and then focus on our simulations of the kagome Heisenberg model, a simple, realistic model of some of the recent experimental spin liquids, where we find a spin liquid ground state.
The Higgs confronts 3 universes at the LHC

Markus Luty University of California, Davis
March 13, 2013

PIRSA:13030095
High Energy Physics
The recent discovery of the Higgs boson is a fundamental advance in particle physics. This talk gives a theorist's perspective of the significance of this discovery. The Higgs boson was proposed in the 1960s, but it is best understood in the context of the quest to understand the weak interactions, which began with Fermi's theory of weak interactions almost 80 years ago. This has led to three very different paradigms for the structure of fundamental interactions at the TeV scale: supersymmetry, compositeness/extra dimensions, and anthropic selection. The Large Hadron Collider is the experimentum crucis for deciding between these different possible universes, and the discovery of the Higgs is a crucial clue. This talk will describe these paradigms, the implications of the Higgs discovery for them, and the outlook for further discoveries that would decide between them.
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Astrophysics
This talk will begin by discussing one by one the various reasons why cosmologists today consider the big bang inflationary cosmology to be the leading, if not proven, theory of the universe and then explaining why each of these reasons is flawed. This leads naturally to the question: what is the alternative? Understanding the flaws helps point the way.
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
High Energy Physics
Non-perturbative effects are responsible for the essential dynamical features of the four-dimensional gauge theories such as QCD. The N=2 supersymmetric four-dimensional theories are an interesting class of models in which non-perturbative computations can be carried out with arbitrary precision using localization of the path integrals. I will explain the new exact non-perturbative results and the relation to classical and quantum integrable systems for a large class of N=2 supersymmetric QCD.
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Astrophysics
As black holes accrete surrounding gas, they often produce relativistic, collimated outflows, or jets. Jets are expected to form in the black hole vicinity making them powerful probes of strong-field gravity. However, how jet properties are connected to black hole and accretion flow properties has been unclear. Recent progress in computer simulations of black hole accretion enables studies of jet formation in unprecedented detail. For the first time, 3D general relativistic magnetohydrodynamic numerical simulations allow one to determine the maximum efficiency with which accretion onto black holes can power relativistic jets. I will present the dependence of this maximum efficiency on black hole spin and discuss how this dependence allows one to probe strong-field gravity. In realistic astrophysical systems, the angular momentum vector of the accretion flow can be tilted relative to the spin of the black hole. I will present the first simulations of jets from such tilted accretion systems and discuss their observational signatures.
Quantum Gravity as Random Geometry

Vincent Rivasseau University of Paris-Saclay
February 27, 2013

PIRSA:13020132
General Relativity & Quantum Cosmology
Matrix models, random maps and Liouville field theory are prime tools which connect random geometry and quantum gravity in two dimensions. The tensor track is a new program to extend this connection to higher dimensions through the corresponding notions of tensor models, colored triangulations and tensor group field theories.
Beyond Massive Gravity

Rachel Rosen Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Astrophysics
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
General Relativity & Quantum Cosmology
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
General Relativity & Quantum Cosmology
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
High Energy Physics
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.

Title	Speaker(s)	Date	Talk Type	Info
Frustrated Magnets and Quantum Spin Liquids	Steven White	2013-03-20	Scientific Series	View details
The Higgs confronts 3 universes at the LHC	Markus Luty	2013-03-13	Scientific Series	View details
Rethinking Cosmology		2013-03-06	Scientific Series	View details
Non-perturbative problems in gauge theories: N=2 quiver QCD	Vasily Pestun	2013-03-06	Scientific Series	View details
Getting the Most out of a Black Hole	Alexander Tchekhovskoy	2013-03-04	Scientific Series	View details
Quantum Gravity as Random Geometry	Vincent Rivasseau	2013-02-27	Scientific Series	View details
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

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Format results

Frustrated Magnets and Quantum Spin Liquids

The Higgs confronts 3 universes at the LHC

Rethinking Cosmology

Non-perturbative problems in gauge theories: N=2 quiver QCD

Getting the Most out of a Black Hole

Quantum Gravity as Random Geometry

Beyond Massive Gravity

The Evolution of Quasars with Cosmic Time

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

Hidden Structure in Linguistics: The Organization of Sound Systems

What is motion? What is time?

Einstein's gravity versus String Gravity

Frustrated Magnets and Quantum Spin Liquids

The Higgs confronts 3 universes at the LHC

Rethinking Cosmology

Non-perturbative problems in gauge theories: N=2 quiver QCD

Getting the Most out of a Black Hole

Quantum Gravity as Random Geometry

Beyond Massive Gravity

The Evolution of Quasars with Cosmic Time

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

Hidden Structure in Linguistics: The Organization of Sound Systems

What is motion? What is time?

Einstein's gravity versus String Gravity