Talks

12685 - 12696 of 20118 Results

12/13 PSI - Explorations in Condensed Matter Lecture 11

Guifre Vidal Alphabet (United States)

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

April 22, 2013

PIRSA:13040057

Condensed Matter
12/13 PSI - Explorations in String Theory Lecture 10

Pedro Vieira Perimeter Institute for Theoretical Physics

April 19, 2013

PIRSA:13040095

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 10

Matthew Johnson York University

April 19, 2013

PIRSA:13040073

Astrophysics
The imaginary part of the gravitational action and black hole entropy

Yasha Neiman Okinawa Institute of Science and Technology Graduate University

April 18, 2013

PIRSA:13040106

General Relativity & Quantum Cosmology
12/13 PSI - Explorations in String Theory Lecture 9

Pedro Vieira Perimeter Institute for Theoretical Physics

April 18, 2013

PIRSA:13040094

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 9

Matthew Johnson York University

April 18, 2013

PIRSA:13040072

Astrophysics
Energy and the Environment - What Physicists Can Do

John Baez University of California, Riverside

April 17, 2013

PIRSA:13040030

Mathematical Physics
12/13 PSI - Explorations in String Theory Lecture 8

Pedro Vieira Perimeter Institute for Theoretical Physics

April 17, 2013

PIRSA:13040093

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 8

Matthew Johnson York University

April 17, 2013

PIRSA:13040071

Astrophysics
The theory of composition in physics

Lucien Hardy Perimeter Institute for Theoretical Physics

April 16, 2013

PIRSA:13040121

Quantum Physics
12/13 PSI - Explorations in String Theory Lecture 7

Pedro Vieira Perimeter Institute for Theoretical Physics

April 16, 2013

PIRSA:13040092

High Energy Physics
Results and highlights from Planck

Kendrick Smith Perimeter Institute for Theoretical Physics

April 16, 2013

PIRSA:13040123

Astrophysics

12/13 PSI - Explorations in Condensed Matter Lecture 11

Guifre Vidal Alphabet (United States)

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

April 22, 2013

PIRSA:13040057

Condensed Matter
12/13 PSI - Explorations in String Theory Lecture 10

Pedro Vieira Perimeter Institute for Theoretical Physics

April 19, 2013

PIRSA:13040095

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 10

Matthew Johnson York University

April 19, 2013

PIRSA:13040073

Astrophysics
The imaginary part of the gravitational action and black hole entropy

Yasha Neiman Okinawa Institute of Science and Technology Graduate University

April 18, 2013

PIRSA:13040106

General Relativity & Quantum Cosmology

I present a candidate for a new derivation of black hole entropy. The key observation is that the action of General Relativity in bounded regions has an imaginary part, arising from the boundary term. The formula for this imaginary part is closely related to the Bekenstein-Hawking entropy formula, and coincides with it for certain classes of regions. This remains true in the presence of matter, and generalizes appropriately to Lovelock gravity. The imaginary part of the action is a versatile notion, requiring neither stationarity nor any knowledge about asymptotic infinity. Thus, it may provide a handle on quantum gravity in finite and dynamical regions. I derive the above results, make connections with standard approaches to black hole entropy, and speculate on the meaning of it all. Implications for loop quantum gravity are also discussed.
12/13 PSI - Explorations in String Theory Lecture 9

Pedro Vieira Perimeter Institute for Theoretical Physics

April 18, 2013

PIRSA:13040094

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 9

Matthew Johnson York University

April 18, 2013

PIRSA:13040072

Astrophysics
Energy and the Environment - What Physicists Can Do

John Baez University of California, Riverside

April 17, 2013

PIRSA:13040030

Mathematical Physics

The global warming crisis is part of a bigger transformation in which humanity realizes that the Earth is a finite system and that our population, energy usage, and the like cannot continue to grow exponentially. While politics and economics pose the biggest challenges, physicists are in a good position to help make this transition a bit easier. After a quick review of the problems, we discuss a few ways physicists can help.
12/13 PSI - Explorations in String Theory Lecture 8

Pedro Vieira Perimeter Institute for Theoretical Physics

April 17, 2013

PIRSA:13040093

High Energy Physics
12/13 PSI - Explorations in Cosmology Lecture 8

Matthew Johnson York University

April 17, 2013

PIRSA:13040071

Astrophysics
The theory of composition in physics

Lucien Hardy Perimeter Institute for Theoretical Physics

April 16, 2013

PIRSA:13040121

Quantum Physics

We develop a theory for describing composite objects in physics. These can be static objects, such as tables, or things that happen in spacetime (such as a region of spacetime with fields on it regarded as being composed of smaller such regions joined together). We propose certain fundamental axioms which, it seems, should be satisfied in any theory of composition. A key axiom is the order independence axiom which says we can describe the composition of a composite object in any order. Then we provide a notation for describing composite objects that naturally leads to these axioms being satisfied. In any given physical context we are interested in the value of certain properties for the objects (such as whether the object is possible, what probability it has, how wide it is, and so on). We associate a generalized state with an object. This can be used to calculate the value of those properties we are interested in for for this object. We then propose a certain principle, the composition principle, which says that we can determine the generalized state of a composite object from the generalized states for the components by means of a calculation having the same structure as the description of the generalized state. The composition principle provides a link between description and prediction.
12/13 PSI - Explorations in String Theory Lecture 7

Pedro Vieira Perimeter Institute for Theoretical Physics

April 16, 2013

PIRSA:13040092

High Energy Physics
Results and highlights from Planck

Kendrick Smith Perimeter Institute for Theoretical Physics

April 16, 2013

PIRSA:13040123

Astrophysics

Cosmological results from Planck, a third-generation satellite mission to measure the cosmic microwave background, have just been announced. These results improve constraints on essentially all cosmological parameters, and have implications for several preexisting sources of tension with the standard cosmological model, while also raising new puzzles. I will discuss these results and their significance, as well as the next steps forward.

Title	Date	Collection	Type	Info
12/13 PSI - Explorations in Condensed Matter Lecture 11	2013‑04‑22	12/13 PSI - Explorations in Condensed Matter	Course	View details
12/13 PSI - Explorations in String Theory Lecture 10	2013‑04‑19	12/13 PSI - Eplorations in String Theory	Course	View details
12/13 PSI - Explorations in Cosmology Lecture 10	2013‑04‑19	12/13 PSI - Explorations in Cosmology	Course	View details
The imaginary part of the gravitational action and black hole entropy	2013‑04‑18	Quantum Gravity	Scientific Series	View details
12/13 PSI - Explorations in String Theory Lecture 9	2013‑04‑18	12/13 PSI - Eplorations in String Theory	Course	View details
12/13 PSI - Explorations in Cosmology Lecture 9	2013‑04‑18	12/13 PSI - Explorations in Cosmology	Course	View details
Energy and the Environment - What Physicists Can Do	2013‑04‑17	Colloquium	Scientific Series	View details
12/13 PSI - Explorations in String Theory Lecture 8	2013‑04‑17	12/13 PSI - Eplorations in String Theory	Course	View details
12/13 PSI - Explorations in Cosmology Lecture 8	2013‑04‑17	12/13 PSI - Explorations in Cosmology	Course	View details
The theory of composition in physics	2013‑04‑16	Quantum Foundations	Scientific Series	View details
12/13 PSI - Explorations in String Theory Lecture 7	2013‑04‑16	12/13 PSI - Eplorations in String Theory	Course	View details
Results and highlights from Planck	2013‑04‑16	Cosmology and Gravitation	Scientific Series	View details

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Format results

12/13 PSI - Explorations in Condensed Matter Lecture 11

12/13 PSI - Explorations in String Theory Lecture 10

12/13 PSI - Explorations in Cosmology Lecture 10

The imaginary part of the gravitational action and black hole entropy

12/13 PSI - Explorations in String Theory Lecture 9

12/13 PSI - Explorations in Cosmology Lecture 9

Energy and the Environment - What Physicists Can Do

12/13 PSI - Explorations in String Theory Lecture 8

12/13 PSI - Explorations in Cosmology Lecture 8

The theory of composition in physics

12/13 PSI - Explorations in String Theory Lecture 7

Results and highlights from Planck

12/13 PSI - Explorations in Condensed Matter Lecture 11

12/13 PSI - Explorations in String Theory Lecture 10

12/13 PSI - Explorations in Cosmology Lecture 10

The imaginary part of the gravitational action and black hole entropy

12/13 PSI - Explorations in String Theory Lecture 9

12/13 PSI - Explorations in Cosmology Lecture 9

Energy and the Environment - What Physicists Can Do

12/13 PSI - Explorations in String Theory Lecture 8

12/13 PSI - Explorations in Cosmology Lecture 8

The theory of composition in physics

12/13 PSI - Explorations in String Theory Lecture 7

Results and highlights from Planck