Gravity Seminars

Dynamical de Sitter phase in strongly coupled gauge theories in expanding Universe

Speaker: 
Ariel Zhitnitsky
Event Date and Time: 
Wed, 2016-10-12 12:00 - 13:00
Location: 
Hennings 318
I discuss a new scenario for  cosmology when  the   de Sitter phase emerges dynamically.   It might be relevant for the present epoch (observed dark energy) and inflationary epoch (early Universe).  This genuine quantum effect occurs as a result of   dynamics of the topologically nontrivial sectors in a   strongly coupled QCD- like gauge theory   in an expanding universe.

Density matrix of the Universe and a new type of hill-top inflation

Speaker: 
Andrei Barvinsky
Event Date and Time: 
Wed, 2016-10-05 12:00 - 13:00
Location: 
Hennings 318
Local Contact: 
Philip Stamp
A widely accepted paradigm of inflationary scenario implies a quasi-vacuum state as an initial state of the Universe, its large scale structure eventually originating
from vacuum fluctuations of the quantum fields. We discuss the alternative scenario with the initial state of the Universe in the form of the microcanonical density matrix.

Dark Energy and Condensate Stars: Macroscopic Effects of the Quantum Trace Anomaly in Low Energy Gravity

Speaker: 
Emil Mottola, LNAL
Event Date and Time: 
Wed, 2016-04-13 11:00 - 12:00
Location: 
Hennings 318
The twin problems of reconciling quantum theory with classical black holes and the existence of cosmological dark energy suggest that something basic is missing in the gravitational sector of the Standard Model at macroscopic distance scales. In an Wilsonian Effective Field Theory (EFT) approach considerations parallel to that in QCD and the chiral anomaly indicate that the action of the conformal trace anomaly should be included in the EFT of low energy gravity.

Loop Quantum Cosmology & The Very Early Universe: Interplay between theory and Observations

Speaker: 
Abhay Ashtekar
Event Date and Time: 
Wed, 2015-10-28 13:00 - 14:00
Location: 
Hennings 318
Local Contact: 
Philip Stamp

Thanks to the spectacular observational advances since the 1990s, a
`standard model' of the early universe has now emerged.

Universal Decoherence due to Gravitational Time Dilation

Speaker: 
Igor Pikovski, Harvard
Event Date and Time: 
Wed, 2015-04-15 13:00 - 14:00
Location: 
Hennings 318
Local Contact: 
Philip Stamp

The disappearance of quantum phenomena on macroscopic scales is usually attributed to decoherence -- the suppression of quantum superpositions due to interaction with an external environment. It is also often speculated that gravity might play a role in the transition to classicality and typical gravitational decoherence models assume an inherent breakdown of unitarity at some scale.

Infrared Quantum Gravity

Speaker: 
John Donoghue, University of Massachusetts Amherst
Event Date and Time: 
Wed, 2015-03-18 13:00 - 14:00
Location: 
Hennings 318
Local Contact: 
Philip Stamp

Effective Field Theory allows one to separate the known particles and interactions at low energy from the unknown physics at high energy. When applied to General Relativity it allows reliable calculation of quantum effects in the infrared.

Quantum Gravity Comes of Age

Speaker: 
Richard Woodard, University of Florida
Event Date and Time: 
Wed, 2015-04-22 13:00 - 14:00
Location: 
Hennings 318
Local Contact: 
Philip Stamp

I argue that cosmological data from the epoch of primordial inflation is catalysing the maturation of quantum gravity from speculation into a hard science.

A Tale of Two Horizons

Speaker: 
Sean Stotyn, UBC
Event Date and Time: 
Wed, 2014-11-26 13:00 - 14:00
Location: 
Hennings 309

It is well-known that the spacetime very near a degenerate horizon - known as the near horizon geometry (NHG) - has an enhanced symmetry. These NHGs can be obtained from non-extremal solutions via limits of specific diffeomorphisms and are thus valid solutions to the Einstein field equations in their own right. The canonical method used to obtain the NHG surprisingly suggests that the 4-volume between two merging horizons remains finite in the extremal limit.

Magnetic Stars for Holography

Speaker: 
Dan Carney, UBC
Event Date and Time: 
Wed, 2014-10-29 13:00 - 14:00
Location: 
Hennigs 318

I'll show how to construct some back-reacted asymptotically AdS_4 backgrounds with both electric and magnetic charges. The system consists of a bulk Dirac field hovering over an electrically and magnetically charged black hole. In the context of holography, such a gravitational solution should be dual to a (2+1)-dimensional CFT at finite density and strong coupling, subjected to a transverse magnetic field.

Holographic Accelerated Heavy Quark-Anti-Quark Pair

Speaker: 
Gordon Semenoff
Event Date and Time: 
Wed, 2014-10-08 13:00 - 14:00
Location: 
Hennings 318
TBA
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