Seminar by 

Jonathan Engle

"Deriving loop quantum cosmology from diffeomorphism invariance" 

Loop quantum gravity is an approach to the quantization of general relativity in which Einstein’s principle of diffeomorphism covariance plays a central role. Loop quantum cosmology is a theory in which the principles of loop quantum gravity are applied in the homogeneous, and optionally isotropic, context, leading to predictions for the cosmic microwave background which are the best chance for testing, through observation, the principles of loop quantum gravity. Several results over the years, including a few results by the speaker and collaborators over the last year, have demonstrated (1.) how the Hilbert space of states of loop quantum cosmology and action of basic operators thereon is uniquely determined by the requirement of diffeomorphism covariance, and (2.) the degree to which the dynamics of loop quantum cosmology is similarly determined. This talk will summarize these results.

Skype Seminar by 

Klaus Liegner

"Hamiltonian Renormalisation"
 

We study the question whether it is possible to reformulate the Wilsonian renormalisation group non-perturbatively directly at the operator (Hamiltonian) level. Hamiltonian renormalisation would be the natural route to follow if one had easier access to an interacting Hamiltonian operator rather than to a path integral, at least in the presence of UV and/or IR cut-off, which is generically the case in complicated gauge theories such as General Relativity. Our guiding principle for the definition of the direct Hamiltonian renormalisation group is that it results in the same continuum theory as the covariant (path integral) renormalisation group. We will investigate this direct Hamiltonian Renormalisation for the case of the free massive quantum scalar field and point out its necessity in a concrete cosmological example for Quantum Gravity.

 

Date: Dec 11, 2017

Time: 9 AM

255 Nicholson

Visit by Andrzej Krolak

 

Prof. Krolak  from Institute of Mathematics, Polish Academy of Sciences at Warsaw is visiting us from Nov 27-Dec 6, 2017. Prof. Krolak has made very seminal contributions to our understanding of strength of singularities, and various aspects of theoretical gravity and gravitational waves. He is the head of the Polish gravitatioanal wave community involved with Virgo gravitational wave detector.

You are welcome to discuss with Andrzej in room 255.

Talk by Andrea Dapor

Speaker: Andea Dapor, FAU-Erlangen, Germany
Place: 241 Nicholson
Date: Tuesday November 14th
Time: 9am

Title: Coherent States in LQG: Cosmology, Black Holes and Effective Dynamics

Seminar by Prof. Christian Fleischhack

Seminar by 

Prof. Christian Fleischhack

 

Symmetries in loop quantum gravity

 

Date: Aug 30, 2017

Time: 11:30 AM

Gravity Suite

Talk by Raul Carballo-Rubio

Seminar by Raul Carballo-Rubio

Talk time and date:

May 17th at 11:00 AM in Nicholson 241

 

Title:  Exponential decay of black holes into white holes

Abstract: In recent years, it has been proposed by different authors that non-perturbative quantum gravity effects may turn black holes into white holes. To evaluate the characteristic time scale of this transition, a theory of quantum gravity that assigns probabilities to geometric interpolations between black hole and white hole geometries is needed. In this talk, I will explain the results that are obtained in a truncation of the problem that assigns probabilities à la Euclidean quantum gravity to a reduced set of interpolating geometries. I will show how an exact exponential decay law is found, extract the characteristic time scale that follows from it, and discuss the astrophysical relevance of this calculation.

Seminar by Andrzej Krolak

Seminar by Andrzej Krolak

 

Strong curvature singularities 

- past and future

 

Time: 12:30 PM 

Date: March 23, 2017

Gravity Suite