English | Français     A A     Connect With Us

Quantum Gravity

This series consists of talks in the area of Quantum Gravity.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

Perturbative Amplitudes and Ultraviolet Behavior of Supergravity Theories

Thursday Jun 13, 2013
Speaker(s):

Recently powerful techniques have emerged for performing multi-loop computations of scattering amplitudes in quantum gravity and  supergravity.  These techniques include generalized unitarity and the double-copy property, related to color-kinematics duality in gauge theory.  Using these  techniques, the ultraviolet divergence structure of N=8 supergravity, and more recently pure N=4 supergravity, have been assessed, not only in four space-time dimensions but also in higher dimensions.

Collection/Series:
Scientific Areas:

CDT without preferred foliation

Thursday May 30, 2013
Speaker(s):

Causal dynamical triangulations (CDT) define a nonperturbative path integral for quantum gravity as a sum over triangulations. Causality is enforced on the kinematical level by means of a preferred
foliation.

Collection/Series:
Scientific Areas:

Quantum Gravity from Causal Dynamical Triangulations

Thursday May 23, 2013
Speaker(s):

By way of presenting some classic and many new results, my talk will indulge shamelessly in
advertising "Causal Dynamical Triangulations (CDT)" as a hands-on approach to nonperturbative quantum gravity that reaches where other approaches currently don't. After summarizing the rationale and basic ingredients of CDT quantum gravity and some of its key findings (like the emergence of a classical de Sitter space), I will focus on some very recent results: how we uncovered the presence of a second-order phase transition (so far unique in 4D quantum

Collection/Series:
Scientific Areas:

The effective field theory of general relativity, running couplings and Asymptotic Safety

Thursday May 09, 2013
Speaker(s):

Effective field
theory techniques allow reliable quantum calculations in general relativity at
low energy. After a review of these techniques, I will discuss the attempts to
define the gravitational corrections to running gauge couplings and to the
couplings of gravity itself. I will also describe an attempt to understand the
relation between the effective field theory and Asymptotic Safety in the region
where they overlap.

Collection/Series:
Scientific Areas:

Loop quantization of a weak-coupling limit of Euclidean gravity

Thursday Apr 25, 2013
Speaker(s):

I will describe recent work in collaboration with Adam
certain $G_{\mathrm{N}}\rightarrow 0$ limit of Euclidean gravity, introduced by
Smolin. The model allows one to test various quantization choices one is faced
with in loop quantum gravity, but in a simplified setting.  The main results are the construction of
finite-triangulation Hamiltonian and diffeomorphism constraint operators whose
continuum limits can be evaluated in a precise sense, such that the quantum

Collection/Series:
Scientific Areas:

The imaginary part of the gravitational action and black hole entropy

Thursday Apr 18, 2013
Speaker(s):

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,

Collection/Series:
Scientific Areas:

Quantum causal dynamics without absolute space or time

Thursday Apr 11, 2013
Speaker(s):

I
will describe a discrete model of spacetime which is quantum-mechanical,
causal, and background free. The kinematics is described by networks whose
vertices are labelled with arrows. These networks can be evolved forwards (or
backwards) in time by using unitary replacement rules. The arrow structure
permits one to define dynamics without using an absolute time parameter.
Based on arXiv:1201.2489.

Collection/Series:
Scientific Areas:

Canonical gravity using unconstrained null initial data

Thursday Mar 28, 2013
Collection/Series:

A CDT Hamiltonian from Horava-Lifshitz gravity

Thursday Mar 14, 2013
Speaker(s):

Causal
Dynamical Triangulations” (CDT) is a lattice theory where aspects of quantum
gravity can be studied. Two-dimensional CDT can be solved analytically and the
continuum (quantum) Hamiltonian obtained.

In this talk I will show that this continuum Hamiltonian is the one obtained by
quantizing two-dimensional projectable Horava-Lifshitz gravity.

Collection/Series:
Scientific Areas:

A Self-consistent Model of the Black Hole Evaporation

Thursday Mar 07, 2013
Speaker(s):

We construct a
self-consistent model which describes a black hole from formation to
evaporation including the back reaction from the Hawking radiation. In the case
where a null shell collapses, at the beginning the evaporation occurs, but it
stops eventually, and a horizon and singularity appear. On the other hand, in
the generic collapse process of a continuously distributed null matter, the
black hole evaporates completely without forming a macroscopically large

Collection/Series:
Scientific Areas:

RECENT PUBLIC LECTURE

In Praise of Weakness

Speaker: Aephraim Steinberg