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# 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.

## Renormalizable Non-Metric Quantum Gravity?

Jeudi nov 30, 2006
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We argue that four-dimensional quantum gravity may be essentially renormalizable provided one relaxes the assumption of metricity of the

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## Algebraic Quantum Gravity

Jeudi sep 07, 2006
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We introduce a new top down approach to canonical quantum gravity, called Algebraic Quantum Gravity (AQG): The quantum kinematics of AQG is determined by an abstract $*-$algebra generated by a countable set of elementary operators labelled by an algebraic graph. The quantum dynamics of AQG is governed by a single Master Constraint operator. While AQG is inspired by Loop Quantum Gravity LQG), it differs drastically from it because in AQG there is fundamentally no topology or differential structure.

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## Making sense of non-Hermitian Hamiltonians

Jeudi avr 13, 2006
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It is a standard axiom of quantum mechanics that the Hamiltonian H must be Hermitian because Hermiticity guarantees that the energy spectrum is real and that time evolution is unitary. In this talk we examine an alternative formulation of quantum mechanics in which the conventional requirement of Hermiticity is replaced by the more general and physical condition of space- time reflection (PT) symmetry. We show that if the PT symmetry of H is unbroken, Then the spectrum of H is real. Examples of PT-symmetric non-Hermitian Hamiltonians are $H=p^2+ix^3$ and $H=p^2-x^4$.

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## Spacetime regions as "quantum subsystems": glimmers of a pre-geometric perspective

Jeudi jan 19, 2006
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Space-time measurements and gravitational experiments are made by the mutual relations between objects, fields, particles etc... Any operationally meaningful assertion about spacetime is therefore intrinsic to the degrees of freedom of the matter (i.e. non-gravitational) fields and concepts such as locality'' and proximity'' should, at least in principle, be definible entirely within the dynamics of the matter fields. We propose to consider the regions of space just as general subsystems''.

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## The universality of highly damped quasinormal modes in generic single horizon black holes

Jeudi jan 12, 2006
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We calculate analytically the highly damped quasinormal mode spectra of generic single-horizon black holes using the rigorous WKB techniques of Andersson and Howls. We thereby provide a firm foundation for previous analysis, and point out some of their possible limitations. The numerical coefficient in the real part of the highly damped frequency is generically determined by the behavior of coupling of the perturbation to the gravitational field near the origin, as expressed in tortoise coordinates.

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## Phenomenological quantum gravity: Pieces of the puzzle

Mardi déc 13, 2005

The phenomenology of quantum gravity can be examined even though the underlying theory is not yet fully understood. Effective extensions of the standard model allow us to study specific features, such as the existence of extra dimensions or a minimal length scale. I will talk about some applications of this approach which can be used to make predictions for particle- and astrophysics, and fill in some blanks in the puzzle of quantum gravity. A central point of this investigations is the physics of black holes.

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## The geometry dependence of the Casimir effect

Vendredi déc 09, 2005
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## Effective theories for loop quantization

Mercredi nov 16, 2005
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## The Pioneer Anomaly

Mardi sep 27, 2005
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## loop quantum gravity seminar "Lorentz violating SQED"

Mardi juil 26, 2005
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## LECTURES ON-DEMAND

### Jocelyn Bell Burnell: University of Oxford

Speaker: Jocelyn Bell Burnell