# 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.

## Making sense of non-Hermitian Hamiltonians

Thursday Apr 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

Thursday 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

Thursday 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

Tuesday Dec 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

Friday Dec 09, 2005
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## Effective theories for loop quantization

Wednesday Nov 16, 2005
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## The Pioneer Anomaly

Tuesday Sep 27, 2005
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## loop quantum gravity seminar "Lorentz violating SQED"

Tuesday Jul 26, 2005
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## Turbulence in the universe

Thursday Jun 16, 2005
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## Complexity of elections: how to measure your voting power?

Thursday Jun 09, 2005
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Observers agree that a citizen of Ohio had much larger voting power than a citizen of Texas or California in the recent US presidential election. Why is it so? A brief introduction to the theory of voting will be provided. We analyze the voting power of a member of a voting body, or of a person which elects his representative, who will take part in the voting on her behalf. The notion of voting power is illustrated by examples of the systems of voting in the European Council. We propose a representative voting system based on the square root law of Penrose.

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