Tue, 24 Nov 2009

12:00 - 13:00
L3

Locally covariant quantum field theory in curved spacetime

CJ Fewster (York)
Abstract

A recent innovation in quantum field theory is the locally covariant

framework developed by Brunetti, Fredenhagen and Verch, in which quantum

field theories are regarded as functors from a category of spacetimes to a

category of *-algebras. I will review these ideas and particularly discuss

the extent to which they correspond to the intuitive idea of formulating the

same physics in all spacetimes.

Tue, 22 Sep 2009

12:00 - 13:00
L3

(HoRSe seminar) Tilting and cluster transfromations

Tom Bridgeland
(University of Sheffield)
Abstract

I'll explain (following Kontsevich and Soibelman) how cluster transformations intertwine non-commutative DT invariants for CY3 algebras related by a tilt.

Thu, 23 Jul 2009
11:30
L3

Shadowing, entropy and a homeomorphism of the pseudoarc.

Piotr Oprocha
(Murcia and Krakow)
Abstract

In this talk we present a method of construction of continuous map f from [0, 1] to itself, such that f is topologically mixing, has the shadowing property and the inverse limit of copies of [0, 1] with f as the bounding map is the pseudoarc. This map indeuces a homeomorphism of the pseudoarc with the shadowing property and positive topological entropy. We therefore answer, in the affirmative, a question posed by Chen and Li in 1993 whether such a homeomorphism exists.

Fri, 03 Jul 2009

16:30 - 18:00
L3

Lecture

Professor Dana Scott
Mon, 22 Jun 2009

12:00 - 13:00
L3

Hidden symmetries and higher-dimensional rotating black holes

Dr D. Kubiznak
(Cambridge)
Abstract

The 4D rotating black hole described by the Kerr geometry possesses many of what was called by Chandrasekhar "miraculous" properties. Most of them can be related to the existence of a fundamental hidden symmetry called the principal conformal Killing-Yano (PCKY) tensor. In my talk I shall demonstrate that, in this context, four dimensions are not exceptional and that the (spherical horizon topology) higher-dimensional rotating black holes are very similar to their four-dimensional cousins. Namely, I shall present the most general spacetime admitting the PCKY tensor and show that is possesses the following properties: 1) it is of the algebraic type D,  2) it allows a separation of variables for the Hamilton-Jacobi, Klein-Gordon, Dirac, gravitational, and stationary string equations, 3) the geodesic motion in such a spacetime is completely integrable, 4) when the Einstein equations with the cosmological constant are imposed the metric becomes the Kerr-NUT-(A)dS spacetime. Some of these properties remain valid even when one includes the electromagnetic field.

Tue, 23 Jun 2009
12:00
L3

Non-existence of stationary two-black-hole configurations

Joerg Hennig
(AEI Golm)
Abstract
We resume former discussions of the question, whether the spin-spin repulsion and the gravitational attraction of two aligned black holes can balance each other. To answer the question we formulate a boundary value problem for two separate (Killing-) horizons and apply the inverse (scattering) method to solve it. Making use of results of Manko, Ruiz and Sanabria-Gómez and a novel black hole criterion, we prove the non-existence of the equilibrium situation in question.

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