Date |
Time |
Speaker |
Topic |
Room |
April 14 |
12:00 |
Alexander Kamenshchik
(Bologna)
|
Soft singularity crossing and transformation of matter properties in general relativity and cosmology |
R 215 |
April 21 |
12:00 |
—
|
Dice seminar — Hacking the quantum revolution: 1925–1975
|
R 215 |
Dice seminar — Hacking the quantum revolution: 1925–1975
The presenter will be determined by the throw of a dice.
Silvan S. Schweber, Eur. Phys. J. H 40 (2015) 1, 53–149
Sections: Introduction, The role of context, pp. 1–6; 4.5 Leo Kadanoff, pp. 45–52
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April 28 |
12:00 |
—
|
Dice seminar — Identification of a gravitational arrow of time
|
R 215 |
Dice seminar — Identification of a gravitational arrow of time
The presenter will be determined by the throw of a dice.
Julian Barbour, Tim Koslowski, and Flavio Mercati, Phys. Rev. Lett. 113 (2014) 18, 181101, arXiv:1409.0917 [gr-qc]
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May 5 |
12:00 |
—
|
Dice seminar — Exotic Statistics for Ordinary Particles in Quantum Gravity
|
R 215 |
Dice seminar — Exotic Statistics for Ordinary Particles in Quantum Gravity
The presenter will be determined by the throw of a dice.
John Swain, Int. J. Mod. Phys. D 17 (2008) 13, 2475, arXiv:0805.2373 [gr-qc]
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May 12 |
12:00 |
—
|
Dice seminar — Cosmology and local physics
|
R 215 |
Dice seminar — Cosmology and local physics
The presenter will be determined by the throw of a dice.
George F. R. Ellis, Int. J. Mod. Phys. A 17 (2002) 20, 2667
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May 19 |
12:00 |
Pranjal Dhole
(Bonn)
|
Emergent Gravity and Cosmology: Thermodynamic Perspective |
R 215 |
May 22 |
14:15 |
Pranjal Dhole
(Köln/Bonn)
|
Master colloquium — Emergent Gravity and Cosmology: Thermodynamic Perspective
|
Room 001 MPIfR Bonn |
Master colloquium — Emergent Gravity and Cosmology: Thermodynamic Perspective
Pranjal Dhole (Köln/Bonn)
This thesis is divided in two parts. First part of this thesis is an attempt to clarify the notion of emergence in Physics. We analyze thermodynamically emergent scenarios of gravity viz. ADS/CFT, Verlinde’s entropic gravity and Padmanabhan’s thermodynamic emergent gravity and clarify how/whether gravity is described as an emergent phenomena in each theory.
The second part of this thesis is dedicated to Padmanabhan’s thermodynamic treatment of gravity. In recent work by T. Padmanabhan et al. [arXiv:1303.1535], a Hamiltonian structure derived from metric density and its corresponding conjugate momentum density was proposed. These variables have thermodynamic analogues in Horizon thermodynamics. We attempt a conformal decomposition of these variables. We start with an alternate description of cosmology that does not originate with gravitational field equations. We postulate that evolution of our universe can be described inside a spacetime box between two de Sitter phases that arises due to breaking of conformal symmetry giving rise to matter degrees of freedom (physical length scales).
We postulate that generation of matter degrees of freedom, in consequence, give rise to holographic discrepancy which drives the evolution of cosmic space along with cosmic time.
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June 2 |
12:00 |
—
|
Dice seminar — The Interpretation of Quantum Mechanics: Many Worlds or Many Words?
|
R 215 |
Dice seminar — The Interpretation of Quantum Mechanics: Many Worlds or Many Words?
The presenter will be determined by the throw of a dice.
M. Tegmark, Fortsch. Phys. 46 (1999) 6–8, 855, arXiv:quant-ph/9709032
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June 9 |
12:00 |
—
|
Dice seminar — On the Classical Limit of Quantum Mechanics
|
R 215 |
Dice seminar — On the Classical Limit of Quantum Mechanics
The presenter will be determined by the throw of a dice.
Valia Allori, Nino Zanghì, arXiv:quant-ph/0112009
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June 16 |
12:00 |
—
|
Dice seminar — The strange equation of quantum gravity
|
R 215 |
Dice seminar — The strange equation of quantum gravity
The presenter will be determined by the throw of a dice.
Carlo Rovelli, Class. Quant. Grav. 32 (2015) 124005, arXiv:1506.00927 [gr-qc]
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June 23 |
12:00 |
—
|
Dice seminar — Boundary conditions in quantum cosmology
|
R 215 |
Dice seminar — Boundary conditions in quantum cosmology
The presenter will be determined by the throw of a dice.
Alexander Vilenkin, Phys. Rev. D 33 (1986) 3560.
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June 30 |
11:00 |
Markus Strehlau
(Köln/AEI Potsdam)
|
Master colloquium — Numerical study of a geometric flow for the Bartnik conjecture in axisymmetry
|
Room 1.63 AEI Potsdam |
Numerical study of a geometric flow for the Bartnik conjecture in axisymmetry
Markus Strehlau (Köln/AEI Potsdam)
The static metric extension conjecture was formulated by Robert Bartnik, motivated by the problem of defining a quasi-local mass. This conjecture can be interpreted as an open boundary problem. The prescribed conditions are the metric on the inner boundary surface of the extension and its mean curvature. To gain further insight into this problem, axisymmetric extensions were used. We define a geometric flow, based on a mean curvature flow, to approach the inner boundary of the extension. This flow was numerically analysed using a pseudo-spectral method.
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June 30 |
12:00 |
—
|
Dice seminar — Is Spacetime Countable?
|
R 215 |
July 7 |
12:00 |
Jens Boos
(Köln) |
Master colloquium — Quasi-normal modes of the BTZ black hole solution of (2+1)-dimensional topological Poincare gauge theory of gravity
|
R 215 |
Quasi-normal modes of the BTZ black hole solution of (2+1)-dimensional topological Poincare gauge theory of gravity
Jens Boos (Cologne)
In this thesis, we study the quasi-normal modes of the BTZ black hole with torsion. Generalizing the results already presented in the literature, we derive the scalar, fermionic, and electromagnetic wave equations from a variational principle and solve them analytically for the BTZ background with torsion. In a second step, demanding outgoing perturbations at the horizon and vanishing flux at infinity gives rise to the quasi-normal modes.
These expressions are shown to fulfill the AdS/CFT correspondence. Tensorial wave equations in coframe and the tensorial part of the Lorentz connection—unique to the Mielke–Baekler model—are derived and compared with the Proca–Chern–Simons system. Their formal similarity suggests that also here, the quasi-normal modes can be found analytically.
Derived from the scalar, spinorial, and electromagnetic quasi-normal modes, the semiclassical entropy spectrum of the non-rotating BTZ black hole is evenly spaced.
Moreover, the minimal noise temperature picked up by a quantum amplifier when measuring the quasi-normal mode transitions of the BTZ black hole is of the order of the Hawking temperature. This is an interesting feature of quasi-normal mode quantum gravity” in (2 + 1)D.
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July 28 |
12:00 |
Alessandro Fasse
(Köln) |
Classical LTB model and naked singularities |
R 215 |
August 4 |
12:00 |
—
|
Dice seminar — Phonon creation by gravitational waves
|
R 215 |
August 25 |
12:00 |
Alessandro Fasse
(Köln) |
An Intoduction to Symplectic Geometry I - Basics |
R 215 |
September 01 |
12:00 |
Alessandro Fasse
(Köln) |
An Intoduction to Symplectic Geometry II - Applications to Physics |
R 215 |
Soft singularity crossing and transformation of matter properties
Alexander Kamenshchik (Uni Bologna/Landau Inst. Moscow)
We investigate particular cosmological models, based either on tachyon fields or on perfect fluids, for which soft future singularities arise in a natural way. Our main result is the description of a smooth crossing of the soft singularity in models with an anti-Chaplygin gas or with a particular tachyon field in the presence of dust. Such a crossing is made possible by certain transformations of matter properties. Some of these cosmological evolutions involving tachyons are compatible with SNIa data. We compute numerically their dynamics involving a first soft singularity crossing, a turning point and a second soft singulatity crossing during recollapse, ending in a Big Crunch singularity.
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