Seminar of Theory of Relativity and Gravitation
2006/2007 | 2007/2008 | 2008/2009 | 2009/2010 | 2010/2011 | 2011/2012 | 2012/2013 | 2013/2014 | 2014/2015 | 2015/2016 | 2016/2017 | 2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025 | Seminar homepage
2017-03-31 (Friday)
room 1.40, Pasteura 5 at 11:15 
Yaser Tavakoli (University of Teheran, Iran)The final state of gravitational collapse in (effective) bouncing gravity models
2017-03-24 (Friday)
room 1.40, Pasteura 5 at 11:15
Jerzy Kijowski (CFT PAN, Warszawa)Hamiltonian description of radiation phenomena
UWAGA! Zmiana sali: B0.14.
2017-03-17 (Friday)
room 1.40, Pasteura 5 at 11:15
Piotr Chruściel (Uniwersytet Wiedeński)Stationary solutions of Einstein-matter equations with a negative cosmological constant
There has been recently a lot of activity in numerically constructing stationary solutions of the Einstein-matter field equations with a negative cosmological constant. I will review these results and show how to prove existence of many families of such solutions.
2017-03-10 (Friday)
room 1.40, Pasteura 5 at 11:15
Aneta Wojnar (UMCS Lublin)Inflationary cosmology in Palatini formalism
We present a simple generalisation of the LCDM model which on the one hand reaches very good agreement with the present day experimental data and provides an internal inflationary mechanism on the other hand. It is based on Palatini modified gravity with quadratic Starobinsky term. The modification provides, besides a current accelerated expansion, the epoch of endogenous inflation driven by type III freeze singularity. The dynamics is reduced to the 2D sewn dynamical system of a Newtonian type. For this aim we use dynamical system theory. We classify all evolutionary paths in the model as well as trajectories in the phase space. We demonstrate that the presence of a degenerate freeze singularity (glued freeze type singularities) is a generic feature of early evolution of the Universe.
2017-03-03 (Friday)
room 1.40, Pasteura 5 at 11:15
Michał Artymowski (UJ, Kraków)Initial conditions for the inflationary Universe
2017-01-27 (Friday)
room 1.40, Pasteura 5 at 11:15
Łukasz Nakonieczny (IFT UW)Starobinsky inflation - loop corrections or new physics?
One of the mostly debated topic in modern cosmology is model building for inflation. Recent Planck data seem to favor simple models, amongst them there is the Starobinsky model based on the modification of the gravitational action. Its characteristic feature is the presence of the Ricci scalar squared term. It is often assumed that such a term could be generated by the loop correction of the matter sector. During the presentation I will show by explicit calculations how to obtain such a term in the framework of quantum field theory in curved spacetime. Surprisingly, the obtained results seem to indicate that the attained inflationary action leads to an incorrect model of inflation.
2017-01-20 (Friday)
room 1.40, Pasteura 5 at 11:15
Mehdi Assanioussi (IFT UW)Deparametrization of gravity and loop quantization
2017-01-13 (Friday)
room 1.40, Pasteura 5 at 11:15
dr hab. Maciej Nieszporski (KMMF UW)Integrable discretisation of Ernst equations
2016-12-16 (Friday)
room 1.40, Pasteura 5 at 11:15
Jakub Bilski (Fudan University, Szanghai, Chiny)Coupling matter to Quantum Reduced Loop Gravity
Loop Quantum Gravity (LQG) is an attempt to quantize Einsteinian gravity, cast in terms of variable with SU(2) symmetry, deploying tools borrowed from lattice gauge theories. I will present a procedure to select a finite amount of degrees of freedom in LQG, which is called Quantum Reduced Loop Gravity (QRLG), and show that it can be applied to all gravitational models with diagonal metric tensor, including all the solutions of the Einstein equations relevant for cosmology and black holes physics. I will discuss the symplectic structure of the phase space of QRLG and comment on the quantization procedure applied to the Hamiltonian constraint for the Standard Model of matter fields. Next I will present results obtained, and show in particular that the Hamiltonian eigenvalues approach the classical Hamiltonian at the leading order in the continuum limit. The next-to-the-leading order corrections can be discussed in conjunction with their possible phenomenological implications. Finally I will discuss how the form of quantum-gravitational corrections are dependent on the chosen representation for matter fields.
2016-12-02 (Friday)
room 1.40, Pasteura 5 at 11:15
Andrzej Rostworowski (UJ, Kraków)Perturbations around spherically symmetric spacetimes
Motivated by AdS (in)stability problem outside spherical symmetry, I will present nonlinear, axially symmetric, gravitational perturbations of AdS space, based on Regge-Wheeler decomposition of metric perturbations. However I will use AdS space as an example, the formalism should be easily adapted for gravitational perturbations around any spherically symmetric solutions of vacuum Einstein equations.