|
|
Gravitational waves in cosmology
Kadlecová, Alžběta ; Svítek, Otakar (advisor) ; Žofka, Martin (referee)
In this work, we study the backreaction of high-frequency gravitational waves on cosmological backgrounds. To describe the wave, we use the Isa- acson formalism, specifically the WKB approximation, which allows us to express the backreaction through an effective stress-energy tensor of the gra- vitational wave. First, we consider the inhomogeneous cosmological model of Charach and Malin, which contains gravitational waves and a massless scalar field mini- mally coupled to gravity. We show that although this is a spatially compacti- fied solution, it is possible to add a high-frequency perturbation and solve Einstein's equations with the effective stress-energy tensor in a consistent way. The bacreaction is of the same order as the influence of the scalar field. Second, we add multiple incoherent high-frequency waves to the homoge- neous Kasner background, and discuss the relation to the late-time limit of the Gowdy (vacuum Charach and Malin) model. 1
|
|
|
Galileo Galilei and His Epoch
Bartošová, Tereza ; Veverková, Kamila (advisor) ; Lášek, Jan Blahoslav (referee)
This thesis deals with the personality and life of the Tuscan Renaissance scientist Galileo Galilei, a time in which he lived, and his relationship with the Catholic Church. The aim of the thesis is to acquaint the reader with the life of Galileo Galilei and Renaissance society, and thus capture important moments and influences that shaped Galileo's personality and life orientation. The thesis is divided into three main chapters. The first part deals with the Renaissance period and the related European Reformation. It focuses on the Renaissance in Italy, then education, religious situation and seeing the world. The second chapter is dedicated to Galileo's biography, with regard to his work and then researchers who were with Galileo joint activity. The last part refers to the religious situation of 16th to 17th century, considering the Council of Trent, the Roman Inquisition and the cosmology of how the people regarded it in antiquity and later the Catholic Church and scientists in the early modern period. This part especially illustrates the conflict Galileo and the Church. It describes the reasons of the conflict, the trial of Galileo and the consequences that flowed from it. The thesis is supplemented with events after Galileo's death. The conclusion summarizes the most important influences that...
|
guest ::
