Cosmological Phase Transitions

Physical processes related to cosmological first-order phase transitions are discussed and reviewed in this introductory part of dissertation. I first describe cosmological phase transitions on a general level, concentrating on bubble nucleation, phase change, and related phenomena. I point out that especially the onset of a cosmological phase transition shows a universal behavior. Then I discuss the electroweak and quark-hadron phase transitions from a more phenomenological point of view, and present a partially quantitative description of the different events that is believed to have taken place during these two cosmological transitions.