Jose Senovilla - What is the surface of a Black Hole?
RMI Elméleti Osztály Jose Senovilla (Basque Country University UPV/EHU, Bilbao) "What is the surface of a Black Hole?" címmel tartandó szemináriuma.
Black Holes (BH) are fundamental objects in Physics predicted classically by General Relativity with intriguing consequences in Quantum Physics because they show a deep fundamental relation between Gravitation, Thermodynamics and Quantum Theory. The characteristic feature of a BH is its Event Horizon: the boundary of the region from where one can send signals to infinity. This Event Horizon is often identified as the surface of the BH but, surprisingly, this leads to several difficulties because the Event Horizon is teleological: it depends on future causes ---and actually on the whole future evolution of the spacetime.
In this talk I will discuss several ideas put forward to solve the problem of how to recognize, locally, the presence of a BH. Most of them rely on the concept of future "trapped surface", a fundamental concept introduced by Penrose in 1965. It is widely believed that closed trapped surfaces are the single most important ingredient in gravitational collapse and in the formation of BHs. Unfortunately, they seem to suffer from global problems similar to those of the Event Horizon: they are "clairvoyant", as they seem to be aware of things happening far away in space, non-locally. Thus, one has to resort to even newer ideas in order to define the instantaneous surface of dynamical BHs, such as a BH in formation. I will present two such ideas, one using the boundary of the region with future trapped surfaces, the other by introducing the novel concept of "cores" of a BH. The ups and downs of these novel ideas will be analyzed in detail.
Helye: Wigner FK RMI III.ép. Tanácsterem
Ideje: 2014. június 27. péntek du. 14:00 óra