Generalized Einstein Theories

Research project P 14650 Generalized Einstein Theories Wolfang KUMMER 09.10.2000 In the recent -past, systematic observations of type Ia Supernovae with large red-shifts, i.e. from early phases of the d ` evelopment of the universe, yield strong evidence for a sizable cosmological constant, or a corresponding field ("quintessence"). This created renewed interest in extensions of Einstein`s theory of gravity towaxds so-called scalax-tensor theories. The simplest situation for such theories that can be studied is the spherically symmetric one. Methods developed by my group in the last five years allow not only a new approach to the classical case but also to the (two- dimensional) quantum gravity of these situations, because they may be treated directly from an effective spher , ically reduced action. We expect new insight, e.g. for the dynamics of black holes in such extended theories. Beside scalax-tensor theories, also another class of Einstein-theory models with two Killing-vectors, the so-called Gowdy metrics, will be treated by the same methods, In the latter, more complicated case, possibly a first glimps to (standard) quantum gravity beyond the strictly 2d-reduced case in physically interesting situations could be obtained.