Concept of time in canonical quantum gravity and string theory

Topics in String Theory and Quantum Gravity

Locality in quantum gravity and string theory

Breakdown of local physics in string theory at distances longer than the string scale is investigated. Such nonlocality would be expected to be visible in ultrahigh-energy scattering. The results of various approaches to such scattering are collected and examined. No evidence is found for nonlocality from strings whose length grows linearly with the energy. However, local quantum field theory d...

AdS2 Quantum Gravity and String Theory

AdS2 has an SL(2, R) isometry group. It is argued that in the context of quantum gravity on AdS2 this group is enlarged to the full infinite-dimensional 1+1 conformal group. Massive scalar fields are coupled to AdS2 gravity and shown to have associated conformal weights h(m) shifted by their mass. For integral values of h primary boundary operators are obtained as h normal derivatives of the sc...

2D String Theory Coupled to Quantum Gravity

We consider self-avoiding Nambu-Goto open strings on a random surface. We have shown that the partition function of such a string theory can be calculated exactly. The string susceptibility for the disk is evaluated to be − 2 . We also consider modifications of the Nambu-Goto action which are exactly soluble on a random surface.

Black hole entropy in canonical quantum gravity and superstring theory.

In this paper the entropy of an eternal Schwarzschild black hole is studied in the limit of infinite black hole mass. The problem is addressed from the point of view of both canonical quantum gravity and superstring theory. The entropy per unit area of a free scalar field propagating in a fixed black hole background is shown to be quadratically divergent near the horizon. It is shown that such ...