  One of the greatest challenges facing theoretical physics lies in reconciling
Einstein's classical theory of gravity - general relativity - with quantum
field theory. Although both theories have been experimentally supported in
their respective regimes, they seem mutually incompatible. This article
summarises the current status of the superstring approach to the problem, the
status of the Ashtekar program, and addresses the problem of time in quantum
gravity. It contains interviews with Abhay Ashtekar, Chris Isham, and Edward
Witten.

General Relativity and Quantum Cosmology;High Energy Physics - Theory