The measurement of time in quantum mechanics is problematic. I am investigating the use of specific models of quantum clocks to obtain unambiguous answers to questions such as how long a particle takes to tunnel through a barrier and the time required for particles to fall in a gravitational field. These topics relate to the question of the conceptual consistency of quantum mechanics and relativity. Quantum clocks might also play a role in biological systems.
The application of quantum field theory to black holes shows that their horizons are a measure of entropy. This idea may be generalized to cosmological horizons for a number of expanding universe problems. I am generalizing the second law of thermodynamics to cosmological horizons as a means to place constraints on cosmological models, and to investigate the status of the so-called holographic principle.
Many cosmologists believe that the universe we observe is an infinitesimal component of a "multiverse," or ensemble of universes, with differing properties and laws. I am developing some new ideas for testing this hypothesis.