Research in General Relativity and Quantum Gravity

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WPCP 2 B V P Z Courier 10cpi 2 x x x , x @ 8 ; X @ BOND - HP Laserjet II HPLASERJ.PRS x @ , t 0# BmX @ 2 N ( #| x 3 ' 3 ' Standard 3 ' 3 ' Standard = rJet Series II Y ( WPCN 2 B V P Z Courier 10cpi 2 x x x , x @ 8 ; X @ BOND - HP Laserjet II HPLASERJ.PRS x @ , t 0# BmX @ 2 L #| x 9307570 Sorkin This project will pursue research in "quantum gravity", which is the important problem of finding a theory in which the behavior of the gravitational field is characterized by a quantum randomness instead of by the deterministic evolution of the classical Einstein theory. One knows such randomness is necessary for consistency, since the known unpredictability of matter (for example, the quantum jumps which occur within atoms) must necessarily give rise to a corresponding unpredictability in the gravitational fields produced by the matter. When a theory of quantum gravity is found one may expect to understand what happens to objects which fall into black holes, and to understand what made the cosmological "big bang" take the form that it did. The approach Prof. Sorkin will follow is based on the hypothesis that spacetime has an "atomic" structure, being what technically is called a causal set. At the current stage of development of this theory a central question in understanding how the spacetime "atoms" interact with each other, is that of l earning which sort of interaction can avoid producing the impression of action at a distance (which would conflict with established physical laws). Prof. Sorkin will study this question using computer simulations of fields like the electromagnetic field propagating on a causal set. Progress in this effort will be a significant step toward a full formulation of causal set dynamics using Feynman's sum over histories method. It might also provide a novel method which one could apply to computer simulations of other problems of physical importance, such as predicting the masses of e lementary particles like the proton. ***