Inflationary Cosmology, Cosmic String Models, and the Vilkovisky-DeWitt Formalism (Physics)

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Professor Allen will initiate a new program of researching in gravitation and cosmology. This will explore two different models of the early universe, to see what they predict about the universe today. The "inflationary" model convincingly accounts for the great size and uniformity of our present-day universe. He will study the production of primordial gravity-waves in this model. To do so, he will resolve some difficulties that have arisen in the treatment of gravitons (the quanta that transmit gravitational forces) in de Sitter space, and understand how quantum effects can influence the physical stability of this model. The "cosmic string" model can account for the temperature fluctuations expected to occur in the microwave background radiation. He is constructing a computer simulation of the motion of loops of "cosmic string" which are supposed to cause galaxies to form in the model. He will study the distribution of these model galaxies in space and compare it with what astronomers observe in the sky. Finally, he will use a new mathematical formalism invented by Vilkovisky and DeWitt for calculating quantum effects. The goal is to understand how the results of this method differ from standard techniques currently in use, and to see if they change the predictions about gravity-wave production in the inflationary model.