This project will entail theoretical studies of several aspects of quantum fluctuations of spacetime and related issues. A key problem in any quantum theory of gravity is understanding these fluctuations and their physical effects. One will be the effects of quantum energy density fluctuation in the early universe, especially in the context of inflationary cosmology. Previous studies by the PI and his collaborators indicate that these effects may be larger than one would have naively guessed, and possibly large enough to cause observable effects today. A related topic is the study of the probability distribution for quantum energy density fluctuations. A better understanding of this distribution, especially the part which describes rare but large fluctuations, can have applications to several questions in quantum theory and cosmology. Other aspects of the project will include a search for secular effects from quantum gravity fluctuations, that is, effects which can accumulate over the history of the universe. If such effects exist and can be detected, it would lead to significant insights. The project will also involve a search for laboratory experiments to detect such effects as negative energy and lightcone fluctuations in analog systems.
This project is expected to have a broader impact through possible benefits to other fields of science, to education, and to technology. The insights and techniques of this work may be useful outside of the specific subfields of physics being investigated. The project is expected to further education through the involvement of graduate students and of faculty at primarily teaching institutions. It should also produce examples which can be used to explain some of the concepts of quantum theory and relativity to students on a variety of educational levels. The results of some of the investigations in this project may be useful in other fields of physics, such as atomic physics and condensed matter physics, and might eventually have technological applications.
