Research on Gravitation and Quantum Fluctuation Phenomena

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This project will involve theoretical studies of several topics relating to quantum fluctuations and gravitation. Particular attention will be paid to issues relating to the correlation and anti-correlation of fluctuations of the quantum stress tensor that describes, among other things, the local energy density in a quantum field. The topics to be investigated include the effects of quantum stress tensor fluctuation in cosmology, especially in inflationary models. Previous work by the PI and his collaborators has indicated that these effects may be able to slowly accumulate, and thereby have a potentially significant role in the evolution of the universe. This possibility will be further studied. A closely related topic is the search for the probability distribution for stress tensor fluctuations, which is of interest in inflationary models, including ones which explore the possibility of a "multiverse" much larger than the observable universe. Other aspects of this project will seek to propose new laboratory experiments looking for negative energy density and related "sub-vacuum" phenomena, where some quantity fluctuates below its usual value in empty space. The project will examine selected aspects of the Casimir force, especially its fluctuations, and of fluctuations in condensed matter systems. These topics are of interest both for their own sake, and as analog models to better understand quantum effects in gravity theory. 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 will further education through the training of graduate students and by the involvement 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 work on Casimir forces may eventually be useful in nanotechnology. A better knowledge of Casimir forces is likely to become important for the construction of small scale devices. Similarly, the study of quantum correlations in this project may have applications to quantum information and quantum computing.