RUI: Impact of Negative Energy in General Relativity and Quantum Field Theory

Central Connecticut State University, New Britain CT

Investigators

Abstract

This award supports a research project to study the implications of a very unusual form of energy. The existence of this so-called ``negative energy'' is allowed by the laws of quantum field theory, which describe the behavior of matter and energy on microscopic scales. Negative energy would also have repulsive gravitational effects. Situations involving negative energy, such as the Casimir effect and squeezed states of light, have been produced in the laboratory. However, the amounts of negative energy generated in these experiments are extremely tiny and hence not directly measurable. However, if the laws of physics impose no constraints on negative energy, then one might be able to create large amounts of it and thereby produce bizarre macroscopic effects. Such effects could include: traversable wormholes (tunnels connecting otherwise distant regions of space and time), warp drives (for faster-than-light travel), time machines for travel into the past, violations of the second law of thermodynamics (e.g., refrigerators requiring no power sources), and the destruction of black holes (the remains of collapsed dead stars). However, research by L. Ford (Tufts U.) and the PI over more than a decade has shown that quantum field theory does impose some rather strong restrictions on negative energy. These constraints have come to be known as ``quantum inequalities,'' and yield severe limitations on the possible macroscopic effects mentioned above because they imply that large negative energies can exist for only short periods of time. The theoretical results obtained to date indicate that negative energy must be subtly intertwined with positive energy in space. An unanswered question is to what extent this must be true in general. Part of the research will be focused on narrowing the gap between distributions of negative energy which can be ruled out and those which are definitely allowed. The primary emphasis will be on a study of quantum states which involve negative energy and which can be produced using the techniques of quantum optics. A related, but smaller, part of the research will aim to study the connections between negative energy, energy conservation, and the evaporation and possible destruction of black holes. This work lies at the intersection of, and deeply impacts, three important areas of physics: quantum field theory, Einstein's theory of gravity (general relativity), and thermodynamics. A primary goal of this research is to establish closer ties between this work on negative energy and the rapidly growing field of quantum optics. Such a link between these two areas of physics might allow experimental tests of at least the indirect effects of negative energy. The last ten years have seen the growth of a small but very active international group of researchers on the subject of negative energy. It is planned to involve undergraduates in this project.