Theoretical research is being carried out in two areas related to gravitational waves and their detection. The first area is the invention of new techniques and technology for advanced laser-interferometer gravitational-wave detectors. These advanced detectors will entail measuring the motions of 40 kilogram sapphire-crystal mirrors with an accuracy so high that the mirrors are governed by the laws of quantum mechanics and not the laws of classical physics. The new techniques and technology entail, among other things, new configurations of mirrors and laser beams designed to deal with quantum effects that are absent in current gravitational-wave detectors, changes in how the laser light is manipulated after it leaves the interferometer, and a reshaping of the cross sections of the interferometer's light beams. The second area of research is the theoretical modeling of astrophysical sources of gravitational waves with the goal of predicting the sources' dynamical behaviors and the details of the waves they emit. Among the sources being modeled are oscillations of rapidly spinning, newborn neutron stars, the spins of neutron stars that are accreting gas from companion stars (``Low-Mass X-Ray Binaries''), the late, highly relativistic phase of inspiral of black-hole/black-hole and black-hole/neutron-star binaries, collisions of black holes, and the tearing apart of a neutron star by a black hole.
The research on new techniques and technology for gravitational-wave detectors is a key underpinning for the advanced detectors that are being proposed for construction in LIGO (the Laser Interferometer Gravitational Wave Observatory) beginning in 2006, and for even more advanced detectors in the subsequent decade. This research makes use of, and contributes to, human knowledge in the area of quantum information theory --- a new, 21st century discipline that also includes quantum computation. This research is likely to have much impact on areas of technology that---in the coming two or three decades---will confront quantum limits on the accuracy of measurement and will try to evade them via ``quantum nondemolition'' (QND) techniques. These areas of technology include quantum optics and nanotechnology. The research on sources of gravitational waves will provide key underpinnings for analyses of the gravitational-wave data to be produced by LIGO: It will improve the ability to find gravitational-wave signals in the noisy LIGO data, and it will provide tools for extracting astrophysical information from the discovered signals. Thus, this research will play a key role in future gravitational-wave-based studies of black holes, neutron stars, and their oscillations and collisions.
