These waves can be generated by acceleration of mass, but matters of our everyday experience generate negligible amount of these waves. The most detectable of gravitational waves are believed (by most) to be those generated by motions of large amount of matter in the distant universe, for example the mergers of binary compact stars (neutron stars, black holes, etc.), the rotation/wobbling of asymmetric pulsars, the explosions that take place at the death of massive stars, and oscillations of matter at the early universe. Even for the most detectable waves, their effects are still extremely weak. Current gravitational wave detectors (e.g., LIGO) are sensitive to relative motions of 10

^{-20}meters at around 100Hz, of two 40 kg test masses separated by 4 kilometers.

Because gravitational waves are weak, and because they are generated by exotic objects and processes, gravitational wave research really involves many disciplines of physics. I’ve worked on several different aspects.

### Gravitational-wave detectors

1. Application of Quantum Measurement Theory to Laser Interferometer Gravitational-wave Detectors.

2. Using Gravitational-wave Detectors to Study Quantum Mechnical Behavior of kg-scale Test Masses.

3. Novel Approaches to Gravitational-wave Detection: designing detectors that are not subject to “displacement noise”, i.e., noisy motions of test masses.

4. Applications of classical physics to LIGO instrument, for example: designs of optical cavities with non-spherical mirrors; studing how diffractive gratings can be used in gravitational-wave detectors; understanding thermal fluctuations in multi-layer dielectric coatings.

### Gravitational-wave sources and general relativity

5. Using analytical tools (post-Newtonian expansion, black-hole perturbation theory, formalism of pseudotensors, etc.) to understand numerical simulations of highly non-linear spacetimes, e.g., binary black hole mergers.

### Strategies for analyzing gravitational-wave data

6. Building theoretical templates for compact binary inspirals, and strategies for searching over them quickly.7. Constructing algorithms that allows LIGO to search for low-mass binary inspirals in real time.