Gravitational waves were detected for the first time by the US-based LIGO observatory on Sept. 14, 2015. This terrific news was announced this morning, Feb. 11, 2016.
The detection of gravitational waves is a mind-boggling achievement, one that will open up a whole new era of "gravitational wave astronomy". From Galileo's first telescope to the current space-age ones, we have peered into our Universe only with the light of the electromagnetic spectrum (radio waves, microwave, infrared, visible light, ultraviolet, x-ray, and gamma rays). Gravitational waves are ripples in the very fabric of spacetime that emanate from the most violent and dynamic events known in astronomy. The gravitational waves detected by LIGO on Sept. 14, 2015 traveled to us from the inspiral and collision of two black holes (each one of which is 30 times more massive than our Sun), over 1 billion years ago. The extremely warped spacetime around the black holes is dragged around as the black holes move and collide, and the resulting gravitational waves propagate outward, like the ripples in a pond after you drop a pebble in it. These gravitational waves stretch and squeeze the space that they pass through, and the signal which we measure on Earth carries the very signature of the event itself. Of course, these waves would be cataclysmic for anyone close to the colliding black holes, but by the time they reach the Earth (in this case, 1 billion years), the perturbation in space that needs to be measured in less than approximately 1/1000 the diameter of a proton. That this measurement was performed and characterized is a colossal achievement on three levels: engineering, data analysis, and numerical relativity. For my part, I have had the privilege and blessing to be able to contribute (in my small way) to the last category.
If you are interested in learning more about this, I recommend the following websites:
As a physicist, my goal is to realize at least a glimpse of the most extreme known regions of space-time distortion: the collision and merging of binary black holes in our Universe. I am doing this by trying to understand (with math) and simulate (with computers) the gravitational wave signals which are produced by these events. As part of the Gravitational Wave Astronomy group at the University of Washington Bothell, and the SimulatingeXtremeSpacetimes collaboration (via Caltech), my aim is to contribute to the detection and interpretation of gravitational waves from the LIGO observatory and the proposed LISA spacecraft.
Some recent / current projects:
1. The implementation of absorbing boundary conditions for binary black hole simulations in SpEC. This would create highly accurate computer-generated waveforms which would in turn lead to a better understanding of the black hole collisions from whence the signals come.
2. The simulation of binary black holes on hyperboloidal slices which extend to future null infinity, where the gravitational waves can be determined unambiguously. If successful, this would give the most accurate waveforms. In addition, these computer simulations would be more efficient than those currently performed. The first part of this work has been to understand how to construct binary black hole initial data on such slices. H. Pfeiffer, J. Bardeen and I addressed this question in Black Hole Initial Data on Hyperboloidal Slices. The top diagram on the right shows two spinning boosted unequal mass black holes on a hyperboloidal slice to future null infinity. J. Bardeen and I wrote a follow-up paper entitled Bondi-Sachs Energy-Momentum for the Constant Mean Curvature Initial Value Problem, in which we compute the Bondi energy, linear momentum, and angular momentum on these slices -- all quantities necessary for initial data construction. The second part of this project is to evolve the binary black hole initial data constructed. J. Bardeen, O. Sarbach and I wrote a theoretical proposal using a 3+1 tetrad formulation of the Einstein equations on constant mean curvature slices, Tetrad formalism for numerical relativity on conformally compactified constant mean curvature hypersurfaces. I owe much gratitude to Frank Estabrook (Jet Propulsion Laboratory), who first introduced me to the non-conformally rescaled version of this formalism, and who continues to inspire my efforts.
In addition to my research, I have had the pleasure of teaching Special and General Relativity to several students. In 2009, I taught high school students Colin Rice (in picture to right) and Griffin Nicoll. Penrose diagrams they computed using Mathematica are also shown on the right side panel. From 2020 - 2021, during my time at the University of Washington, Bothell, I taught Special and General relativity to Tim Kostersitz and Andrew Evans in addition to supervising their research. Here are links to my Faculty Page and Research Summary Page at the University of Washington, Bothell.