Time: Wednesday 21 October 2015 – 3:00 for 3:30pm
Place: Science Lecture Theatre S3, 16 Rainforest Walk
The Nonlinear Dynamics of Curved Spacetime: From Computer Simulations to Advanced LIGO's Observations
Emeritus Professor Kip Thorne, Californian Institute of Technology,
How does curved, empty spacetime behave when excited into large-amplitude, nonlinear oscillations, like the ocean excited by a storm? John Wheeler posed this problem sixty years ago, calling it "geometrodynamics", but only recently have we had the tools to begin answering it: On the theoretical front, numerical relativity simulations; on the observational front, LIGO's gravitational-wave observations. The simulations reveal, for example, vortices of twisting space, attached to colliding black holes. When the holes' horizons merge, the two holes' vortices fight with each other, then throw each other off the merged hole and then embrace each other to create an expanding torus of twisting space, which becomes a gravitational wave that LIGO will detect. Kicking back at the hole, the departing torus creates weaker clones of the original vortices, which fight, eject, embrace, and generate a sequence of gravitational-wave tori. Advanced LIGO has recently embarked on its first observational search for these and other gravitational waves, and is likely to have success sometime between now and 2019. Thorne will describe the simulations and their predictions, and how LIGO will search for the waves and extract the rich information they carry.