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Yi-Zen Chu

I am a postdoctoral fellow in the high energy group and in the Center for Particle Cosmology.  I am interested in gravitational physics, cosmology, quantum and classical field theory, and particle physics.  I have worked on  the (weak field) n body problem in General Relativity using field theory based methods; this may be of increasing importance as we push our tests of gravity to ever higher levels of sensitivity. Currently I am looking at modifications to the n body gravitational dynamics arising from a class of scalar field theories known as Galileons. I am also actively trying to understand -- from first principles -- how light propagates over cosmological distances. This is crucial, in this data driven era of the discipline, to ensuring that we are interpreting cosmological observations accurately. In particular, light in the perturbed spatially flat FLRW universe we live in does not solely travel on null geodesics, but also travel at all speeds less than unity. To my knowledge, this latter "off-the-null-cone" piece of light has never been examined before in the literature. Other pursuits I am involved in include: (with Tanmay Vachaspati) the calculation of the rate of quantum scattering of cosmic microwave background photons and neutrinos off cosmic strings in motion, i.e. the cosmic 'gravitational Aharonov-Bohm effect'.