Testing Gravity with Hi-COLA Simulations of Large-Scale Structure

In 1999 Einstein's untouchable theory was thrown into doubt by observations of exploding stars: supernovae. These indicated that the expansion rate of the universe is accelerating, and this feature cannot be simultaneously reconciled with both General Relativity and quantum theory. An intriguing alternative is that Einstein's theory is not the last word in gravity. Could it be that gravity -- one of the fundamental forces of nature -- behaves differently on the largest distances in the cosmos than it does on the scale of humans and planets? I was drawn to this question by the immense repercussions that the answer `yes' would have. As the dominant force sculpting the universe, a flaw in our understanding of gravity would cause essentially every textbook on physics to be rewritten.

My work aims to answer this question by building computer simulations and mathematical tools that connect the latest developments in theoretical physics with the observations from astronomical telescopes. I can predict, for example, how the distribution of galaxies in the universe would change, if gravity behaves differently from General Relativity. My work also allows us to use the first detections of gravitational waves -- an experimental reality since only 2015 -- which may hold the key to proving Einstein right or wrong.