"My driving impulse: understand the origin of spacetime and the particles that populate it."
How did spacetime and its contents get to be the way it is today?My dual interest in ideas from across physics and astronomy has lead me on an unusual professional trajectory, earning one degree in Physics and Astronomy and Astrophysics (AB, Harvard), one in Astronomy and Astrophysics (MSc, Santa Cruz), and one in Physics (PhD, Waterloo/Perimeter). I have no regrets about being one of the few people to pass a qualifying exam in both physics and astronomy graduate programs! I enjoy thinking broadly and borrowing ideas from across physics to address fascinating problems across the cosmic timeline. In August 2016, I became Principal Investigator on an FQXi Large Grant, Epistemological Schemata of Astro | Physics: A Reconstruction of Observers. In relation, I maintain a Decolonising Science Reading List.
For a quick overview of what science I've worked on, check out my descriptions below. A version of my constantly evolving Curriculum Vitae is available, and my publications are listed in the ADS database.
Dark matter & AXIONS
What is the dark matter? This is one of the biggest questions in physics. It turns out that most of the matter in the Universe isn't the every day stuff that Earth is made of. Rather, the amount of matter that we can count based on collecting light in telescopes does not match with our calculations of how much should be there. As a result, we believe that there is something called the dark matter making up the majority of matter -- over 80% -- in the universe.
Over the years, theoretical physicists have suggested many candidates for the dark matter. One such candidate is the hypothetical axion, which is a particle that helps to resolve a completely separate problem in particle physics. This is one reason the axion is such a great candidate: it's a twofer!
Most recently, my research into the axion has focused on whether it forms an exotic matter phase called a Bose-Einstein condensate, where a large number of axions would act as if they were one particle, like a hive mind. Whether axions form this matter state or not could have implications for how galaxies and ultimately every structure in the universe was formed.
My curiosity about axions has lead to ongoing collaborations with people who have diverse areas of expertise, including Dr. Julie Dumas (galaxy formation expert), Professor Reneé Hložek (cosmologist), and Professor Kay Kirkpatrick (mathematician). In addition, I have joined the Science Working Group of the NASA STROBE-X Probe (which is in the Concept Study phase), where I am leading axion search/constraint efforts.
Why is the universe so big but essentially the same everywhere? This important question is likely addressed by a phenomenon called inflation where, when the universe was just a fraction of a second old, spacetime expanded faster than the speed of light. This does not violate the universal speed limit because that limit only applies to the contents of spacetime, not spacetime itself. Although we have a general understanding of inflation, the exact nature of the equations that describe it remain elusive. Further, we don't know much about what happened immediately afterward. This time period immediately after inflation is known as reheating, and some of my work focuses on models of this era.
The Edge of Quantum Field Theory
How do we do calculations which describe particle formation? Quantum Field Theory (QFT) is the mathematical framework that we use to describe all of particle physics. It evolved as the intersection of Einstein's special relativity, which describes matter when it is moving very fast, and quantum mechanics, which describes matter at microscopic scales. Together they describe particles, which are small and often moving fast. There is still much we don't understand about how to do QFT calculations, especially when we add in the wrinkle that spacetime is not always as it is described in special relativity, flat. Sometimes it is curved, and this leads to fun new phenomena, like the fact that it's not possible to define a region of space that has no particles. One of my areas of interest is helping to push the boundaries of what we can calculate.