Chris Choi (최민영)

I am a 1st-year PhD student studying Physics at Carnegie Mellon University, which I started in the fall of 2023. I graduated from CMU with a Bachelors in Physics, in the Astrophysics Track, and a minor in Math in 2024. I am currently advised by Prof. Tina Kahniashvili in the Mellon College of Science. I have worked with Prof. Roy A. Briere (CMU) on experimental particle physics during my undergrad in 2022, and I worked with Prof. Tina Kahniashvili from 2023 onward.

Background

I am originally from South Korea, and grew up in New York City. I grew up in an eastern neighborhood in Queens known as Bayside, and I attended Stuyvasant High School in Tribeca, Manhattan. My parents are from Jeollabuk-do, but I myself was born in Seoul. I like to think of myself as being from North Jeolla. I moved to the US less than a year after I was born, to Los Angeles, California, and then moved to NYC 5 years after that. I have been living in Pittsburgh, PA for the past 4 years, and will be living here for the foreseeable future. Although I love the bicycle trails here, my heart will forever belong to New York City. The diverse (vegan) food, the piers along the rivers, and beaches on Long Island, and the millions of things to do in the city, it is simply unmatched.

General Interests

I enjoy reading hard sci-fi novels and short stories, such as those by Greg Egan, Liu Cixin, Neal Stephenson, Ursula Le Guin, Issac Asimov, Olaf Stapledon. I also enjoy speculative fiction, especially Ted Chiang and CM Kosemen, and you can check out my Goodreads account. My favorite novel is Diaspora by Greg Egan, a must-read for anyone who calls themselves a theoretical physicist or a pure mathematician. I also enjoy recreationally cycling. I have a road bike that I love to ride around when I want to unwind from all the research and courses. My longest ride so far is about 51 mi, but I hope to do an imperial century soon. Remember to always wear a helmet! I also love listening to music, especially the genre of prog rock and prog metal. I really enjoy retro prog rock from Sweden, with bands such as Moon Safari, A.C.T., Kaipa, Karmakanic, The Flower Kings, and Brighteye Brison. I have a particular interest in long songs known as ‘epics’. You can read all about it in my blog post. I also enjoy consuming anime in my free time. I watch about 30 anime concurrently, a grab-bag of shows that currently are airing as well as shows from the past, and I have seen 548 according to myanimelist. I am also competitive speedcuber: mainly an all-rounder (which means I like to do every offical event in the World Cubing Association), but I particularly enjoy doing FTO (Face-Turning Octahedron) recently. I became 4th in the world over the summer of 2024, and I have been very active in the community and spreading the word about this wonderfully fun puzzle. I hope to help make it an official event. I also like to draw in my spare time. I first started drawing in the middle of my senior year of high school, and I have been doing it on and off since. I have a collection of artwork (mostly in the anime artstyle) on my art instagram.

Research Interests

My research explores how we can utilize the theory of gravitational waves to explore and constrain theoretical cosmology models, like alternatives to general relativity such as massive gravity. I also utilize multi-messenger astronomical data, particularly that of pulsar timing arrays, to gain information about the gravitational wave background, and potentially explain it with new theories of cosmology and gravity. In the recent past, my group used a time-dependent model of massive gravity, specifically one known as the minimal theory of massive gravity, to explain the stochastic gravitational wave background detected by NANOGrav in their 15-year dataset. There is a decent possibility that the source of the gravitational wave background is in some part due to some exotic cosmological origin, because the astrophysical explanation (supermassive black holes and neutron stars colliding) falls short of completely explaining the background. I am also interested in the ways gravitational waves can be altered by free-streaming neutrinos, something I investigated with my group years ago. We explored the possibility of establishing a particular damping amplitude and comparing the results with previous work. Currently, I am working on constraining the Hubble parameter with the time-dependent minimal theory of massive gravity, and potentially addressing the sigma-8 tension in cosmology with such a theory. My hopes are that the study of gravitational waves and these alternative theories can help bring us closer to figuring out the long-elusive Theory of Everything and understanding the nature of the graviton.