Matthew Heffernan

I am an AI Verification Engineer at Zoox, working as an Applied Scientist on AI verification for autonomous driving. My work focuses on quantitative modeling, large-scale scientific computing, and building reliable, high-performance statistical tools.

Previously, I completed my Ph.D. in Physics at McGill University, where I focused on quantification of the Quark-Gluon Plasma using statistical learning methods. During my PhD, I was an organizing committee member of the McGill Physics Hackathon and served as VP Communications of the McGill Graduate Association of Physics Students.

When I get the chance, I enjoy working on various side projects, marathon and ultrarunning, skating, and looking for opportunities to go hiking. I also played on one of the departmental intramural hockey teams, the Absolute Zeroes. I am also a violist, having performed as a soloist, member of a small ensemble, and of orchestras in both Scotland and the United States. This musical work involved the east coast premiere of a new work by Mark O’Connor: W&M’s Gallery Players present Elevations for String Orchestra by Mark O’Connor; First Movement.

Research

I earned my PhD in the Nuclear Theory group at McGill under the supervision of Charles Gale. We worked on uncertainty quantification and Bayesian inference using state-of-the-art numerical models of hot and dense strongly-interacting matter. Bayesian techniques are increasingly employed in heavy ion collisions and we provided the most realistic quantification of the properties of strongly-interacting matter with their corresponding uncertainty.

What is strongly-interacting matter? Strongly-interacting matter (also known as Quark-Gluon Plasma in our use) is a phase of matter where what normally makes up atomic nuclei has “melted”. This highly energetic phase of matter exhibits collective behavior, allowing it to be modeled as a relativistic fluid. It is possible to produce QGP at particle colliders by colliding atomic nuclei, such as two lead or gold nuclei together at speeds comparable to the speed of light. This is done at terrestrial colliders, such as the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven or the Large Hadron Collider (LHC) at CERN in Geneva.

I also worked on computational applications in low-energy nuclear systems and aspects of beyond Standard Model physics. This research explored if extra degrees of freedom were present in the immediately post-Big Bang universe. Limits on this exotic physics can be probed using Big Bang Nucleosynthesis, which is how elements were formed in the early universe. Computational tests of variation yield strict limits on variation of “fundamental” Standard Model constants.

I was supported during my PhD by a Canada Graduate Scholarship - Doctoral and a Postgraduate Scholarship - Doctoral from the Natural Sciences and Engineering Research Council of Canada (NSERC). I was also partially supported at McGill as a Graduate Teaching Assistant. I worked with Nikolas Provatas as a STEM Graduate Teaching Development Fellow, working to flip the classroom for McGill’s large Physics 102 course. This involved writing new and challenging questions for students to solve, providing clear solutions, and recording select problem solutions. Some of these are available as worked solutions on the course YouTube page.

Research Experience

Graduate Research Assistant - McGill University (2016-2022)
Quantified the properties of quark-gluon plasma using state-of-the-art physical models with Bayesian inference for the first time. My work focused on using the best available models of heavy ion collisions, combined with methodological improvements to the Bayesian inference used in the field. Additional time was spent as a member of the JETSCAPE Collaboration’s Simulations and Distributed Computing Working Group.

Undergraduate Student Researcher - The College of William & Mary (2013-2016)
Undergraduate honors thesis using computational methods (Python, Fortran) to probe Big Bang Nucleosynthesis for limits on Beyond Standard Model physics. This work was performed under the direction of Andre Walker-Loud.

Stirling Cycle Analyst for Nuclear Space Power Applications - NASA Glenn Research Center (2015)
LERCIP Intern with the Thermal Energy Conversion Branch working to improve model fidelity and performing simulations for the Test Demonstration Unit (TDU) for the pre-testing Test Readiness Review. Additional work was done to optimize Stirling engines to map power density-efficiency space and customize the piston-displacer waveform. Future applications of this work include deep space and space exploration applications as passive power units

REU Student - Texas A&M University and Cyclotron Institute (2014)
National Science Foundation (US)-funded studentship under Ralf Rapp resulting in a state-of-the-art parametrization of thermal photon production in hadronic matter.