I am a Distinguished Scientist in the Scientific Computing and Theoretical Physics Groups at Oak Ridge National Laboratory and I currently serve as the Director of Science for the Oak Ridge Leadership Computing Facility. I am also a Joint Faculty Professor in the Department of Physics & Astronomy at the University of Tennessee.
I have spent a lot of time learning about, using, helping to build, programming, and otherwise finding excuses to be around many of the world’s biggest computers over the past 25 years or so. A lot of this effort has been dedicated to using these machines to study the death of stars and the formation of compact objects like neutron stars and black holes.

Fellow, American Physical Society (2025)
Member – American Physical Society Committee on Informing the Public (2018–2020)
Technical Papers Committee – ACM/IEEE Supercomputing Conference (SC16, SC17, SC18, SC19, SC22, SC24, SC25)
Co-Chair – Nuclear Astrophysics, ASCR-NP Exascale Requirements Review (2016)
Working Group Organizer – Astrophysics Theory and Computing, Division of Nuclear Physics Town Meeting on Nuclear Astrophysics (2014)
PhD in Physics, 2000
University of Tennessee
BS in Physics, 1991
University of Tennessee
ExaStar was a collaboration between Berkeley Lab, Oak Ridge Lab, Argonne Lab, and Stony Brook University, and was an application development project within the DOE Exascale Computing Project.
CHIMERA is our multi-dimensional core-collapse supernova code, capable of tracking the evolution of these systems from the pre-collapse stellar stage to up to a second of evolution time after the core bounce.
Toward Exascale Astrophysics of Mergers and Supernovae: This SciDAC project aims to study the sites of R-process nucleosynthesis using realistic simualtions of core-collapse supernovae and neutron star mergers.
A collaborative effort of application development teams and staff from the OLCF Scientific Computing group, CAAR is focused on redesigning, porting, and optimizing application codes for Frontier’s hybrid CPU–GPU architecture.