William Detmold: Looking deep into atoms’ hearts

William Detmold, 40
MIT | Nuclear Physics
Graduate school: University of Adelaide, Australia 

William Detmold exposes matter at its most fundamental — with the help of some serious processing power.

The MIT theoretical physicist uses supercomputers to simulate how parcels of matter far too small to be seen through a microscope bind together to form the nuclei of atoms. His research complements findings from particle physics facilities such as the Large Hadron Collider near Geneva. Detmold’s simulations could also point physicists toward undiscovered varieties of matter.

Detmold grew up in Adelaide, Australia, hooked on solving mathematical puzzles. Then he turned his attention to theoretical physics. He happened to be pursuing his Ph.D. at a time when physicists were relying on heavy doses of math to work through a key puzzle: understanding the makeup of atoms.

High school textbooks depict the nucleus of an atom as a simple repository for protons and neutrons. But protons and neutrons are composed of even smaller particles called quarks, which are held together by force-carrying particles called gluons. A complex set of equations within the theory of quantum chromodynamics, or QCD, describes how quarks and gluons interact. By the mid-2000s, supercomputers had finally attained enough processing power to simulate the activity of quarks and gluons within a tiny three-dimensional space over time. Physicists ran these “lattice QCD” simulations to study the structure of two-quark particles called mesons and three-quark particles such as protons.

Now Detmold is leading the charge to extend the usefulness of lattice QCD to larger chunks of matter. In a study published last year in Physical Review Letters, Detmold and colleagues simulate­­­d the quark-gluon interactions for hydrogen and helium nuclei. Similar calculations could reveal properties, such as the nuclei’s intrinsic magnetism, that are difficult to measure experimentally. Any discrepancy between the computers’ output and experimental measurements could signal the existence of new particles or forces.

Detmold has also explored the fundamental structure of matter not yet seen. In a pair of studies published last year in Physical Review D, he and colleagues used lattice QCD to show how particles that don’t interact with ordinary matter could form “dark nuclei.” These mysterious nuclei could help explain dark matter, which makes up most of the universe’s mass. “I’m interested in describing stuff we know is there,” Detmold says, “but also using those same tools to look beyond.”