MIT Physicist Jessica Fry on the Hunt for Dark Matter Axions

A Quiet Hunt for an Invisible Particle

In a basement laboratory at the Massachusetts Institute of Technology, physicist Jessica Fry is chasing one of the most elusive quarry in modern science: the axion. This hypothetical particle, first proposed in the 1970s, is a leading candidate for dark matter — the invisible substance that makes up about 27% of the universe yet has never been directly observed.

Fry's work is part of a broader global effort to detect axions, which if found would not only solve the dark matter puzzle but also answer fundamental questions about the forces that shape our cosmos. Her team's approach involves an experiment that can fit on a tabletop, a stark contrast to the massive particle accelerators used in other searches.

Why Axions Could Explain Dark Matter

Dark matter is inferred from its gravitational effects on galaxies and galaxy clusters. It does not emit, absorb, or reflect light, making it invisible to conventional telescopes. For decades, physicists have proposed various particles to explain it, and the axion has emerged as a strong contender.

The axion was originally theorised to solve a separate puzzle in particle physics — the strong CP problem — but it was quickly realised that axions, if they exist, could have been produced in abundance in the early universe. That makes them a natural dark matter candidate, and their properties could also help explain why the universe is made of matter rather than antimatter.

The Experiment: Listening for a Whisper

Fry's experiment is designed to detect axions by looking for their conversion into photons in a strong magnetic field. This process, known as the Primakoff effect, would produce a faint microwave signal that is almost indistinguishable from noise. To capture it, the team uses superconducting quantum sensors that are extremely sensitive to single particles of light.

One of the key challenges is background noise. The detectors must be cooled to temperatures just above absolute zero, and the entire apparatus is shielded from stray electromagnetic signals. The experiment runs for months at a time, collecting data in the hope of catching a rare blip that matches the predicted axion signal.

Speaking about the project, Fry noted that the search is as much about ruling out possibilities as it is about finding the particle. Every null result narrows the parameter space, helping theorists refine their models.

A Long Road Ahead

Despite decades of searching, no experiment has yet detected an axion. But the field has seen a resurgence in recent years, driven by advances in quantum sensing and cryogenic technology. New experiments in the United States, Europe, and Asia are all vying to be the first to spot the particle.

Fry's work is part of this wave, and the MIT team is optimistic that the sensitivity of their detectors will give them an edge. However, the search remains a long shot. The axion's mass, if it exists, is not known precisely, so experiments must scan a wide range of frequencies.

The team is currently in a data-taking phase, and they plan to expand the search to new frequency ranges in the coming months. While no signal has emerged yet, Fry emphasised that the journey is as important as the destination. Every experiment that probes the unknown adds a piece to the puzzle, even if it ends in a null result.

For now, the hunt continues. If the axion is found, it would be a discovery on par with the Higgs boson, unlocking a new frontier in physics. If not, it will further constrain the possibilities, guiding future searches. Either way, the quiet work in that basement lab is helping to answer one of the biggest questions in science: what is the universe made of?

What to Watch

In the coming year, Fry and her colleagues plan to release their latest results. The broader axion community is also watching several other experiments that are reaching similar sensitivity levels. A confirmed detection would be a historic moment, but even a null result will sharpen the search for dark matter.