Apr 7, 2021 - Science

So much depends on the wobble of a muon

The Muon g-2 ring, at the Fermi National Accelerator Laboratory in Batavia, Illinois. Photo: Reidar Hahn/Fermilab, via U.S. Department of Energy

The Muon g-2 ring, at the Fermi National Accelerator Laboratory in Batavia, Illinois. Photo: Reidar Hahn/Fermilab, via U.S. Department of Energy

The results of high-energy physics experiments released on Wednesday open the possibility that a tiny subatomic particle called a muon may act in ways that break the known laws of physics.

The big picture: The experimental work — while still far from conclusive — underscores the fact that science still has much to learn about the fundamental workings of the universe, and it points the way toward further breakthroughs.

Driving the news: In a news conference and virtual seminar on Wednesday, as well as a set of papers published the same day, scientists announced the first results of the Muon g-2 experiments being carried out at the Fermi National Accelerator Laboratory, or Fermilab.

  • Muons are subatomic particles similar to electrons but possess 207 times as much mass — hence the rather unflattering nickname "fat electrons."
  • The particles — which have puzzled scientists since they were first discovered in 1936 — are produced in large amounts during collider experiments at places like Fermilab that involve smashing particles together at high speeds.

What they found: When the muons were sent through intense magnetic fields at Fermilab's Muon g-2 ring, they behaved in ways that didn't quite line up with theoretical predictions, wobbling more than expected.

  • Anytime nature throws us a curveball, scientists take notice, and the fact that the Fermilab experiments lined up with similar work at Brookhaven National Laboratory in 2001, which has long puzzled researchers, is notable.
  • The experiments suggest the Standard Model — physics' fundamental theory about how particles interact with each other — may be far from complete.

The catch: The scientists behind the experiments reported that the results had a 1 in 40,000 chance of being a fluke — pretty good, but still short of the certainty required to claim an official discovery in physics.

The bottom line: Wednesday's results represent just 6% of the data ultimately expected to come from the Fermilab muon experiments in the years to come, which means plenty more time for new revelations — and plenty more work for high-energy particle physicists.

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