Welcome to this week’s installment of The Intelligence Brief. In this edition, we’ll be devoting special attention to the Muon g-2 experiment, and of particular significance is 1) whether this represents a breakthrough in our understanding of physics, and what that could mean, 2) why this research has been decades in the making, and 3) what the curious relationship between muons, a kind of “cousin” to the electron, and magnetic fields might tell us about strange, little-understood phenomena in physics.
A pair of experiments are leading physicists to believe that our fundamental understanding of how the universe works may be flawed, according to research conducted in the United States and Europe.
The experiments are strongly suggestive of the existence of undiscovered particles or forces, in research lead by the United States Department of Energy’s Argonne National Laboratory and the Fermi National Accelerator Laboratory with collaboration from an international team of 46 other institutions.
“This new physics could help explain long-standing scientific mysteries, and the new insight adds to a storehouse of information that scientists can tap into when modeling our universe and developing new technologies,” PhysOrg reports.
The experiments are a continuation of research that began decades ago at the Department of Energy’s (DOE) Brookhaven National Laboratory involving the muon, a variety of unstable subatomic particle similar to electrons, but possessing significantly greater mass. Physicists recognize muons as representing a large portion of the cosmic radiation that makes its way to our planet.
Muon g-2: A Disturbance in the Force
In the 1990s, the experiments at Brookhaven measured magnetic properties of the muon, and found that the measurements differed significantly from that predicted by the Standard Model of physics. Muons possess a property identified as their g-factor, which according to the Standard Model, says they should behave a certain way when in the presence of a magnetic field. In the Brookhaven study, a slight difference of just a few parts per million was detected in the behavior of muons under such circumstances, which physicists interpreted as representing an unknown interaction occurring between muons and magnetic fields.
One interpretation at the time had been that the anomalous interactions between muons and magnetic fields might be explained by the presence of mysterious new particles, or possibly even entirely new forces. A disturbance in the force, indeed.
The experiments were dubbed Muon g-2 (which physicists express as Muon “g minus two”) on account of their aim to measure the muon’s deviation from their known value of two. Fundamentally, physicists aim to either confirm the deviations observed in the experiments that took place in the 1990s or refute them.
Presently, the new results appear to confirm the earlier Brookhaven studies, and although the measurable deviations were slightly less than that required by scientists to be able to claim a discovery, they are still significant, and very unlikely to represent a statistical fluctuation. If the results do end up representing new and little understood areas of physics, scientists believe such discoveries could help us pin down longstanding mysteries that include dark matter, which remains undetected by physicists, though believed to exist throughout the universe.
“Today is an extraordinary day, long awaited not only by us but by the whole international physics community,” spokesman Graziano Venanzoni was quoted saying in a news release at the Fermilab website. “A large amount of credit goes to our young researchers who, with their talent, ideas and enthusiasm, have allowed us to achieve this incredible result.” Venanzoni is a physicist at the Italian National Institute for Nuclear Physics and co-spokesman of the Muon g-2 experiment.
Muons and Magnets
As the muons circulate in the Muon g-2 magnet, they also interact with a quantum foam of subatomic particles popping in and out of existence,” said a news release from Fermilab providing additional details on the experiment. “Interactions with these short-lived particles affect the value of the g-factor, causing the muons’ precession to speed up or slow down very slightly.”
“The Standard Model predicts this so-called anomalous magnetic moment extremely precisely,” the news release said. “But if the quantum foam contains additional forces or particles not accounted for by the Standard Model, that would tweak the muon g-factor further.”
“The secrets don’t just live in matter. They live in something that seems to fill in all of space and time,” says David Kaplan, a Johns Hopkins University theoretical physicist.
“These are quantum fields. We’re putting energy into the vacuum and seeing what comes out.”
“This is something wrong,” Kaplan said, adding that the results have the potential to throw out previous calculations related to the world of particle physics, adding that the physicists checked in every way that they could to ascertain whether there was simply an error involving equipment or other factors on the more human side of this mysterious equation.
“This is an exciting time for particle physics research, and Fermilab is at the forefront,” Fermilab Deputy Director of Research Joe Lykken said, adding that the ability for scientists to successfully pin down the subtleties of the behavior of muons may be the game-changing event in modern physics that will propel research beyond the Standard Model toward new horizons in our understanding of the mechanics of the universe.