Scientists just revealed new findings from an experiment called Muon g-2 — designed to give answers to a strange discrepancy between theoretical predictions and real-tests and theoretical expectations from 20 years ago, according to a press release from the U.S. Department of Energy's Fermilab.
Following decades of speculation, an experiment showing an inexplicable discrepancy from the Standard Model was raised to a confidence level of 4.2 sigma — which means it has a 1 in 40,000 chance of being a statistical quirk — lending more strength to the worry that some unexplained particle or force may be responsible for the excess wobbling of muons not predicted by theoretical particle physics.
Fermilab's muon g-2 experiment revealed something weird happening to reality
"Today is an extraordinary day, long awaited not only by us but by the whole international physics community," said Graziano Venanzoni, a co-spokesperson for the Muon g-2 experiment, who is also a physicist at the Italian National Institute for Nuclear Physics, in a statement from the entity. "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."
The experiment involves particles called muons — which are much like electrons but 200 times the mass. Both electrons and muons have magnetic fields capable of revealing new and fundamental information about particle physics — and thus the universe itself. For decades, scientists have worked to build a viable theory in particle physics called the Standard Model — capable of explaining several of the forces and interactions that determine the motion and behavior of matter on the tiniest scales. But sometimes, gaps appear between the experimental findings and the Standard Model.
When scientists introduce muons to an external magnetic field, the internal magnet of muons begins to "wobble," for which the Standard Model accounts. But a 2001 experiment from the Department of Energy's (DOE) Brookhaven National Laboratory (BNL) proved that a muon's magnet wobbles a lot more than theory predicted — which hinted at the possibility of a new particle or force working behind the scenes and creating this unforeseen property.
For a long time, the BNL findings retained a margin of error of roughly three standards of deviation — called a "three-sigma" variation from the theoretical predictions. For a finding to qualify as a valid breakthrough, scientists look for a five-sigma level of deviation, which means the findings have a 1 in 3.5 million chance of stemming from an error, instead of a viable discovery.
Supercomputers help scientists probe the Standard Model for answers
The new BNL experiment serves as a double-confirmation, of the anomaly itself, and in raising the confidence level of the findings to 4.2 sigma — which means the odds of the discrepancy being a statistical error are roughly 1 in 40,000. While this isn't strong enough to completely validate the observation, since it didn't cross the five-sigma threshold, it does lend credence to the consensus that something strange and undiscovered is influencing the magnetic field of muons. Something beyond the Standard Model.
Another paper published in the journal Nature suggests the muon's magnetic behavior still works with the Standard Model — which would mean we don't need new physics to explain the excess wobbling. This study takes a different approach than Fermilab, basing theoretical calculations through supercomputers strewn about the European continent, instead of empirical results. Whether the answer lies in theory or in experimentation, both theories need more work to narrow down the facts of what the muon is up to, and how this affects our scientific grasp of the physical universe. This is why the Fermilab team stressed the early stage of their Muon g-2 experiment, with data of greater precision due to arrive in the coming years.
"So far we have analyzed less than 6% of the data that the experiment will eventually collect," said Co-Spokesperson Chris Polly of the BNL Muon g-2 experiment, in the statement from the DOE's Fermilab. "Although these first results are telling us that there is an intriguing difference with the Standard Model, we will learn much more in the next couple of years."
Particle physics is constantly evolving. But describing the profoundly tiny world of muons and electrons with statistically-vetted probabilities also makes our grasp of it a slow, methodical process. We've reached a level of the universe where empirical study is just as difficult as working the math — with the former requiring expensive machinery like CERN and Fermilab and the latter pushing into the realm of supercomputers. And the coming years will see us push even further beyond the ordinary world of human senses than most can imagine.
This was a breaking story and was regularly updated as new information became available.