New evidence suggests a fifth force of nature exists

8 Apr 2021

Muon g-2 magnet. Image: Fermilab

New evidence suggests a tiny subatomic particle could break the known laws of physics, hinting at the existence of a fifth force of nature.

From walking down the road to launching a rocket into space, there are four known forces of nature that are constantly at work in the world.

But new evidence suggests the existence of a fifth force of nature, which could open a whole new understanding of the laws of physics.

The forces currently known to scientists are gravity, electromagnetism, the weak force and the strong force. But a new experiment with fundamental particles known as muons suggests there may be forms of matter and energy vital to the nature and evolution of the cosmos that are not yet known to science.

The findings come from physicists at Fermilab, the US Department of Energy Office’s national laboratory.

‘This is our Mars rover landing moment’

Muons are similar to electrons in that they act as if they have a tiny internal magnet and occur naturally when cosmic rays strike Earth’s atmosphere.

In the Muon g-2 experiment, the scientists exposed muons to an intense magnetic field by sending them around a 50-foot-diameter magnetised ring at Fermilab. When doing this, the team found the muons wobbled in unpredictable ways, defying the fundamental theory of how particles interact.

“This is strong evidence that the muon is sensitive to something that is not in our best theory,” said Renee Fatemi, a physicist at the University of Kentucky and the simulations manager for the Muon g-2 experiment.

The Fermilab experiment builds on a previous experiment at Brookhaven National Laboratory around 20 years ago.

The Brookhaven experiment had hinted that the muon’s behaviour disagreed with the standard model of particle physics. Fermilab’s experiment strongly agrees with the value found in the original experiment and diverges from theory with the most precise measurement to date.

“After the 20 years that have passed since the Brookhaven experiment ended, it is so gratifying to finally be resolving this mystery,” said Fermilab’s Chris Polly. “This is our Mars rover landing moment.”

The results of the experiment are to be published in a set of papers submitted to several peer-reviewed journals.

Elsewhere, there have been other experiments hinting at a new kind of physics. Last month, scientists at the Large Hadron Collider near Geneva found unstable particles that fail to decay as the standard model suggests.

Jenny Darmody is the editor of Silicon Republic