Physicists have found more indications of a fifth fundamental force of nature.

Several studies over the last few years have hinted that the four established forces of nature are not all there is. 

Scientists have historically reduced the forces of the universe into the following four categories: gravity, electromagnetism, the strong force and the weak force.

But now, the UK's Science and Technology Facilities Council (STFC) says research carried out at a laboratory near Chicago “provides strong evidence for the existence of an undiscovered sub-atomic particle or new force”.

They say there is a one in 40,000 chance that the result could be a statistical fluke - putting the study at 4.1 sigma statistical level of confidence. 

Confidence of 5 sigma would be a one in 3.5 million chance of the observation being a coincidence. This is the level needed to claim a discovery of this type.

The researchers were studying the behaviour of sub-atomic particles called muons.

Muons are even smaller than atoms, a fundamental particle similar to the electron, but more than 200 times heavier.

The Muon g-2 experiment involves sending particles around a 14-metre ring into a magnetic field, which the Standard Model of physics should have made the muons wobble at a certain rate.

Instead, they wobbled at a faster rate than expected, potentially caused by a force of nature that is completely new to science.

Prof Mark Lancaster, the UK lead for the experiment, told reporters: “We have found the interaction of muons are not in agreement with the Standard Model [the current model to explain the building blocks of the Universe]”.

“Clearly, this is very exciting because it potentially points to a future with new laws of physics, new particles and a new force which we have not seen to date.”

It is unclear what this potential new force might do, other than influence muon particles. It has been speculated that the force may be associated with an as-yet undiscovered sub-atomic particle. 

Prof Ben Allanach from Cambridge University, who was not involved in the latest study, is very excited. 

“My Spidey sense is tingling and telling me that this is going to be real,” he told reporters.

“I have been looking all my career for forces and particles beyond what we know already, and this is it. This is the moment that I have been waiting for and I'm not getting a lot of sleep because I'm too excited.”