Fifth force of nature a strong possibility: Scientists

New York: We know four fundamental forces - gravitation, electromagnetism, and the strong and weak nuclear forces. Now, scientists have discovered what can be the fifth force of nature.

A previously unknown subatomic light particle may be evidence of a fifth fundamental force of nature and a key to understanding dark matter in universe, according to theoretical physicists at the University of California - Irvine (UCI), US.

"If true, it's revolutionary. If confirmed by further experiments, this discovery of a possible fifth force would completely change our understanding of the universe, with consequences for the unification of forces and dark matter,” explained Jonathan Feng, Professor of physics and astronomy.

The researchers came upon a mid-2015 study by experimental nuclear physicists at the Hungarian Academy of Sciences who were searching for "dark photons.”

These are particles that would signify unseen dark matter which, physicists say, makes up about 85 percent of the universe's mass. 

The Hungarians' work uncovered a radioactive decay anomaly that points to the existence of a light particle just 30 times heavier than an electron.

"The experimentalists weren't able to claim that it was a new force," Feng said. 

“They simply saw an excess of events that indicated a new particle, but it was not clear to them whether it was a matter particle or a force-carrying particle,” he added in a paper published in the journal Physical Review Letters. 

The UCI work demonstrates that instead of being a dark photon, the particle may be a “protophobic X boson.” 

While the normal electric force acts on electrons and protons, this newfound boson interacts only with electrons and neutrons - and at an extremely limited range. 

Like many scientific breakthroughs, this one opens entirely new fields of inquiry.

This potential fifth force might be joined to the electromagnetic and strong and weak nuclear forces as "manifestations of one grander, more fundamental force."

“In a broader sense, it fits in with our original research to understand the nature of dark matter,” the authors noted.