According to a paper published in the journal Physical Review Letters, theoretical physicists at the University of California, Irvine (UCI) might have found the fifth fundamental force of the universe, a previously unknown subatomic particle.

The team got the inspiration from a 2015 research from the Hungarian Academy of Sciences. This study suggested the existence of “dark photons,” unknown dark matter, from which 85% of the universe is apparently created. The Hungarian experimental nuclear physicists uncovered “a radioactive decay anomaly,” which means there might exist a light particle that is thirty times heavier than an electron, according to the UCI News page.

Dark Matter has been a matter of intense study in modern physics since Albert Einstein spoke about in his theories of the universe. Image Credit: Gizmodo

Author Jonathan Feng claimed that if proven, the existence of this fifth force would be “revolutionary,” although the experimentalists have not been able to confirm this yet.

“For decades, we’ve known of four fundamental forces: gravitation, electromagnetism, and the strong and weak nuclear forces. 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,” said Jonathan Feng, professor of physics & astronomy, according to

The Research

What the UCI team did was to study the data collected by the Hungarian researchers, and analyze them alongside all other prior experiments, concluding that dark photons and matter particles are not a thing.

However, the experimentalists made a turn of the events and found that instead, all the data provide evidence of a fifth fundamental force, a “protophobic X boson,” that is supposed to act only with neutrons and electrons, as opposed to the other forces that interact with protons and electrons.

Timothy Tait, professor of physics & astronomy and co-author, stated the X just means “unknown”, and that the researchers have never observed another boson acting the same way before.

In April they published an initial draft of their foundings on the public arXiv online server, and on Friday they released a more definitive article on the same page.

More research is needed

Since the article is not conclusive, further experiments need to be done. According to Feng, the technology to study this fifth force has been available since the fifties, whoever, the boson’s interactions are “very feeble”.

Feng also said that now that scientists now “where to look,” various smaller labs can join the investigation to confirm the existence of the new force.

He also has stated he is hopeful that this fifth force may work in conjunction with the two nuclear forces, making one mega-fundamental force.

However, the ‘dark sector’ might still be real, composed of its forces and matter uniquely its own. “This dark sector force may manifest itself as this protophobic force we’re seeing as a result of the Hungarian experiment. In a broader sense, it fits in with our original research to understand the nature of dark matter” said Feng.

It is also believed the two sectors interact and “communicate” with each other through other “fundamental interactions.”

The four other forces: 

Weak Nuclear Force 

The existence of the W and Z bosons, generators of the weak nuclear force was not confirmed until 1983.

These bosons interact with each other, emitting and absorbing their forces, and with protons and neutrons, whose masses are way lighter than the bosons’ ones.

This is why the weak force is short-ranged because its field strength is lesser than the electromagnetic force and the strong nuclear force.

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Strong Nuclear Force

This force is the strongest one, hence its name. According to data, this force is approximately 1038 times stronger than gravitation, 137 times stronger than electromagnetism and a million times stronger than weak nuclear force. The strong nuclear force ensures the stability of ordinary matter, confining quarks

This fundamental force is significant since it maintains the balance of the ordinary matter, by confining quarks inside protons and neutrons.

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The primary force of gravity was coined by Isaac Newton in his law of universal gravitation, famously after an apple fell on his head.

The fundamental principle is that two bodies of mass are attracted to each other, through a gravitational-mathematical force.

This is what keeps the galaxies and its planets “together” (i.e. why the moon rotates around the Earth). This is true even for the smaller particles known, quarks, protons, and neutrons.

Gravity has an infinite range, although this range is thoroughly affected by distance, which is why is weaker against the strong nuclear force.

Gravity is also famously and most accurately studied in Einstein’s 1915 general theory of relativity, where he states that more than a “force,” the phenomenon is a consequence of a curvature in the space-time.

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The strong nuclear force may keep the stability of the ordinary matter, but is the fundamental force of electromagnetism what determines its form by determining its internal properties.

This force also led Einstein to develop his special relativity theory in 1905. Electrons are chained to atomic nuclei thanks to electromagnetism, governing the chemistry processes, which are a consequence of the electrons’ interaction with atoms.

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Sources: The University of California, Irvine