Mysterious 'Particle X17' Could Carry a Newfound Fifth Force of Nature, But Most Experts Are Skeptical

abstract image of a particle
(Image credit: Shutterstock)

Our universe is governed by four fundamental forces. At least that's what physicists have long thought. 

Now, however, new research suggests that there's a fifth force, a discovery that could upend much of modern physics. 

On Oct. 23, researchers at the Institute of Nuclear Research in Hungary published a new study to the arXiv database offering further evidence of an entirely new particle first suggested three years ago. Dubbed X17, this particle might help scientists resolve one of the biggest mysteries in astronomy: what dark matter is.

The particle's existence would also require a rewriting of the Standard Model of particle physics, the theory that describes the fundamental forces and classifies subatomic particles. 

But that's only if the particle's existence can be verified. The new paper has not yet been peer reviewed. And most physicists are skeptical — in part because no outside scientists have yet been able to independently validate earlier findings from the same research team Richard Milner, physicist at the Massachusetts Institute of Technology who was not involved in the research, told Live Science.

In 2016, the same group of researchers reported the first evidence of the particle, in experiments done with radioactive beryllium atoms. The physicists measured the light and particles released by the beryllium as it broke down. They noticed that emitted pairs of electrons and their antimatter partners, positrons, tended to go speeding off at a certain angle, behavior that didn't seem explainable with existing physics. 

Crunching the numbers, the physicists concluded that there must be some unknown intermediate particle that the beryllium decayed into before that particle then emitted the electron and positron pair. This unknown "particle X" was calculated to have a mass of nearly 17 megaelectronvolts, hence its name, X17. (For comparison, that makes X17 about 34 times bigger than an electron.) 

The new study added more observations of the proposed particle, seen in the decay of helium atoms. A similar experimental setup again showed evidence of an intermediate particle with effectively the same mass. The findings show that this proposed X17 particle isn't a fermion — the type of particle that makes up ordinary matter — but rather a boson, a particle that carries energy and sometimes forces. This means that X17 might convey a previously unknown, fifth force, which the physicists said could help explain dark matter. That mysterious substance makes up 85% of the matter in the universe; it's detectable through gravity but doesn't interact with light. 

But most physicists are waiting for independent measurements before they accept the findings. 

"I'm skeptical. I think, as an experimentalist, that's my natural position when I see something like this, but I think it needs to be investigated," Milner, told Live Science. 

Part of the skepticism arises because the European Organization for Nuclear Research, or CERN, tried to hunt for the X17 particle and failed to find any evidence of it. In light of the new evidence, many more groups will likely continue to search for the particle, Milner told Live Science. 

If confirmed, the discovery could also open a whole new way of doing particle physics, Milner told Live Science. For the past half-century, physicists have made huge progress in defining the Standard Model by focusing on the high-energy realm, which requires huge international collaborations and expensive accelerators to smash particles together at mind-boggling speeds. The new work, done at much lower energies and costs, would be an entirely new direction for physicists to look for new particles. 

"The Standard Model of physics is very well defined," Milner told Live Science. "So if one finds a new interaction beyond it, that is just tremendously important."

Originally published on Live Science.

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Mara Johnson-Groh
Live Science Contributor

Mara Johnson-Groh is a contributing writer for Live Science. She writes about everything under the sun, and even things beyond it, for a variety of publications including Discover, Science News, Scientific American, Eos and more, and is also a science writer for NASA. Mara has a bachelor's degree in physics and Scandinavian studies from Gustavus Adolphus College in Minnesota and a master's degree in astronomy from the University of Victoria in Canada. 

  • rod
    Interesting, a possible fifth force. Some could argue that dark energy in cosmology is a fifth force or Einstein cosmological constant in GR equations. We have other particles in inflation theory in cosmology today like the inflaton and magnetic monopoles. Quantum mechanics is getting very interesting.
    Reply
  • Alexanderzi
    I could explain it for you. This fifth source Is actually first. We talking about very density compressed metal's, which has structure form like a straight line 1. Without any curves. So probably all cold dark matter at the Milky Way consist of the metal's, this explain why the metal's are cold it self, because metal's mean matter - the cold matter, which emission from the center of our galaxy. So every beginning from the matter, the matter are primary. So that's why our number 1 wrote like a thin stick, because this number repeating a physic of the center of the Milky Way, if you will look at our galaxy, you will notice that galaxy has thin stick form, so it is a cold world of 1K
    Reply
  • rod
    Alexanderzi said:
    I could explain it for you. This fifth source Is actually first. We talking about very density compressed metal's, which has structure form like a straight line 1. Without any curves. So probably all cold dark matter at the Milky Way consist of the metal's, this explain why the metal's are cold it self, because metal's mean matter - the cold matter, which emission from the center of our galaxy. So every beginning from the matter, the matter are primary. So that's why our number 1 wrote like a thin stick, because this number repeating a physic of the center of the Milky Way, if you will look at our galaxy, you will notice that galaxy has thin stick form, so it is a cold world of 1K

    Interesting. In your model of "How the Universe Works" described, is the Earth immovable in a geocentric universe or is the heliocentric solar system true, i.e. the Earth moves around the Sun?
    Reply
  • Alexanderzi
    rod said:
    Interesting. In your model of "How the Universe Works" described, is the Earth immovable in a geocentric universe or is the heliocentric solar system true, i.e. the Earth moves around the Sun?
    Yes I think that earth moves "around the sun", but this is not actually full round circle, because sun it self move too, so we are doing a circle behind sun, and following the sun. But this is not actually mean that it is a sun system. If you will look at the bathroom funnel where the water is leave, you will notice the same roundness funnel-shaped movement of the water, because this is the same physic of chemical deviing of the element's, another words - the sun is the last point of the energy fission, where hydrogen becoming very hot, and everything are heating and spreading to the space with lighting. It's death. So I think real picture of the sun system beginning in the Pluto, and slowly (by the planet's) this energy transforming to the another variables of the element's - like Neptune, Uran, Jupiter and more... So I think that sun system itself something like "frozen" picture of how the energy (slowly through milliards years) going decay. Probably Pluto could consist of the something similar of which consist dark matter - a very density metal's, Pluto (1) has many Nitrogen particles, than this become to the Hydrogen Neptune (2), than it become to the acid oxide's like at Uran (3), than this all coming to the Saturn (4) - you can even translate etymology of word Saturn - it mean Chaturn - chatur -mean four (Russian four), or just CH. So after that everything become to the middle of the worlds to the Jupiter (5), here are the center of the 2 worlds V, energy become great with pressure, after Jupiter everything going to the new cicle, the new circle appear after 5, the Mars (6) - must be with very high carbo-silica beds, finally coming to our world Earth (7) we are the center of this new circle of 5-9 of the two world's of good and evil, than Venus (8) which the same Neptune (2) , mercury (9), totally burnt and finally the end - sun. That's why ancient's egyptian's was pictured in the gravestone's many solary signs, because it mean heating and death. But you must know that this number's has a mirror system the 4 for instance repeating 2 , 5 repeating 1, than at the new cicle we have new overlay where the 6 repeating 1 too, and has another things in it, 6 consist of 2+2+2, or 3+3 but 6 - 1 itself. So that's why the life has carbon particles , because Carbon has numerical value 6. This probably like a mirror where 7 repeating 3 probably, 8 must repeat 2, but everything consist with the previous numbers. Actually this is very hard system where I couldn't figure it out completely, because this probably most harder thing in life - How everything are work by the specific law's.
    So I think that ancient knowing has the basis, this basis exist inside the number's , everything following this law's. Venus was the goddess of the love, Venus just repeating the Neptune actually , because Neptune Hydrogen 2, so that's why here 2=8 , 1-2 and 9-8, this is the mirror, which turned.
    Reply
  • Alexanderzi
    rod said:
    Interesting. In your model of "How the Universe Works" described, is the Earth immovable in a geocentric universe or is the heliocentric solar system true, i.e. the Earth moves around the Sun?
    The number system you could notice everything, with approve of my words, I could give some example. You know constellation Orion, this constellation in the belt has a 3 star's , so that's one of the reason why you must think that number 3 in our alphabet mean letter R, that's why oRion wrote with R letter. Some people's pictured Orion with the green colour's , it mean that the gReen colour explaining numerical value 3. So that's why I think that this constellation must consist of the very bright star's with great energizing , because there are all matter must be with oxide thing's , so Orion must have very magnitude star's with great energy , and it is. And they are could be with green colour , like a Uran for instance, because our Uran is greeny. And really look where Orion is standing, between two worlds, with the milky way, and little outside in the empty space, it is a something like a jew of the star's
    Reply
  • rod
    Alexanderzi said:
    The number system you could notice everything, with approve of my words, I could give some example. You know constellation Orion, this constellation in the belt has a 3 star's , so that's one of the reason why you must think that number 3 in our alphabet mean letter R, that's why oRion wrote with R letter. Some people's pictured Orion with the green colour's , it mean that the gReen colour explaining numerical value 3. So that's why I think that this constellation must consist of the very bright star's with great energizing , because there are all matter must be with oxide thing's , so Orion must have very magnitude star's with great energy , and it is. And they are could be with green colour , like a Uran for instance, because our Uran is greeny. And really look where Orion is standing, between two worlds, with the milky way, and little outside in the empty space, it is a something like a jew of the star's

    Okay, in your model for celestial motion - I am confused as to the model and terms you are using. Does your model for celestial motion use Kepler's planetary laws, the law of gravity? Does the model work with Jean Meeus, Astronomical Algorithms and can be used to make predictions of celestial events, e.g. the next Mercury transit visible?
    Reply
  • Alexanderzi
    rod said:
    Okay, in your model for celestial motion - I am confused as to the model and terms you are using. Does your model for celestial motion use Kepler's planetary laws, the law of gravity? Does the model work with Jean Meeus, Astronomical Algorithms and can be used to make predictions of celestial events, e.g. the next Mercury transit visible?
    Sorry, I don't tracking planet's transit in real time. Yes it is Kepler law's with Sun gravity, but this is not the way, it is a curving in the end, each planet rotate around a sun, the planet's just forced do it, because the sun itself is something like golden ratio of decay, with spiral motion. But you can notice that the Pluto has the different orbit with another angle, because pluto could be much denser than another planet's.
    Reply