The Fifth Force of Nature Could Be Real and Fantastic

Caroline Delbert
Photo credit: zmeel - Getty Images
Photo credit: zmeel - Getty Images

From Popular Mechanics

  • Hungarian researchers have followed up a major 2016 observation with a second similar one, both suggesting a fifth force of nature and a new kind of subatomic particle.

  • The scientists used a radiation particle accelerator to blast helium nuclei in order to observe the explosion.

  • Their paper is awaiting peer review and will likely spark a new wave of research to help explain what they saw.

In 2016, Attila Krasznahorkay made news around the world when his team published its discovery of evidence of a fifth force of nature. Now, the scientists are making news again with a second observation of the same force, which may be the beginning of a unified fifth force theory. The researchers have made their original LaTeX paper available prior to acceptance by a peer-reviewed journal.

Study of the hypothesized fifth force, a subfield all by itself, is centered on trying to explain missing pieces in our understanding of physics, like dark matter, which could be expanded or validated by an important new discovery or piece of evidence. Scientists and specifically cosmologists are baffled by the amount of our universe made of dark matter and energy we can’t observe except in indirect ways and still don’t understand.

The scientists’ first observation in 2016 was of an isotope of beryllium, and their second is of an isotope of helium. Both observations involved circumstantial evidence of a force exerted by a new form of particle the researchers are calling X17 because of its energy potential of 17 megaelectronvolts. In 2016, the researchers wrote, “The deviation between the experimental and theoretical angular correlations is significant and can be described by assuming the creation and subsequent decay of a boson.” This new boson is the proposed X17 particle.

Krasznahorkay and his colleagues work from Hungary’s Atomki facility, where they used a Van de Graaff accelerator to observe beryllium in 2016 and helium in 2019. You may have seen a small, user-friendly Van de Graaff accelerator, or generator as it’s usually known, throwing off branching “lightning” or making your hair stand on end in your local science museum. The technology dates to the 1930s, subsumed by the cyclotron and later the synchrotron for some purposes, but still useful for many others.

The Van de Graaff shoots particles through a vacuum tube at super high speeds. Krasznahorkay’s team used the accelerator to watch isotopes decay, when the nucleus ruptures and particles generate light as they fly out. The scientists expected the flying particles to act a certain way because of the law of conservation of energy, but they observed a different behavior that couldn’t be explained by existing knowledge. They posit their new X17 particle as the reason for the anomalies they’ve now observed in two different elements.

Beryllium, a brittle metal with atomic number 4, and helium, a noble gas with atomic number 2, are similar in ways that could influence the observation of the X17 particle anomaly in both elements. The proposed new boson is 33 times more energetic than an electron but exists for a minuscule fraction of a second—less than a trillionth.

Science Alert points out that scientists on other teams have already been looking for a particle that fits the description of the X17 particle, like how the Atomki team gave a description to a criminal sketch artist who is now trying to matchmake the sketch with a logical explanation. The more scientists who are on the hunt for the fifth force, the more likely their research will all eventually cohere into one explanation.

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