Scientists may have discovered a fifth force of nature that, if confirmed, could provide answers to the question of dark matter.
As far as scientists are aware, everything in our Universe is held together or pushed apart by four fundamental forces: gravity, electromagnetism, and two nuclear interactions.
The forces are determined by the fact they do not appear to be reducible to more basic interactions between particles, but the existence of a fifth force has long been speculated as there are unexplained gaps in the standard model of particle physics.
There have been many unsubstantiated claims of the existence of a fifth fundamental force, and scientists continue to hunt for dark matter – which is thought to account for approximately 85% of the matter in the Universe – with no success.
Now, however, scientists from Hungary’s Atomki Nuclear Research Institute believe they may have found substantial evidence of the mystery, as they’ve spotted the actions of a fifth physical force emerging from a helium atom.
The researchers claim to have first glimpsed the force at work in 2015, while studying the light emitted during the radioactive decay of beryllium-8, an unstable isotope, but now the same team has seen a second example of the mysterious force at play.
The 2015 study found that when firing protons at the isotope lithium-7, which creates beryllium-8, the subsequent decay of the particles did not produce exactly the expected light emissions.
If the light being emitted is energetic enough, it transforms into an electron and a positron, which push away from one another at a predictable angle. Instead, scientists found the electrons and positrons were frequently pushing away from each other at exactly 140 degrees.
Researchers suggested a whole new particle could be responsible for the anomaly, and its characteristics suggested it had to be a completely new kind of fundamental boson, a particle that can carry forces.
The suspected new boson, which has been named X17, couldn’t be one of the particles carrying the four known forces as it has a distinctive mass and a tiny lifespan, meaning the signs indicate it is the carrier of some new, fifth force.
The more recent study appeared to measure the same results in stable helium atoms, however instead of the electrons and positrons in the helium atoms separating at 140 degrees, the angle was closer to 115 degrees.
In arXiv, where the research was published, the scientists explained:
This feature is similar to the anomaly observed in [beryllium-8], and seems to be in agreement with the X17 boson decay scenario.
We are expecting more, independent experimental results to come for the X17 particle in the coming years.
While original experiment was accepted in the journal Physical Review Letters, the latest study is yet to be peer reviewed. If the particle’s existence is confirmed, physicists will have to reassess the interactions of the existing four fundamental forces and make way for a fifth.
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Emily Brown first began delivering important news stories aged just 13, when she launched her career with a paper round. She graduated with a BA Hons in English Language in the Media from Lancaster University, and went on to become a freelance writer and blogger. Emily contributed to The Sunday Times Travel Magazine and Student Problems before becoming a journalist at UNILAD, where she works on breaking news as well as longer form features.