Scientists have recently uncovered compelling evidence of antimatter in cosmic rays, which may offer a glimpse into the existence of an entirely new class of particles that have never been observed before.
These particles could potentially hold the key to solving one of the most elusive mysteries in modern physics: dark matter.
This strange and invisible substance is thought to make up around 85% of the mass of the universe, yet it has never been directly detected or observed in a laboratory setting.
Now, a groundbreaking new study has proposed that particles of antihelium, which are the antimatter counterparts of helium, detected by instruments aboard the International Space Station (ISS), could have been produced by a new category of particles known as Weakly Interacting Massive Particles (WIMPs).
These WIMPs are believed to be strong candidates for the composition of dark matter.
Pedro De la Torre Luque, the lead author of the study and a physicist at the Institute of Theoretical Physics in Madrid, explained the significance of this finding in the paper. She said: “WIMPs are theoretical particles that have never been observed directly, but they could very well be the ideal candidate for dark matter. While many of the proposed models for dark matter have been ruled out, only a few remain viable, and WIMPs are among the leading possibilities.”
The antihelium nuclei detected by the Alpha Magnetic Spectrometer (AMS-02) aboard the space station may have been produced through a process in which two WIMPs collide and annihilate each other. This annihilation could result in the creation of both matter and antimatter, along with the release of energy, a phenomenon that could help explain some of the unexplained signals observed in cosmic rays.
Antimatter, in simple terms, can be thought of as a mirror image of regular matter. While antimatter shares the same mass as ordinary matter, its properties, such as electric charge, are opposite. For example, where a proton has a positive charge, an antiproton would have a negative charge. The interaction between matter and antimatter leads to annihilation, releasing large amounts of energy, which is why it has fascinated scientists for so long.
Theories about antimatter suggest that it was likely created in large amounts during the Big Bang. While some antimatter is still being generated by high-energy cosmic events today, it is extremely difficult to detect. The universe is overwhelmingly composed of regular matter, and when antimatter is produced, it often annihilates with matter almost instantly, making it elusive to current detection methods.
However, the detection of antihelium, a particularly rare form of antimatter, is especially noteworthy. The AMS-02, which is designed to scan cosmic rays and capture high-energy particles in space, observed antihelium nuclei in the cosmic rays it monitored. Normally, cosmic rays consist of high-energy particles like protons and heavier nuclei that travel through space, and these particles can sometimes interact with gas and dust in the interstellar medium to produce antiparticles. But theoretical models had predicted that the production of antihelium—let alone its detection—would be extraordinarily rare.
Mr De la Torre Luque elaborated on the significance of this rare observation.
He said: “Theoretical predictions suggested that, while cosmic rays could generate antiparticles through their interactions with the interstellar medium, the creation of antinuclei like antihelium should be incredibly scarce. We expected to detect only one antihelium event every few tens of years, but the fact that we observed around ten antihelium events was a striking result. These numbers are many orders of magnitude higher than what standard models of cosmic-ray interactions predicted.”
This unexpected surplus of antihelium events has excited the scientific community, as it may point to a new and extraordinary cosmic phenomenon—the annihilation of WIMPs. Such annihilation events could potentially produce antihelium nuclei and offer a tantalising clue to the nature of dark matter.
The hunt for dark matter has been one of the greatest challenges in modern astrophysics. While scientists have long known that dark matter must exist because of its gravitational effects on galaxies and large-scale structures, no one has yet been able to directly detect dark matter particles.
Many candidates have been proposed for what dark matter might be made of, and WIMPs are widely considered one of the most promising explanations. These particles are theorized to interact very weakly with regular matter, making them difficult to detect with current technology. But if WIMPs exist, their annihilation could leave behind detectable traces, such as the rare antihelium nuclei observed by AMS-02.
Mr De la Torre Luque further emphasised the importance of the discovery, explaining: “If these antihelium nuclei are indeed the result of WIMP annihilation, it would provide us with an invaluable clue to the existence and properties of dark matter. It would represent a breakthrough in our understanding of the most abundant substance in the universe, even though it has remained entirely invisible to us until now.”
While the discovery is exciting, scientists note that more data are necessary before they can definitively confirm the role of WIMPs in the production of antihelium. The detection of such rare particles could open up new avenues for exploring dark matter and its interactions with the universe at large, but much work remains to be done before we can fully understand the implications of these findings.
This post was originally published on here
