Scientists Found an Incredibly Powerful Particle That May Have Come From a Fifth Dimension

3 min readIn the middle of the night on February 13, 2023, the Cubic Kilometer Neutrino Telescope (KM3NeT)—one of the newer technological additions to humanity’s scientific arsenal for sniffing out neutrinos—detected a “ghost particle” unlike anything ever seen. The muon contained 35 times more energy than any previous detection, including the IceCube Neutrino Observatory’s entire 15 years of operation (with a detection area 20 times the size of KM3NeT).But the particle’s incredibly high energy reading is only the beginning of its weirdness. Unlike most neutrino detections, this particle—named KM3-230213A—wasn’t accompanied by other photons, and other observatories, such as IceCube, didn’t record anything unusual during the event. These three attributes have puzzled scientists who’ve tried for more than a year to piece together this strange, subatomic mystery, and because of the nature of neutrinos, the task isn’t an easy one.“Neutrinos are the closest thing to nothing that we can imagine,” KM3NeT spokesperson Paschal Coyle, a researcher at the French National Centre for Scientific Research, said back in 2025, “but they are key to fully understanding the workings of the universe.”And also the workings of the fifth dimension—at least that’s according to a new paper published in the journal Physical Review D. Since the announcement of the particle’s discovery last year, scientists have been trying to piece together its origin. Not long after the initial announcement, scientists reported that the particle likely came from a blazar, an active galactic nucleus (AGN) powered by a supermassive black hole with a relativistic jet pointed toward Earth, located some eight billion light-years away. Another study suggested the particle could be evidence of dark matter scattering in the Earth’s crust, and the scientists explain that this could be why KM3NeT detected the particle while IceCube did not.This new study takes an entirely different approach by pointing the explanatory finger at primordial black holes (PBHs), a theoretical relic of the early universe that’s also a possible alternative explanation for dark matter. In September last year, a study from MIT scientists showed that PBHs located within 2,000 astronomical units (roughly the very beginning of the Oort Cloud) could produce ultrahigh-energy neutrinos like the one observed by KM3NeT.However, this new study takes the idea a step further by suggesting that the particle originated from an exploding PBH formed by cosmic strings (a key component of string theory) while nestled in the fifth dimension, which is also known as the “dark dimension” due to this theoretical micron-sized dimension forming the physical link between dark matter and dark energy. Speaking with Scientific American, Max Planck Institute’s Dieter Lüst, a co-author of the study, says this concept could “completely resolve this puzzle” of a neutrino unaccompanied by photons, saying that only neutrinos would be able to leak into our observable dimension.If this sounds like some pretty far out stuff, that’s because it is. For one, scientists have never even glimpsed a PBH in our dimension, which are typically theorized to have formed during the rapid inflation of the early universe. While the smallest of these black holes would’ve already decayed, Scientific American notes that black holes with the approximate mass of an asteroid would only be evaporating our current era of the universe.For now, the description of KM3-230213A as the result of a PBH—let alone one in the fifth dimension—is a far-fetched one, as there are likely other explanations that require fewer theoretical leaps. But more than three years after its initial detection, scientists still don’t now what to make of this “ghostly” particle from the stars.Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.