An illustration of “Hawking radiation” emanating from a black hole. New research into the origins of an unusually powerful particle detected on Earth could be key to confirming some of Hawking's key theories about black holes. (Image credit: VICTOR de SCHWANBERG/SCIENCE PHOTO LIBRARY via Getty Images)
Fifty years ago, renowned astrophysicist Stephen Hawking hypothesized that the Big Bang may have left tiny black holes in the universe. Now scientists believe they may have witnessed the explosion of one.
In February 2025, the European collaboration KM3NeT, consisting of underwater detectors off the coast of France, Italy, and Greece, announced the discovery of an incredibly powerful neutrino. This invisible particle had an energy of about 100 PeV — 25 times more powerful than particles accelerated by the Large Hadron Collider, the most powerful atom smasher in the world.
Physicists have long sought an explanation for the high energy of neutrinos. But now a team of researchers not involved in the original discovery has come up with a surprising hypothesis: that neutrinos are a sign of an evaporating black hole. The team described their theory in a paper uploaded to the arXiv database, which has not yet been peer-reviewed.
Hawking's Elephant-Sized Black Holes
In the 1970s, Hawking discovered that black holes are not completely black. Instead, through complex interactions between the black hole’s event horizon and the quantum fields of spacetime, they can emit a slow but steady stream of energy known as Hawking radiation. This means that black holes evaporate and eventually disappear. In fact, as a black hole shrinks, it emits more and more energy until it explodes in a brilliant storm of high-energy particles and radiation — like the neutrinos discovered by the KM3Net collaboration.
But all known black holes are very large—at least several times the mass of the Sun, and often much larger. Even the smallest known black hole would take more than 10^100 years to disappear. If the KM3NeT neutrino was caused by a black hole exploding, it would have to be considerably smaller—on the order of 22,000 pounds (10,000 kilograms). That’s about the same weight as two adult African elephants squeezed into a black hole smaller than an atom.
The only known way for such tiny black holes to be created is through the chaotic events of the early Big Bang, which may have left behind “primordial” black holes in space. The smallest primordial black holes formed in the Big Bang may have exploded long ago, while larger ones may have survived to the present day.
Unfortunately, a 22,000-pound black hole shouldn’t have survived from the Big Bang to the present day. However, the authors noted that there may be an additional quantum mechanism — known as the “memory burden” — that allows black holes to resist decay. This could allow a 22,000-pound black hole to survive for billions of years before it finally exploded, sending high-energy neutrinos hurtling toward Earth in the process.
Primordial black holes may be an explanation for dark matter – the invisible substance that makes up much of the matter in the universe – but the search for them has so far been unsuccessful. This new insight may provide an intriguing clue. The researchers found that if primordial black holes in this mass range are numerous enough to account for all the dark matter, they should explode fairly regularly. They calculated that if this hypothesis is correct, the KM3NeT collaboration should see another amazing neutrino in the next few years.
If this happens, we may have to radically revise our view of dark matter, high-energy neutrinos, and even the physics of the early universe.
Sourse: www.livescience.com
