In the stillness of the Mediterranean seabed, deep beneath the waves where sunlight cannot reach, the world’s most sensitive instruments are listening for whispers from the cosmos. Recently, those instruments caught a signal—a fleeting trace of a neutrino, a “ghost particle” that can slip through entire planets as if they weren’t there. But this was no ordinary neutrino. It carried more energy than any ever recorded, a level so extreme that it defied explanation.
Neutrinos are the most elusive of particles, passing invisibly through our bodies and the Earth in unimaginable numbers every second. Yet, one of them carried a secret so powerful that it could rewrite our understanding of black holes, dark matter, and even the fate of the universe. A new study from MIT physicists now suggests that the neutrino may be the dying gasp of a primordial black hole—an ancient relic from the birth of the cosmos, evaporating in a final burst of unimaginable energy.
If true, this discovery would be nothing less than historic: the first observation of Hawking radiation, a phenomenon long predicted by Stephen Hawking but never directly seen, and the first possible evidence that primordial black holes may be the key to unlocking the mystery of dark matter.
The Ghost Particle Mystery
To grasp the significance of this idea, we must understand just how strange neutrinos are. They are called “ghost particles” for a reason. Though they are the most abundant matter particles in the universe, they interact so rarely with other forms of matter that they pass right through stars, planets, and our own bodies unnoticed. Only immense detectors buried in ice or water can occasionally catch their trace.
In early 2025, one such detector, the Cubic Kilometer Neutrino Telescope (KM3NeT), which lies anchored to the seafloor of the Mediterranean, detected something extraordinary: a neutrino with an energy exceeding 100 peta-electron-volts. That’s a quadrillion electron volts, far beyond what any human-made particle accelerator can produce.
This event dwarfed the scale of neutrinos previously captured by another observatory, the IceCube Neutrino Detector in Antarctica. IceCube had seen half a dozen unusually energetic neutrinos over the past decade, but nothing remotely as powerful as the KM3NeT discovery. The question was obvious: where could such a particle come from?
Primordial Black Holes: Relics of Creation
The MIT team proposed an answer that reads like science fiction but is rooted in real physics. The culprit, they argue, may be a primordial black hole (PBH) in its final moments of existence.
Unlike the titanic black holes born from collapsing stars or those that anchor galaxies, primordial black holes are thought to have formed in the first fractions of a second after the Big Bang. During that chaotic infancy, when the universe was dense with radiation and matter, fluctuations could have compressed certain regions enough to collapse directly into black holes.
These black holes would be tiny—many smaller than an asteroid, some as small as a mountain, others no larger than an atom. Despite their minuscule size, they are enormously dense and could have survived for billions of years. Some scientists believe they could even make up the mysterious dark matter, which accounts for 85% of all matter in the universe but has never been directly detected.
If PBHs exist, they would not live forever. According to Hawking radiation, a black hole slowly loses mass over time, leaking particles and energy into the cosmos. The smaller the black hole, the faster this process accelerates. For primordial black holes, the end comes in a final, catastrophic burst of energy—an explosion bright not in light but in exotic, high-energy particles.
The Last Gasp of a Black Hole
The MIT researchers, led by graduate student Alexandra Klipfel and professor David Kaiser, calculated what such an explosion might look like. As a PBH evaporates, it grows hotter and emits increasingly energetic particles. In its final instant—less than a billionth of a second—it would release a storm of radiation, including a staggering number of neutrinos.
According to their calculations, a PBH smaller than an atom would emit about 10²⁰ neutrinos in its final breath. Among this swarm would be particles carrying energies on the same scale as the KM3NeT neutrino.
If PBHs are indeed abundant throughout the Milky Way, as some theories suggest, then a handful of them should be exploding even now, scattering bursts of ghost particles into space. Every so often, one of these bursts could reach Earth, leaving a trace in detectors like KM3NeT or IceCube.
The MIT team went further, estimating how often such an event might happen near enough to Earth to detect. Their results suggest that there is an 8% chance every 14 years that a nearby PBH explosion could send ultra-high-energy neutrinos our way. While that might sound rare, it is significant enough to be taken seriously—especially since no other known astrophysical process seems capable of producing neutrinos at these extraordinary energies.
The First Evidence of Hawking Radiation?
If this interpretation is correct, the implications are staggering. It would mean that humanity has, for the first time, witnessed Hawking radiation—the slow leaking of energy that Stephen Hawking predicted would eventually dissolve black holes. Until now, Hawking radiation has remained theoretical, a cornerstone of modern physics that has never been observed.
Moreover, this could be the first indirect evidence that primordial black holes are real—and not only real, but possibly the very stuff of dark matter itself. If PBHs account for the majority of dark matter, then they are not just cosmic curiosities but the unseen scaffolding that shapes galaxies and holds the universe together.
As Kaiser put it, “It turns out there’s this scenario where everything seems to line up.” The KM3NeT neutrino, along with past detections by IceCube, could be the first faint signals of exploding PBHs scattered across our galaxy.
A Universe in Tension
What makes this hypothesis even more compelling is the tension between observations. IceCube has long puzzled over its handful of ultra-energetic neutrinos, which defy easy explanation. But the KM3NeT event pushes the mystery further, with energies so high they challenge existing models.
If both sets of observations are tied to PBH explosions, the pieces fall into place. It would suggest that we are not only glimpsing the death throes of ancient black holes but also detecting the signature of Hawking radiation itself.
Still, the evidence is not yet definitive. The theory awaits further confirmation, and the physics community will look to future detections for clarity. The key will be gathering more data—more neutrinos at “insanely high energies,” as Klipfel describes them.
The Hunt for Cosmic Ghosts
For now, scientists wait and watch. Detectors buried deep in Antarctic ice, anchored to the Mediterranean seafloor, or spread across the globe are tuned to catch these rare messengers from the cosmos. Each neutrino that leaves a trace in these detectors could be another piece of evidence pointing toward—or away from—the primordial black hole scenario.
And the stakes are enormous. Confirming the existence of PBHs would open a new chapter in cosmology. Detecting Hawking radiation would validate one of the most profound predictions of modern theoretical physics. And linking both to dark matter could finally solve a riddle that has haunted science for nearly a century.
The Cosmic Echo of Creation
Imagine it: a black hole born in the furnace of the Big Bang, surviving for nearly 14 billion years, only to end its existence in a final outburst that sends a single particle across the cosmos. That particle travels through space for millennia before it slams into Earth, leaving the faintest trace in a detector built by human hands. In that moment, across vast stretches of space and time, the birth and death of the universe are connected.
The MIT study reminds us of something profound: the universe is not silent. Its past lingers in the present, carried by particles so faint and fleeting we barely notice them. Yet, in those whispers lies the potential to unlock the deepest mysteries of existence.
Perhaps one day, when enough of these ghostly signals have been gathered, we will be able to say with certainty: yes, primordial black holes exist; yes, Hawking was right; yes, dark matter’s secret is finally revealed. Until then, we continue to listen for the echoes of creation—the last gasps of ancient black holes, still speaking to us across the stars.
More information: Alexandra P. Klipfel et al, Ultrahigh-Energy Neutrinos from Primordial Black Holes, Physical Review Letters (2025). DOI: 10.1103/vnm4-7wdc journals.aps.org/prl/abstract/10.1103/vnm4-7wdc
