In 2023, a neutrino telescope submerged deep in the Mediterranean Sea struck quantum gold, detecting a neutrino with 100,000 times more energy than even the Large Hadron Collider, Earth’s most powerful particle accelerator, can produce. Put simply, it seemed to be an impossible event. Now, physicists from the University of Massachusetts Amherst think this particle may be evidence of an explosion from a black hole that originated at the beginning of time.
Ordinary black holes are created when old stars collapse and die, but Stephen Hawking theorized that another type of black hole could have originated shortly after the Big Bang, before stars existed. Called “primordial black holes” (PBHs), these cosmic dinosaurs would have formed from pockets of subatomic material densely packed together when the universe was in its infancy.
PBHs are thought to be smaller and lighter than ordinary black holes, and able to emit radiation that could eventually lead to an explosion.
“The lighter a black hole is, the hotter it should be and the more particles it will emit,” Andrea Thamm, co-author of the new research published in Physical Review Letters, explained in a statement. “As PBHs evaporate, they become ever lighter, and so hotter, emitting even more radiation in a runaway process until explosion. It’s that Hawking radiation that our telescopes can detect.”
Read more: “The Black Sheep of Black Holes”
Observing such an explosion could unlock secrets of the universe. Like cracking a cosmic piñata, an exploding PBH would reveal every subatomic particle in existence, including those that have only existed in theory, like dark matter and energy.
So was the superneutrino of 2023 a remnant from a PBH explosion?
Unfortunately, there was a bit of a complication. A second neutrino telescope, IceCube, buried in ice at the South Pole, failed to detect any highly charged neutrinos or even anything close to them. If, as the UMass Amherst team theorized earlier, PBH explosions occur frequently in the universe, why hasn’t IceCube detected them?
“We think that PBHs with a ‘dark charge’—what we call quasi-extremal PBHs—are the missing link,” study co-author Joaquim Iguaz Juan said. This “dark charge” is basically the same as the electrical force, but instead of a regular electron, it’s carried by a heavier, theoretical particle the team calls a “dark electron.”
“There are other, simpler models of PBHs out there,” study co-author Michael Baker added. “Our dark-charge model is more complex, which means it may provide a more accurate model of reality. What’s so cool is to see that our model can explain this otherwise unexplainable phenomenon.” 
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Lead image: NASA's Goddard Space Flight Center
