A Signal From Before the Stars

A Signal From Before the Stars By Mark Thompson - March 27, 2026 04:27 PM UTC | Cosmology Black holes that are formed when massive stars die in spectacular supernova explosions, typically weigh several times as much as the Sun. But last November, LIGO, the gravitational wave detector that has been listening to the universe's most violent events since 2015, picked up a signal from something far lighter. At least one of the objects involved almost certainly weighed less than a single solar mass. And that shouldn't be possible through any known process of stellar evolution. So the question remains, what was it? Nico Cappelluti and Alberto Magaraggia, astrophysicists at the University of Miami, think they know. Their new study, published in the Astrophysical Journal, makes the case that the signal is consistent with a primordial black hole, a type of black hole not formed from a dying star, but from the extreme density of the universe itself in the first fleeting moments after the Big Bang. *LIGO Hanford Observatory (Credit : LIGO) The idea has been around since the 1960s, first proposed by Soviet physicists Yakov Zeldovich and Igor Novikov, and later expanded by Stephen Hawking. In the earliest instants of the life of the universe, matter was compressed into such an extraordinarily dense state that some regions may have collapsed directly into black holes before a single star had formed. These objects, if they exist, could range from asteroid sized to enormous, but they've never been directly detected. Until, possibly now! "The most plausible explanation for the LIGO signal, which lacks any conventional astrophysical explanation, is the detection of a primordial black hole,” - Nico Cappelluti from the University of Miami. The team modelled how many such objects should exist, how often they should merge, and how frequently LIGO should detect them. The answers lined up encouragingly with what has actually been observed, one rare event, exactly as the theory predicts. Pri...