LIGO May Have Detected the First Primordial Black Hole From the Dawn of the Universe
A strange gravitational wave signal detected in November 2025 may provide the first direct evidence of primordial black holes, hypothetical objects formed within the first fraction of a second after the Big Bang. If confirmed, the discovery could solve one of cosmology's greatest mysteries: the nature of dark matter.
The Unusual Signal
On November 12, 2025, the LIGO and Virgo detectors captured a gravitational wave signal labeled S251112cm. What made it extraordinary was that at least one of the colliding objects had a mass less than the Sun's. Normal black holes, formed from collapsing stars, are typically much heavier, at least 1.4 solar masses. No known astrophysical process produces a black hole that light.
University of Miami astrophysicists Nico Cappelluti and Alberto Magaraggia argue this is consistent with a primordial black hole, one that formed not from a dying star, but from dense pockets of matter in the newborn universe.
Why It Matters for Dark Matter
Dark matter makes up about 85% of all matter in the universe. It holds galaxies together, yet it has never been directly detected. Primordial black holes have long been proposed as one possible explanation.
Cappelluti and Magaraggia calculated how frequently LIGO should detect such events if primordial black holes exist. Their predictions matched the observed rarity of the signal. "We believe our study will aid in confirming that they actually do exist," Cappelluti said.
What Are Primordial Black Holes?
Unlike ordinary black holes, which form when massive stars collapse, primordial black holes would have been created in the extremely dense conditions of the universe's first moments, within a second after the Big Bang. They could range in mass from tiny (asteroid-sized) to very large. Soviet scientists Yakov Zeldovich and Igor Novikov first proposed their existence in the 1960s.
Confirmation Will Take Time
The signal could also be noise in the detectors, or involve exotic neutron stars. Further detections from LIGO and future observatories like the European Space Agency's LISA mission (launching 2035) and the planned Cosmic Explorer will be needed. "We'll need to detect another such signal or even several others to get the smoking-gun confirmation," Cappelluti said.
The research will be published in The Astrophysical Journal.