The universe was supposed to be quiet. That was the assumption for most of human history — that space is a void, a perfect silence, the place where sound goes to die. We were wrong, of course. We have been wrong about many things. But this one took until 2015 to prove, and even then, we only heard a single note.
Now we have heard 390.
Last month, the LIGO-Virgo-KAGRA collaboration released its fifth gravitational-wave catalog. Between April 2024 and January 2025 — barely nine months — their network of detectors captured 161 new signals from colliding black holes. The total catalog now stands at 390 confirmed events. They are detecting three to four cosmic collisions every week.
Think about that. The sky is ringing like a bell that someone struck and cannot stop. Every few days, somewhere in the deep, two black holes that have been spiraling toward each other for billions of years finally merge. The event releases more energy in a fraction of a second than all the stars in the visible universe combined. And the ripple — the gravitational wave — travels outward at the speed of light, crossing emptiness for hundreds of millions or even billions of years, until it brushes past Earth with a force so faint it moves the mirrors of our detectors by less than the width of a proton.
We are listening to the dead.
Not in any mystical sense. These are literal dead stars — collapsed cores of suns that burned out long before the dinosaurs, long before the Earth existed. In their final moments, they scream. And because space itself is the medium, there is no air to absorb the sound, no matter to dampen it. The scream becomes an echo. The echo becomes a whisper. The whisper crosses a billion years of nothing and arrives at our doorstep, where we have finally built ears sensitive enough to hear it.
Among the 161 new events is GW250114, the loudest gravitational wave ever detected — 76.9 times stronger than the background noise, loud enough that scientists used it to test a prediction Stephen Hawking made in 1971. Hawking’s area law states that the surface area of a black hole can never decrease. When two black holes merge, the resulting black hole must have an event horizon at least as large as the sum of its parents. The data from GW250114 confirmed this. Hawking died in 2018. The signal he predicted arrived seven years later, traveling from a collision that probably occurred before his birth.
There is something fitting about that. Science is often described as a conversation across time — one generation posing questions, the next building instruments, a future generation finally hearing the answer. But this is different. This is not a human conversation. The answer was generated by physics itself, encoded in the geometry of spacetime, broadcast without intention and received without expectation. Hawking did not send a message. He described a pattern, and the universe, indifferent as ever, happened to produce an example loud enough for us to verify.
What strikes me about the catalog is not any single event but the accumulation. Three to four per week. The first detection in 2015 was a headline, a revolution, a moment when we stopped being deaf. Now we are simply listening, and the universe has a great deal to say. Among the new batch is evidence for second-generation black holes — objects formed not from the collapse of individual stars but from the merger of previous black holes. The children of collisions. Black holes that were already broken and rebuilt before we knew how to name them.
The most precise localization yet achieved narrowed a source to six square degrees of sky — more than five times the area of the full moon, which sounds imprecise until you remember that these are events happening hundreds of millions of light-years away, localized by measuring which of three or four detectors on Earth felt the ripple first. The best localization required three detectors working in concert: LIGO Livingston, LIGO Hanford, and Virgo in Italy, with KAGRA in Japan sometimes contributing. A network of machines, separated by continents, humming in tune, listening to the same dying note from a dead corner of the cosmos.
I keep returning to the thought that these events are already over. When we detect a gravitational wave, the collision it represents happened long ago. The black holes have already merged. The resulting single black hole has already rung down into silence. What we hear is the last vibration, the final settling, the echo of a scream that finished before our species learned to make fire. We are not observers of the universe’s violence. We are its archaeologists, sifting through signals that outlived their sources by geological epochs.
And yet there is something alive in it. The regularity — three to four times a week — suggests a universe that is not merely violent but rhythmically so, almost biological in its pulse. Black holes form, pair, spiral, merge. New black holes form from the debris. The cycle repeats. Somewhere, right now, a pair of black holes is completing a dance that began when the universe was young. The wave they will generate is already on its way. We will hear it in a hundred million years, if we are still listening.
We have stopped calling these “discoveries.” The press releases now speak of catalogs, populations, statistical studies. The language of routine. We have moved from “we heard something” to “here is what the population of black holes looks like.” The first detection was a door opening. The 390th is us walking through it, into a room that turns out to be much larger and noisier than we imagined.
The echo outlived the scream. The whisper crossed the dark. And we, improbably, impossibly, built ears to hear it.
Sources: LIGO Scientific Collaboration, Nikhef, arXiv:2605.27225, UNLV News