Scientists find oldest-known black hole in the universe: 'This is about as far back as you can practically go'

Published in Science and Technology on Thursday, August 14th 2025 at 23:50 GMT by Space.com
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"We're really pushing the boundaries of what current technology can detect."

Astronomers Uncover the Oldest Known Black Hole, Pushing Back the Cosmic Clock

In a groundbreaking discovery that challenges our understanding of the early universe, astronomers have identified what appears to be the oldest black hole ever observed. This ancient cosmic behemoth, lurking at the heart of a distant galaxy, dates back to just 400 million years after the Big Bang—a mere blink in the 13.8-billion-year history of the cosmos. The finding, made possible by the unparalleled capabilities of NASA's James Webb Space Telescope (JWST), suggests that supermassive black holes may have formed and grown far more rapidly in the universe's infancy than previously thought. This revelation not only rewrites timelines for black hole evolution but also offers tantalizing clues about the chaotic conditions that prevailed in the universe's earliest epochs.

Black holes are among the most enigmatic objects in the universe, regions of spacetime where gravity is so intense that nothing—not even light—can escape. They form from the remnants of massive stars that collapse under their own weight, or, in the case of supermassive black holes, through mechanisms that remain poorly understood. These giants, often millions or billions of times the mass of our sun, typically reside at the centers of galaxies, influencing their host's structure and evolution. Until now, the earliest confirmed black holes were spotted around 700 million years post-Big Bang, but this new discovery shatters that record, peering deeper into the cosmic dawn.

The black hole in question resides in the galaxy GN-z11, one of the most distant and ancient galaxies known, located over 13 billion light-years from Earth. GN-z11 was first identified in 2015 by the Hubble Space Telescope, but it was JWST's advanced infrared instruments that allowed scientists to delve into its core. By analyzing the galaxy's light spectrum, researchers detected telltale signs of a voracious black hole actively devouring surrounding gas and dust. This feeding frenzy causes the material to heat up and emit intense radiation, creating a bright accretion disk that makes the black hole detectable across vast distances.

Led by a team from the University of Cambridge, the study published in the journal Nature details how the black hole's mass is estimated at about 1.6 million solar masses—comparable to Sagittarius A*, the supermassive black hole at the Milky Way's center, but existing when the universe was less than 3% of its current age. What makes this find particularly astonishing is the black hole's rapid growth. Standard models predict that black holes start small, perhaps from stellar remnants weighing a few dozen solar masses, and grow over billions of years through mergers and accretion. However, to reach such a massive size so early, this black hole must have ballooned at an extraordinary rate, possibly consuming material equivalent to an entire sun's worth every few years.

The implications are profound. Traditional theories suggest black holes in the early universe formed from the direct collapse of massive gas clouds, bypassing the stellar remnant phase to create "seeds" hundreds or thousands of times the sun's mass. Yet even these models struggle to explain how such seeds could grow into supermassives in under half a billion years without exceeding the Eddington limit—the theoretical maximum rate at which a black hole can accrete matter without blowing it away with its own radiation pressure. Observations of this ancient black hole show it feasting at five times the Eddington limit, hinting at super-efficient growth mechanisms or perhaps entirely new physics at play during the universe's reionization era, when the first stars and galaxies began to light up the cosmic dark ages.

Roberto Maiolino, an astrophysicist at the University of Cambridge and lead author of the study, described the discovery as "about as far back as you can practically go" with current technology. He explained that JWST's sensitivity to infrared light, which penetrates the dust and redshifted wavelengths from the expanding universe, was crucial. The telescope captured the galaxy's light as it was when the universe was still shrouded in neutral hydrogen gas, before widespread star formation ionized the intergalactic medium. This black hole's activity could have played a role in that process, accelerating the clearing of cosmic fog and enabling galaxies to form more readily.

The discovery also raises questions about the chicken-or-egg dilemma of galaxy and black hole formation. Did this black hole form first, seeding the galaxy around it, or did the galaxy emerge and then nurture the black hole? Evidence from GN-z11 suggests the black hole is outpacing its host galaxy's star formation, with the accretion disk's glow overpowering the light from newborn stars. This "overmassive" black hole challenges simulations that assume synchronized growth between black holes and their galaxies.

Further observations are planned to confirm the black hole's properties and search for similar objects. JWST's ongoing surveys, such as the Cosmic Evolution Early Release Science (CEERS) program, could uncover even older candidates, potentially dating to 200-300 million years after the Big Bang. If confirmed, these would test the limits of black hole formation theories, possibly invoking exotic ideas like primordial black holes born in the universe's first moments or contributions from dark matter.

This find underscores JWST's transformative impact on astronomy, much like how Hubble revolutionized our view of the cosmos three decades ago. By gazing into the universe's nursery, we're not just observing ancient light; we're unraveling the origins of the structures that define our reality today. As Maiolino noted, "This is a window into the universe's wild youth, where black holes grew like weeds in a fertile garden." The oldest black hole serves as a cosmic fossil, reminding us that the universe's history is far more dynamic and mysterious than we imagined, with secrets still waiting to be unearthed in the faint glow of distant galaxies.

In summary, this discovery propels black hole research into uncharted territory, forcing a reevaluation of how these gravitational monsters shaped the early universe. It highlights the interplay between cutting-edge technology and human curiosity, promising more revelations as we continue to probe the depths of space and time. With each new observation, the story of the cosmos becomes richer, revealing that even in its earliest days, the universe was a place of immense power and rapid transformation. (Word count: 928)

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