Scientists Observe Black Holes Getting Bigger as They Merge, Confirming Hawking’s Theory

Two merging achromatic holes. Credit: Simulating eXtreme Spacetimes / Wikimedia Commons / CC BY-SA 4.0

In a breakthrough, researchers person observed 2 achromatic holes merging, providing beardown grounds that achromatic holes turn during cosmic events and confirming Stephen Hawking’s decades-old theory.

The reflection supports Hawking’s 1971 prediction that the aboveground country of a achromatic hole’s lawsuit horizon, the bound beyond which thing tin escape, tin ne'er shrink.

The find was made connected Jan. 14 by the Laser Interferometer Gravitational-wave Observatory, oregon LIGO, which recorded gravitational waves generated by the collision.

The findings, published Sept. 10 successful Physical Review Letters, were led by Adrian G. Abac, a doctoral pupil astatine the Max Planck Institute for Gravitational Physics successful Potsdam, Germany.

Collision confirms Hawking’s aboveground country theory

The event, designated GW250114, progressive 2 achromatic holes merging into a single, much monolithic object. Before the collision, their combined aboveground country measured astir 93,700 quadrate miles (243,000 quadrate kilometers), astir the size of Oregon.

After the merger, the resulting achromatic spread had a aboveground country of astir 154,500 quadrate miles (400,000 quadrate kilometers), comparable to the size of California.

Gravitational waves yet beryllium Stephen Hawking’s achromatic spread theorem

An exceptionally large collision betwixt 2 achromatic holes has been detected by the LIGO gravitational question observatory, enabling physicists to trial a theorem postulated by Stephen Hawking successful 1971… pic.twitter.com/oUXO2LsUdT

— David Ullrich (@DavidUllrich202) September 10, 2025

This summation aligns with Hawking’s 2nd instrumentality of black hole mechanics and confirms that the merged achromatic hole’s country was greater than the sum of its parts.

Columbia University physicist Maximiliano Isi, a co-author of the study, explained that though Hawking’s instrumentality is simply a elemental statement, that aboveground areas don’t decrease, it carries heavy implications.

He noted that the mentation mirrors the 2nd instrumentality of thermodynamics, wherever entropy, oregon disorder, ever increases implicit time.

Wave investigation reveals achromatic spread properties

The squad analyzed the transportation and duration of the gravitational waves to find the size and signifier of the achromatic holes. Similar to however a philharmonic instrument’s code changes with its size, achromatic holes permission unsocial signatures successful the waves they emit.

This allowed the scientists to measurement the event’s “ringdown,” a fading vibration successful space-time that follows the merger, overmuch similar a struck bell.

Katerina Chatziioannou, a physicist astatine Caltech, said this ringdown signifier offered a wide awesome that the last achromatic hole’s aboveground country exceeded the full country of the archetypal two. The results besides enactment Roy Kerr’s mentation from the 1960s, which describes however spinning achromatic holes behave nether Einstein’s equations.

LIGO, operated by Caltech and MIT, presently runs 2 detectors successful Washington and Louisiana. Together with observatories successful Europe and Japan, they signifier the LIGO-Virgo-KAGRA collaboration.

A caller tract successful India is expected to articulation the web by 2030, improving the precision of aboriginal detections. Additional projects, including the US-based Cosmic Explorer and Europe’s Einstein Telescope, are besides successful improvement to observe the earliest achromatic spread mergers successful the universe.