A ‘ringing’ black hole proves Einstein and Hawking right
In January 2025 the clearest black-hole merger ever recorded let physicists ‘hear’ the new black hole ring down — confirming predictions by Einstein and Hawking.
On 14 January 2025 the LIGO detectors recorded GW250114, the clearest gravitational-wave signal ever measured — roughly twice as sharp as any before. Two black holes, each about 30 times the Sun’s mass, spiralled together a billion light-years away; the merged black hole then briefly vibrated, or “rang,” before settling down.
Reported on 10 September 2025 in Physical Review Letters by the LIGO–Virgo–KAGRA collaboration, the measurement confirmed Stephen Hawking’s 1971 area theorem and showed that a black hole is fully described by just its mass and spin — exactly as Einstein’s general relativity (the Kerr solution) predicts. Listening to the “ringdown” this precisely is a milestone for the young field of black-hole spectroscopy.