LIGO Detects Gravitational Waves From Colliding Black Holes
A century after Einstein predicted them, ripples in spacetime itself are finally measured directly
Quick facts
- Detection date
- 14 September 2015
- Public announcement
- 11 February 2016
- Source
- Merger of two black holes (c. 29 and 36 solar masses)
- Detectors
- LIGO, Livingston LA and Hanford WA
What happened
On 14 September 2015, at 5:51 a.m. Eastern Daylight Time, both twin detectors of the Laser Interferometer Gravitational-Wave Observatory, in Livingston, Louisiana, and Hanford, Washington, registered a gravitational wave signal, the first direct detection of ripples in spacetime ever recorded. Physicists concluded that the waves were produced during the final fraction of a second of the merger of two black holes, with masses of about 29 and 36 times the mass of the Sun, an event that took place roughly 1.3 billion years ago; about three solar masses of matter were converted directly into gravitational wave energy in that instant, with a peak power output about 50 times that of the entire visible universe. The National Science Foundation formally announced the detection on 11 February 2016, confirming a phenomenon Albert Einstein had predicted a century earlier in his general theory of relativity, one that scientists had been trying to detect directly for roughly 50 years.
Why it matters
The detection confirmed a century-old prediction of general relativity and opened an entirely new observational channel for astronomy, one that does not rely on light or any other form of electromagnetic radiation at all. Gravitational wave astronomy has since let scientists observe black hole and neutron star mergers directly, events that were previously undetectable by any telescope.
How we know
The detection was independently registered by two geographically separated LIGO observatories using matching interferometer instruments, and the announcement was accompanied by peer-reviewed publication of the waveform data, which matched general relativity's predictions for a black hole merger with high statistical confidence.
Sources
- NASA. NSF's LIGO Has Detected Gravitational Waves · Reputable sourcenasa.gov · The domain "nasa.gov" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- NASA Jet Propulsion Laboratory. Gravitational Waves Detected 100 Years After Einstein's Prediction · Reputable sourcejpl.nasa.gov · The domain "jpl.nasa.gov" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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Related timelines
- Space Exploration → · Gravitational wave astronomy complements decades of space-based observation; see the Space Exploration timeline for NASA's parallel role in multi-messenger astronomy.