LIGO

LIGO's first gravitational-wave detection confirmed a century-old prediction of general relativity and opened a new way to observe the universe.

Black holes come in sizes that span 10 orders of magnitude, from a few solar masses to tens of billions — but the range between roughly 65 and a few hundred solar masses appears nearly empty. A 2020 gravitational wave event punched straight through that forbidden zone, and nobody fully agrees on how.

On September 14, 2015, LIGO detected a ripple in spacetime from two merging black holes a billion light-years away. Here is how the instrument works and what it measured.

What is a black hole, really? Event horizons, Hawking radiation, spaghettification, the nearest known black holes, and the first images of M87* and Sgr A*.

LIGO's gravitational wave detectors produce a constant roar of noise. Machine learning is the ear that hears the cosmos whispering beneath it.

How LIGO detected gravitational waves from colliding black holes, confirming Einstein's prediction

Einstein predicted them in 1916. We detected them for the first time in 2015. Gravitational waves let us "hear" cosmic events that produce no light. Here's how they work and what they reveal.