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Gravitational waves detection
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LIGO detected mergers of black holes.
LIGO detected the merger of two black holes (GW150914) in 2015 by a differential arm-length change of 10⁻¹⁸ m; later events include neutron star mergers seen in light too.
Waves took 1.3 billion years to arrive.
Opened gravitational-wave astronomy.
In more detail
Gravitational waves are ripples in spacetime that travel at the speed of light. They were first detected by LIGO in 2015 from the merger of two black holes.
Real-world uses
- Gravitational wave detectors such as LIGO and Virgo observe mergers.
- Gravitational wave astronomy opens a new way to observe the universe.
- LIGO and Virgo detected gravitational waves from merging black holes, confirming an important prediction of general relativity.
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Frequently asked questions
How were they detected?
Laser interferometers measure tiny changes in arm length caused by the passing waves.
Why were they hard to detect?
The signals are extraordinarily small, changing distances by less than a proton's width.
Why are gravitational waves detected only from large events?
Only violent, massive events produce waves strong enough to stretch space by a measurable amount on Earth.
Related topics in Relativity
Schwarzschild metric · Black hole event horizon · Hawking radiation · Frame dragging · Light bending by the Sun · Cosmological redshift