Home / Topics / Gravitation & Orbits
Gravitational waves
Advanced
Ripples in spacetime from accelerating masses, first detected in 2015.
Accelerating masses produce ripples in spacetime travelling at c. LIGO detected two black holes merging in 2015 via a length change of 10⁻¹⁸ m.
Neutron star merger GW170817 had an optical counterpart.
Detectable only for extreme events.
In more detail
Gravitational waves are ripples in spacetime produced by accelerating massive objects, such as merging black holes. They were first detected by LIGO in 2015.
Real-world uses
- LIGO and Virgo detect gravitational waves from merging black holes.
- Gravitational wave astronomy opens a new window on the universe.
- The LIGO and Virgo detectors observe gravitational waves from merging black holes and neutron stars.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
How were they detected?
By measuring tiny changes in the length of laser interferometer arms.
Are they strong?
Very weak at Earth, changing distances by less than a proton's width.
Why are gravitational waves so hard to detect?
They stretch and squeeze space by a tiny fraction, so detectors must measure changes smaller than a proton over kilometres.
Related topics in Gravitation & Orbits
Binary stars · Weighing the Sun and planets · Gravitational lensing · Black holes · Schwarzschild radius · Neutron stars and white dwarfs