Loading…
Loading contentLoading…
Loading contentHow the universe is now observed in gravitational waves, neutrinos, and light at once — the detectors that feel a merger a billion light-years away, the sources that ring spacetime, and the race from alert to counterpart. Built on real detectors and events; proposed detectors are stated as such.
The merger of two neutron stars — a gravitational-wave source that also lights up across the electromagnetic spectrum, producing a short gamma-ray burst and a kilonova. The 2017 event GW170817 was seen in both gravitational waves and light, founding multi-messenger astronomy with gravitational waves.
The technique behind the ground-based detectors: a laser beam is split down two perpendicular kilometre-scale arms and recombined, and a passing gravitational wave stretches one arm and squeezes the other by a fraction of a proton's width, shifting the interference pattern. LIGO, Virgo, and KAGRA all work this way.
Inferring the properties of a gravitational-wave source — the masses and spins of the merging objects, the distance, the orientation — by comparing the waveform against models. It is how a chirp becomes a measurement, including the standard-siren distance that probes the expansion of the universe.
Observing a source in both gravitational waves and electromagnetic light — the channel that transformed astronomy when GW170817 was caught in both, pinning down where a kilonova came from and confirming that neutron-star mergers forge heavy elements.