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Gravitational waves

Einstein published the first papers predicting the existence of gravitational waves — ripples in the fabric of space-time — almost a century ago. Physicists at the recently upgraded Laser Interferometer Gravitational-Wave Observatory (LIGO) have announced that they have measured these cosmic deformations, opening up a new field of gravitational-wave astronomy. Discover Nature’s coverage of the unfolding story and other gravitational-wave experiments, as well as everything you ever wanted to know about Einstein’s general theory of relativity.

Key reads

Latest news

Nature highlights just a few of the people who played a crucial part in the discovery of gravitational waves — but didn’t win the Nobel Prize.

News | | Nature News

In depth

After two decades and more than half a billion dollars, LIGO, the world's largest gravitational-wave observatory, is on the verge of a detection. Maybe.

News Feature | | Nature News

Research & Review

The discovery of gravitational waves from a merging black-hole system opens a window on the Universe that promises to test gravity at its strongest, and to reveal many surprises about black holes and other astrophysical systems.

News & Views | | Nature

A third gravitational-wave signal has been detected with confidence, produced again by the merger of two black holes. The combined data from these detections help to reveal the histories of the stars that left these black holes behind.

News & Views | | Nature

One of the best-measured parameters from the gravitational wave chirps caused by merging binary black holes is the effective spin of the binary—a combination of the spins of the individual black holes. If the black holes came from a pre-existing binary star system, then the expectation is that the spins will be aligned. On the other hand, if the binary black hole systems were formed through dynamical interactions, the spins will be randomly aligned. William Farr et al. examine the spin parameters for the four mergers reported so far and find at 2.4σ significance that the spins were not aligned. Only ten more merger events will be needed to raise this to 5σ if most of the spins are not aligned.

News & Views | | Nature

Merging neutron stars are potential sources of gravitational waves and have long been predicted to produce jets of material as part of a low-luminosity transient known as a 'kilonova'. There is growing evidence that neutron-star mergers also give rise to short, hard gamma-ray bursts. A group of papers in this issue report observations of a transient associated with the gravitational-wave event GW170817—a signature of two neutron stars merging and a gamma-ray flash—that was detected in August 2017. The observed gamma-ray, X-ray, optical and infrared radiation signatures support the predictions of an outflow of matter from double neutron-star mergers and present a clear origin for gamma-ray bursts. Previous predictions differ over whether the jet material would combine to form light or heavy elements. These papers now show that the early part of the outflow was associated with lighter elements whereas the later observations can be explained by heavier elements, the origins of which have been uncertain. However, one paper (by Stephen Smartt and colleagues) argues that only light elements are needed for the entire event. Additionally, Eleonora Troja and colleagues report X-ray observations and radio emissions that suggest that the 'kilonova' jet was observed off-axis, which could explain why gamma-ray-burst detections are seen as dim.

News & Views | | Nature