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2017 Nobel Prize in Physics

We present this Collection of research, review and comment from Nature Research to celebrate the award of the 2017 Nobel Prize in Physics to Rainer Weiss, Barry Barish and Kip Thorne — who are recognized "for decisive contributions to the LIGO detector and the observation of gravitational waves". The success of LIGO is a testament to their vision, ingenuity and sheer perseverance over several decades. 

Comment & Review

The detection of gravitational waves is the culmination of many decades of persistent theoretical, observational and engineering work. While heralded as surprising, that the first detected wavescame from binary black holes was indeed theoretically expected.

Perspective | | Nature Astronomy

The announcement confirming the discovery of gravitational waves created sensational media interest. But educational outreach and communication must remain high on the agenda if the general public is to understand such a landmark result.

Commentary | | Nature Physics

Gravitational waves are predicted by general relativity, but their direct observation from astronomical sources hinges on large improvements in detection sensitivity. The authors review how squeezed light and other quantum optical concepts are being applied in the development of next generation interferometric detectors.

Review Article | | Nature Communications

The Laser Interferometer Gravitational Wave Observatory in the USA is searching for gravitational-wave emissions from cataclysmic astrophysical events. The task has required the construction of the world's largest and most sensitive optical strain sensor.

Commentary | | Nature Photonics

Observables & Implications

The general theory of relativity predicts that all accelerating objects produce gravitational waves — analogous to electromagnetic waves — that should be detectable for instance in the case of extremely massive objects such as black holes undergoing acceleration. The existence of such waves has been inferred indirectly, but an important goal in physics is their direct observation, a feat that would both validate Einstein's theory and lead to new areas of cosmology. Now early results from LIGO (the Laser Interferometer Gravitational-Wave Observatory), one of the handful of detectors searching for gravity waves, have provided a starting point for further gravity hunts by deriving an upper limit for the stochastic background of gravitational waves of cosmological origin. The data rule out models of early Universe evolution with a relatively large equation-of-state parameter, as well as cosmic (super)string models with relatively small string tension that are favoured in some string theory models.

Letter | | Nature

Advanced LIGO has detected gravitational waves from two binary black hole mergers, plus a merger candidate. Here the authors use the COMPAS code to show that all three events can be explained by a single evolutionary channel via a common envelope phase, and characterize the progenitor metallicity and masses.

Article | Open Access | | Nature Communications

Numerical simulations of the formation of binary black holes provide a framework within which to interpret the recent detection of the first gravitational-wave source and to predict the properties of subsequent binary-black-hole gravitational-wave events; the calculations predict detections of about 1,000 black-hole mergers per year once gravitational-wave observatories reach full sensitivity.

Letter | | Nature

Metrology

Researchers demonstrate a laser interferometer that achieves simultaneous nonclassical readout of two conjugated observables. Because their system uses steady-state entanglement, it does not require any conditioning or post-selection. By distinguishing between scientific and parasitic signals, its sensitivity exceeds the standard quantum limit by about 6 dB.

Letter | | Nature Photonics

Quantum metrology employs the properties of quantum states to further enhance the accuracy of some of the most precise measurement schemes to date. Here, a method for estimating the upper bounds to achievable precision in quantum-enhanced metrology protocols in the presence of decoherence is presented.

Article | Open Access | | Nature Communications

‘Squeezed light’ enables quantum noise in one aspect of light to be reduced by increasing the noise, or more accurately the quantum uncertainty, of a complementary aspect. This has now been used to push the detectors at the heart of the GEO600 gravitational wave observatory to unprecedented levels of sensitivity.

Letter | | Nature Physics

Substantial improvements, through the use of squeezed light, in the sensitivity of a prototype gravitational-wave detector built with quasi-free suspended optics represents the next step in moving such devices out of the lab and into orbit.

Letter | | Nature Physics

Beyond LIGO

On astronomical scales, gravity is the engine of the Universe. The launch of LISA Pathfinder this year to prepare the technology to detect gravitational waves will help us 'listen' to the whole Universe.

Commentary | | Nature Physics

The first detection of electromagnetic emission from a gravitational wave source bridges the gap between one of the most energetic phenomena in the Universe and their dark, difficult to detect progenitors.

News & Views | | Nature Astronomy