Three US scientists have won the Nobel Prize in Physics for their discovery of gravitational waves ¨C a phenomenon first predicted by Albert Einstein a hundred years ago.

This year¡¯s prize for physics is split: Rainer Weiss, a professor of physics at the Massachusetts Institute of Technology is awarded one half of the SKr9 million?award (?825,000), and Professors Kip Thorne and Barry Barish, both from the California Institute of Technology, take the other half of the prize.

All three researchers played a key role in their work on the Laser Interferometer Gravitational-Wave Observatory, or ¡°Ligo¡± experiment, which made the first historic observation of gravitational waves in September 2015.

Gravitational waves spread at the speed of light, filling the universe. Albert Einstein described the phenomenon, which came from a collision between two black holes, in his general theory of relativity, but remained convinced it was theoretically impossible to measure them.

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Using Ligo?¨C the world¡¯s most sophisticated detector ¨C this year¡¯s Nobel laureates were able to listen to the waves as two giant black holes rotated around each other.

It took 1.3 billion years for the waves to arrive at the Ligo detector. Scientists described the signal as "extremely weak" when it first reached Earth, but said its discovery was already promising a "revolution in astrophysics".

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While many varieties of electromagnetic radiation and particles, such as cosmic rays or neutrinos, have previously been used to explore the universe, the Ligo project succeeded by using a pair of huge laser interferometers to measure a change thousands of times smaller than an atomic nucleus.

Announcing the winners in Stockholm on Tuesday, the Nobel committee described Ligo as the ¡°most sensitive instrument ever devised by man¡±. More than 1,000 researchers from more than 20 countries have worked on the project since its birth, they noted.

A statement issued by the Nobel prize committee said: ¡°The 2017 Nobel Laureates have, with their enthusiasm and determination, each been invaluable to the success of Ligo.

¡°Pioneers Rainer Weiss and Kip S. Thorne, together with Barry C. Barish, the scientist and leader who brought the project to completion, ensured that four decades of effort led to gravitational waves finally being observed.¡±

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rachael.pells@timeshighereducation.com