Science Names LIGO 2016 Breakthrough of the Year

Science has chosen as its 2016 Breakthrough of the Year the discovery of tiny ripples in the fabric of spacetime called gravitational waves — a finding that confirmed a century-old prediction by Albert Einstein and “shook the scientific world,” said staff writer Adrian Cho. But scientists are even more excited about what may come next, as the waves reveal the collision of two black holes. The findings could provide a new way of observing the universe and a major tool for astronomers.

“When the reporters and editors sat down to discuss the big news in science, we didn’t take long to pick a Breakthrough of the Year,” explained News Editor Tim Appenzeller. “The year 2016 saw lots of fantastic achievements, from fertile eggs created from stem cells to evidence of a new ninth planet. But the discovery of gravitational waves towered over everything else. One of Einstein’s wildest predictions beautifully confirmed, launching a whole new field of gravitational-wave astronomy — how can you beat that?”

Einstein theorized that whirling concentrations of mass such as two stars orbiting each other would radiate ripples in spacetime, but in the days before neutron stars and black holes had been discovered, he thought those gravitational waves would be too minuscule to detect. However, last February, physicists working with the Laser Interferometer Gravitational-Wave Observatory, or LIGO, announced evidence of a burst of waves created 1.3 billion light years away, as two black holes spiraled into each other. “Simply put, the discovery counts as one of the biggest in physics ever,” said Cho.

Cho’s article highlights the clever setup of each of LIGO's two massive detectors — two arms with mirrors at either end, housed in a large L-shaped vacuum chamber. By bouncing laser light between the mirrors, physicists could compare the arms’ lengths with razor-sharp precision — to within 1/10,000 the width of a proton. They observed the arms were stretched by different amounts, indicating a passing gravitational wave.

“Now physicists are eagerly anticipating what may come next, as gravitational waves promise an entirely novel way to peer into the cosmos,” said Cho. As a first step, they are eagerly hoping to witness many more events, and are already off to a promising start — LIGO already has detected a second black-hole merger in addition to a third, weaker, signal. “The interferometers resumed taking data last month, and if they can reach their design sensitivity, they may eventually see a black-hole merger on average once a day.”

LIGO’s discovery marks the culmination of a legendary, four-decade-long quest, said Cho, as researchers had been working on developing, building and improving LIGO since the 1970s, all without a guarantee that they would ever detect anything. “The whole experiment sets a standard for audacity, tenacity and dedication. LIGO’s success is a testament to the vision of its originators, especially Massachusetts Institute of Technology physicist Rainer Weiss, who by all accounts — except perhaps his own — is the father of LIGO. So the story is every bit as compelling on the human level as the scientific level."

Other instruments will soon join LIGO’s work, including detectors in Italy, Japan and India. Three or more detectors working together should be able to more precisely pinpoint a gravitational wave source in the sky by triangulation, which could help simultaneously hone in on the same event and possibly even enable conventional telescopes to detect light and other signals from it. That approach could enable astrophysicists to do unprecedented things, such as probe the properties of neutron-star matter.

This year’s special Breakthrough section of Science also includes the results of a readers’ choice poll in which the public voted on its favorite science breakthrough, declaring human embryos growing in lab culture their winner.

The runners-up include a substantial list of heavy-hitting science. Among them is the story of human origins. Three genetic studies in 2016 concluded that a single group of modern humans migrated out of Africa some 50,000 to 60,000 years ago, spreading in different directions to populate the globe. These analyses finally put to rest the long-debated hypothesis that Australia was colonized by a separate and earlier dispersal of people. The rapid development of Zika vaccines was also recognized as a contender. Researchers acted with lightning speed to fight the Zika epidemic with several potential vaccines. Now, clinical testing of these vaccines is underway.

Science also deemed Brexit and Donald Trump’s election to presidency “areas to watch,” as it remains unclear the consequences these events will have on science overall.

[Associated image credit: Flickr/ Charly W. Karl/ CC BY-ND 2.0]