Breakthrough of the Year 2017: Two Neutron Stars Collide and Drive Physicists Wild

In case you hadn’t heard, LIGO—or, the Laser Interferometer Gravitational-Wave Observatory—is kind of a big deal. Earlier this year, this technology allowed researchers to detect two neutron stars circling each other before colliding more than 130 million light years away. This first-ever observation on Earth of two neutron stars merging was named the 2017 Breakthrough of the Year by Science magazine.  

“The amount of information we have been able to extract with one event blows my mind,” Laura Cadonati a physicist at the Georgia Institute of Technology and spokesperson for LIGO told Science Magazine.

If you’ve read the announcement or any of the many stories about it, you may be wondering: What is LIGO, and why do we care about it?

LIGO is the world’s largest gravitational wave observatory and “physics experiment.” As CalTech puts it, unlike optical or radio telescopes, LIGO is “blind” to visible light and the rest of the electromagnetic spectrum. It “cares” about detecting gravitational waves, which, unlike physical light, are not part of the electromagnetic spectrum. The LIGO “observatory” itself is made up of twin sites in Louisiana and Washington, according to CalTech. 

As for why we care about it, LIGO was behind the greatest discoveries in physics this year: the first full observation of a collision of two neutron stars. A neutron star, as Science put it, is “a ball of nearly pure neutrons, the densest stuff there is.” LIGO had earlier made headlines for helping to detect gravitational waves from black holes. 

This past summer, as Newsweek had previously reported, “The 100-second-long signal” of the collision “arrived at 8:41 a.m. ET on August 17, just three days after the machines sensed their fourth black hole collision, four days before a total solar eclipse swept across America and eight days before LIGO turned off to begin a year of upgrades.”

The event, which took place more than 130 million light years away, gave off signals that reached all the way to Earth, and researchers were able to detect them. Gravitational wave detectors are located in Washington state, Louisiana and Europe. All three were involved in the neutron star observation. 

Shortly (as in, seconds) after that, as Science reported, NASA’s Gamma ray space telescope detected a pulse of gamma rays coming from the same source. This provided the opportunity for researchers to collect a second kind of data on the event, which was soon joined by a third: light. After a little looking around, researchers captured a photograph of a kilonova, the explosion caused by a collision of two neutron stars, for the first time.

Thousands of researchers from hundreds of universities and institutions examined the event, which Science called the “most the history of astronomy.”

As Science wrote, the merger of the two stars has provided a treasure trove of information for physicists, and helped to confirm key models in the field.