The Nobel Prize–winning Laser Interferometer Gravitational-Wave Observatory (LIGO) observatory has already changed the world of astronomy.
When the scientists in the LIGO collaboration announced the first detection of gravitational waves in 2016, it meant they’d discovered a new way to observe the universe.
For the first time, scientists could “listen” to ripples in spacetime created by the collision of massive objects like black holes.
But that was just the beginning. The dream, all along, was to combine gravitational wave detections with observations from more traditional telescopes.
On Monday, a team of thousands of LIGO scientists around the globe published an incredible finding spread throughout several papers in the journal Physical Review Letters.
Not only did these scientists detect, for the first time, the gravitational waves produced from two colliding neutron stars, but they were able to pinpoint their location in the sky and witness the event with optical and electromagnetic telescopes.
The gravitational waves tell physicists how large and how far away the objects are, and allow scientists to recreate the moments before they collided.
Then the observations in optical light and electromagnetic waves fill in the blanks that gravitational waves can’t answer.
They help astronomers nail down exactly what the objects were made out of, and which elements their collisions produced.
In this case, the scientists were able to conclude that the resulting explosion from a neutron star merger produces heavy elements like gold, platinum, and uranium.
On August 17 at 8:41 am, LIGO detected gravitational waves — literal distortions in space and time — passing through Earth.
LIGO is a pair of L-shaped observatories in Washington state and Louisiana that can detect when these waves temporarily squish and stretch the fabric of spacetime around us.
In the past two years, LIGO had detected gravitational waves generated by black holes that had crashed into one another.
When LIGO detects gravitational waves, it automatically sends out alerts to hundreds of scientists across the world. Brown was one of them.
“We got on the phone very quickly, and we realized this was a very loud gravitational wave signal. It blew our socks off,” he says.
On the day of the gravitational wave detection, the scientists immediately got another clue that something big was happening.
Two seconds after LIGO detected the gravitational waves, Fermi, a NASA satellite, detected a gamma-ray burst, one of the most powerful explosions of energy we know of in the universe.
It had long been theorized that neutron star mergers could create gamma-ray bursts. This couldn’t be a coincidence.
But light from the neutron star merger and subsequent explosion would soon dim. And so the LIGO collaboration scientists were suddenly under intense pressure to move quickly.
“The sooner you get telescopes on this thing, the more information you get,” Brown says.
Studying that light, and how it changes, would teach scientists a huge amount about neutron stars and how their collisions transform matter.
This discovery is so exciting because it means we’re truly in a new age of astronomy.
It means scientists can study celestial objects not just in terms of the light or radiation they emit they can also combine those observations with data from gravitational waves.
It means scientists have data on the entirety of this collision. They have data on how the two neutron stars danced around each other, they have data on the moment of impact, and they have extensive data on the aftermath.
Scientists expect to observe more black hole mergers, more neutron star mergers. But stranger, cooler observations may come through as well.
If LIGO and VIRGO continue to be upgraded, it’s possible they could detect gravitational waves still rippling away from the Big Bang.
Or, more excitingly, they could detect sources of gravitational waves that have never been predicted or observed.
“I was a little sad I was not alive for the first moon landing,” Thomas Corbitt, a physicist and LIGO collaborator at Louisiana State University, says.
“But when you see things like this, which are a testament to what people can do when they work together, it really is inspiring, and it teaches us about the universe.”
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