Embry-Riddle Scientists, Students Contribute to Nobel-Winning Research
This year’s Nobel Prize in Physics was awarded to three men, but the detection of gravitational waves was the work of a thousand scientists and students — 10 of them from Embry-Riddle Aeronautical University in Prescott.
“A lot of people don’t know that there is actually good research going on in Prescott — it’s not just a little town in the north of Arizona,” said Michele Zanolin, who leads the Embry-Riddle LIGO team.
The Laser Interferometer Gravitational-Wave Observatory’s sensors might lie in Louisiana and Washington State, but the people who built them, run them and crunch their data work around the world.
“It’s a large collaboration — hundreds of institutes. We’re all contributing our own pieces of it,” said Brennan Hughey, an assistant professor of in ERAU’s Physics and Astronomy Department who specializes in analyzing and addressing noise in LIGO data.
Two years ago, the small army that makes up the LIGO collaboration finally confirmed a prediction Albert Einstein made, a bit grudgingly, a century earlier: that gravity could cause moving ripples in space-time.
“They spread around because space-time behaves like a Jell-O, and all of these are vibrations of the Jell-O that propagate and go away. And we listen to the vibration of the Jell-O,” Zanolin said.
One-point-three billion years ago, two black holes, each as massive as 30 suns, merged, kicking off a space-time tsunami of gravitational waves. The signal that reached Earth was music to physicists’ ears: It followed just the pattern they’d expected, pitching higher as the black holes spiraled in, then spiking in “the chirp” as they coalesced.
“And if that had been different than what we had expected, then we would have had to make some major adjustments to how we understood gravity,” said Andri Gretarsson, who works with students and fellow scientists to improve coatings for mirrors in future detectors.
“If you want to be able to hear further, you have to be able to have a better coating," Gretarsson said.
Gravitational waves are about mass and motion, but spotting them is a matter of optics.
Each LIGO detector splits a laser beam down two tunnels 4 kilometers long, where mirrors bounce them back. Reunited, they should cancel each other out. If they don’t, it might mean a passing gravitational wave has literally stretched and squeezed local space.
But those signals can dip to a fraction of an atom’s size, and that’s a problem, said Hughey.
“If you’re sensitive to these tiny, tiny perturbations in space-time, your instruments are also sensitive to a lot of other things you don’t want to detect,” Hughey said.
So scientists must isolate them from external vibrations, small defects — even the motion of atoms on the mirror’s coating.
Now that LIGO is detecting signals, the research potential for gravitational waves is substantial, particularly when such data are cross-referenced with other areas of astronomy.
Zanolin said that, by linking gravitational wave signals with optical, radio or gamma ray observations, we can further expand our knowledge of the cosmos.
“Only a few percent of the matter out there emits light — electromagnetic radiation — which is what we use in traditional telescopes," Zanolin said.
“We want to be able to tell the people with optical telescopes and radio telescopes, ‘Hey, we heard something, and it came from there. Could you look and see if you see anything?’ And vice-versa, too," Gretarsson said.
In other words, gravitational wave detectors aren’t some one-off novelty. They mark the advent of a new era of astronomy.
“The first detection is really exciting, but we think things are just going to keep getting more exciting in the future,” Hughey said.
It’s as if, up to now, we’ve been watching MTV with the mute button on. We’re still a long way from 7.1 digital surround sound, but at least we can hear the beat.
“This is just the beginning. That’s the main thing — the most exciting thing: Humanity has another frontier,” Zanolin said.
Scientists have detected three more black hole collisions so far, with more likely to come as instruments grow more sensitive, and as additional detectors come online globally.