The Royal Swedish Academy of Sciences awarded researchers the Nobel Prize in Physics last week for the first detection of gravitational waves, thus confirming one of Albert Einstein’s century-old predictions.
“It’s kind of surreal to me that it actually happened,” said Ryan Lang, assistant professor of physics with academic ties to the award-winning researchers from the Laser Interferometer Gravitational-Wave Observatory. “Logically I wasn’t surprised, but it’s still amazing to see it actually happen: people that you’ve met and interacted with becoming Nobel laureates.”
According to Lang, LIGO’s gravitational wave detections are one of the most groundbreaking discoveries in physics of this century. Both he and a Hillsdale alumnus contributed to the LIGO collaboration.
Although LIGO’s first detection occurred in 2015, the organization just announced a fourth detection last week. This detection was the first time LIGO observed a black hole merger from three separate angles, providing more detailed information for both LIGO collaborators and astronomers.
Gravitational waves come from merging black holes from a billion light years away, according to Lang. When these gravitational waves travel to Earth, they slightly squeeze and stretch everything on the Earth. To detect these waves, LIGO has two detectors in Washington and Louisiana that contain free-hanging mirrors with lasers bouncing back and forth between them. If a gravitational wave passes through, it will move the mirrors slightly — roughly a billionth of an atom’s diameter relative to each other — and the bouncing laser will signal any movement that occurs.
LIGO’s most recent detection was the first time the Virgo interferometer in Italy detected a gravitational wave in collaboration with LIGO’s two detectors. According to Lang, detecting a gravitational wave from three separate instruments helps astronomers to narrow down the location of the wave’s source.
“Wave detectors are more like ears than like eyes; you don’t point them,” Lang said. “With ears, we hear things from all around, and gravitational wave detectors work the same way: They get signals from all over, and it’s kind of hard to tell exactly where they come from…When you have a third detector like the one in Italy, it brings it down to a much more manageable size region.”
Lang said the third detector is also significant, because it helps scientists determine exactly how a gravitational wave stretches a detector. This was a test LIGO could not perform with only two detectors.
One of Lang’s former students, Joshua Ramette ’17, worked for LIGO in the summer of 2015, specifically assisting with a device called a ring heater on the Louisiana detector’s mirrors. The ring heater helps to keep the temperature consistent across the entire mirror. Without the ring-heater, the laser will heat the middle of the mirror more than the edges and thereby disturb the instrument’s results.
Ramette said this is not a large problem when the lasers are on low power, but in order to use the instrument at its full capacity, LIGO would eventually need a mathematical model to explicitly show how heating the mirror with the ring-heater would affect the temperature of the mirror. Ramette developed this model for the collaboration and published a paper about it.
Hillsdale also has ties to one of the Nobel Prize winners, Kip Thorne, who is the former doctorate adviser of Lang’s former doctorate adviser at the Massachusetts Institute of Technology, or Lang’s “academic grandfather.”
“He’s pretty famous for a lot of stuff about black holes and popular books and things like that,” Lang said. “He’s sort of the theorist of the group.”
Ramette, who now is currently pursuing his doctorate at MIT, said he got to participate in the festivities for Nobel Prize winner Rainer Weiss, an emeritus professor of physics at MIT and one of LIGO’s founders.
“There was a big party that was thrown for Rai here,” Ramette said. “I actually got to stop by and see him give his impromptu Nobel Prize talk here on campus…What was really great was that he was super humble in that he acknowledged that LIGO’s discovery was the work of over a thousand people working for many decades.”
Assistant Professor of Physics Timothy Dolch also studies gravitational waves that are emitted from black holes that are much earlier in the process of merging and also have a much larger mass than the ones LIGO studies. Dolch said the Nobel Prize award was a victory for the whole field of gravitational-wave study.
“The first thing I did in the morning was check my phone to see if they got it,” Dolch said. “It was really good news obviously for LIGO but then for our whole field, too. One of the reasons this is so significant is that this is a whole new way of doing astronomy, and LIGO is one of the instruments that is helping open up the gravitational wave sky.”
Lang also said the award is significant to everyone in the LIGO community.
“It was a good week for everybody,” Lang said. “I mean, only three people won, but it was the work of a lot of people that got them here, and the whole community’s excited because it’s what we’ve been hoping for for decades.”