A team of international scientists, including a group from LSU, has made another monumental discovery involving gravitational waves and black holes.
The Laser Interferometer Gravitational-Wave Observatory, called LIGO, in Livingston and in Hanford, Washington – along with the French-Italian Virgo facility near Pisa, Italy – on Aug. 14 all detected gravitational waves from the collision of two black holes nearly 2 billion years ago, researchers announced Wednesday.
“This is not about testing Einstein’s theory anymore,” Gabriela Gonzalez, an LSU professor of physics and astronomy and a member of the team, said Wednesday morning just prior to the announcement in Turin, Italy. The announcement coincided with the acceptance of a scholarly paper in the influential Physical Review Letters, a scientific journal.
“It tells us about how big the black holes can be, how often they form binary systems, where they are in the sky,” Gonzalez said. “And that’s what we can now do that we were never able to do before.”
This is the fourth time LIGO scientists have charted gravitational waves since February 2015 when LIGO first detected the waves and proved a theory forwarded by Albert Einstein a century ago. But this is the first time the event was observed by three different facilities.
“This is a very big deal,” said Joseph A. Giaim, an LSU professor of physics and astronomy and observatory head of LIGO in Livingston.
Astronomers can triangulate the source of the waves and determine where to look in the sky to observe the collision of black holes. That allows “optical telescopes and other instruments to follow up, potentially allowing the community to learn much more about the source,” he said in an email.
Gravitational waves are ripples that travel through the dimensions of space and time. The mirrors and instruments, stretching out two-and-a-half miles, in Livingston Parish and in rural Washington State measured the gravitational waves as they passed.
Black holes are collapsed stars that have such strong gravitational pulls that even light cannot escape. Einstein’s theory and those that followed postulated that black holes bend space time in much the same way a ball would cause an indentation in an otherwise taut blanket.
But black holes have not been seen before, Gonzalez said, “because, well, they’re black.”
The best hope of studying the phenomenon are the gravitational waves created by violent events, such as the collision of two black holes.
Astronomers can calculate the masses of the two stars that are orbiting each other in binary star systems.
Astronomers and scientists have been trading rumors about the most recent discovery for months. Science Alert website called it “A Huge Gravitational Wave Announcement.” Italian scientists at the press conference referred back to Galileo Galilei, who determined the sun was at the center of our solar system, when talking about the discovery.
Wednesday’s announcement furthers a new astronomy that can study the universe using a different medium, Gonzalez said, repeating what Stephen Hawking, the prominent British physicist said about the initial discovery.
LIGO is funded by the National Science Foundation and operated by Caltech and MIT, which conceived and built the project. More than 1,200 scientists from around the world participate in the effort through the LIGO Scientific Collaboration.
The Virgo collaboration consists of more than 280 physicists and engineers belonging to 20 different European research groups
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