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Astrophysicists help make history

It is the first time we have detected gravitational waves here on Earth, and it’s the first observation of a binary black hole.”

Vicky Kalogera,
astrophysicist

One hundred years after Albert Einstein laid out his general theory of relativity, Northwestern scientists -- with a consortium of scientists around the world -- finally did what the father of modern physics thought could never be done.

A group of more than 1,000 scientists and engineers from universities around the United States and in 14 other countries (the LIGO Scientific Collaboration) for the first time ever detected gravitational waves -- confirming Einstein’s theory and opening an unprecedented new window onto the cosmos.

The discovery -- detected through twin Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors in the U.S. -- was announced with great fanfare today at a news conference in Washington, D.C.

Shortly after a five-year upgrade of the LIGO detectors, a burst of gravitational waves was detected at 4:41 a.m. (Chicago time) Sept. 14, 2015.

LIGO main video project from Northwestern News on Vimeo.

Northwestern astrophysicist Vicky Kalogera, an expert in black-hole formation in binary systems and in LIGO data analysis, had worked for nearly two decades for this moment. She and her Northwestern colleague Shane Larson, both members of the LIGO Scientific Collaboration, have barely slept since they learned the news. 

“It is the first time we have detected gravitational waves here on Earth, and it’s the first observation of a binary black hole,” said Kalogera, who attended the press conference.

“Two black holes, in orbit, spiraling together, and, at the end, they merge into one heavier black hole, creating the biggest explosion we have ever detected in the universe. This event outshines all the stars -- the billions and billions of stars in the billions and billions of galaxies in the universe.”

Another Northwestern colleague, Selim Shahriar, who is not an astrophysicist but an electrical engineer, focuses on the laser physics of this enterprise.

Einstein never imagined gravitational waves would have any significance for understanding the universe, the Northwestern scientists said.  

“The idea that now, 100 years later, not only are we confirming his predictions, but we also are using these observations to learn about black holes, was unimaginable to Einstein, first of all, but even to us,” said Kalogera, director of Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).

During a five-year redesign and rebuild, the two detectors were significantly upgraded and made much more sensitive than the first-generation LIGO detectors, said Larson, a research associate professor of physics and astronomy at Northwestern, a CIERA member and an astronomer at the Adler Planetarium in Chicago.

“To detect something in the first few days after turning on our new detectors and to have a detection of an unexpected source -- binary black holes -- is just amazing,” Larson said. “I can’t comprehend it.”

Northwestern has created a special feature with stories, videos and images related to the discovery, including written and video-recorded interviews with the Northwestern astrophysicists who made the historical moment possible.

Learn more

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