Minnesota profs help find a ripple in space and time

University of Minnesota physicist Vuk Mandic and Carleton College professor Nelson Christensen haven't had much time to celebrate their roles in the groundbreaking physics event this week that confirmed a slice of Albert Einstein's theory of general relativity.

They've been too busy.

First, they jetted off to Washington, D.C., for a news conference Thursday. Then they bounded back to Minnesota — Mandic for a Friday afternoon seminar at the U, Christensen to teach class at Carleton. But that hasn't dampened their elation.

"We've been working all our lives for this moment," Christensen said Friday. Mandic called it "the climax of a scientific career."

The findings released Thursday support a part of Einstein's theory of general relativity that had yet to be confirmed: the presence of gravitational waves, or ripples in the fabric of space-time. The discovery was made when a signal from two black holes spiraling into each other surfaced at two identical detectors in Louisiana and Washington state in September, making a loud chirp sound.

The stretching and contraction of the universe has never been observed in that way, Christensen said. He said it's one of the biggest discoveries in physics in a generation.

The discovery improves scientists' understanding of the universe, Mandic said. And it comes just in time for the 100th anniversary of the publication in which Einstein predicted the existence of gravitational waves.

The theory of general relativity predicted that black holes, places where the pull of gravity is so strong that light can't escape, orbiting each other will lose energy through the emission of gravitational waves. They will converge slowly over billions of years, then much more quickly in their last minutes before colliding.

The observation in September detected gravitational waves, confirming Einstein's theory, Mandic said. "The fact that we saw this means that we are capable of seeing other things as well through gravitational waves," he said.

The professors were two out of 1,004 authors on the study in the Physical Review Letters journal, a team made up of other professors, undergraduate and graduate students, engineers, statisticians and scientists at different points in their careers.

The Laser Interferometer Gravitational-Wave Observatory (LIGO), built by Caltech and MIT, is operated by a team of scientists from around the world.

The group from the U has led data analyses looking for gravitational waves in LIGO data and studies to improve the performance of LIGO detectors and their gravitational wave responses. Carleton contributed work identifying noise in detectors and diving into the physical matter that produces detector signals.

Nathaniel Strauss is a physics undergraduate student at Carleton whose name joins the hundreds of other scientists on the study.

"I just feel really lucky to have had the opportunity to have this so early on in my physics career," he said.

Though the major discovery has been made, Christensen said he's not ready to relax. There's still data to analyze, and the detectors will turn back on in the summer. But for now, he is savoring the announcement that he's worked toward for years.

"As a scientist, this is the moment that I've waited for."

Zoe Peterson contributed to this report.