February 26, 2016

Researchers Contribute to Gravity Wave Finding

A team of University of Chicago researchers contributed to the groundbreaking detection of gravitational waves, which was announced earlier this month.

Dr. Daniel Holz, a senior member of the Kavli Institute for Cosmological Physics, Ben Farr, a McCormick Fellow with the Enrico Fermi Institute, graduate students Hsin-Yu Chen and Zoheyr Doctor, and more than 1,000 authors from other universities and organizations contributed to the discovery.

The group of scientists had various roles in the project, from constructing the detectors to dissecting their output. According to Dr. Holz, the gravity of this discovery is immense.

“This is our first time listening to the universe, and it truly opens up a new chapter in physics. You don’t get to do that very often,” he said.

They found the gravitational waves to be caused by a collision of two black holes that released a high level of energy in a very short time. University of Chicago physicist and Nobel laureate Subrahmanyan Chandrasekhar initially theorized in the 1930s that certain types of collapsing stars could form black holes. This detection has added to the concrete data that already supported some of his theories about black holes.

For Holz, gravitational waves have been a career-long pursuit. “I’ve been working on gravitational waves for many years, since I was an undergraduate. I officially joined the LIGO [Laser Interferometer Gravitational-Wave Observatory] collaboration about two years ago,” he said.

All waves are ripples in a medium, which propagate from a source. In this case, the waves ripple in space time and travel at the speed of light, carrying the force and information of objects accelerating in spacetime.

According to Holz, a major advantage of detecting gravitational waves is the ability to indirectly observe massive objects that may be transparent, such as dark matter. He believes that these waves will open a new paradigm in physics research.

“These waves offer us an entirely new way to learn about the universe. For example, they have already given us an unprecedented probe of the surface of black holes… These observations confirm that gravitational waves exist and behave exactly as Einstein’s theory predicts they should,” Holz said.

The UChicago team contributed to the discovery by acting as mediator between the detectors and the world of physics researchers. They translated the raw output of the detectors into statements about the universe. One piece of information they passed, according to Holz, was the magnitude of the astrophysical event. “We helped figure out that the gravitational waves were produced from the collision of two black holes, each 30 times the mass of the Sun, at a distance of over one billion light years away from us.”

Holz said that the significance of this discovery is exhilarating, opening up new possibilities for research in the field. “We have a whole new way to explore the Universe. This is a truly new window, and we have no idea what is out there.”

As leader of the UChicago team, Holz is excited for LIGO’s outlook. “I’m reasonably confident that we’ll continue to detect all sorts of interesting things with LIGO. And I’ll be very surprised if I’m not surprised by what we discover,” he said. “Our first detection was the collision of two big black holes; who knows what will be next?”

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