The gravitational 'chirp' explained

The universe is a chirping, jiggling, rippling thing.

What is the sound of two black holes colliding? Peter Shawhan can tell you

Two black holes, the product of the destruction of a massive star, spin, move and collide with one another. (Illustration: SXS - University of Maryland)

The universe is a chirping, jiggling, rippling thing.

Peter Shawhan, a physicist and researcher at the University of Maryland, will tell an audience gathered at Laurentian University as much tonight.

The visiting scientist is part of an international conference on astroparticle physics, hosted by SNOLAB this week.

Shawhan told CBC's Morning North the work he has been doing focuses on gravitational waves and how they interact with spacetime.

"Gravitational waves are variations in the geometry of spacetime," Shawhan said. "Instead of being a fixed coordinate system in which something happens, spacetime can jiggle and gravitational waves are those ripples which travel through the spacetime."

"A gravitational wave changes the distance scale of the universe ever so slightly," Shawhan said. "Our instruments can pick that up and record it as data."

"We can play it back as a sound, or through computer analysis. That's where the name 'gravitational chirp' comes from."

Shawhan asks you to imagine two black holes orbiting each other. They're going around and around, getting closer and closer and increasing in speed because they're emitting energy. If we convert it to a sound, it sounds like this:

"That sound is the sound of the gravitational wave," Shawhan said.

"It could be a billion light years away, travelling through the universe and sweeping past the earth."

Gravitational waves were first detected at the Laser Interferometer Gravitational-Wave Observatory (LIGO), an observatory with two installations in the United States. Scientists from around the world have been working together to analyze data from the waves and conduct further research. 

So far, the team's research has been able to detect black holes orbiting and merging together, Shawhan said. They've been leftover from massive stars that have collapsed, leaving black holes in pairs.

He said he hopes the research helps provide a greater understanding of the universe, especially the origins and evolution of galaxies.

The lecture is scheduled for 7: 00 p.m. at Laurentian's Fraser Auditorium. Doors open at 6:30 p.m.

Listen to the interview about gravitational chirps here.


To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.

Become a CBC Account Holder

Join the conversation  Create account

Already have an account?