This is the sound of two black holes that collide with each other

two black holes

In the darkness of space, they said that no one can hear you screaming.

When two black holes collide, this is quite another matter.

Each weight exceeds the sun and travels about 650 million kilometers per hour. If you can hear these galaxy giants crash together, it sounds like…an explosive noise.

“I think it sounds a bit like a slide whistle. Look a ‘whoooooooop’ and then a sudden ‘pop’ when the two collide,” says Dr Rory Smith.

Listen to the sound Here

Dr Smith and his Monash University colleague Dr Eric Thrane are black hole hunters. But rather than looking for them with telescopes, the pair is trying to ‘listen’ for them, across the vast silences of space.

Astronomy changed in 2015 when scientists managed to spot a gravitational wave for the first time.

Black holes are so big when they collide and merge their energy causes ripples in space time. Those waves spread out through the galaxy (see artist’s impression, right).

Scientists detect waves as they ripple through earth using a giant laser in 4 kilometre pipe. As a wave comes through, the pipe lengthens slightly, then shrinks slightly, as space-time warps around us. In fact everything on earth, including humans, grows and shrinks slightly each time a wave passes through.

A black hole collides with another somewhere in the universe about every 200 seconds – so there are lots of ripples to pick up.

After we detect them, the ripples can be converted into a sound wave. Played through a computer, you can hear the sounds of the universe.

Dr Thrane and Dr Smith were part of the original international team that made the first discovery. Now they want to use waves to listen in on black holes.

It’s sort of like listening to a horn beep and trying to identify the car. Only, the car is on the other side of the universe.

But in a study published today in Physical Review X, they show how it could be done.

The LIGO gravitational wave detector in Louisiana gathers huge amounts of ‘static’ – gravitational waves bouncing randomly through the universe.

Working at the ARC Centre for Gravitational Wave Discovery, the pair has developed an algorithm that, coupled with a powerful enough computer, can listen to that static and pick out the sounds of black holes colliding.

“It’s the same thing your brain does when your car radio goes out of reception and goes to static,” says Dr Smith.

“Little bits and pieces come of radio stations still come through – but your brain is able to put them together and work out what song is playing.”

With their new algorithm they expect to pick out thousands of black hole collisions from LIGO’s data. Then, they can use the ‘sound’ to learn more about the black hole that made it.

“Black holes are really some of the most mysterious objects in our universe. Ask a question about what’s inside a black hole, and all the laws of physics break down,” Dr Smith says.

Seeing further into the night sky once meant building a bigger telescope. But astronomy is now increasingly the province of computers and algorithms.

“When I was a kid, I thought to be an astronomer you had to stand on a mountain and stare up with a telescope,” says Dr Smith.

“It’s certainly different from that,” agrees Dr Thrane. “But I’ve really fallen in love with data and working with computers to find things – it’s now how I pictured it, but it’s beautiful.”

My name is Amy Stone & My professional life has been mostly in hospitality, while studying international business in college. Of course, now I covers topics for us, mostly in the business, science and health fields.