New ways of understanding the universe opened by discovery of gravitational waves

Imagine watching a television with the sound turned off and having to figure out the story behind the images.

How much easier does your task become when the sound is suddenly turned on?

That's how one astrophysicist is describing the magnitude of the discovery of gravitational waves, announced Thursday by the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO).

"Once you turn that sound on you might be able to figure out all sorts of different things to support what you've seen with your eyes but also new things you might not even have expected," said Robert Ferdman, a research associate with McGill University's department of physics.

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By detecting the gravitational waves, the LIGO scientists confirmed the remaining unproven element of Albert Einstein's theory of relativity.

As part of this theory, first advanced in 1916, Einstein held that when massive objects change shape such as when black holes merge ripples will be created in space time.

These ripples are gravitational waves.

But for many years, it was thought detecting a gravitational wave would be impossible, because no light is given off when black holes merge.

So, instead, scientists began listening for them. As part of its announcement on Thursday, LIGO released a soundtrack of a chirp against a backdrop of whirring noise.

A ripple in the fabric of space time

The sound was a ripple in the fabric of space time, created as two black holes merged 1.3 billion light years away from Earth.

"What you're hearing is two black holes orbiting each other faster and faster, until they actually merge and coalesce," Ferdman said.

In other words, the sound has finally been turned on as we stare into the universe and try to make sense of what we're seeing.

"As astronomers we would normally look at objects in the universe through the light they emit optical light, radio waves or x-rays for example but this opens up a completely new way of looking at these objects," said Ferdman, whose research focuses on testing Einstein's theory of relativity.

He predicted the confirmation of the existence of gravitational waves will lead to further discoveries about the formation and evolution of black holes. We may also be able to learn more about the beginnings of the universe itself.

"People are talking Galileo looking through a telescope for the first time," he said. "It's a really monumental discovery."