Following weeks of rumours that gravitational waves have finally been discovered, scientists are set to make an announcement Thursday morning.

Scientists with the U.S.-based Laser Interferometer Gravitational-Wave Observatory, which includes some Canadians, will provide an update on the search for gravitational waves at 10:30 a.m. Thursday, LIGO announced earlier this week. The event will be webcast live on from the National Press Club in Washington, D.C., starting 10:30 a.m. ET.

Gravitational waves are ripples in space-time that Albert Einstein's theory of general relativity predicted would be produced by massive phenomena such as neutron stars or black holes colliding.

Harald Pfeiffer Heather Fong Prayush Kumar LIGO

University of Toronto's LIGO team members Harald Pfeiffer, Heather Fong and Prayush Kumar used supercomputers to solve general relativity equations and predict what gravitational waves would look like if they came from different kinds of black hole and neutron star collisions. ( Diana Tyszko/University of Toronto)

Such events don't normally give off light and can't be detected using normal telescopes, so observing their gravitational waves would allow scientists to study things that have never been seen before. It would also tell physicists whether Einstein's general theory of relativity is really correct.


U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO) has two detectors - one in Hanford, Washington, and the other in Livingston, Louisiana (above). (LIGO)

The theory turned 100 years old this year. And despite decades of searching, gravitational waves have not yet been officially detected.

But rumours have been heating up that LIGO has finally seen something. Twitter posts about that from Arizona State University theoretical physicist Lawrence Krauss, who is not part of the LIGO collaboration, caused a huge buzz on the internet in January.

Since then, many people have been waiting for an official announcement from LIGO.

Harald Pfeiffer and his team at the Canadian Institute for Theoretical Astrophysics at the University of Toronto helped make the software used to analyze the data and look for gravity waves. 

In particular, they helped predict what gravity waves from different kinds of black holes might look like.

"It's easier to find things if you know what you're looking for," Pfeiffer said.

LIGO test mass

Gravitational waves are detected by LIGO using lasers and mirrors like this one to detect small changes in the apparent length of the arms in an L-shaped detector. (LIGO)

LIGO is designed to detect gravitational waves by measuring their effect using two L-shaped detectors about 3,200 kilometres apart. Passing gravitational waves are expected to make light take slightly longer to travel in one direction than the other. To us, that make it looks like a decrease in the length of one arm of the L and an increase in the other. The minuscule change is measured using lasers and mirrors. A real gravitational wave should be detected by both detectors.