“There's going to be a revolution.” So says Erik Katsavounidis of MIT, one of the team behind the long-awaited discovery of gravitational waves.
On 11 February, the Laser Interferometer Gravitational-Wave observatory, or LIGO, announced it had spotted gravitational waves, the stretching and squeezing of space-time caused by the movement of massive objects.
The announcement caused a sensation among physicists and astronomers across the world, and they are now gearing up to exploit this new window on the universe. Gravitational waves will allow us to explore fundamental physics, examine the weirdest objects in the universe and possibly even peer back to the universe’s earliest moments. “We can potentially see almost all the way to the big bang,” says Dejan Stojkovic of the State University of New York in Buffalo.
The signal was picked up by LIGO’s two observatories in Hanford, Washington, and Livingston, Louisiana, on 14 September 2015. It was created by two black holes colliding, each about 30 times the mass of the sun. The details of the signal suggest they circled each other closer and closer until they finally merged into one.
This immediately resolved one open question for astronomers. Before the signal came in, the very existence of such black hole binaries was contested. Because they are dark, black holes of these masses are almost impossible to spot unless something bright – like a star – orbits them.
“Signals from black hole mergers could help us understand the nature of dark energy“
The next target is to observe gravitational waves from the death spiral of two neutron stars. Unlike black holes, which hide their mass behind an event horizon even as they crash, colliding neutron stars spew hot, bright matter across space, which could help us explore other mysteries. For example, studying these explosions may explain short gamma-ray bursts – mysterious and incredibly bright electromagnetic phenomena. They might also help explain where much of the universe’s heavy elements, like uranium, thorium and gold, are forged.
Within the next two years, LIGO should be sensitive enough to detect gravitational waves from any neutron star mergers that happen within the nearest 300,000 galaxies. That means we should see about one signal per month.
These single event detections are just the start, however. Put several together and we should be able to get new insights into the history and composition of the universe as a whole, says Avi Loeb of Harvard University. The signals from a number of black hole mergers, for example, can be combined to help understand the nature of dark energy, which is causing the universe’s expansion to accelerate.
To read more, click here.