To confirm the propagation of gravitational waves, LIGO is comprised of 2 observing stations, one in Louisiana and the other in Washington. To rule out false positives, a candidate gravitational wave signal needs to be detected by both stations. And the Sept. 14 event was detected first in Louisiana and then 7 milliseconds later in Washington. The signals matched and, through triangulation, physicists were able to learn that it originated in Southern Hemisphere skies.
Gravitational Waves - What Are They Good For?
So we have a confirmed black hole merger signal, what now? This discovery is historic, that much is clear - one hundred years ago, Einstein wouldn't have dreamed that these waves would be detectable, but here they are.
ANALYSIS: Colliding Black Holes and the Dawn of Gravitational Astronomy
General relativity was is one of the most profound scientific and philosophical realizations of the 20th Century and it forms the basis of some of our most intellectual investigations into reality itself. Astronomically, the applications of general relativity are clear; from gravitational lensing to measuring the expansion of the universe. But what's not so clear are the everyday applications of Einstein's theories, but much of today's technology uses lessons from general relativity and things we take for granted. Take, for example, global positioning satellites: they wouldn't be the precise tools that they are if simple corrections for time dilation (a general relativity prediction) weren't considered.
It's clear that general relativity has real-world applications, but when Einstein presented his new theory in 1916, it's highly doubtful that any application would have seemed obvious. He was simply piecing together the universe as he saw it and general relativity was born. So now another component of general relativity has been proven, how might gravitational waves be used? Well, astrophysicists and cosmologists are obviously thrilled.
"Once we've collected data from pairs of black holes, they will be like lighthouses scattered through the universe," said theoretical physicist Neil Turok, Perimeter Institute Director, in a video presentation on Thursday. "We will be able to measure the rate the universe is expanding, or how much dark energy there is in the universe to extraordinary precision, far, far greater than what we can do today "Einstein developed his theory with some clues from Nature but made basically on the grounds of logical consistency. One hundred years later you're seeing its predictions confirmed at exquisite precision."
ANALYSIS: Gravitational Waves vs. Gravity Waves: Know the Difference!
What's more, the Sept. 14 event has some peculiarities physicists are looking forward to investigating. For example, Lehner pointed out that from analysis of the gravitational wave signal, the "spin" or angular momentum of the merged black hole can be measured. "If you've worked on the theory for long enough, you'll know that spin the black hole has is very, very peculiar," he said.