The first direct detection of a gravitational wave by a pair of observatories in the United States will offer science a new way of seeing the universe, a sort of gravitational wave astronomy, physicists say.
Leaders of the LIGO experiment, twin observatories in Louisiana and Washington State, announced Thursday that, back in September, their devices detected a split-second ripple through space-time caused by some distant cosmic cataclysm.
“Until this moment we had our eyes on the sky and we couldn’t hear the music,” said Columbia University astrophysicist Szabolcs Marka, a member of the discovery team. “The skies will never be the same.”
It was the shock wave from the merging of two black holes 1.3 billion years ago, each about 30 times the mass of the Sun, said David Reitze, a physicist and a spokesman for the team.
“What’s really exciting is what comes next,” said Reitze, comparing it to Galileo’s pioneering use of the telescope. “We will also hear things that we never expected, and as we open a new window onto the universe, we may see things we have never seen before.”
September’s discovery prompted a flurry of analysis to make sure this was a real signal. It marked the first time a binary black hole has been observed merging. Most importantly, though, it was the first direct observation of a gravitational wave, predicted a century ago by Albert Einstein, in his theory of general relativity, which introduced the concept of a four-dimensional structure to the universe, known as space-time. Einstein predicted that waves could ripple through this structure, like a swell on the ocean or sound through the air, and the century since has seen many efforts to detect the biggest of these, created in the explosions of supernovae, the collision of two black holes, or the whirling orbital dance of a pair of neutron stars.
Ligo, which uses lasers to measure the distance between two large mirrors as it is distorted by passing gravity waves, was the biggest investment ever made by the National Science Foundation, and a huge risk. Reitze called it a “scientific moon shot,” and said its significance will be measured by what comes next, in the new field of gravitational wave astronomy.
It is in this sense like discovering a new wavelength of light. The Planck surveyor satellite, for example, looked out into the cosmos in the microwave and infrared spectrum. It was able to see back in time all the way to the orangey reddish lingering flash of the Big Bang, and prove how the universe is expanding.
Being able to observe gravitational waves will likewise offer a chance to watch the grandest events in the cosmos.
“This is the first time that you’re really testing general relativity in the limit that the gravitational fields are very very strong. It’s not just a new window in astronomy, but it’s a new window in terms of testing gravity, and I think that’s one of the big questions — how well can we test Einstein’s theory and how well does it predict these signals that we’re seeing, and what can we learn,” said Sean Tulin, a theoretical physicist at York University.
the rest and videos: Gravitational waves finally detected in massive breakthrough Einstein predicted a century ago
