【】

On August 14, the after-effects of an extreme cosmic blast rippled through you, me, and everyone we know.

But you didn't feel it.

The only instruments on Earth that knew the fabric of space and time was stretching around and through us were located in Washington, Louisiana, and Italy. On Wednesday, we learned what they saw, and, in fact, heard.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) in the U.S. and the Virgo Observatory in Italy detected the ripples in space and time created by two huge black holes -- at 31 and 25 times the mass of the sun -- crashing into each other at a distance of 1.8 billion light-years away.

This is the fourth time humans have observed those ripples -- called gravitational waves -- and the first time three detectors on two continents have been used to catch sight of them.

Having Virgo up and running is a real boon in the hunt for gravitational waves, since it helps validate results from the U.S.-based network.

"...Virgo is allowing us to localize the origin of our gravitational waves to a much higher accuracy than could be possible with only two detectors," said Laura Cadonati, deputy spokesperson for LIGO, via email.

"A smaller search area enables follow-up observations with telescopes and satellites for cosmic events that produce gravitational waves and emissions of light, such as the collision of neutron stars," Cadonati said.

If all three detectors see a signal, it bolsters the idea that the signal is real because LIGO and Virgo use somewhat different technology, Cadonati said.

Think of our universe as a sheet on a bed. If you put objects onto that bed, they will warp and dimple the sheet in different ways, depending on how massive they are.

If two of those objects -- like the huge black holes that created this signal -- were to spin around each other, that sheet would move, sending ripples outward.

LIGO and Virgo detected those faint ripples in the fabric of our universe.

If you convert the signal from the gravitational waves into sound, it actually resembles a chirp, going from a lower frequency to a high frequency right at the end. This of course, led some delightful scientists to "chirp" for LIGO on video ahead of the first announcement in 2016.

While this detection may not be quite as exciting as the first time gravitational waves were announced in February 2016, it's a great example of how iterative science is.

With every gravitational wave observation, we get ever so slightly closer to figuring out exactly how black holes work and what we can learn about all the weird objects in our universe.

“This is just the beginning of observations with the network enabled by Virgo and LIGO working together,” said David Shoemaker, the spokesman for the LIGO Scientific Collaboration, in a statement.

Shoemaker said to expect a ramp-up in the rate of detections of gravitational waves beginning with the next observing run in the fall of 2018. “We can expect such detections weekly or even more often,” he said.

When the first detection was announced, scientists ushered in a new era of astrophysics. Today's announcement is further evidence that the field is shifting.

The new discovery will be detailed in the journal Physical Review Letters,but you can read it now online.

最新评论