Gravitational waves: discovery hailed as breakthrough of the century
Scientists announce discovery of clear gravitational wave signal, ripples in spacetime first predicted by Albert Einstein
By Tim Radford

Physicists have announced the discovery of gravitational waves, ripples in spacetime first anticipated by Albert Einstein a century ago.

“We have detected gravitational waves. We did it,” said David Reitze, executive director of the Laser Interferometer Gravitational Wave Observatory (Ligo), at a press conference in Washington.

The announcement is the climax of a century of speculation, 50 years of trial and error, and 25 years perfecting a set of instruments so sensitive they could identify a distortion in spacetime a thousandth the diameter of one atomic nucleus across a 4km strip of laserbeam and mirror.

The phenomenon was detected by the collision of two black holes. Using the world’s most sophisticated detector, the project scientists listened for 20 thousandths of a second as the two giant black holes, one 35 times the mass of the sun, the other slightly smaller, circled around each other.

At the beginning of the signal, their calculations told them how stars perish: the two objects had begun by circling each other 30 times a second. By the end of the 20 millisecond snatch of data, the two had accelerated to 250 times a second before the final collision and dark merger.

The observation signals the opening of a new window onto the universe.

“This is transformational,” said Professor Alberto Vecchio, of the University of Birmingham, and one of the researchers working on Ligo. “This observation is truly incredible science and marks three milestones for physics: the direct detection of gravitational waves, the first detection of a binary black hole, and the most convincing evidence to date that nature’s black holes are the objects predicted by Einstein’s theory.”

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Scientists just looked beyond the Milky Way — and discovered hundreds of new galaxies

Using a radio telescope called the Parkes telescope, a team of international researchers looked past the Milky Way and discovered an astounding 883 galaxies, 240 of which were previously unseen by scientists.

While the discovery by itself is pretty rad, it’s also notable because it may provide some answers for the mystery scientists call the Great Attractor.

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LIGO - What is a Gravitational Wave?

In less than an hour we’ll know more about gravitational waves, well, we’ll know the same more or less, but will get direct evidence of them. Check it out in this NSF channel webcast.

Also read:

  • The wave nature of simple gravitational waves (Einstein Online)
  • Gravitational Waves Explained (PHD Comics)
  • Gravitational waves: 6 cosmic questions they can tackle (Nature)
  • LIGO wows: black holes heavy as 36+29 merge to 62 Suns + 3 Suns of gravitational waves (The Reference Frame)

(An artist’s impression of binary black holes. Image: NASA. From “Binary black holes found verging on merging”, Astronomy Now)

Star Streams and the Whale Galaxy : NGC 4631 is a spiral galaxy found only 25 million light-years away, toward the well-trained northern constellation Canes Venatici. Seen ege-on, the galaxy is similar in size to the Milky Way. Its distorted wedge shape suggests to some a cosmic herring and to others its popular moniker, The Whale Galaxy. The large galaxys small, remarkably bright elliptical companion NGC 4627 lies just above its dusty yellowish core, but also identifiable are recently discovered, faint dwarf galaxies within the halo of NGC 4631. In fact, the faint extended features below NGC 4631 are now recognized as tidal star streams. The star streams are remnants of a dwarf satellite galaxy disrupted by repeated encounters with the Whale that began about 3.5 billion years ago. Even in nearby galaxies, the presence of tidal star streams is predicted by cosmological models of galaxy formation, including the formation of our own Milky Way. via NASA