US scientists detect ripples in spacetime
US researchers have confirmed they have successfully measured “ripples in the fabric of spacetime”.
"We have detected gravitational waves, we did it," David Reitze, the executive director of the Laser Interferometer Gravitational Wave Observatory (Ligo) announced yesterday, reported Deutsche Welle.
In a highly-anticipated news conference in Washington, he confirmed that his team on September 14, 2015, had detected the waves from two colliding black holes, remnant stars with gravitational fields so intense that no matter or radiation could escape.
"It took us months of careful checking, rechecking, looking at every available piece of data ... to make sure that what we saw ... was a gravitational wave," he added.
Reitze added that it was "exactly" what Albert Einstein predicted about the waves for two colliding black holes a century ago.
"The two black holes are indeed about 30 solar masses. They are about 1.3 billion light years away," he added.
Playing an audio clip of the short wave that the team were able to measure, another Ligo researcher Gabriela González said the signal took a billion years to come to earth.
"The signal came from the Southern sky, in the rough direction of the Magellanic clouds [the satellite galaxies of the Milky Way]," adding that they couldn't tell with existing technology, exactly where the black holes merged.
Hailing their discovery, she added from now on, "We will not only be able to see the universe but we will be listening to it too."
The international team doing the research says the detection of these gravitational waves will usher in a new era for astronomy. It is the culmination of decades of search and could ultimately offer a window on the Big Bang, reports the BBC.
Being able to detect gravitational waves enables astronomers finally to probe what they call "dark Universe", the majority part of the cosmos that is invisible to the light telescopes in use today.
The research, by the Ligo Collaboration, has been accepted for publication in the journal Physical Review Letters. The collaboration operates a number of labs around the world that fire lasers through long tunnels, trying to sense ripples in the fabric of spacetime, the concept of time and space fused together.
For the detection, the idea is to split a high-powered laser beam and send separate light paths down two long vacuum tunnels that are arranged in an L-shaped configuration. The two paths are bounced back and forth by mirrors, before eventually returning to their starting point. The beam is then reconstructed and sent to detectors. If gravitational waves have passed through the lab, the light paths will have been ever so slightly offset, and this will be evident in the analysis. The approach is called laser interferometry.
When gravitational waves pass through the Earth, the space and time Earth occupies should alternately stretch and squeeze, like a pair of stockings. The Advanced Ligo interferometers have been searching for this stretching and squeezing for over a decade, gradually improving the sensitivity of their equipment. The expectation was that their experiments would need to detect disturbances no bigger than a fraction of the width of a proton, the particle that makes up the nucleus of all atoms.
The Ligo laser interferometers in Hanford, in Washington, and Livingstone, in Louisiana, were only recently refurbished and had just come back online when they sensed the signal from the collision on September 14.
Prof Karsten Danzmann, from the Max Planck Institute for Gravitational Physics and Leibniz University in Hannover, Germany, said the detection was one of the most important developments in science since the discovery of the Higgs particle, and on par with the determination of the structure of DNA.
"There is a Nobel Prize in it … there is no doubt," he told the BBC.
Prof Stephen Hawking, an expert on black holes, speaking to the BBC said he believed that the detection marked a moment in scientific history.
"Gravitational waves provide a completely new way at looking at the Universe. The ability to detect them has the potential to revolutionise astronomy. This discovery is the first detection of a black hole binary system and the first observation of black holes merging," he said.
"Apart from testing [Albert Einstein's theory of] General Relativity, we could hope to see black holes through the history of the Universe. We may even see relics of the very early Universe during the Big Bang at some of the most extreme energies possible."
Not only will they be able to investigate black holes and strange objects known as neutron stars (giant suns that have collapsed to the size of cities), they should also be able to "look" much deeper into the Universe and thus farther back in time. It may even be possible eventually to sense the moment of the Big Bang.
"Gravitational waves go through everything. They are hardly affected by what they pass through, and that means that they are perfect messengers," said Prof Bernard Schutz, from Cardiff University, UK.
"The information carried on the gravitational wave is exactly the same as when the system sent it out; and that is unusual in astronomy. We can't see light from whole regions of our own galaxy because of the dust that is in the way, and we can't see the early part of the Big Bang because the Universe was opaque to light earlier than a certain time.
"With gravitational waves, we do expect eventually to see the Big Bang itself," he told the BBC.
In addition, the study of gravitational waves may ultimately help scientists in their quest to solve some of the biggest problems in physics, such as the unification of forces, linking quantum theory with gravity.
Einstein himself actually thought a detection might be beyond the reach of technology.
His theory of General Relativity suggests that objects such as stars and planets can warp space around them -- in the same way that a billiard ball creates a dip when placed on a thin, stretched, rubber sheet.
Gravity is a consequence of that distortion. Objects will be attracted to the warped space in the same way that a pea will fall in to the dip created by the billiard ball.
Einstein predicted that if the gravity in an area was changed suddenly, by an exploding star per say, waves of gravitational energy would ripple across the Universe at light speed, stretching and squeezing space as they travelled.
Comments