 "Scientists detect Einstein's 'gravitational waves'")
In a breakthrough for the world of astronomy, scientists on Thursday said that they had detected ‘gravitational waves’, the ripples in the fabric of space-time that Einstein had predicted a century ago.
Scientists likened the breakthrough to the moment Galileo took up a telescope to look at the planets.
The discovery of these waves, created by violent collisions in the universe, excites astronomers because it opens the door to a new way of observing the cosmos. For them, it’s like turning a silent movie into a talkie because these waves are the soundtrack of the cosmos.
An all-star international team of astrophysicists used a newly upgraded and excruciatingly sensitive $1.1-billion instrument, known as the Laser Interferometer Gravitational-Wave Observatory (Ligo), to detect a gravitational wave from the distant crash of two black holes, one of the ways these ripples are created.
Some physicists said this was as big a deal as the 2012 discovery of the subatomic Higgs boson, sometimes called the “God particle”. Some said this was even bigger.
“It’s really comparable only to Galileo taking up the telescope and looking at the planets,” said Penn State physics theorist Abhay Ashtekar, who wasn’t part of the discovery team. “Our understanding of the heavens changed dramatically.”
Gravitational waves, first theorised by Albert Einstein in 1916 as part of his theory of general relativity, are extraordinarily faint ripples in space-time, the hard-to-fathom fourth dimension that combines time with the familiar up, down, left and right.
When massive but compact objects like black holes or neutron stars collide, their gravity sends ripples across the universe.
Scientists found indirect proof of the existence of the gravitational waves in the 1970s — computations that showed they ever so slightly changed the orbits of two colliding stars — and the work was honoured as part of the 1993 Nobel Prize in physics.
But Thursday’s announcement was a direct detection of a gravitational wave. And that is considered a big difference.
“It’s one thing to know sound waves exist, but it’s another to actually hear Beethoven’s Fifth Symphony,” said Marc Kamionkowsi, a physicist at Johns Hopkins University who wasn’t part of the discovery team.
“In this case, we are actually getting to hear black holes merging.”
Gravitational waves are the “soundtrack of the universe,” said team member Chad Hanna of Pennsylvania State University.
Detecting gravitational waves is so difficult that when Einstein first theorised about them, he figured scientists would never be able to hear them. Einstein later doubted himself and even questioned in the 1930s whether they really did exist, but by the 1960s scientists had concluded they probably did, Ashtekar said.
In 1979, the National Science Foundation decided to give money to the California Institute of Technology and the Massachusetts Institute of Technology to come up with a way to detect the waves.
Twenty years later, they started building two Ligo detectors in Hanford, Washington, and Livingston, Louisiana, and they were turned on in 2001.
But after years with no luck, scientists realised they had to build a more advanced detection system, which was turned on last September.
The new Ligo in some frequencies is three times more sensitive than the old one and is able to detect ripples at lower frequencies that the old one couldn’t. And more upgrades are planned.
Sensitivity is crucial because the stretching and squeezing of space-time by these gravitational waves is incredibly tiny. Essentially, Ligo detects waves that stretch and squeeze the entire Milky Way galaxy “by the width of your thumb”, Hanna said.
Scientists likened the breakthrough to the moment Galileo took up a telescope to look at the planets.
The discovery of these waves, created by violent collisions in the universe, excites astronomers because it opens the door to a new way of observing the cosmos. For them, it’s like turning a silent movie into a talkie because these waves are the soundtrack of the cosmos.
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“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.”
An all-star international team of astrophysicists used a newly upgraded and excruciatingly sensitive $1.1-billion instrument, known as the Laser Interferometer Gravitational-Wave Observatory (Ligo), to detect a gravitational wave from the distant crash of two black holes, one of the ways these ripples are created.
Some physicists said this was as big a deal as the 2012 discovery of the subatomic Higgs boson, sometimes called the “God particle”. Some said this was even bigger.
“It’s really comparable only to Galileo taking up the telescope and looking at the planets,” said Penn State physics theorist Abhay Ashtekar, who wasn’t part of the discovery team. “Our understanding of the heavens changed dramatically.”
Gravitational waves, first theorised by Albert Einstein in 1916 as part of his theory of general relativity, are extraordinarily faint ripples in space-time, the hard-to-fathom fourth dimension that combines time with the familiar up, down, left and right.
When massive but compact objects like black holes or neutron stars collide, their gravity sends ripples across the universe.
Scientists found indirect proof of the existence of the gravitational waves in the 1970s — computations that showed they ever so slightly changed the orbits of two colliding stars — and the work was honoured as part of the 1993 Nobel Prize in physics.
But Thursday’s announcement was a direct detection of a gravitational wave. And that is considered a big difference.
“It’s one thing to know sound waves exist, but it’s another to actually hear Beethoven’s Fifth Symphony,” said Marc Kamionkowsi, a physicist at Johns Hopkins University who wasn’t part of the discovery team.
“In this case, we are actually getting to hear black holes merging.”
Gravitational waves are the “soundtrack of the universe,” said team member Chad Hanna of Pennsylvania State University.
Detecting gravitational waves is so difficult that when Einstein first theorised about them, he figured scientists would never be able to hear them. Einstein later doubted himself and even questioned in the 1930s whether they really did exist, but by the 1960s scientists had concluded they probably did, Ashtekar said.
In 1979, the National Science Foundation decided to give money to the California Institute of Technology and the Massachusetts Institute of Technology to come up with a way to detect the waves.
Twenty years later, they started building two Ligo detectors in Hanford, Washington, and Livingston, Louisiana, and they were turned on in 2001.
But after years with no luck, scientists realised they had to build a more advanced detection system, which was turned on last September.
The new Ligo in some frequencies is three times more sensitive than the old one and is able to detect ripples at lower frequencies that the old one couldn’t. And more upgrades are planned.
Sensitivity is crucial because the stretching and squeezing of space-time by these gravitational waves is incredibly tiny. Essentially, Ligo detects waves that stretch and squeeze the entire Milky Way galaxy “by the width of your thumb”, Hanna said.