Science

Gravitational waves detected, providing the final piece of the puzzle for general relativity

Two black holes colliding far out in space have produced gravity waves that have been detected by super-sensitive equipment on Earth for the very first time
Two black holes colliding far out in space have produced gravity waves that have been detected by super-sensitive equipment on Earth for the very first time
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A chart showing the signals that confirm the detection of gravity waves for the very first time
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A chart showing the signals that confirm the detection of gravity waves for the very first time
Two black holes colliding far out in space have produced gravity waves that have been detected by super-sensitive equipment on Earth for the very first time
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Two black holes colliding far out in space have produced gravity waves that have been detected by super-sensitive equipment on Earth for the very first time

An international team of scientists today announced what could be the biggest breakthrough in physics in a hundred years. Specifically, they claim to have at last detected gravitational waves, the enigmatic and elusive ripples in the fabric of spacetime that Albert Einstein first predicted in 1916, in his theory of general relativity.

Reported today by the Advanced Laser Interferometer Gravitational-Wave Observatory (Advanced LIGO) team, astronomers say the detection of gravitational waves reveals an entirely new way to observe the universe, revealing distant events that aren't able to be observed using optical telescopes, but whose faint tremors can be felt across the cosmos.

"This detection is the beginning of a new era: The field of gravitational wave astronomy is now a reality," said Gabriela González, LSC spokesperson and professor of physics and astronomy at Louisiana State University.

First detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC), the gravitational waves were recorded by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington.

The event detected was the arrival of gravitational waves on Earth produced by two massive black holes colliding around 1.3 billion years ago. In the collision, some three times the mass of our sun was turned into gravitational waves in microseconds creating a power output at the height of the collision about 50 times that of the entire visible universe.

The LIGO device reflected laser beams repeatedly along two L-shaped detectors in its 4-km (2.5-mile)-long arms onto mirrors equipped with exceptionally sensitive movement sensors, to search for coincident expansions and contractions caused by gravitational waves as they passed by the Earth. As a result of the black holes colliding, the scientists measured minuscule changes in the length of the arms, as tiny as one thousandth the width of a proton.

A previously impossibly small perturbation to measure, LIGO has finally achieved its purpose some 50 years after it was originally proposed as a possible means of detecting gravitational waves by scientists from Caltech and MIT.

"Our observation of gravitational waves accomplishes an ambitious goal set out over five decades ago to directly detect this elusive phenomenon and better understand the universe, and, fittingly, fulfills Einstein's legacy on the 100th anniversary of his general theory of relativity," said Caltech's David H. Reitze, executive director of the LIGO Laboratory.

When Einstein's theory of general relativity turned Newton's understanding of gravity on its head by showing that matter and time were inextricably linked, the theory of space-time was born and the four-dimensional structure of the universe in which matter, energy and gravity are all interlinked elements of that structure, gravitational waves became an inevitable conclusion from this theory.

A chart showing the signals that confirm the detection of gravity waves for the very first time
A chart showing the signals that confirm the detection of gravity waves for the very first time

Undetectable in Einstein's time, these tiny ripples in the fabric of space-time are so weak that it took the eventual production of the most sensitive detectors ever made and the incredible force of two black holes crashing into each other to make their presence known.

"The description of this observation is beautifully described in the Einstein theory of general relativity formulated 100 years ago and comprises the first test of the theory in strong gravitation," said Rainer Weiss, Emeritus Professor at MIT, and one of the original proponents of gravitational wave detection. "It would have been wonderful to watch Einstein's face had we been able to tell him."

LIGO research is performed by the LIGO Scientific Collaboration (LSC), a collective of more than 1,000 scientists from universities around the United States and 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data, and around 250 students are contributing members to the collaboration.

Source: Caltech

16 comments
Nairda
If the Ligo can detect something so far away, maybe we can turn it inwards to look at the gravitational map of our sun and possibly other planets in our solar system. These fields would fluctuate all the time as planets pass each other
idp
So how do they know that the measurement indicated on their equipment was caused by that specific event that happened 1.3 billion years ago? Surely the event itself would have have taken thousands of years to complete, why is a few milliseconds of recording attributed to an event lasting thousands of years. They haven't even begun to discover the extents of the universe! Heck, a whole new planet has just supposedly been discovered the other day that's in our solar system.
hibni
Actually the gravitational vawes were jointly detected in U.S. and Italy, near Pisa. The L-shaped interferometer can be clearly seen here: https://goo.gl/maps/8zfu9oMUSmF2
Chuck Anziulewicz
DEAR IDP: Maybe this article by astronomer Phil Plait will explain things better: http://www.slate.com/blogs/bad_astronomy/2016/02/11/gravitational_waves_finally_detected_at_ligo.html
chidrbmt
Celebrate as Einstein and Newton is partying with Darwin on his 207th birthday today!
Bob Flint
How are they so sure that the sensitive instruments picked up two voids or ( black holes)colliding. When those same instruments are fixed by gravity on this planet, it could also have been an earth shudder....Since if it were and event of that magnitude as ripples on a pond, there were or will still be more to come...
hgdorsey
Of course, all of this is so little for all the energy put into the experiment. Gravity has been engineered for over a century but kept totally secret from the public, as revealed in books like “The Covert Colonization of Our Solar System” and “Secret Science and the Secret Space Program.” Thomas Townsend Brown experimentally discovered the link between Electromagnetism and Gravity in the 1920s and Nikola Tesla even earlier. Brown even developed a gravitational wave communication device in the 1950s. So, this is much ado about almost nothing. http://www.amazon.com/gp/product/1478768835 http://www.amazon.com/Secret-Science-Space-Program/dp/057815238X
James Oss
I would like to ask could the rings of Saturn be used to detect gravity waves? Would not waves passing thru the Saturn system disrupt them and that disturbance be detected by a laser beam thru or across the rings? Thank you for considering and commenting on this., Jim
noteugene
Exactly what I was thinking Bob, a plate ripple would cause the same effect. Before the scientist get so excited about the theory being proven they would have to prove the latter did not occur. Maybe they did but this article does not mention that fact. I believe Einstein's theory was correct but not convinced that this test has proven anything. I'm not a scientist, just a cynic, what do I know?
Graham
Wow! One thousandth the width of a proton in a chunk of stuff 2.5mile long strains credulity..! .. For me, because even on the last tenth of a millimetere of the very ends of a 2.5 mile anything, is a pile of billions of protons, all in motion, having only a probability of positions, knowledge of which is apparently limited (Heisenberg). Then the 2.5 mile thing, attached to an Earth which is shifted and waggled by every sesmic tremor remnant, any one of which is orders of magnitude larger than the (unknown) journey of said protons. Yet all of this is on a thing (Earth) where the centre of mass is not in the middle, but is distributed, with much of it internally on the move. Pulled by the moon, and the Planets, and our Sun, and rocked by tides, and on smaller scale, by every other galactic event between here and 1.3 billion light years away. Data correlation gone mad! How we know, with such certainty, that these two detectors were looking at this distant place, instead of experiencing something that would have tweaked them both. Maybe if we had some of these grav-wave detectors elsewhere than on the same Earth, instead of both being on the same tectonic plate! OK - if true, then I have to be impressed, and congratulatory! I am also a now bit alarmed about how much I don't understand about position measurement science, and how we know that viewing something (say optically) happen at the same time as the detector wiggled could not have been replaced by some other event elsewhere. There is so much universe, such must be happening almost continuously! To cap it all, the only way the information about these events could have arrived here after 1.3 billion years still requires us to accept that in the beginning, that mass somehow, near instantaneously banged it's way to this far distant place, without the need to obey the speeds of the very waves that now arrive, or they would have passed away from us long ago.