Science history: Gravitational waves detected, proving Einstein right — Sept. 14, 2015
Rapid facts
Discovery: First of all gravitational waves detected
Discovery date: September 14, 2015 at 5:51 a.m. Hae (09:51 UTC)
Or: Livingston, Louisiana and Hanford, Washington
WHOs: Scientists with scientific collaboration Ligo
Ten years ago today, on September 14, physicists detected undulating gravitational waves for the first time in the cosmos.
The roots of this discovery date back to a century. General d’Albert Einstein relativity predicts that massive objects would deform space-time. When such massive objects accelerate – like two black holes Collide-They would send undulations through the cosmos, called gravitational waves, he posed.
Einstein never thought that we could detect them, because the distortion of space-time caused by these waves would be much smaller than one atom.
However, in the 1970s, the MIT physicist Rainer WeissWHO died in Augustproposed that it may be possible to detect these tiny waves by collizing massive black holes.
The key to his scheme was the interferometer, which would divide a bundle of laser light. From there, the light descended two separate paths before bouncing on suspended mirrors and recominating at their source, where a light detector measured their arrival. Usually, if the paths had the same lengths, these two beams would return at the same time.
But if a gravitational wave passed, Welcome Weiss, these beams would still be as slightly destroyed. Indeed, the gravitational waves are temporarily smoosh and stretch space-time, thus creating fluctuations in the length of the passages through which the laser radiates.
Weiss, with Caltech physicist Kip Thorneproposed the idea of trying to measure these elusive waves. The detector tracks, they argued, had to be very long to detect such tiny signals. And the project would need two largely spaced detectors to eliminate the possibility that signals come from local disturbances and to help locate the source of cosmic collisions.
In 1990, the project of the laser interferomed gravitational observatory (LIGO) had been approved and two identical detectors, with 2.5 miles (4 kilometers) long, were built in Hanford, Washington and Livingston, in Louisiana, respectively.
For years, detectors have found nothing. Ligo has therefore been improved to become more sensitive to increasingly stimulating signals. A large part of this involved Protect the equipment from vibrations Caused by nearby traffic, aircraft or distant earthquakes, which could obscure the signals of the distant universe.
In September 2015, scientists lit the improved instruments.
Overnight, on September 14, researchers from the two Ligo sites detected something interesting.
“I arrived on the computer and I watched the screen. And here, there is this incredible image of the waveform, and it was exactly like the thing that had been imagined by Einstein,” said Weiss in a Documentary on discovery.
It was a strong “chirp”, or a fluctuation in the length of the detector arms, and it was a thousand times smaller than the diameter of a nucleus.
On February 11, 2016, scientists announced that the event they had detected came from the crushing of two massive black holes that collided about 1.3 billion years ago. The experience of the gravitational waves of Europe, called Virgin, detected the same event.
The discovery inaugurated a whole new way of studying the most extreme events of the universe. Since this first detection, Ligo detectors, as well as his experience as a virgin European counterpart and the Japanese Kamioka gravitational wave detector (Kagra), have detected around 300 collisionsIncluding the triple mergers of black hole and the collision of black holes and neutron stars. In June 2023, a team of scientists announced that a weakness “gravitational wavefall“Permet the universe thanks to pairs of black holes that saw the collision in all space and time. And in September 2025, scientists of Ligo collaboration Valida The old theory of Stephen Hawking on black holes, linking quantum mechanics and general relativity.
Weiss and Thorne, as well as their colleague Barry Barishreceived the 2017 Nobel Prize for their work.
