Thursday, February 11, 2016

Physicists announce they have detected gravitational waves Einstein – TF1

“We have detected gravitational waves, we have succeeded,” he said to applause David Reitze, a physicist at Caltech (California Institute of Technology), director of the observatory Ligo (Laser Interferometer Gravitational-wave Observatory) which allowed the observation on September 14 after 50 years of efforts.

“This detection is the beginning of a new era of astronomy of gravitational waves has now become a reality,” he told Gabriela Gonzalez , spokesman for the Ligo team, Professor of astrophysics at Louisiana State University.

“With this discovery, humanity embarks on a wonderful quest to explore the most extreme places in the universe where objects and phenomena are formed by deformation of space-time, “said Kip Thorne, professor of theoretical physics at Caltech. “The collision of two black holes and gravitational waves are our first fantastic examples of this new adventure,” said he said.

A discovery “comparable when Galileo pointed for the first time his telescope to the sky “

France Cordova, director of the National Science Foundation, which funds the laboratory Ligo, explained that this observation” marks the birth of astrophysics entirely new, comparable when Galileo pointed his first telescope to the sky “in the seventeenth century.

Gravitational waves are produced by slight disturbances to the fabric of space-time as a result of displacement a large mass of object, much like the deformation of a net in which a weight is placed. They travel at the speed of light and nothing can stop them.

The physicist Benedict Mours, the National Centre for Scientific Research (CNRS) French, ruled this advanced “historical” it “directly verify these predictions of the theory of general relativity.”

For this discovery, physicists have determined that gravitational waves detected in September were formed at the last split second before the merger of two black holes, very dense objects still mysterious.

A phenomenon predicted by Einstein but never observed

the possibility of a collision between such bodies had been predicted by Einstein but this phenomenon, extreme example of gravity, had never been observed.

According to the theory of relativity, a pair of black holes in orbit around each other loses energy, producing gravitational waves. It is these waves that were detected 14 September 2015 at exactly 4:51 p.m. GMT, an incredible time, said David Reitze, “I could not believe it, it was too good to be true.”

The data analysis has determined that these two black holes merged there are about 1.3 billion years. They were 29 and 36 times more massive than our Sun, a diameter of only 150 km.

The comparison of the arrival times of gravitational wave detectors in both Ligo, 3,000 kilometers distant from each other (7.1 milliseconds apart), and study characteristics the measured signals confirmed the identification.

The source of these waves located in the southern hemisphere


We know that the source of these waves was located in the southern hemisphere of the sky but more detectors would have enabled a more precise location.

“The first applications that we see now are for black holes, because they do not emit light and we could not have seen without gravitational waves,” said the astrophysicist David Shoemaker, head of Ligo at the Massachusetts Institute of Technology (MIT), noting that it is still unclear how these objects, which are at the center of virtually all galaxies grow.

As such, “gravitational waves may help explain how galaxies form,” believes David Shoemaker. “Gravity is the force that controls the universe and being able to see its radiation allows us to observe the most violent and fundamental phenomena of the cosmos, which are almost nobservables otherwise,” assented Tuck Stebbins, head of laboratory gravitational Astrophysics at Goddard NASA.

A new step to explain the Big Bang

the ability to detect these waves traveling undisturbed for billions of years makes it possible to trace the first millisecond of the Big Bang.


> an indirect proof of the existence of gravitational waves was generated by the discovery in 1974 of a pulsar and a neutron star rotating around each other at high speed, by Russell Hulse and Joseph Taylor . This earned them the Nobel Prize for Physics in 1993.

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