It is not known how long the dance lasted, but there are about 1400 million years two black holes that were spinning around themselves merged. This approach and fusion did release a lot of energy, making rattling the “fabric” of space-time to create the famous gravitational waves. The last of these waves hit the Earth at the end of last year, more precisely to 3h38m of 26 December. The two detectors of the international scientific collaboration LIGO (Laser Interferometer Gravitational-Wave Observatory) felt them, reveals an article published Wednesday in the journal Physical Review Letters .
You the second time confirms the passage of gravitational waves by the Earth. The first time the LIGO detected these waves was 14 September 2015. When the rest of the world learned this first detection, on 11 February this year, was an important milestone for astronomy and science in general. Gravitational waves had been predicted by physicist Albert Einstein in 1916 and until then had never been proved their existence.
At the time, explained experts that detection opened the way for “astronomy of gravitational waves” which would allow detection of new objects and phenomena in the universe, as binary black holes and neutron stars colliding. This second discovery, made jointly by the LIGO collaborations, the United States, and Virgo, which brings together physicists and engineers from 19 European research groups, marks the dawn of this new type of astronomy.
The second discovery ” truly put the letter in the acronym the Observatory LIGO, “says Albert Lazzarini, director of LIGO at Caltech (California Institute of Technology) in the United States, quoted in a statement from the University of Maryland (USA). “With the detection of two strong events in just four months, we can start to make predictions about the frequency with which we hear gravitational waves in the future.”
Gravitational waves are forces that travel at the speed of light. “The concept is very simple,” says Publico Vitor Cardoso, a physicist at the Instituto Superior Técnico in Lisbon, which was linked to the international experience of detection of gravitational waves LIGO observatory and today continues to study black holes. “The Earth attracts everything and exerts a force on the Moon. If I shake the earth, the force on the Moon will have to undergo a shake. It turns out that when the earth shakes, this gravitational force travels to the rest of the universe, “he added.
It is this force that the LIGO instruments are prepared to detect. Designed in 1992, the LIGO consists of two identical detectors, one is in Livingston in Louisiana, and the other is in Hanford, in Washington State. Each structure has two “arms” perpendicular, each arm has four kilometers long.
There is always a laser traveling in both arms of each building. The light begins to be separated into two halves at the junction of the arms. Each laser subfeixes travels to the end of the arm, which is reflected by a mirror and back to back, returning to the intersection of the arms and interfering with the light of subfeixe the other arm.
The structure it was constructed to be the least possible external interference in the constant travel of the laser, which can be caused, for example, by earthquakes. Therefore, the laser usually go through the arms of the detector without changes. But as a gravitational wave passes through the planet, the matter that formed the Earth will be very depressing slightly for a short time. And one of the arms of each detector is momentarily because of shorter wave, while the other is longer. This causes the two laser beams no longer coincide for a moment and it is this discrepancy in the time-space is detected.
Both detectors serve to confirm if a discrepancy in the laser movement is even caused by a gravitational wave. If a wave to interfere with the laser movement in the detectors, then sooner or later it will arrive at the other detector and interfere with its laser.
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