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Gravitational Waves Detected

Scientists first observed space-time fluctuations - gravitational waves that came to Earth from a catastrophe which occurred far away in the universe. This confirms an important prediction of the general theory of relativity, made by Albert Einstein on the year of 1915 and opens an unprecedented new vision of the cosmos. This was reported today by researchers from LIGO collaboration at a press conference in Washington, London and Moscow.


Gravitational waves were recorded September 14, 2015 at 5:51 am EST summer time (13:51 Moscow time) on two twin detectors of laser interferometer gravitational wave observatory (LIGO - Laser Interferometric Gravitational Observatory), located in Livingston, Louisiana, and Hanford, Washington, USA. This collaboration involved more than 1,000 people, including two Russian groups who are researchers at the Physics Department of Lomonosov Moscow State University and the Institute for Applied Physics of the Russian Academy of Sciences (Nizhny Novgorod).

The effect of gravitational waves in the world is that they cause a very small change in body size (in LIGO directly measured body are called test masses).

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LIGO detectors discovered relative fluctuations pairs of test masses separated by 4 kilometers, the size of  fluctuations were 10-19 m (it is as many times less size of an atom, as the atom is less than apple), thus proving the arrival of waves to Earth.

"The scientific significance of this discovery is quite huge. As in the case of electromagnetic waves, we’ll realize the value in full only after some time has passed- says Valery Mitrofanov who is Professor of the Physics Department of Moscow State University and the head of the Moscow group of LIGO collaboration.

According to Mitrofanov, after the waves were discovered the LIGO recorded several more bursts of gravitational waves from catastrophic events in space, but they are much weaker than the very first one and now the processing of the received data is on the way to confirm that the spikes has indeed been real. Mitrofanov noted that even the most powerful burst was processed almost six months. At the same time Mikhail Gorodetsky from the same group noticed that in fact the very first burst was recorded before the official launch of the LIGO - during test runs.

According to the professor of Moscow State University Sergei  Vyatchanin, the LIGO performed direct registration of gravitational waves, however indirectly they found in the 1970s, for which later the Nobel Prize in Physics has been awarded.

"It is very important and it is noteworthy that the fundamental discoveries made by outstanding Russian scientist Vladimir Borisovich Braginsky and his colleagues i.e. quantum limits, methods of quantum measurement and quantum fluctuations - were in demand in this project," - explains the role of the group Igor Bilenko, who is professor of the Physics Department of Moscow State University .

He also clarified that the study finally answers the the question whether black holes are real - in his words, the received signals can come only from these intriguing space objects.

"A number of our studies has influenced the decisions taken at LIGO. The Moscow group has done a lot to combat noise and to search for a variety of effects, which on everyday life almost never occur. They are very difficult to detect, but they have an effect on very sensitive detectors of LIGO », - clarifies the assistant Leonid Prokhorov.

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Reference

In the working process, the Moscow group of the LIGO project obtained results that are important not only for the project search for gravitational waves, but also for physics in whole:

- A unique suspension test masses made of fused silica was fabricated. The measured decay time of pendulum oscillations of test masses was about 5 years old. It was demonstrated experimentally that no redundant mechanical noises are present in quartz suspensions whereas the noises are detected in the steel filaments.

- The noises associated with electric charges located on the quartz mirrors of detectors were studied in detail.

- A new class of fundamental thermodynamic noise detector in the mirror was found. Their analysis led to a significant change in the current optical configuration of the LIGO.

- Scientistis pointed out the danger that effect of parametric instability in interferometer can occur. This effect was later found in the LIGO detectors, methods to prevent the effect were proposed.

- New topologies of the optical system of gravity-wave detectors were proposed that are based on the principles of quantum measurement theory. The developed methods will improve sensitivity of next generation detectors and contribute to development of gravitational-wave astronomy.
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Gravitational waves carry information that can not be obtained any other way on the origin and the dramatic nature of gravity. Physicists have come to the conclusion that the observed gravitational waves are generated by the two black holes in the last fraction of a second they merge to form a single, more massive rotating black hole. The possibility of collision of two black holes was predicted, but such an event never before seen.

Based on the observed signals LIGO scientists estimated that the black holes,that participated in this event, had a mass of 29 and 36 times the mass of the Sun, this happened 1.3 billion years ago. For a split second about three solar masses turned into gravitational waves, the maximum radiation power which was about 50 times greater than that of the entire visible universe. Analyzing the moments of arrival of signals ( - detector Livigstone recorded event on 7 milliseconds before the detector in Hanford) - scientists can say that the source was located in the southern hemisphere.

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According to the general theory of relativity, a pair of black holes orbiting each other, lose energy to  emit gravitational waves, which causes them to gradually converge over billions of years, and much faster during the last minute. The last fraction of a second two black holes encounter almost with half speed of light bring a more massive black hole to birth. A part of the fused mass of black holes is converted into energy according to Einstein's formula E = mc2. This energy is emitted in the form of a strong burst of gravitational waves, which have been observed by LIGO.

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