Image: C. Henze / NASA Ames Research Center
Physics at the Observatory LIGO (Laser Interferometric Gravitational Observatory) recorded for the first time gravitational waves — perturbations of spacetime, predicted a hundred years ago the Creator of the General theory of relativity by albert Einstein. About the discovery during a live broadcast, organized “Ribbon.ru” and Moscow state University (MSU) named after M. V. Lomonosov, reported scientists in the faculty, participants of the international collaboration LIGO. “Ribbon.ru” I talked with one of them, the Russian physicist Sergei Vyatchanin.
Sergey Vyatchanin
Photo: phys.msu.ru
Doctor of physico-mathematical Sciences Sergey Vyatchanin since 2012 heads the Department of physics of oscillations, faculty of physics. Research interests focus on the study of quantum-non-influence measurements, the laser gravitational-wave antennas, mechanisms of dissipation, the fundamental noise and non-linear optical effects. The scientist collaborated with the California Institute of technology in USA and the max Planck Society in Germany.
What are gravitational waves?
Sergey Vyatchanin: the law of universal gravitation Newton’s two bodies attract each other with a force inversely proportional to the square of the distance between them. This theory describes, for example, the rotation of the Earth and moon in the flat space and universal time. Einstein, developing his special theory of relativity, he realized that time and space are one substance, and proposed the General theory of relativity — theory of gravitation, based on the fact that gravitation is manifested as curvature of space-time that matter creates.
You can imagine the elastic range. If you throw him an easy ball, it would roll in a straight line. If in the center of the circle to put heavy Apple, then the trajectory will curve. From the equations of General relativity, Einstein immediately got that the possible gravitational waves. But at the time believed (in the early twentieth century) the effect is extremely weak. We can say that gravitational waves are ripples of space-time. The bad news is that this is an extremely weak interaction.
If you take the same (electromagnetic) waves, then there was the experience of Hertz placed the emitter in one corner of the room and receiver in another. With gravitational waves it does not work. Too weak interaction. One can only rely on astrophysical catastrophe.
How does gravitational antenna?
There is a Fabry-Perot interferometer, two masses, separated by four kilometers. The distance between the masses is controlled. If the wave comes from above, the distance changes slightly.
Gravitational waves registered on September 14, 2015 at 05:51 am by summer et (13:51 Moscow time) on two detectors of the twin laser interferometer gravitational-wave Observatory LIGO, located in Livingston (Louisiana) and the Hanford (Washington) in the USA. The LIGO detectors are found relative fluctuations in the magnitude of ten to the minus 19 meters (this is approximately equal to the ratio of diameter of atom and diameter of Apple) pairs separated by four kilometers of the proof mass. The perturbation generated by a pair of black holes (29 and 36 times heavier than the Sun) in the last split second before they merge into more massive rotating gravitational object (in 62 times heavier than the Sun). Within seconds three solar masses into gravitational waves, the maximum radiation power was about 50 times greater than that of the entire visible Universe. Merging black holes occurred 1.3 billion years ago (so much time gravitational disturbance spread to the Ground). Analyzing the moments of arrival of the signals (the detector in Livingston recorded the event on seven milliseconds ahead of the detector in Hanford), scientists have assumed that the signal source is located in the southern hemisphere. The results of scientists sent for publication in the journal Physical Review Letters.
The gravitational disturbance is, in fact, the distortion metric?
You could say that. Mathematics is described as a slight curvature of space. Use a laser to detect gravitational waves in 1962 suggested that gertsenshtein and Pustovoit. It was such Soviet art, fantasy… Nice, but still a flight of fancy. Americans thought and decided in the 1990-ies (Kip Thorne, Ronald Drever and Rainer Weiss) to make a laser gravitational antenna. Moreover, two antennas are required, because if there will be events, you must use the schema matches. And then it all started. It’s a long story. We work with over Caltech since 1992, and on a formal contractual basis passed in 1998.
Don’t you think that the reality of gravitational waves was never in doubt?
In General, the scientific community was confident that they exist, and to discover them is a matter of time. The Khalsa and Taylor were awarded the Nobel prize for the discovery of actual gravitational waves. What did they do? There are double stars — pulsars. Once they are spinning, that radiate gravitational waves. To watch them we can’t. But if they radiate gravitational waves, we give energy. So, their rotation slows down, as if from friction. The stars approach each other, and you can see the frequency change. They looked and saw (1974 — approx. “The tape.ru”). This is an indirect evidence of the existence of gravitational waves.
Now — direct?
Now — direct. A signal that registered at the two detectors.
The fidelity is high?
It is enough to open.
Gravitational wave detectors in two
Image: ligo.caltech.edu
What is the contribution of Russian scientists in this experiment?
Key. In initial LIGO (an early version of the antenna — approx. “The tape.ru”) was used desyatikilogrammovy mass, and they were hanging on the steel threads. Our scientist Braginsky already expressed the idea of using quartz fibres. The work that showed that quartz threads “noise” is much smaller. And now the masses (in advanced LIGO, the setting — approx. “The tape.ru”) hanging on quartz threads.
The second contribution is an experimental and is associated with the charges. Mass, separated by four kilometers, must somehow align with electrostatic actuators. This system better than magnetic, which was used earlier, but she feels the charge. In particular, each second through the hand of man is a huge number of particles — muons, which can leave the charge. Now with this problem are struggling. Our group (Valery Mitrofanov and Leonid Prokhorov) that experimentally is involved and greatly skilled.
In the early 2000-ies was the idea to use on advanced LIGO sapphire filament as formally sapphire q-factor above. Why is it important? The higher the factor, the less noise. This is the General rule. Our group considered the so-called thermoelastic noise and showed that it is better to use quartz instead of sapphire.
And yet. The sensitivity of the gravitational antenna close to the quantum limit. There are so-called standard quantum limit, if you measure the coordinate, then according to the Heisenberg uncertainty principle you stir up her and. If you continuously measure the coordinate, you are all the time it amazes me. Very accurately measure the coordinate of the bad: there is a wide inverse fluctuation effect. It showed in 1968 Braginsky. Estimate for LIGO. It turned out that for initial LIGO sensitivity over the standard quantum limit is about ten times.
The scheme of the interferometers and their locations in US
Image: ligo.caltech.edu
Now it is hoped that advanced LIGO will reach the standard quantum limit. Maybe lowered. It’s all a dream. Can you imagine that? You will have a macroscopic quantum apparatus: two heavy masses at a distance of four kilometers.
This seemingly not very compatible.
This paradoxical. So it turns out fantastic. It seems, smacks of quackery, but actually — no, all is fair. But while it is dreams. Standard quantum limit is not reached. It needs more work. But it is clear that it is close.
There is hope that this will happen?
Yes. Need to overcome the standard quantum limit, and our group participated in the development of methods of how to do it. This so-called quantum non-influence measure, what particular measurement scheme desired — this or that… Because when you examine theoretically, calculations are worthless, and the experiment — roads. In LIGO achieved an accuracy of ten to the minus 19 meters.
Remember the children’s example. If we reduced the Earth to the size of an orange, and then it will decrease at the same time, we get the size of an atom. Now, if we reduce the atom at the same time, we will get ten to the minus 19 meters. It’s a crazy thing. This achievement of civilization.
This is very important, Yes. So that means for science is the discovery of gravitational waves? It is believed that it may alter Supervisory methods of astronomy.
What do we have? Astronomy in the normal range. Radio telescopes, infrared telescopes, x-ray Observatory.
In all electromagnetic bands?
Yes. In addition, there is a neutrino Observatory. There is a registration of cosmic particles. This is another channel of information. If gravitational antenna will give astrophysical information, the researchers will have at their disposal multiple channels of observation, by which to test the theory. It offers a number of cosmological theories competing with each other. It will be possible to weed out. For example, when the Large hadron Collider discovered the Higgs boson, immediately disappeared a few theories.
That is, it will contribute to the selection of the working cosmological models. Another question. Is it possible to use a gravitational antenna for high-precision measurement of the accelerated expansion of the Universe?
While sensitivity is very small.
And in the future?
In the long term can be used to measure the relic gravitational background. But any experimentalist will tell you, “AI-ya-Yai!” That is far from it. God forbid that we registered astrophysical catastrophe.
The collision of black holes…
Yes. After all, it’s a disaster. God forbid there be. We wouldn’t be. And here is fonic like this… Until… “the optimistic hopes, the joy of serving the elders”.
The LIGO interferometer
Photo credit: LIGO Laboratory
Could it be the discovery of gravitational waves is yet another confirmation of existence of black holes? After all, there are still those who do not believe that they are.
Yes. How to work in LIGO? Recording signal, for explaining which scientists are developing templates and compare them with observations. The collision of neutron stars, neutron star falls into the black hole, a supernova explosion, a black hole merges with a black hole… will change the parameters such as mass ratio, the initial time… What should we see? Recording is in progress, and at the time of the signal is evaluated the performance of the templates. If a template is developed for the collision of two black holes, approached the signal, it’s proof. But it is not absolute.
The best explanation, no? The discovery of gravitational waves it is easiest explained by the collision of black holes?
At the moment, Yes. Now the scientific community believed that it was a merger of black holes. But the collective community is the opinion of many, a consensus. Of course, if there are any new factors, it can be waived.
When will be able to register gravitational waves from massive objects? Does this mean that we must build new and more sensitive Observatory?
There is a program of the next generation of LIGO. This is the second. Will be the third. There’s a lot of options. You can increase the distance, increase capacity, suspension. Now everything is discussed. At the level of brainstorming. If confirmed by the observation of the gravitational signal, it will be easier to get money for upgrading the Observatory.
It is expected construction boom gravitational observatories?
I do not know. It’s expensive (LIGO cost about $ 370 million — approx. “The tape.ru”). After all, the Americans offered to build Australia in the southern hemisphere the antenna and has agreed to provide all equipment. Australia refused. Too expensive toy. The Observatory would have taken the entire science budget of the country.
Russia participates financially in LIGO?
We cooperate with the Americans. What happens next is unclear. While we have relationships with scientists is good, but policy is ruled by all the same… So you need to watch. They appreciate us. We give the results really on the level. But no they decide to be friends with Russia or not.
Unfortunately, Yes.
This is the life, wait.
In Russia it is planned to construct gravitational Observatory?
Observatory LIGO is funded by the National science Foundation of the USA. Research in LIGO are held in the framework of the same collaboration more than a thousand scientists from the U.S. and 14 other countries, including Russia, represented by two groups from Moscow state University and Institute of applied physics of the Russian Academy of Sciences (Nizhny Novgorod).
Not planned yet. In the 1980s, the State astronomical Institute named after Sternberg of the Moscow state University wanted to build in the Baksan gorge the same gravitational antenna, only on a smaller scale. But came perestroika, and all the long covered with a copper basin. Now the Sternberg astronomical Institute of Moscow state University is trying to do something, but as long as the antenna doesn’t work…
What else you can try to check with the help of gravitational antennas?
The validity of the theory of gravity. Because most of the existing theories based on Einstein’s theory.
Nobody still can’t refute.
It holds the leading position. An alternative theory is designed so that basically lead to the same experimental consequences. And this is natural. We need new facts that would rule out incorrect theories.
How would you briefly formulated the importance of this discovery?
Actually started gravitational astronomy. And the first wave of space curvature were hooked. Not indirectly, but directly. A man admires a: Ah Yes I, Ah Yes son of a bitch!
