In early 2016, an international collaboration of physicists registered gravitational waves for the first time in human history. The waves were generated by the merger of two black holes and were detected using a special detector-interferometer LIGO, which is located in the United States. What are gravitational waves, why did it take a century to discover them, and what is the role of Russian scientists in this? The head of the Astronomical Observatory of ISU, scientific director of the Irkutsk Planetarium Sergei Yazev told about this to "Oblastnaya".
- A hundred years ago, Albert Einstein completed his work on the general theory of relativity. The theory, new at that time, allowed the existence of so-called gravitational waves, which arise constantly and everywhere. A simple example: we wave our hand, gravitational waves diverge from the hand. But gravity is the weakest force in nature, and two factors are needed to fix gravitational waves. First, there must be some powerful event in which gigantic masses are involved, for example, the merging of stars with each other, the fall of one star on another, or something similar. And secondly, we need incredibly sensitive equipment that would record the signal from this event on Earth.
The idea of how to register gravitational waves has been around for decades. Physicists perfectly understood what needed to be done, but the necessary technologies simply did not exist for a long time. The US-based LIGO interferometer detector, which detected gravitational wave signals, was conceived back in 1992. For a long time physicists were unable to fix anything, because the installation lacked sensitivity. The fact is that gravitational waves are, in fact, vibrations of a certain entity, which physicists call "space-time". This means, for example, that the distance between two elements of the installation may begin to fluctuate, because the space itself changes its properties. It turned out that the required sensitivity of the device is beyond the limits of real perception - the amplitude of oscillations should be about 10 thousand times less,than the size of the atomic nucleus. This is fantastic accuracy. Last year, the installation was modernized, after which it was possible to record a signal from the depths of the Universe about an extremely powerful event - the merger of two black holes. It happened one billion three hundred million years ago, and only on September 14 last year, its echoes reached the Earth. Thanks to the simultaneously recorded gamma-ray burst, it became clear that this is not random noise. Experts have been checking the result for a very long time and only in February they risked informing the world that a great discovery had been made.and only on September 14 last year its echoes reached the Earth. Thanks to the simultaneously recorded gamma-ray burst, it became clear that this is not random noise. Experts have been checking the result for a very long time and only in February they risked informing the world that a great discovery had been made.and only on September 14 last year did its echoes reach the Earth. Thanks to the simultaneously recorded gamma-ray burst, it became clear that this is not random noise. Experts checked the result for a very long time and only in February did they risk to notify the world that a great discovery had been made.
Sergey Arturovich, what is the significance of the discovery of gravitational waves for science?
- Gravitational waves go through anything. This means that we will receive a new type of information about physical processes. During the September 14 event, the three masses of the Sun, when two black holes merged, turned into energy of gravitational waves. This is a monstrous energy, so even at a distance of one billion three hundred million light years, we felt this event. Imagine: a tremor of space that has spread throughout the entire universe.
It is important to note that several other discoveries were made simultaneously with the registration of gravitational waves. First, evidence of the existence of black holes has been obtained. Astronomers and astrophysicists did not doubt this, but some theoretical physicists until recently denied the existence of such objects. Second, it was confirmed that gravitational waves travel at the speed of light, which was predicted in general relativity.
One more discovery must be said. There is such a concept of "black hole event horizon". Two holes merged with each other, the event horizon took on a certain complex shape and fluctuated. The result is a shell, under which there is already a black hole, but not yet outside. This effect - the dynamics of the event horizon - was first recorded during observations, although no one expected this kind of discovery.
Did Russian scientists take part in an experiment to register gravitational waves?
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- The detector-interferometer is American, but the experience was provided by an international team, which included Russian specialists. The installation caught the gravitational waves themselves, but it was necessary to understand where they came from, what event caused them. So, for this, the program used telescopes from all over the world, including the Russian network of telescopes "MASTER". However, it was still possible to determine the source of the waves with the help of foreign technology.
Many of the theoretical foundations of the experiment staged in the United States were created in Russia. In our country, one of the pioneers of the search for gravitational waves was the famous physicist, an employee of Moscow State University, Vladimir Braginsky.
Moscow astrophysicist, head of the MASTER project, Vladimir Lipunov, together with his colleagues, back in 1992 published an article in which it was said that the first event for fixing gravitational waves would be precisely the merging of black holes. In addition, it is known that Russian scientists have contributed to the development of the design of the detector-interferometer. In general, about a thousand people, one way or another, took part in the project, and Russian physicists made their contribution to the common cause.
Can the discovery of gravitational waves qualify for the Nobel Prize in Physics?
- In general, the discovery of gravitational waves is a Nobel-class event. In most cases, discoveries happen unexpectedly. But in the past few years, there have been two exceptions where discoveries were predicted and they did happen. We are talking about the Higgs boson, the discovery of which had been waiting for several decades, and gravitational waves, which took a hundred years to confirm. All these events were predicted theoretically, in both cases the theory turned out to be correct and confirmed by observations. In 2013, the top prize in physics went to François Engler and Peter Higgs. I think that the Nobel Prize will also be awarded for the discovery of gravitational waves.