On February 11, 2016, LIGO (Laser Interferometric Gravitational-Wave Observatory, see photo) announced the discovery of gravitational waves: two black holes with masses of 30 solar masses merged at a distance of about 1.3 billion light years from the Earth.
Should we believe this statement?
The LIGO observatory has recorded some shake and claims that this shake is caused by gravitational waves from the confluence of two black holes. How do scientists distinguish the shake of instruments caused by gravitational waves, from a shake caused by something else, for example, a very weak earthquake? From the materials of the press, it is not clear at all what exactly scientists discovered, and why they interpreted this as the influence of gravitational waves.
Someone may object: “Well, after all, scientists understand what they are doing, once announced, they had grounds.” Of course, the grounds were. But which ones?
A brief history of the search for gravitational waves.
In the late 1960s, a famous scientist, expert in Einstein’s theory of gravity Josew Weber began to publish articles in which he claimed that he was detecting gravitational waves. No scientist made such a statement, and the very possibility of detecting such waves was not considered obvious. However, Weber was an authority in his field, he was engaged in the search for gravitational waves for more than ten years, and so colleagues took his statement with full seriousness. Weber’s reports became a scientific sensation, numerous groups around the world began to build similar detectors.
Weber used as detectors aluminum cylinders of a meter length with piezoelectric sensors at the ends. They were placed in a vacuum chamber and were isolated with the greatest care from external mechanical influences. Two such cylinders Weber installed in a bunker on the golf course of Maryland University and one in the Argonne National Laboratory near Chicago.
The idea of the experiment is simple. The space under the action of gravitational waves is compressed and stretched, so the cylinder vibrates in the longitudinal direction, acting as a gravitational wave antenna. Piezoelectric crystals respond to vibration by electrical polarization, which can be measured. Passage of gravitational waves simultaneously acts on detectors, separated by a thousand kilometers, which allows them to filter out noise. This principle of detecting gravitational waves is still unchanged.
The Weber sensors were able to observe the displacement of the end faces of the cylinder, which are only 10-15 of its length. It was such fluctuations Weber managed to decect about which he first reported in 1969 on the pages of Physical Review Letters. All attempts to repeat these results were in vain. Weber’s data also contradicted theoretical calculations, which did not allow us to expect relative displacements above 10-18. It is possible that Weber got confused at the statistical processing of the results, but this is just a hypothesis. In short, the first attempt to detect gravitational radiation failed.
Subsequently, gravitational wave antennas were significantly improved. American physicist William Fairbanks proposed to cool them in liquid helium. This made it possible to get rid of most of the thermal noise. By the beginning of the 1980s, physicists at Stanford University built an installation with a sensitivity of about 10-18, but no waves were recorded. Now in a number of countries, ultra-gravity vibrational detectors of gravitational waves operate at temperatures of only tenths and hundredths of a degree above absolute zero. This, for example, is the installation of AURIGA in the Italian city of Padua. Antenna for it is a three-meter cylinder made of an aluminum-magnesium alloy, whose diameter is 60 cm, and weight is 2.3 tons. It is suspended in a vacuum chamber, cooled to 0.1 kelvin. Its concussions (with a frequency of the order of 1000 hertz) are transmitted to an auxiliary resonator with a mass of 1 kg, which oscillates with the same frequency, but with a much larger amplitude. These vibrations are recorded by measuring equipment and analyzed by a computer. The sensitivity of the complex AURIGA is about 10-21.
Another method for detecting gravitational waves is based on the use of a light interferometer. The passing wave deforms the space and changes the length of each arm of the interferometer, stretching one and squeezing the other. As a result, the interference picture changes, and this change is recorded. Today the biggest such installation is the American LIGO complex.
Now think about this. In the 70s and 80s of the last century, gravity specialists seriously hoped to detect gravitational waves. There are formulas for the magnitude of gravitational waves, the sensitivity of instruments is also known. The specialists in gravitation probably did some calculations to show that they are REALLY able to detect gravitational waves. Otherwise they would not have been allocated funds. But the 21st century came. Sensitivity of instruments has grown thousands of times, and gravitational waves still could not be detected. Conclusion: in the 70th and 80th years of the last century there was no possibility to detect gravitational waves. Experts thought and even were sure that it was real. Conclusion, they did not understand the topic well. That is, they were not specialists. Today’s specialists are their students and they work with the same specialists. How can they be trusted?
Let’s look at the facts.
- LIGO consists of two observatories: in Livingstone (Louisiana) and in Hanford (state of Washington), 3002 kilometers distant from each other. Since the speed of propagation of gravitational waves is expected to be equal to the speed of light, this distance gives a difference of 10 milliseconds, which will allow to determine the direction to the source of the recorded signal.
- The international scientific community LIGO is a growing group of researchers every year: about 40 research institutes and 600 individual scientists are working on analyzing data coming from LIGO and other observatories.
- The project is funded by the US National Science Foundation. Its cost is 365 million dollars. This project is the most ambitious among all ever financed by the fund.
- For 15 years of LIGO’s work, only one event has been registered or rather, just one statement about one event.
Question. If the investors of the LIGO project knew that there would be NOTHING in 15 years, and then there would be ONLY one statement about one event, would they finance the project? Unlikely.
The LIGO project has been modernized several times and improved. Investors continued to invest in it.
Question. If there was NOT a statement about the event, would the investors of the project agree to continue its financing? Yes or no? If not, then the entire collaboration of forty institutions would have remained without work. We should add to this that this year marks the 100th anniversary of the creation of the general theory of relativity.
The most important thing. A distinctive feature of science is the ability to reproduce the results. How can we repeat the merging of 2 black holes to check all this?
The photo shows two superimposed signals from two LIGO units, which were interpreted as a collision of two black holes.
Who can refute or confirm such an interpretation?
When writing the text the author used information from Wikipedia: (https://ru.wikipedia.org/wiki/LIGO) and “Troitsky variant”: