1845, arago, then director of the Paris Observatory, suggested that Urbain Le Verrier study the abnormal motion of Uranus. Using a large number of observation data about Uranus and Newton's law of universal gravitation, Leveyer calculated the orbit and mass of the unknown planet disturbing Uranus and predicted its position. He submitted the calculation results to the French Academy of Sciences, and at the same time wrote to several astronomers with large telescopes at that time, asking for help in observation. His work was snubbed by his French colleagues, but he got help from the German astronomer John G Galle. 1846 On September 23rd, Caleb observed and searched the night he received the letter from Le Ye Wei. It took him only an hour and a half to observe the star that was not on the map at that time, which was later famous Neptune, which was located 52' away from Le Ye Wei's prediction. The discovery of Neptune pushed Newtonian mechanics to the peak of science.
Later, Levell discovered that the precession of Mercury's perihelion, after excluding the influence of solar gravity and other known celestial orbital perturbations, still has 43 angular seconds of excess precession every hundred years. This cannot be explained by Newton's gravity. Inspired by the discovery of Neptune, Le Ye Wei predicted the existence of "water planets". However, Le Ye Wei failed to find the predicted planet in his lifetime. His observation of the precession of Mercury's perihelion was later successfully explained by Einstein with general relativity. Unlike Newtonian mechanics, in general relativity, the gravitational force between two non-rotating objects is different from that after their rotation. This effect will cause the precession of the rotating shaft, and the precession of Mercury is caused by this effect.
Verification of Einstein's general theory of relativity by astronomical observation
The verification of general relativity is mainly carried out through astronomical observation. One of the "astronomical verification" is the successful explanation of Mercury perihelion precession by general relativity. After deducting the influence of other planets, the calculated annual difference is 42.9 1 ″ per 100, which is in good agreement with the observed value of 43 ″. The observed perihelion age differences of planets such as Earth and Venus are also in good agreement with the calculated values of general relativity.
The second "astronomical verification" is to use the observation of total solar eclipse to verify whether the amount of light bending in the gravitational field conforms to the general theory of relativity. Einstein predicted this phenomenon in theory in 19 1 1 year. He believes that in the event of a total solar eclipse, the deflection angle can be measured by measuring the starlight of a star in the gravitational field near the sun and comparing it with the position of the previous star. Astronomers made many total solar eclipses from 19 12 to 1922. In particular, Arthur S. Eddington, a famous British astronomer, has supported Einstein's prediction since he put forward this theory and made a lot of total solar eclipse observations. The correctness of Einstein's prediction that "the gravity of the sun may lead to the star deflection of light" was tested by the observation results of William W Campbell (1922) and finally confirmed by the mainstream scientific community. .
The third "astronomical verification" is that the gravitational red shift of the spectral line was observed on a white dwarf. General relativity holds that the frequency of light will change when it propagates in the gravitational field. When light propagates from a place with strong gravitational field to a place with weak gravitational field, its frequency will be slightly reduced, that is, gravitational redshift will occur. 19 1 1 year, Einstein calculated that the relative gravitational red shift of light from the sun to the earth is 2× 10-6. This value is very small and difficult to measure. The mass of the white dwarf is close to that of the sun, but its radius is only 1% of that of the sun, so the gravitational redshift effect of the light emitted by the white dwarf is quite obvious. 1925, American astronomer Walter S. Adams observed a white dwarf star (Sirius B), and the measured gravitational redshift was basically consistent with the theoretical calculation of general relativity.
It is worth mentioning that in 1974, American scientists hoels and Joseph H. Taylor discovered a new pulse binary star PSR1913+16. By measuring the decay of the rotation period of this pulsar, the gravitational wave predicted by general relativity is indirectly confirmed. Hall and Taylor also won the 1993 Nobel Prize in Physics for their work.
Astronomical observation overthrew the dominant position of Ptolemy's geocentric theory
After 30 years of astronomical observation, Copernicus gradually became suspicious of Ptolemy's geocentric theory, which ruled religion for a long time. Copernicus discussed in detail the movements of the sun, the earth, the moon and the planets in his Theory of the Movement of Celestial Bodies. He believes that the sun is motionless and the center of the universe, while the earth is just an ordinary planet revolving around the sun.
1609, Galileo made his first astronomical observation with a telescope, and found some new astronomical phenomena that could support Heliocentrism. Then Heliocentrism began to attract people's attention. These celestial phenomena are mainly the discovery of Europa system, which directly shows that the earth is not the only center, and the discovery of Venus' profit and loss exposes the error of Ptolemy's geocentric theory. However, since neither the data supporting Copernicus and Heliocentrism nor the data supporting ptolemaic system were consistent with Tycho's observation, Heliocentrism still had no advantage at that time. It was not until Kepler corrected Heliocentrism with elliptical orbit instead of circular orbit that Heliocentrism won a real victory in the long-term struggle with the geocentric theory. Man finally realized that the earth is not the center of the universe. Goethe, a German poet, once said, "Copernicus shocked human consciousness so deeply that there were no original ideas or inventions since ancient times." It is no exaggeration to say that Heliocentrism of Copernicus opened the curtain of modern scientific revolution.
However, is the sun really the center of the universe? This is a problem that people have always been very concerned about. Since18th century, many famous astronomers, including Herschel, believe that the sun is located in the center of the Milky Way. American astronomer Shapley observed that globular clusters are not evenly distributed throughout the day, but concentrated in the southern sky, especially Sagittarius. He boldly and clearly pointed out that this is because the sun is not in the center of the Milky Way, but far away from the center, and the center of the Milky Way is in the direction of Sagittarius. Shapley moved the sun away from the center of the Milky Way and put it where it should be. His views are of great significance.
1924, Hubble analyzed the brightness of a batch of Cepheid variables with the 2.54m telescope of Mount Wilson Observatory, and concluded that these Cepheid variables and their "nebulae" are hundreds of thousands of light years away from us, so they must be located outside the Milky Way. This discovery makes people have to change their view of the universe, that is, the Milky Way is also a very common galaxy in the universe. 1925, Hubble's latest observation of extragalactic galaxies shows that galaxies seem to be moving away from us, and the farther away they are, the faster they are moving away. This discovery is a great achievement of astronomy in the 20th century, which subverts the understanding and knowledge of the universe in the past. People have always thought that the universe is static, and now it is of far-reaching significance to find that the universe is expanding. Today, through astronomical observation, human beings finally realize that the universe has no center, and all parts of the universe are moving away from each other and expanding at an accelerated rate.
Astronomical observation is gradually overthrowing the theory that the earth is the center of life in the universe.
In the process of giving up the earth as the center of the universe, human beings have also raised the question of whether the earth is the only home of life in the universe, that is, whether the earth is the center of life in the universe. In fact, everyone is looking for answers to the above questions according to their own understanding. Answers and reflections on these questions run through the whole history of literature, art and science. New scientific discoveries have brought us closer to uncovering some basic problems of life outside the solar system, but they have also raised more new problems.
With the advent of the new millennium, mankind hopes to answer these oldest and deepest questions with its advanced scientific and technological capabilities. Although there is no definite answer to this question, at least the theory of the existence of extrasolar planets has been confirmed by the latest astronomical observations in recent years. Since the 1990s, many breakthroughs have been made in the discovery of star-planet systems similar to the solar system through the observation of large-aperture optical telescopes. So far, astronomers have identified more than 400 candidate stars with planetary systems. Observations also show that these star systems with planets around them and the planets themselves are diverse. About 40 star planetary systems have multiple planets, one of which has five planets and two star systems have four planets. According to statistics, at least 5% of sun-like stars have planetary systems. Recently, a candidate terrestrial planet with a mass about twice that of the earth was detected. What is particularly exciting is that astronomers have successively discovered atmospheric spectral lines such as carbon monoxide, carbon dioxide, methane and water, which are necessary for life, in many planetary nebulae and planets. Astronomers have even been able to directly observe planets orbiting stars through large telescopes and advanced technical methods. At present, through the detection of extrasolar planets, it is developing in the direction of overthrowing the theory of life center in the universe. More and more astronomical observations show that the earth is not the only living planet in the universe.
We have reason to believe that human's innate curiosity and thirst for knowledge will become the driving force for people to find extrasolar planets and their lives. New astronomical observations and discoveries will and will continue to profoundly influence and change the world outlook of the whole mankind and deepen human understanding of the universe. This kind of practical activity under the guidance of reason embodies the spirit of modern scientific exploration, which will certainly bring endless benefits to human beings in understanding nature and living in harmony with it.