On the evening of June 30, 2022, the seventh lecture "Guanya Interdisciplinary Workshop" was held online and offline simultaneously. In this issue, Professor Wu Jianfeng from the Department of Astronomy of Xiamen University was invited to give a lecture on the theme "black holes: thoughts shine into reality". Professor Liu Feng pointed out that the current accounting research largely repeats the existing achievements, but today, with the popularization of computer technology, this repetition has little significance. In order to enhance the imagination of accounting scholars, Professor Wu Jianfeng is specially invited to lead you to broaden your research horizons and dare to imagine boldly.
Professor Wu Jianfeng slowly opened the door to black hole research in the form of drama. First, in the prologue, Professor Wu Jianfeng introduced the structure of the universe at different levels, such as the solar system and the Milky way. Professor Wu Jianfeng explained the concept that the universe includes both time dimension and space dimension by "in the past, in the future, and in the four directions".
In the first act, Professor Wu Jianfeng mainly discussed the thoughts of Newton and Einstein. Newton once said, "if I see farther than others, it is because I stand on the shoulders of giants." Judging from the discovery process of black holes, the early Danish astronomer Tycho designed and built exquisite instruments to accurately measure the motion of planets. Then Tycho's assistant Kepler inherited Tycho's valuable observation data and summarized the three laws of planetary motion. On the basis of previous studies, Newton put forward the "law of universal gravitation", and then led to the concept of black hole from the perspective of material escape. The first recorded person to discuss black holes was John Michel. Michel defined "dark star" from the particle nature of light, that is, when the star mass is greater than a certain value, the particles of light will not escape its gravitational field. However, the discovery of mercury perihelion precession challenged Newton's view. In order to better explain this phenomenon, Einstein put forward the theory of general relativity. Based on the theory of general relativity, German physicist Schwarzschild calculated the first exact solution of Einstein's gravitational field equation, namely Schwarzschild metric.
In the second act, Professor Wu Jianfeng introduced the final fate of massive stars. Michel once proposed that another star in the binary system can be used to detect "dark stars", which is also the first way for people to find black holes. According to the work of Oppenheimer et al., from the perspective of mass, when the mass of a compact star exceeds the Oppenheimer limit, that is, three times the mass of the sun, it can only be a black hole. At present, we have confirmed 23 black hole binary systems through mass measurement. However, it is theoretically estimated that there should be at least 10million stellar black holes in the galaxy. With the development of big data, more and more black holes have been discovered. In 2019, Chinese astronomers found the largest stellar black hole so far
With human exploration of the universe, astronomers continue to find theoretical and empirical evidence to confirm the existence of black holes. From the perspective of stellar black holes, its research process ranges from the Schwarzschild solution proposed by scholars through theoretical derivation, to the improvement of stellar evolution theory, to the deconstruction of binary systems, and finally to the detection of black hole mergers. From the perspective of supermassive black holes, humans first discovered quasars, then proposed a black hole accretion model, then detected the silver core black hole, and finally took pictures of black holes. With the progress of technology, human exploration of black holes will be further deepened.
Finally, Professor Wu Jianfeng had an exchange and discussion with online and offline teachers and students. This lecture has a successful conclusion!
