Zu Chongzhi (429-500) was a mathematician, astronomer, and physicist in the Southern and Northern Dynasties of China. Zu Chongzhi's grandfather was named Zuchang, and he was an official in charge of court buildings in the Song Dynasty. Zu Chongzhi grew up in such a family and read a lot of books since he was a child. People praised him as a learned young man. He was particularly fond of studying mathematics and astronomy and calendars. He often observed the movements of the sun and planets and kept detailed records.
Emperor Xiaowu of the Song Dynasty heard about his reputation and sent him to work in the "Hualin Academic Province", an official agency specializing in academic research. He was not interested in being an official, but there he could concentrate more on studying mathematics and astronomy.
Our country has had officials who studied astronomy in all dynasties, and calendars were formulated based on the results of astronomical research. By the time of the Song Dynasty, the calendar had made great progress, but Zu Chongzhi thought it was not accurate enough. Based on the results of his long-term observations, he created a new calendar called the "Daming Calendar" ("Daming" is the reign name of Emperor Xiaowu of the Song Dynasty). The number of days in each tropical year (that is, the time between two winter solstice points) measured by this calendar is only fifty seconds different from that measured by modern science; the number of days it takes for the moon to circle around is not different from that measured by modern science. To one second, you can see how accurate it is.
In 462 AD, Zu Chongzhi asked Emperor Xiaowu of the Song Dynasty to promulgate a new calendar, and Emperor Xiaowu convened ministers for discussion. At that time, Dai Faxing, a favored minister of the emperor, came out to object, believing that Zu Chongzhi's unauthorized change of the ancient calendar was an act of deviance. Zu Chongzhi used the data he studied to refute Dai Faxing on the spot. Dai Faxing relied on the emperor's favor and said arrogantly: "The calendar was established by the ancients and should not be changed by future generations." Zu Chongzhi was not afraid at all. He said solemnly: "If you have factual basis, just use it to argue. Don't scare people with empty words." Emperor Xiaowu of the Song Dynasty wanted to help Dai Faxing, so he found some people who knew the calendar to argue with Zu Chongzhi, but they were all refuted by Zu Chongzhi. . However, Emperor Xiaowu of Song Dynasty still refused to promulgate the new calendar. It was not until ten years after Zu Chongzhi's death that the Daming Calendar created by him was implemented.
Although the society was very turbulent at that time, Zu Chongzhi still studied science tirelessly. His greater achievement was in mathematics. He once commented on the ancient mathematical work "Nine Chapters on Arithmetic" and compiled a book "Zhu Shu". His most outstanding contribution was the fairly accurate calculation of pi. After long-term and painstaking research, he calculated that pi is between 3.1415926 and 3.1415927, becoming the first scientist in the world to calculate the pi value to more than seven digits.
Zu Chongzhi was a generalist in scientific inventions. He built a compass car. No matter how the car turned, the bronze figure on the car always pointed south; he also built " The "thousand-mile ship" was tested on the Xinting River (southwest of today's Nanjing City) and could sail more than a hundred miles a day. He also used water power to turn stone mills and pound rice to grind millet, which was called "water mill".