Shulou(Shulou.com)11/24 Report--

Zu Chongzhi, the word Wenyuan, was born on April 20, 429 AD and died in 500 AD. He was born in Huailai County, Hebei Province. He is an outstanding mathematician and scientist in ancient China. At the end of the Western Jin Dynasty, due to the continuous wars in the north, he moved to the south of the Yangtze River with his father. Zu Chongzhi received a family science education from an early age. As an adult, he successively held local official posts in Zhenjiang and other places, and at the same time engaged in research in the then academic institution-- Hualin Science Province. Zu Chongzhi made important contributions in mathematics, astronomical calendar and machinery.

Zu Chongzhi has a wide range of interests in natural science, literature, astronomy and philosophy. he is proficient in rhythm and chess, and advocates not to "falsely push the ancients" all his life, but to "search the past and the present", that is, to absorb the quintessence of ancient and modern times and not to worship the ancients blindly. He extensively collected all kinds of documents from the ancient times to the 6th century and carefully investigated them.

In scientific observation and research, Zu Chong-chih has a rigorous academic practice. As he said, "measure the main ruler, examine the leakage of the instrument, make every effort, and make plans in your heart." and insist on astronomical observation and mathematical calculation in his spare time. It was his rigorous work style and rich and solid knowledge that enabled him not only to accumulate a large number of new materials, but also to make many valuable achievements in mathematics, astronomy and machinery manufacturing, making him a rare erudite in Chinese history. Unfortunately, most of his works have been lost.

In the process of creating the Daming Calendar, Zu Chongzhi also discovered the phenomenon of precession. At the moment of the Winter Solstice every year, after a return year, the sun returns to the winter solstice of the zodiac. However, the winter solstice is not at the same point of the zodiac, but moves slowly in the air. The annual movement is called precession. Through continuous observation, Zu Chongzhi clearly pointed out that "where the Winter Solstice is, there is a slight difference in the years." He was the first to calculate the precession, and introduced the precession as an important factor into the calculation of the calendar, which is of great significance to improve the accuracy of the calendar. More importantly, he distinguishes the two concepts of the sidereal year in which the sun moves around the ecliptic and the regression year that reflects the cycle of the four seasons, and uses precession to compile the calendar, which is a major reform in the history of calendar compilation and becomes the basis followed by later generations.

Zu Chongzhi estimated that the number of days in the return year is 365.24281481 days (currently 365.24219819 days). He also invented a method to determine the time of the Winter Solstice by measuring the shadow length of the sun before and after the Winter Solstice. In addition, he adopted the leap method of 144 months per 391 years, and accurately calculated for the first time that the number of days and months at the intersection point was 27.21223 (currently 27.21222). Due to the accurate determination of this value, the accurate prediction of solar and lunar eclipses is possible.

Zu Chongzhi also created the Great Ming Calendar and used this calendar to accurately calculate the four solar and lunar eclipses that would occur in the 23 years from 436 to 459, and all his subsequent forecasts were successful. In addition, he accurately measured Jupiter's orbit period of 11.858 years (currently 11.862 years).

In the year 500 AD, there can be neither advanced mathematical theory nor precise instruments. Zu Chongzhi's accurate calculation of these values and perfect application show his meticulous thinking and exquisite technology.

In terms of machinery, Zu Chongzhi designed and supervised the water mill for removing rice husks, which is a tool for hydraulic processing of grain. It has also made a copper guide car, a boat that can travel hundreds of miles a day, land transport similar to a wooden ox and a horse, an hourglass with accurate timing, and ingenious tools.

The most wonderful thing about the copper guide car is Zu Chongzhi's calculation of pi. Pi is the most mysterious, difficult and attractive number in mathematics, which attracts the attention of many people at home and abroad. It took more than 4,000 years from ancient humans to Mayans, Mesopotamians, Chaldaeans, Hebrews, Arabs, and modern people from the 20th to the 21st century. Many people are attracted by the value of π and stubbornly pursue its exact value. Zu Chongzhi is one of them.

Around AD 100, the π value calculated by Zhang Heng, a famous scientist in the Eastern Han Dynasty, was 3.162; around 250 AD, Liu Hui in the Wei and Jin dynasties invented circle cutting, that is, by using the method of approaching polygons, the π value obtained by Zu Chongzhi was between 3.1415926 and 3.1415927, accurate to the 7th decimal place, which was a remarkable achievement at that time.

According to records, around 820 AD, the value of π calculated by Persian scholars was 3.1416, which indicated that the value of π calculated by Zu Chongzhi was at least 300 years ahead of the world until 1400 AD. Zu Chongzhi's record was broken by the Arab mathematician El Kashgar. Therefore, Zu Chongzhi's record was selected as the highest in the world, and was determined by the World Records Association as the first mathematician in the world to calculate pi to the 7th decimal place.

Zu Chongzhi also gave two common approximations of the value of π, that is, the approximate rate of 22max 7 and the density of 355max 113, in which the secret rate has been accurate to the seventh place after the decimal point, which was not discovered by the Dutch mathematician Otto in the 16th century. Exactly what method Zu Chongzhi used to get such a calculation result, there is no historical data to test, and many people speculate that it is the approach method of external polygons. No matter what the method is, its calculation is a very difficult and time-consuming task. The job is boring for others, but fun for those you love. After Zu Chongzhi's death, his son Zuyi inherited his father's career and further discovered a way to calculate the volume of the ball.

On November 9, 1964, to commemorate Zuchongzhi's great contribution to science and culture, the Zijinshan Observatory in Nanjing, China named the asteroid 1888 named "Zuchong Star", which made Zuchongzhi shine for generations.

Source: 365 days in the History of Science, slightly edited by: Wei Fengwen Wu Yi Editor: Zhang Runxin this article comes from the official account of Wechat: Origin Reading (ID:tupydread), author: Wei Fengwen, Wu Yi, Editor: Zhang Runxin

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