Mathematical allusions and mathematical stories

Eula not only values ??education, but also values ??talents. At that time, Lagrange in France was only 19 years old, while Euler was 48 years old. Lagrange and Euler communicated to discuss the "isoperiod problem", and Euler was also studying this problem. Later, when Lagrange achieved results, Euler suppressed his own paper and let Lagrange publish it first, making him famous in one fell swoop.

When Euler graduated from college at the age of 19, he did not find a suitable job in Switzerland. In the spring of 1727, he tried unsuccessfully to take up the vacant post of director of the Faculty in Basel. At this time, the Russian Academy of Sciences in St. Petersburg had just been established and was recruiting scientists from all over the country and searching for talents extensively. Daniel Bernoulli, who had applied to work in Petersburg, was well aware of Euler's talents, so he tried his best to hire Euler to go to Russia. Under these circumstances, Euler left his homeland. Due to Daniel's recommendation, Euler was invited to St. Petersburg in 1727 to be Daniel's assistant. At the St. Petersburg Academy of Sciences, he successfully obtained the position of associate professor of advanced mathematics. In 1731, he was appointed to lead the work of the theoretical physics and experimental physics teaching and research offices. In 1733, Euler, who was only 26 years old, succeeded Daniel, who returned to Switzerland, and became professor of mathematics and leader of the mathematics department of the Petersburg Academy of Sciences.

During this period, Euler worked diligently and published a large number of excellent mathematical papers, as well as other papers and books.

The foundation of classical mechanics was laid by Newton, and Euler was its main architect. In 1736, Euler published "Mechanics, or the Theory of Analytical Description of Motion", where he was the first to clearly propose the concept of a particle or particle, and was the first to study the velocity of a particle moving along any curve, and in relation to velocity and acceleration Apply vector concepts to the problem.

At the same time, he founded analytical mechanics and rigid body mechanics, and researched and developed elastic theory, vibration theory and material mechanics. And he applied vibration theory to music theory. In 1739, he published a work on music theory. In 1738, the French Academy of Sciences established a prize for essays answering questions about the nature of heat, and Euler won the prize for his essay "On Fire." In this article, Euler regarded the essence of heat as the vibration of molecules.

The most distinctive feature of Euler’s research problems is that he put his mathematical research hands deep into the depths of nature and society. He is not only an outstanding mathematician, but also a master of integrating theory with practice and a master of applied mathematics. He likes to work on specific concrete problems, unlike some modern mathematicians who are too interested in working on general theories.

Precisely because the problems Euler studied were closely connected with the actual production, social needs and military needs of the time, Euler's creative talents were fully utilized and he achieved amazing achievements. While engaging in scientific research, Euler also applied mathematics to practice, solved many scientific problems for the Russian government, and made important contributions to society. Such as the renovation plan of the Fino Canal, the design review of the palace extension drainage facilities, writing teaching materials for schools, and helping the government survey and map maps; when working at the Committee of Weights and Measures, he participated in the study of the accuracy of various weighing instruments. In addition, he also writes comments for the Academy of Sciences' official publications and chairs committee work for a long time. Not only did he do a lot of work for the Academy of Sciences, but he also found time to give lectures at the university, give public lectures, write popular science articles, provide astronomical data to the meteorological department, and assist construction units in mechanical analysis of designed structures. In 1735, Euler set out to solve an astronomical problem - calculating the trajectory of a comet (this problem took several famous mathematicians several months of hard work to complete). Because Euler used a new method invented by himself, it only took three days. However, three days of continuous exertion also caused Euler to become ill due to overwork. The disease made the 28-year-old Euler blind in his right eye. Such a disaster did not make Euler succumb. He was still obsessed with science and worked selflessly. However, due to the long-term power struggle among the Russian ruling groups, Euler's work was increasingly affected, making Euler very depressed. As it happened, the Prussian King Frederick the Great (reigned 1740-1786) learned of Euler's situation and invited Euler to Berlin. Although Euler loved his second hometown very much (he lived and worked here for 14 years), for the sake of scientific career, he temporarily left the St. Petersburg Academy of Sciences in 1741 and went to the Berlin Academy of Sciences as director of the Institute of Mathematical Physics. In 1759 he became leader of the Berlin Academy of Sciences.

While working in Berlin, he did not forget Russia. He guided his students in Russia through letters and sent his scientific works to Russia, which played a great role in the development of Russian science.