On this day, 187 years ago, on February 18, 1838 (January 24, 1838, lunar calendar), Austrian physicist and named the speed quantifier "Mach" Mach was born. Ernst Mach, from 1838 to 1916, was an Austrian Czech physicist, philosopher, and biologist. He was born on February 18, 1838 in Chillitz. My father is a governess. In his childhood, he was good at observing the cause and effect of things with hearing and touch under the charm of nature. In junior high school, he was not interested in the curriculum of missionary schools and was regarded as a child who was not suitable for studying knowledge and had poor grades. His father's library became a treasure house for his self-study. Studied mathematics, physics and philosophy at the University of Vienna, graduating in 1860 with a doctorate. From 1864 to 1867, he served as professor of mathematics and experimental physics at the University of Graz, and from 1867 to 1895, he served as professor of experimental physics at the University of Prague, and was twice elected president. Retired in 1901, but continued to write science at home. He died on February 19, 1916 in Testeten, Germany. Mach devoted his life to the study of experimental physics and philosophy. Published more than 100 research papers and reports on mechanics, acoustics and optics. When he studied the high-speed movement of objects in a gas, he discovered shock waves. The ratio of object velocity to sound velocity (i.e. Mach number) was determined as a standard to describe the supersonic motion of an object. Terms named after Mach, such as Mach effect, Mach wave, Mach angle, etc., are widely used in aerodynamics. This is Mach's historic contribution to mechanics. He first used instruments to demonstrate the acoustic Doppler effect and proposed the theory of n-dimensional atoms. Mach is a critical theoretical physicist. Through his historical investigation of science and analysis of scientific methodology, he wrote several works with strong epistemological color and historical viewpoints. Among them,"Introduction to the Critical History of Mechanics and Its Development"(referred to as "Review of the History of Mechanics") in 1883. This work has the greatest impact and has had a profound impact on the development of physics. In his book, his criticism of Newton's absolute time and absolute space and his understanding of inertia played a positive role in Einstein's establishment of general relativity and became the basis for the latter to write the gravitational field equation. Later Einstein called his idea Mach's principle. Mach's scientific epistemology has had a strong response among natural scientists. The most famous scientists influenced by it are Einstein and Bridgman, as well as some physicists from the Copenhagen School of Quantum Mechanics. Mach also wrote "Physics Course for College Students"(1891) and "Natural Science Textbook for Lower Secondary School Students"(1886), which were reprinted 20 times and used for 40 years. He was a well-known physics educator. Mach was a philosophical idealist and logical positivist. He denied the kinetic theory of gases and the authenticity of atoms and molecules. Boltzmann had sharp criticism of this. Lenin also criticized Mach's idealistic views in his book "Materialism and Empirical Criticism".