Wang Yusheng
The 20th century is a century of rapid development of science and technology. In this century, the scientific and technological achievements and material wealth created by mankind have surpassed any previous era. They are decisive factors to promote the sustainable development of economy and society, and have changed and will continue to change the face of the world. Some of them are great achievements recognized by the scientific and technological circles and will shine brilliantly in human history forever.
Two great achievements of scientific revolution in the early 20th century.
Science in the 20th century was developed on the basis of major theoretical achievements in19th century, such as thermodynamics and electromagnetism, chemical atomism, biological evolution, cell theory and so on. /kloc-Three discoveries (X-ray, radioactivity and electron) in the 0/9th century triggered the physics revolution in the first 30 years of the 20th century, and gave birth to the theory of relativity and quantum mechanics, which became the forerunner and foundation of scientific development in the 20th century.
1, relativity
1905, Einstein, the greatest scientific genius in the 20th century, founded the special theory of relativity at the age of 26, and put forward a brand-new concept of time and space and the equivalence relation of mass (m), energy (e) and e = mc2 (here, the speed of light c = 3× 108m/s), which opened the way for the theoretical application of atomic energy.
It is inconceivable that e = mc2, that is, the energy stored by an object is equal to the mass of the object multiplied by the square of the speed of light. For example, the energy of 1 g material completely converted is equivalent to all the heat energy released by burning 36,000 tons of coal under normal conditions; In other words, the mass of 1 g is equivalent to 25 million kWh of electricity.
19 15 years, Einstein founded the general theory of relativity, which profoundly revealed the internal relationship between time, space, matter and motion-time and space change with the distribution of matter and the speed of motion. It has become one of the basic theories of modern physics.
Starting from 1923, Einstein devoted himself to the exploration of unified field theory in the latter half of his life, trying to establish a unified field theory including both gravitational field and electromagnetic field. Although they failed, they founded the "Young-Mills Field Equation" in 1950s and developed the so-called gauge field theory, which enabled Einstein's dream unified field theory to be realized on the basis of gauge field.
2. Quantum mechanics
1900, Planck founded quantum theory, and put forward a new concept that energy is not infinitely divisible, and the change of energy is discontinuous. 1905, Einstein put forward the quantum theory of light and revealed the "wave-particle duality" of light. 19 13, Bohr introduced the concept of quantization into the theory of atomic structure. 1923, De Broglie put forward the theory of matter wave. 1925, Heisenberg and Schrodinger established matrix mechanics and wave mechanics respectively. 1928, Dirac, 26, put forward the relativistic motion equation of electrons in electromagnetic field and the original form of quantum field theory, which made great progress in quantum mechanics including matrix force and wave mechanics.
The establishment of quantum mechanics at the end of 20th century is another revolutionary breakthrough in classical physics after the establishment of 1905- 19 15 theory of relativity. It successfully reveals the basic laws of the microscopic material world, accelerates the development of atomic physics and solid state physics, prepares the theoretical foundation for nuclear physics and particle physics, and promotes the production of chemical bond theory and molecular biology. Therefore, quantum mechanics can be said to be the richest scientific theory in the 20th century, and it still has strong vitality.
Five scientific achievements in the middle and late 20th century
Since 1930s, the basic structure of matter, gauge field, BIGBANG, molecular double helix structure of genetic matter, plate theory, information theory, cybernetics, system theory and other theories have been established one after another, which has further expanded human vision to more comprehensive, macro and micro fields and become a great driving force for the progress of human civilization.
1, the basic structure of matter
Since ancient times, people have been discussing what matter is made of and whether there is a public basic unit. Until the end of 19, people thought that the same primitive was an atom. 19 1 1 year, Rutherford discovered that there was a nucleus inside the atom; 19 13 years, Bohr pointed out that radioactive changes took place inside the nucleus, which led to nuclear physics that studied the composition, changing law and internal binding force of the nucleus.
1932, chadwick discovered neutrons. Since then, people have realized that all kinds of atoms are composed of electrons, protons and neutrons, so these three kinds of particles and photons are called elementary particles.
However, elementary particles are not "elementary". On the one hand, new elementary particles such as positrons, neutrinos and mesons have been discovered one after another; On the other hand, elementary particles also have their internal structures. Since 1960s, quark model and straton model of basic particle structure have appeared one after another, which makes a new independent discipline-basic particle physics (also called high-energy physics) born in the late 1940s still in the ascendant and fruitful.
2. The Big Bang Theory
The study of modern cosmology originated from Einstein. After he founded the general theory of relativity in 19 15, he used it to investigate the structure of the universe, and put forward a finite and infinite model of the universe in 19 17. 1922, Friedman put forward a non-static model of the universe, thinking that the universe can expand. 1929, Hubble determined the linear relationship between the redshift (i.e. the regression velocity) of galaxies and the distance, and confirmed the theory of cosmic expansion. 1932, Lemaistre put forward the theory of cosmic explosion.
1948, Gamov combined the knowledge of nuclear physics with the theory of cosmic expansion, developed the Big Bang theory, and used it to explain the origin of chemical elements. This big bang theory is strongly supported by the cosmic background radiation phenomenon discovered in 1965 and the galaxies detected by Hubble telescope in 1998, which are 200 million light years away from the earth/kloc-0.
3.DNA molecular double helix model
1On April 25th, 953, the British magazine Nature published a molecular model of ——DNA double helix structure, which was the result of cooperative research by Watson, 25, and Crick, 37. This achievement was later hailed as the greatest discovery of biology in the 20th century, and it was also considered as the symbol of the birth of molecular biology.
DNA is the abbreviation of deoxyribonucleic acid, which is the material carrier of genetic genes. During the period from 19 15 to 1928, Morgan proved that the genes located on the chromosomes in the nucleus determined the biological characteristics through the experiments of Drosophila melanogaster, thus establishing the gene theory. Chromosomes consist of protein and DNA. In the past, biologists always thought that protein was the carrier of genetic information. It was not until 1944 that Avery and others proved that the genetic vector was not protein, but DNA. The establishment of double helix model of 1953 DNA molecular structure is the key to solve the genetic mystery. In 1960s, Njogu Berger and others cracked the genetic code, proving that the genetic code of all living things on the earth is the same-the four nucleotide base sequences of ——DNA represent the genetic information of genes, which determines the composition and arrangement order of 20 amino acids in protein. DNA, as the carrier of genes, is the backstage commander of life, and all the characters of life are represented by protein determined by DNA.
4. Tectonic plate theory.
19 12, Wei Gena put forward the theory of continental drift, thinking that in the Paleozoic in geological history, there was only one huge land in the world, surrounded by an ocean; Since Mesozoic, this ancient land began to split and drift, and gradually became several continents and countless islands. The original ocean was divided into several oceans and several small seas.
After more than half a century's development, the theory of continental drift has developed from mantle convection theory (1928) and submarine spreading theory (19 1 year) to the global plate tectonics theory proposed by 1968 Rebichon, which divides the world into Europe, Asia, America, Africa, the Pacific Ocean and so on.
5, information theory, cybernetics, system theory
1948, the publication of Shen Nong's Mathematical Theory of Communication, Wiener's Cybernetics: The Science of Control and Communication in Animals and Machines, and Bertalanfi's Life Problems marked the birth of interdisciplinary scientific information theory, cybernetics and general system theory. From 65438 to 0957, the publication of System Engineering by Goode et al. laid the foundation of system engineering theory. Since the 1960s, new interdisciplinary subjects have emerged-catastrophe theory, synergy theory and dissipative structure theory.
Interdisciplinary science not only communicates a large number of natural science disciplines, but also communicates natural science and social science in methodology. It provides people with a quantitative, accurate and optimal way to understand the world, which has a far-reaching impact on human society.
Five frontier scientific and technological achievements in the 20th century.
Under the guidance of science and the promotion of production, five frontier technologies were developed in the 20th century: nuclear technology, aerospace technology, information technology, laser technology and biotechnology, and great progress was made in energy, materials, automation, ocean and environment.
1, nuclear energy and nuclear technology
The energy produced and released by nuclear fission and fusion reaction is far greater than that produced by mechanical energy and chemical energy. The peaceful use of nuclear energy provides mankind with a safe, clean and inexhaustible energy treasure house.
1942, the United States built the world's first atomic reactor, and realized the chain nuclear fission reaction controlled manually for the first time. 1945 the first atomic bomb exploded successfully. 1952 the first light nuclear fusion hydrogen bomb exploded successfully. 1954, the Soviet Union built the world's first atomic power station. After the 1960s, nuclear power plants entered the practical stage and have become an important energy source, accounting for about 1/5 of the global total power generation.
Nuclear technology is also widely used in agriculture, medical care, materials, archaeology and environmental protection. The mass production of radioisotopes began in the 1940s, and Billy invented the dating method of C 14 in 1947. In 195 1, radioactive elements such as Co60 are used to treat cancer. Since 1970s, computed tomography (CT) has been widely used in clinic, and it developed into magnetic resonance scanning (MRI) in the early 1980s.
2. Aerospace and space technology
1903- 19 14, tsiolkovsky put forward the navigation theory powered by rockets, which laid the foundation of astronautics. 19 19, Goddard put forward the mathematical principle of rocket flight, and successfully launched the world's first liquid fuel rocket in 1926. From 65438 to 0942, the liquid military flying arrow designed and launched by Braun became the blueprint of rocket development in various countries after World War II.
1957, the Soviet union launched the world's first artificial earth satellite with the rocket device of intercontinental missiles, and the "space age" began. 196 1 year, the Soviet union launched a manned spacecraft, and humans flew into space for the first time. 1969, American Apollo 1 1 landed on the moon, and man left his first footprint on the moon. 197 1 year, the Soviet union built a space station, and for the first time, human beings had an activity base in space. 198 1 year, the United States successfully launched the space shuttle, and since then, humans have been free to enter and leave space.
Since the late 1950s, human beings have begun to explore the moon, planets in the solar system and distant interplanetary space. Up to now, more than 65,438+000 space probes have been launched to reveal the formation and evolution of the universe, explore the origin of life and the influence of space environment on human living environment.
3. Information technology
Information technology is the fastest developing technology field in the 20th century. It has had a great and far-reaching impact on human society, economy, politics and culture.
1906, the invention of triode electron tube amplified the electric signal, thus making long-distance radio communication possible. 1947, the birth of the first transistor provided an important foundation for the integration and digitization of electronic circuits. 1945 electronic computers have experienced the development of the first generation (electron tubes, from the mid-1940s to the late 1950s), the second generation (transistors, from the late 1950s to the mid-1960s), the third generation (integrated circuits, from the mid-1960s to the early 1970s) and the fourth generation (large-scale and ultra-large-scale integrated circuits, starting from the early 1970s).
With the appearance of large-scale integrated circuits, computers are developing towards the extreme of giant and miniaturization. In the mid-1970s, the vector operation speed of supercomputers exceeded 1 100 million times per second; Microcomputer has entered thousands of households, marking the arrival of the personal computer era. Nowadays, the computing speed of supercomputers has reached 3.9 trillion times per second, and the computer Internet has created a brand-new way of work and life in the study, research, communication, trade and even entertainment of more than 200 million netizens.
4. Laser technology
19 17 years, Einstein put forward the concept of "stimulated radiation" in the process of studying the radiation of light, which laid the theoretical foundation of laser. The laser was discovered in 1958. 1960, the United States made the world's first laser. It uses ruby crystal as luminescent material and pulse xenon lamp with high luminous intensity as excitation light source. The super-strong beam produced by this stimulated radiation is laser.
After ruby laser, semiconductor laser (1963), gas laser (1964), free electron laser (1977) and even atomic laser (1977) came out one after another.
5. Biotechnology
Gene recombination technology (also known as genetic engineering) is the frontier of modern biotechnology, which flourished in the second half of the 20th century. From the late 1960s to the early 1970s, Albert and Smith discovered that there are two kinds of "tool enzymes" in cells, which can "cut" and "connect" DNA. Nathan used tool enzymes to cut and bind DNA for the first time. The recombination of DNA can creatively use biological resources and realize the will of human beings to transform biological genetic characteristics and produce biological types that human beings need. Since 1980s, hundreds of transgenic plants and animals have been obtained, which is of great significance to agricultural development. The development and production of transgenic drugs will bring new gospel to human health.
Besides genetic engineering, biotechnology (bioengineering) also includes cell engineering, enzyme engineering, fermentation engineering and protein engineering. 1978 the birth of the first test-tube baby Louis, 1996 the birth of Dolly the cloned sheep, are all masterpieces of cell engineering. Enzyme washing powder and tender meat powder are all products of enzyme engineering; Modern fermentation industry started with the production of penicillin, and now antibiotics have been produced on a large scale through fermentation engineering. As for the need to transform the genes of natural protein to produce new high-quality protein, this kind of protein does not exist in nature, and it has been paid more and more attention, which is called the second generation genetic engineering.
The legacy brought by the development of science and technology in the 20th century will include the globalization and socialization of science, the scientization of society, the intersection, complexity and comprehensiveness of science, the close combination and interaction between science and society, and the promotion of science and technology to world peace and the coordinated development of man and nature. With these foundations, mankind can meet the new era of global knowledge economy with confidence!
(The writer is a doctor of science from China Academy of Sciences, a researcher at the Institute of Natural Science History of Chinese Academy of Sciences, and the secretary-general of the China Society of Science and Technology History. )