Descartes
Rene descartes (1596 ~ 1650), born in France, is a French mathematician, scientist and philosopher.
Descartes not only opened up a new path in the field of philosophy, but also was a scientist who dared to explore and made commendable innovations in physics, physiology and other fields, especially in physics. Descartes began to read Johannes Kepler's optical works from 16 19, and has been paying attention to the lens theory, and has participated in the research on the essence of light, reflection and refractive index, and lens grinding from both theoretical and practical aspects. He believes that the theory of light is the most important part of the whole knowledge system.
Descartes used his coordinate geometry to engage in optical research, and put forward the theoretical derivation of refraction law for the first time in Refractive Optics. He thinks that light is the propagation of pressure in the ether. From the viewpoint of light emission theory, he calculated the reflection, refraction and total reflection of light on the interface between two media by using the model of tennis ball hitting cloth, and thus deduced the law of refraction for the first time under the assumption that the velocity component parallel to the interface is unchanged. But his hypothesis is wrong, and his deduction leads to the wrong conclusion that the speed of light increases when it enters the dense medium from the sparse medium. He also made an optical analysis of people's eyes, explained that the cause of vision impairment was the deformation of the lens, and designed a lens to correct vision.
Willebrord Snellius
Willebrord Snellius (159 1 ~ 1626), a mathematician and physicist in Leiden, the Netherlands, was a professor of mathematics at Leiden University. Laughter first discovered the law of refraction of light, which made it possible to accurately calculate geometric optics. Snell's law of refraction (also known as Snell's law) is obtained from experiments without any theoretical deduction. Although correct, it has never been officially published. It was only later that Huygens and Isaac Voss saw this record when they examined his manuscript.
It was Descartes who first expressed the law of refraction in today's form. He didn't do any experiments, but based on some assumptions, he deduced the law theoretically. Descartes discussed this problem in his book Bending Optics (1637).
The law of refraction is one of the most important basic laws of geometry. Snell's discovery laid a theoretical foundation for the development of geometric optics and greatly promoted the development of optics.
Huygens
Christiaan huygens (1629 ~ 1695) was born in The Hague on April 1629. He is a famous Dutch physicist, astronomer and mathematician. He is an important pioneer in physics between Galileo and Newton and one of the most famous physicists in history. He has outstanding research on the development of mechanics and optics.
1645 ~ 1647 studying law and mathematics at Leiden university; 1647 ~ 1649 transferred to Brayda college for further study. Under the direct influence of Archimedes and Descartes, he devoted himself to the study of mechanics, optics, astronomy and mathematics. He is good at combining scientific practice with theoretical research to solve problems thoroughly. Therefore, outstanding achievements have been made in the invention of pendulum clock, the design of astronomical instruments, the collision of elastic bodies and the wave theory of light.
Huygens principle is an important basic theory of modern optics. But although it can predict the existence of light diffraction, it can't explain these phenomena, that is, it can determine the propagation direction of light waves, but it can't determine the amplitude of vibration propagating in different directions. Therefore, Huygens principle is an approximate understanding of optical phenomena by human beings. It was not until Fresnel developed and supplemented Huygens' optical theory and founded huygens-fresnel principle that the diffraction phenomenon was well explained and the whole theory of light wave theory was completed.
1678, he publicly opposed Newton's theory of light particles in a speech at the French Academy of Sciences. He said that if light is a particle, it will change direction when it passes through. However, people did not find this phenomenon at that time, and using particle theory to explain refraction phenomenon will get contradictory results with reality. Therefore, Huygens formally put forward the theory of light fluctuation in the book On Light published in 1690, and established the famous Huygens principle. On the basis of this principle, he deduced the law of reflection and refraction of light, which satisfactorily explained the reason why the speed of light decreased in dense media, and also explained the birefringence phenomenon after light entered Iceland spar, which was thought to be caused by oval molecular particles of Iceland spar.
fresnel
Fresnel (1788 ~ 1827) is a French physicist and railway engineer. /Kloc-0 was born in brolly in May, 788;/Kloc-0 graduated from the Polytechnic Institute in Paris;/Kloc-0 graduated from the Institute of Bridges and Highways in Paris. 1823 was elected as an academician of the French Academy of Sciences, and 1825 was elected as a member of the Royal Society. 1827 17 died of lung disease on July 4, at the age of 39.
Fresnel's scientific achievements mainly lie in two aspects. One is diffraction. Based on Huygens' principle and interference principle, he established huygens-fresnel principle in a new quantitative form and perfected the diffraction theory of light. His experiments are very intuitive and sensitive, and many experiments and optical elements still in use today are crowned with Fresnel's surname, such as double-mirror interference, zone plate, Fresnel lens, circular aperture diffraction and so on. Another achievement is polarization. Together with arago, he studied the interference of polarized light and determined that light is shear wave (182 1). He discovered the circular polarization and elliptical polarization of light (1823), and explained the rotation of polarization plane with wave theory. He deduced the quantitative law of reflection law and refraction law, namely Fresnel formula; The polarization and birefringence of Marius reflected light are explained, which lays the foundation of crystal optics.
Fresnel is known as "the founder of physical optics" because of its great achievements in the research of physical optics.
roentgen
Wilhelm konrad rontgen (1845 ~ 1923), a German physicist, 1845 was born in Le Nop on March 27th. At the age of three, his family moved to Holland and became Dutch. 1865, he moved to Zurich, Switzerland. Roentgen entered department of mechanical engineering of Swiss Federal Institute of Technology in Zurich and graduated from 1868. 1869 received a doctorate from the university of Zurich and served as an assistant to A. Conte, a professor of physics; /kloc-0 returned to Germany with Kong Di in 0/870, went to the University of Wü rzburg with him in 0/871year, and worked with him at the University of Strasbourg in 0/872. 65438-0894 President of the University of Wü rzburg, 65438-0900 Professor of Physics and Director of the Institute of Physics. 1February 923 10 died in Munich.
Roentgen has done experimental research in many fields of physics all his life, such as magnetic effect of dielectric moving in charged capacitor, specific heat capacity of gas, thermal conductivity of crystal, pyroelectric and piezoelectric phenomena, rotation of polarization plane of light in gas, photoelectric relationship, elasticity of matter, capillary phenomenon and so on. He won great honor for discovering X-rays, so that most of these contributions were ignored.
1895165438+1October 8th, Roentgen noticed for the first time that the small screen of cyanoplatinum barium placed near the X-ray tube was shining. After several days of sleepless nights, he determined that the luminescence of the fluorescent screen was caused by some kind of radiation from the ray tube. Because little was known about the nature and properties of this ray at that time, he called it X-ray, which means unknown. In the same year, on February 28th, 12, the Journal of the Wü rzburg Physical Medicine Society published his first report on this discovery. He continued to study this kind of ray and published new papers in 1896 and 1897 respectively. 1896 65438+1On October 23rd, Roentgen made his first report in his own research institute. At the end of the report, he took an X-ray picture of Krickel's hand, a famous anatomy professor at the University of Wü rzburg. Crick took the lead in cheering for Roentgen three times and suggested that this ray be named Roentgen ray.
At this time, the news of the discovery of X-rays caused a great shock all over the world. At that time, people were infinitely surprised by these rays: almost everything was transparent to them and people could see their bones with these rays. Fingers without meat but with rings are clear, like bullets embedded in the body. People immediately realized its influence on medicine. On October 23rd, 65438/KLOC-0, Roentgen made the only public speech about his discovery for the Physical Medicine Association. People welcomed him with stormy applause. With the knowledge at that time, Roentgen was completely qualified to work with X-rays, but he didn't understand the nature of X-rays. Roentgen wrote at the end of the famous paper 1895: These new rays are not the longitudinal vibration of the ether, are they? I must admit that in the course of my research, I became more and more convinced, so I should announce my guess, although I know this explanation needs further confirmation. This kind of "further confirmation" has never been obtained. It took sixteen years to solve the debate about the nature of X-rays, relying on the work of Max von Laue, Friedrich and Knipping.
In the months after the discovery of X-rays, Roentgen received lectures from all over the world, but he declined all the invitations except one because he wanted to continue studying his X-rays. He wrote a short message to his colleague who asked him to demonstrate the new ray, expressing his apology and explaining that he didn't have time to give any reports or performances. The only exception is the emperor, who demonstrated his X-rays to the emperor in June 1896+ 10/3. Roentgen is always nervous about performing for the emperor. "I hope I will be lucky when I use this pipe," he said. "Because these pipes are very fragile and often damaged, it takes four days to empty a pipe." But nothing happened. Roentgen received such an invitation to go to the palace, in addition to giving speeches and demonstrations, he also had dinner with the emperor and received a medal (the second-class crown medal). Take a step back when you leave to show your respect for your majesty. In this regard, Richard Wilstedt, an organic chemist who explained the complex mechanism of chlorophyll, said that he and Fritz hubbell, an ammonia synthesizer, had been expecting an invitation from the emperor after making their discovery. So they practice walking backwards. Wilstedt is a collector of fine porcelain. There is an expensive porcelain bottle in the room where they practice dumping. As expected, their practice ended in the porcelain bottle being broken. Although they were not invited by the emperor, the exercises they did were not in vain. Later, both of them won the Nobel Prize. According to the etiquette, they have to walk backwards after receiving the prize from the king of Sweden. After Roentgen discovered X-rays, physicists and medical professionals quickly studied this new kind of rays. In 1896, there are more than 1000 papers on this subject. Between 1896 and 1897, Roentgen only wrote two articles about X-rays. Then, he returned to his original research topic, wrote seven articles that only aroused short-term interest in the next 24 years, and handed over the research on X-rays to other young new forces. People can only guess why he did it. Roentgen won the first Nobel Prize in physics at 190 1. 1900, he moved to Munich, where he became the director of the Institute of Experimental Physics. 19 14, he signed a declaration of famous German scientists, claiming that they were closely related to militaristic Germany, but later he regretted it. During the First World War and the subsequent inflation, he was quite distressed. 1923 February, Roentgen died in Munich at the age of 78.
Albert Abrahan Michelson
Michelson (1852 ~ 193 1) was awarded the 1907 Nobel Prize in Physics for his invention of precision optical instruments and his contribution to the study of spectroscopy and metrology.
Michelson, 1852 19 February 19, was born in Strano, Prussia (present-day Poland) and lived in the United States with his parents as a child. Under the guidance of the headmaster of San Francisco Boys' Middle School, Michelson became interested in science, especially optics and acoustics, and showed his experimental ability. 1869 was selected to study at Annapolis Naval Academy. After graduation, he was a lecturer in physics and chemistry in this school. 1880 ~ 1882 was allowed to go to Europe for postgraduate study, and studied in Berlin University, Heidelberg University and French Academy successively. 1883 Professor of Physics, Case College of Applied Sciences, Cleveland, Ohio. From 65438 to 0889, he became a professor of physics at Clark University in Worcester, Massachusetts, where he began a grand metrology project. 1892, he was appointed as a professor of physics at the university of Chicago, and later served as the first dean of the physics department of the university, where he cultivated his interest in astronomical spectroscopy. 1910 ~191President of the American Association for the Advancement of Science, 1923 ~ 1927 President of the American Academy of Sciences. 193 1 died of cerebral hemorrhage in Pasadena, California on May 9 at the age of 79.
Michelson's name is associated with Michelson interferometer and Michelson-Morey experiment, which is actually the most important contribution of Michelson's life. In Michelson's time, people thought that light and all electromagnetic waves must be propagated by the absolutely static "ether", and whether the "ether" existed or not was still a mystery at that time. Some people tried to prove the existence and static characteristics of the ether by measuring the "etheric wind" produced by the earth's movement on the static ether, but because of the limited accuracy of the instrument, they encountered difficulties. In 1879, Maxwell wrote to D.P. Todd of the American Bureau of Navigation Calendar, suggesting that Romer's astronomical method be used to study this problem. Knowing this situation, Michelson decided to design a method to improve the sensitivity to 100 million and measure the related effects.
188 1 year worked in Helmholtz laboratory of Berlin University, so a high-precision Michelson interferometer was invented and the famous ether drift experiment was carried out. He believes that if the earth revolves around the sun, it takes different time for light to pass the same distance in the direction parallel to the earth and perpendicular to the earth, so when the instrument rotates 90, there must be 0.04 stripes moving in the interference generated before and after. 188 1 year, Michelson did experiments with the interferometer originally built. The optical part of this instrument is sealed on the platform with wax, which is inconvenient to adjust. It often takes several hours to measure a data. The experiment got a negative result. Encouraged by Rayleigh and Kelvin who visited the United States in 1884, he cooperated with chemist Morey to improve the sensitivity of the interferometer, and the result was still negative. 1887, they continued to improve the instrument, and the optical path increased to 1 1 meter. It took five days to carefully observe the relative motion of the earth along the orbit and the static ether, and the result was still negative. This experiment has aroused the shock and concern of scientists, and it is called "two dark clouds in the history of science" together with the "ultraviolet disaster" in thermal radiation. Subsequently, more than 10 people repeated this experiment for 50 years. Further research on it led to the new development of physics.
Another important contribution of Michelson is the measurement of the speed of light. As early as when he was working in the Naval Academy, he became interested in the measurement of the speed of light because of the actual needs of navigation, and started the measurement of the speed of light at 1879. He is the fourth person to measure the speed of light on the ground after Fizzo, Foucault and Kono. He received financial support from his father-in-law and the government, which enabled him to improve the experimental device. He replaced the rotating mirror in Foucault's experiment with a regular octagonal steel prism, thus extending the optical path by 600 meters. The displacement of the returning light reaches 133 mm, which improves the accuracy and Foucault method. He has continuously measured the speed of light for many times. The most accurate measurement was carried out on the 35km long optical road from 1924 to 1926 in the mountainous area of southern California, and the value was (299,796 4) km/s. Michelson was never satisfied with the accuracy he achieved. He is always improving, experimenting repeatedly, working tirelessly and constantly improving. It took him half a century. Finally, in an elaborate measurement of the speed of light, he died of a stroke. Later, his colleagues published the measurement results. He really devoted his whole life to the measurement of the speed of light.
1920, Michelson cooperated with astronomer F.G. Pease, and put a 20-foot (about 6 meters) interferometer behind the reflecting telescope of 100 inch (about 254 meters) to form a stellar interferometer, which was used to measure the diameter of Betelgeuse (the first variable of Orion). This method was later used to determine the diameters of other stars.
Michelson's first important contribution was the invention of Michelson interferometer, which was used to complete the famous Michelson-Morey experiment. According to classical physics theory, light and even all electromagnetic waves must propagate through static ether. The revolution of the earth produces motion relative to the ether, so the time for light to pass through the same distance in two vertical directions on the earth should be different, and this difference should produce an interference fringe of 0.04 moving on the Michelson interferometer. 188 1 year, Michelson did not observe this kind of fringe movement in the experiment. 1887, Michelson cooperated with the famous chemist Morey to improve the experimental device, but no fringe movement was found. This experimental result exposes the defects of ether theory, shakes the foundation of classical physics, and paves the way for the establishment of special relativity.
Michelson was the first scientist who advocated using the wavelength of light wave as the length benchmark. 1892, Michelson measured the red line wavelength of cadmium at 6438.4696 angstrom with a special interferometer at the temperature of 15℃ and the pressure of 760 mm Hg, so 1 m is equal to 1553 164 times of cadmium. This is the first time that mankind has obtained an eternal and indestructible length benchmark.
In spectroscopy, Michelson discovered the fine structure of hydrogen spectrum and the ultra-fine structure of mercury and thallium spectrum, which played an important role in modern atomic theory. Michelson also used the "visibility curve method" invented by himself to study the relationship between spectral line shape and pressure, and the relationship between spectral line broadening and molecular motion in detail. These results have a great influence on modern molecular physics, atomic spectroscopy and laser spectroscopy. 1898, he invented the stepped grating to study Zeeman effect, and its resolution is much higher than that of ordinary diffraction grating.
Michelson is an excellent experimental physicist. His experiment is famous for its exquisite design and high accuracy. Einstein once praised him as "an artist in science".
Lippmann
Lippmann (1845 ~ 192 1) won the 1908 Nobel Prize in Physics for inventing color photography based on interference phenomenon.
Lippmann is a famous French physicist. He was born in Luxembourg on August 1845. My father is from Lorraine and my mother is from Alsace. Both of them worked as tutors in the aristocratic government of Luxembourg and lived comfortably. But they deeply feel that they are French and should raise their sons in the embrace of their motherland. At the age of three, Lippmann's parents left Luxembourg and returned to France. Despite the repeated requests of their owners, they settled in the Latin quarter with the strongest cultural atmosphere in Paris.
Lipman was born in such a scholarly family, and his parents are practical, modest and educated people. Their attitude towards learning is serious and meticulous. This has played a subtle role in the formation of Lippmann's ideological and moral character. Lippmann is ambitious and hardworking. 1868 was admitted to the Department of Education of Paris Teachers College, but showed a strong interest in mathematics and physics, so he transferred to the Department of Physics the next year. In the following 10 years, he explored all aspects of physics, especially made many contributions in experimental physics. 1882 was hired as a professor of mathematics and physics at the University of Paris, and later became famous at home and abroad for his outstanding achievements in experimental physics. 1886 was elected as an academician of the French Academy of Sciences.
189 1 year, lippman invented a method to copy color photos, that is, color photographic interferometry. This method does not use dyes and pigments, but uses natural colors with different wavelengths. Lippmann described his color photography as follows: "Put a flat plate with photographic film in a box with mercury. During exposure, mercury contacts the photosensitive film to form a reflective surface. After exposure, the photosensitive plate is treated according to the ordinary method, and after the plate is dried, color appears. This color can be seen by reflection and will never fade. This result is due to the interference phenomenon inside the sensitive film. During exposure, the incident light interferes with the light reflected by the reflecting surface, thus forming half-wavelength interference fringes. It is these stripes that are recorded on the film by photography, thus leaving the characteristics of the projected light. In the future, when observing the negative film by white light irradiation, due to selective reflection, each point on the negative film only reflects the selected color recorded on it to people's eyes, and other colors are offset by interference. So what people see at every point in the photo is the color of the image, which is just a selective reflection phenomenon. The photo itself is made of colorless substances. "
Because of the long exposure time and color saturation, this method was eventually replaced by Maxwell's tricolor photography, but it is still an important step in the development of color photography.
Lippmann has made great achievements in physics and studied a wide range, especially in electricity, heat, optics and optoelectronics. At that time, the European scientific community recognized him as an authority.
19 12, lippmann was elected president of French academy of sciences. 192 1 year, lippman went to Canada and the United States to give lectures, fell ill abroad, and died on his way back to China in July 13.
Raman
Raman (1888 ~ 1970) won the 1930 Nobel Prize in physics for his research work in light scattering and the discovery of Raman effect.
Raman is an Indian and the first Asian scientist to win the Nobel Prize in Physics. Raman is also an educator. He is engaged in postgraduate training and has sent many outstanding talents to many important positions in India.
Raman1888165438+10 was born in Ricino, southern India. My father is a professor of mathematics and physics at the university. He received science education from an early age and cultivated his interest in music and musical instruments.
Raman was gifted. He graduated from university at the age of 16 and won the gold medal in physics with the first place. 19 years old, obtained a master's degree with honors. 1906, at the age of 18, he published a paper on the diffraction effect of light in the famous British scientific magazine Nature. Due to illness, Raman lost the opportunity to do a doctoral thesis in a famous British university. Before independence, India was not qualified to engage in scientific and cultural work if it did not receive a doctorate from Britain. But the accounting industry is the only exception, and you don't need to go to the UK for training first. So Raman applied to the Ministry of Finance for a job, won the first place and was awarded the position of chief accounting assistant.
Raman has done a good job in the Ministry of Finance, and his responsibilities are getting heavier and heavier, but he doesn't want to immerse himself in officialdom. He stuck to his scientific goals and spent all his spare time continuing to study acoustics and musical instrument theory. In Kolkata, there is an academic institution called Indian Association for Science Education, which has a laboratory where Raman conducts his acoustic and optical research. After 10 years of efforts, Raman has independently completed a series of achievements and published many papers without the guidance of senior researchers.
19 17, the university of Calcutta made an exception and invited him to be a professor of physics, so that he could concentrate on scientific research from now on. During his 16 years as a teacher at the University of Calcutta, he also conducted experiments at the Indian Association for Science Education. Students, teachers and visiting scholars all came here to learn from him and cooperate with him, and gradually formed an academic group with him as the core. Encouraged by his example and achievements, many people embarked on the road of scientific research. Among them are the famous physicists Shaha and Bose. At this time, Kolkata was setting up an Indian research center, and the University of Kolkata and Raman Group became the core of popular support. 192 1 year, Raman gave a lecture in Britain on behalf of the University of Calcutta, which showed that their achievements were internationally recognized.
1934, Raman and other scholars founded the Indian Academy of Sciences and personally served as the president. 1947, Raman Institute was established. He has made great achievements in the development of science in India. Raman has a good eye for the theme of molecular scattering. In his continuous efforts for many years, there is obviously an idea, that is, to persistently carry out basic research in view of the weak links in theory. Raman attaches great importance to discovering talents. From the Indian Association for Science Education to the Raman Institute, he is always surrounded by groups of talented students and collaborators. According to the statistics of light scattering, in the past 30 years, 66 scholars have published 377 papers in his laboratory. He is very kind to his students and is admired and loved by them. Raman likes music, flowers and rocks. He studied the structure of diamonds and spent most of his prize money. In his later years, he devoted himself to the spectral analysis of flowers. On his 80th birthday, he published his album Visual Physiology. Raman loves roses more than anything else. He owns a rose garden. Raman died in 1970 at the age of 82 and was cremated in his garden according to his wishes.
After the Compton effect of X-rays was discovered, Heisenberg predicted in 1925 that visible light would have a similar effect. 1928, Raman pointed out in the article "A New Radiation" that when monochromatic light directionally passes through transparent materials, some light will be scattered. The spectrum of scattered light contains not only some original wavelength light, but also some weak light, and its wavelength is different from the original wavelength by a constant. This phenomenon that the frequency of monochromatic light changes after being scattered by medium molecules is called combined scattering effect, also known as Raman effect. This discovery was quickly recognized. The Royal Society officially called it "one of the three or four most outstanding discoveries in experimental physics in the 1920s".
Raman effect provides new evidence for the quantum theory of light. Later studies show that Raman effect is very important for studying molecular structure and chemical analysis.
There is a special effect in light scattering, which is similar to Compton effect of X-ray scattering. The frequency of light will change after scattering. The change of frequency depends on the characteristics of scattering matter. This is the Raman effect, which was discovered by 1928 Raman in the process of studying light scattering. A few months after Raman and his collaborators announced the discovery of this effect, Landsberg and Mandelstein of the former Soviet Union also independently discovered this effect, which they called joint scattering. Raman spectrum is the result of the superposition of the vibrational energy or rotational energy of the molecule and the photon energy when the incident photon collides with the molecule. Using Raman spectroscopy, the molecular energy spectrum in infrared region can be transferred to visible region for observation. Therefore, Raman spectroscopy, as a supplement to infrared spectroscopy, is a powerful weapon to study molecular structure.