PERRIN (Perrin), Jean( French physicist, Nobel Prize in Physics, 1926)
Comments for PERRIN (Perrin), Jean
Biography PERRIN (Perrin), Jean
September 30, 1870, Mr.. - April 17, 1942
French physicist Jean Baptiste Perrin was born in Lille. He, along with two sisters raised by his mother after their father, an officer, died from wounds received during the Franco-Prussian War. Receiving primary education in local schools, P. graduated from Liceum Jeanson-de-Sayi in Paris, serving a year of military service, and in 1891. entered the Ecole normal syuperer. From 1894 to 1897. He was an assistant physicist at the ц+cole normal syuperer and during this period, conducted research on cathode rays and X. This topic was the subject of his doctoral dissertation.
At a time when P. performed his experiments, had not yet produced a consensus about the nature of cathode rays emitted by the negative electrode (cathode) in a vacuum tube with electric discharge. Some scientists believed that these rays are a form of light radiation, but in 1895. Research P. shown that they are a stream of negatively charged particles. Dzh.Dzh. Thomson, P. modifying the experiment, confirmed his findings in 1897. identified the most important characteristic of these particles by measuring the ratio of their charge to mass by measuring the deflection in the electric and magnetic fields. Weight was about 2 thousand. times smaller than the mass of an atom of hydrogen, the lightest among all the atoms. It soon became subject to the opinion that these negative particles called electrons, constitute an integral part of the atoms. Based on the results of their work, P. participated in a discussion about the atomic or discrete nature of matter. Her party has become and Marcel Brillouin, one of the teachers of AP, a former strong supporter of the atomic theory.
. The atomic theory states that the elements are composed of discrete particles called atoms, and that chemical compounds consist of molecules, particles of larger size, containing two or more atoms
. By the end of XIX century. atomic theory has gained wide acceptance among scholars, especially among chemists. However, some physicists believed that atoms and molecules - is nothing more than mock objects, which are introduced for reasons of convenience and are useful in the numerical processing of the results of chemical reactions. Austrian physicist and philosopher Ernst Mach believed that the question of the primary structure of matter insoluble in principle and should not be the subject of research scientists. For supporters of atomism proof of discreteness of matter was one of the fundamental issues remain unresolved in physics.
In 1897. P. received his doctorate in the same year he began to read a new course of physical chemistry at the University of Paris (Sorbonne). The course was a huge success. (P. in 1910. headed in the Sorbonne chair of physical chemistry and up to 1940. remained in this post.) Continuing to develop the atomic theory, he put forward in 1901. hypothesis that the atom is a miniature solar system, but he could not prove it. Ten years later, Ernest Rutherford proposed his model of a compact positively charged nucleus surrounded by negative electrons, and this idea has gained the most popularity. In the model of Thomson's atom was like 'plum pudding' in the form of positively charged sphere in which electrons are sprinkled like raisins. Although the work of P. in the field of physical chemistry was a departure from his earlier studies of cathode rays, he focused on issues related to the molecular nature of compounds, including thermodynamics, osmosis, ion movement and crystallization. The study of colloids (suspensions of fine particles) led to his famous experiments on Brownian motion, which served as evidence of the existence of molecules.
. Brownian motion was first described by English botanist Robert Brown in 1827, Mr.
. If tiny particles like grains of pollen placed in suspension in a liquid, . it can be seen under the microscope, . they make occasional surges, . if they are subjected to continuous bombardment by certain invisible objects,
. Were put forward different explanations for this movement, in t.ch. under the influence of electric forces, convection currents, or collision with a constantly moving molecules of the liquid. In 1905, Mr.. Albert Einstein published a paper on Brownian motion, which were given to the theoretical foundations of molecular hypotheses. He gave some quantitative predictions, however, necessary for their verification experiments required great precision so that Einstein doubted the feasibility. From 1908 to 1913. P. (initially not knowing about the work of Einstein) has complied with subtle observations of Brownian motion, which confirmed Einstein's predictions.
P. realized, . that if the motion of suspended particles caused by collisions with molecules, . then, . based on the well-known gas laws, . can predict the average displacement over time, . if you know their size, . density and some characteristics of the liquid (eg, . temperature and density),
. It required only a properly reconcile these predictions with measurements, and then appeared to strongly supports the existence of molecules. However, to obtain the desired particle size and uniformity was not so easy. After many months of painstaking centrifugation P. succeeded in isolating a few tenths of a gram of homogeneous particles gamboge (yellowish substance derived from the milky sap of plants). After measuring the characteristics of the Brownian motion of these particles results were quite relevant molecular theory.
P. also studied the sedimentation, or settling, the smallest suspended particles. If the molecular theory is correct, . he reasoned, . particles, . dimensions are less than a certain, . does not sink to the bottom of the vessel: directed upward momentum component, . obtained as a result of collisions with molecules, . will always oppose the downward force of gravity,
. If the suspension is not subject to disturbances, then eventually be established sedimentation equilibrium, after which the concentration of particles at different depths will not change. If the properties of the suspension are known, we can predict the equilibrium distribution of the vertical.
P. spent a few thousand observations, very subtly and cleverly using the microscopic technique and counting the number of particles at different depths in a single drop of liquid with a step depth of twelve-hundredths of a millimeter. He found, . that the concentration of particles in the liquid decreases exponentially with decreasing depth, . with the numerical characteristics are so well agreed with the predictions of the molecular theory, . that the results of his experiments were widely recognized as a decisive confirmation of the existence of molecules,
. Later he came up with ways to measure not only the linear displacement of the particles in Brownian motion, but their rotation. Research II. allowed him to calculate the size of molecules and Avogadro's number, ie. number of molecules in one mole (amount of substance whose mass in grams, numerically equal to the molecular weight of the substance). He checked it had received value of Avogadro's number with five different types of observations and found that it satisfies all of them, taking into account the minimum experimental error. (The decision is now the value of this number is approximately 6.02 бT 1023; P. obtained a value of 6% higher.) By 1913, . when he summed up the already numerous by the time the certificate of a discrete nature of matter in his book 'atoms' ( 'Atoms'), . reality of atoms as, . and molecules has been recognized almost everywhere.,
. In 1926, Mr.
. P. received the Nobel Prize in Physics "for his work on the discrete nature of matter and especially for his discovery of sedimentation equilibrium '. In a presentation to the winner. Oseen, a member of the Royal Swedish Academy of Sciences, summed up the work of P. and gave evidence in support of its conclusions.
During World War II. served as an officer of the engineering corps of the French army, developing such technical problems as the detection of submarines using acoustic methods. After the war he became interested in nuclear physics and was one of the first who has suggested the likely source of heat emanating from the Sun, explains the long persistence of its. With his direct participation were established the National Center for Scientific Research, Institute of Physical and Chemical Biology and Institute of Astrophysics. His desire to popularize science, especially among the younger generation, helped to create the palace are open at the International Exhibition in Paris in 1937
As a socialist and a staunch opponent of fascism, P. left France after its occupation by Germany in 1940. and went to the United States, where his son taught physics at Columbia University. While in exile, P. called for increased American support for the French military effort. He also founded the New York University, French. He died in New York in 1942. In 1948, Mr.. his remains were transported to France and buried in the Pantheon in Paris.
P. married Henrietta Dyuportal in 1897. They had a son and daughter. Pleasant conversationalist, he was liked by all, especially the sympathy aroused in youth. He arranged in his laboratory in the evening, which invited the whole group of young scientists in the debates. Nevertheless, he was more drawn to the pilot experience, rather than theoretical considerations. Once, when a certain professor forced him to admit 'incontrovertible dignity' of a new physical concept, P. replied that 'it is extremely difficult to invent a false theory'.
Among the awards AP, except the Nobel Prize, the prize may be called Joule's Royal Society of London (1896) and the prize Lyakaza French Academy of Sciences (1914). P. become a member of the French Academy of Sciences in 1923. and its president in 1938. He was awarded an honorary degree from University of Brussels, Liege, Ghent, Calcutta, Manchester, New York, Princeton and Oxford. He was a member of the Royal Society of London, as well as science academies of Italy, Czechoslovakia, Belgium, Sweden, Romania and China.