Biographical encyclopedia
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501 [772] CANTOR
ROENTGEN [774] in the first group is associated with the even integer in the second group that is equal to just twice itself. For every num ber in the first group there is one and only one number in the second; for every number in the second, one and only one in the first. This is one-to-one correspondence. In this way one can fairly argue that the number of even integers is equal to the number of all integers, regardless of the fact that common sense would have it that the number of all integers is twice that of the number of even integers. The arithmetic of the infinite is not the same as the familiar arithmetic of the finite. Galileo [166] had caught a glimpse of this in 1636 when he argued in similar fashion that the number of square inte gers was equal to the number of all inte gers. Cantor went on, however, to erect a complete logical structure in which a whole series of transfinite numbers was postulated, representing different orders of infinity, so to speak. Thus, all rational numbers could be set equal to the inte gers, but rational plus irrational numbers could not be. These together were the “real numbers” and they represented a higher transfinite number than the inte gers did. The number of points on a line matched all the real numbers and also represented the higher transfinite num ber. This correspondence between the points on a line and the set of real num bers was rigorously demonstrated by Cantor and Dedekind. Cantor’s views were not accepted by all his colleagues. Though Hermite [641] was sympathetic, Kronecker, who pos sessed a Zeno-like suspicion of the infinite, attacked Cantor’s work with great vigor. Inspired by professional jeal ousy, Kronecker prevented Cantor’s ad vancement, keeping him from a post at the University of Berlin, for instance. Cantor’s mental health broke in 1884 under the strains of the controversy that followed and much of the rest of his life was spent in severe depression. He died in a mental hospital. With the twentieth century, his work came to be accepted. Kronecker’s objec tions are not taken very seriously by most mathematicians. [773] PFEFFER, Wilhelm (pfefer) German botanist Born: Grebenstein, Hesse, March 9, 1845
Died: Kassel, Hesse, January 31, 1920
Pfeifer, the son of an apothecary, was put to work in the family shop when he was fifteen. Eventually, though, he man aged to enter the University of Got tingen and to get his Ph.D. there in 1865. He went on to teach botany at the Uni versity of Bonn. In 1877 Pfeifer became a pioneer in serious work with semipermeable mem branes (those with apertures so tiny that small molecules could go through but large ones, like those of proteins, could not). If a protein solution is separated from water by such a semipermeable membrane, water passes more easily across the membrane into the solution than out of it. Fluid, and pressure, accu mulate on the solution side of the mem brane. The process is osmosis and Pfeifer showed how one might measure the os motic pressure resulting. Pfeifer also showed that this osmotic pressure depended on the size of the molecules that were too large to pass through. This meant that, from osmotic pressure, the molecular weight of specific proteins could be determined. In this way Pfeffer was able to make the first reasonably reliable measurements of the size of giant molecules. His life ended in disaster. There was his nation’s shattering defeat in World War I and the death of his only son, killed in action less than two months be fore the armistice. [774] ROENTGEN, Wilhelm Konrad (runt'gen) German physicist Born: Lennep, Rhenish Prussia, March 27, 1845 Died: Munich, Bavaria, February 10, 1923 Roentgen’s father was a textile mer chant and his mother was Dutch. He was educated in Holland and Switzerland 5 0 2
[774] ROENTGEN
ROENTGEN [774] and his undergraduate degree was in me chanical engineering. (He was expelled from one school for ridiculing a teacher.) At the University of Zürich, he studied under Clausius [633] and Kundt [744] and decided to make physics his profes sion. After obtaining his doctoral degree in 1869, he worked as an assistant to Kundt. Kundt accepted positions in Ger many and Roentgen accompanied him, doing solid work in many branches of physics. The great moment that lifted Roent gen out of mere competence and made him immortal came in the autumn of 1895 when he was head of the depart ment of physics at the University of Würzburg in Bavaria. He was working on cathode rays and repeating some of the experiments of Lenard [920] and Crookes [695]. He was particularly inter ested in the luminescence these rays set up in certain chemicals. In order to observe the faint lumines cence, he darkened the room and en closed the cathode ray tube in thin black cardboard. On November 5, 1895, he set the enclosed cathode ray tube into action and a flash of light that did not come from the tube caught his eye. He looked up and quite a distance from the tube he noted that a sheet of paper coated with barium platinocyanide was glowing. It was one of the luminescent substances, but it was luminescing now even though the cathode rays, blocked off by card board, could not possibly be reaching it. He turned off the tube; the coated paper darkened. He turned it on again; it glowed. He walked into the next room with the coated paper, closed the door, and pulled down the blinds. The paper continued to glow while the tube was in operation. It seemed to Roentgen that some sort of radiation was emerging from the cath ode-ray tube, a radiation that was highly penetrating and yet invisible to the eye. By experiment he found the radia tion could pass through considerable thicknesses of paper and even through thin layers of metal. Since he had no idea of the nature of the radiation, he called it X rays, X being the usual math ematical symbol for the unknown. This name persists today even though the na ture of the radiation is now known. For a time, there was a tendency to call them Roentgen rays, but the inability of the non-Teutonic tongue to wrap itself about the German oe diphthong militated against that. The unit of X-ray dosage is, however, officially called the roentgen. Roentgen was fully aware of the im portance of the discovery and was in a fever to publish before he was antici pated. Yet he recognized the fantastic nature of the discovery, and he dared not publish without as much data as he could find. (Someone, years later, asked him what he thought when he discovered X rays. He answered peevishly, “I didn’t think; I experimented.”) For seven weeks he experimented furiously and then, finally, on December 28, 1895, submitted his first paper, in which he not only announced the discovery but re ported all the fundamental properties of X rays, such as their ability to ionize gases and their failure to respond to elec tric or magnetic fields. The first public lecture on the new phenomenon was given by Roentgen on January 23, 1896. When he had finished talking, he called for a volunteer, and Kolliker [600], almost eighty years old at the time, stepped up. An X-ray photo graph was taken of his hand—which shows the bones in beautiful shape for an octogenarian. There was wild ap plause, and interest in X rays swept over Europe and America. Other physicists quickly confirmed Roentgen’s result. In fact, Crookes found he had actually observed X rays before Roentgen without realizing what he had. X rays offered a new tool for medical diagnosis, for they penetrated the soft tissues of the body easily, but passed through bone only with considerable ab sorption. A beam of X rays passing through tissue on its way to a photo graphic plate will therefore cast a shadow of bones in white on black. Metal objects such as bullets, swallowed safety pins, and so on will show up very clearly. Decay in teeth will show up as gray on white. Only four days after
[774] ROENTGEN
MECHNIKOV [775] news of Roentgen’s discovery reached America, X rays were used to locate a bullet in a patient’s leg. (It took a few tragic years to discover that X rays were also dangerous and could cause cancer, particularly that form called leukemia.) Aside from its obvious applications, Roentgen’s discovery galvanized the world of physics and led to a rash of further discoveries that so completely overturned the old concepts of the sci ence, that the discovery of X rays is sometimes considered the first stroke of the Second Scientific Revolution. (The First Scientific Revolution is, of course, that which included Galileo [166] and his experiments on falling bodies.) Within a matter of months, investi gations of X rays led to the discovery of radioactivity by Becquerel [834]. Physi cists now term all of nineteenth-century physics (with just a faint air of conde scension) as classical physics. The importance of the discovery was recognized in its own time but not al ways understood. Panicky members of the New Jersey legislature tried to push through a law preventing the use of X rays in opera glasses to protect maidenly modesty—about par, perhaps, for legis lative intelligence. Nevertheless there was intelligent interest, too. Within a year of Roentgen’s discovery, a thousand papers on X rays were published. In 1896 Roentgen shared the Rumford medal with Lenard and in 1901, when the Nobel Prizes were set up, the first to be honored with a Nobel Prize in physics was Roentgen. He had an opportunity to accept en noblement from the king of Bavaria, with the right of using von before his name, but this he refused. He also made no attempt whatever to patent any as pect of X-ray production or to make any financial gain from a discovery that proved infinitely precious to science, medicine, and industry, a fact upon which Edison [788] commented with a kind of tolerant humor. (Still, Edison himself refused to patent a fluoroscope out of humanitarian motives.) This was not because he could not have used the money. The aftermath of World War I was an inflation that im poverished many Germans, including Roentgen. He died at the worst of it and in quite straitened circumstances. [775] MECHNIKOV, Ilya Ilich (mech'- nih-kuf) Russian-French bacteriologist Born: Ivanovka, Ukraine, May 16, 1845 Died: Paris, France, July 15, 1916
Mechnikov was the son of an officer of the Imperial Guard, though his mother was of Jewish descent. He had the best education that the Russian Em pire could afford, which, of course, wasn’t much. After graduating from the University of Kharkov he traveled to Germany for advanced study. Siebold [537] and Leuckart [640] were among his teachers, and he also worked with Kovalevski [750]. In 1867 he returned to Russia and ob tained an academic position at the new university in Odessa. He was troubled by poor eyesight, a violent temper, and the general difficulty of working in tsarist Russia. In 1873, after his wife of five years died of tuberculosis, he even tried suicide by swallowing morphine, but took too large a dose and threw it up. In 1882 Mechnikov resigned to devote himself to research. He was interested in digestion and while working with simple animals (so simple as to be transparent) he noted that they possessed semi-in dependent cells, which, although playing no direct part in digestion, were never theless capable of ingesting small parti cles. Any damage to the animals brought these cells to the spot at once. Mechnikov followed up this lead in more complicated animals and eventu ally was able to show that the white cor puscles in animal blood (including human blood) corresponded to these cells, that it was their function to ingest bacteria. They flocked to the site of any infection and what followed was a battle between bacteria and what Mechnikov called phagocytes (“eating cells”). When the phagocytes lost heavily, their disinte grated structure made up pus. The white 504 [776] LAVERAN
DARWIN [777] corpuscles, Mechnikov held, were an im portant factor in resistance to infection and disease. Virchow [632], on having phagocytes demonstrated to him, shook his head; he was not impressed. Mechni kov did not allow that to discourage him.
By 1888 Mechnikov’s work had at tracted the attention of Louis Pasteur [642], and the Russian was invited to join the Pasteur Institute. This he did, remaining in France till his death. It is for this reason that his name is some times seen in its French version, Elie Metchnikoff. On Pasteur’s death in 1895, Mechnikov succeeded Pasteur as director of the Institute. Mechnikov continued studies of the bacteria infesting the large intestine and became fascinated by their possible con nection with longevity or the lack of it. He held that the natural life-span of man was one hundred and fifty years and believed that drinking cultured milk would help him attain it. His work on white corpuscles earned for him, along with Ehrlich [845], the 1908 Nobel Prize in medicine and physi ology. His work on longevity, which lent itself unfortunately to exploitation by dietary quacks and food faddists, re quires only the comment that Mechni kov died at seventy-one. [776] LAVERAN, Charles Louis Al phonse (la-vrahnO French physician
The son of a military surgeon, La veran took his medical degree in 1867 at the University of Strasbourg and eventu ally took up the role of military surgeon himself and served in Metz when it was under siege in the Franco-Prussian War. Between 1878 and 1883, he was sta tioned in Algeria and there he had ample opportunity to study malaria. In 1880 he discovered the causative factor of ma laria and found it to be not a bacterium but a protozoon. It was the first case in which a protozoon, a one-celled animal, rather than a bacterium, was shown to cause a disease. The discovery made no particular splash at first, however, and his career was not particularly benefited. After another decade of service in France itself, Laveran retired from the army, entered the Pasteur Institute in 1896, and devoted the rest of his life to research on tropical disease. In 1907 the splash came at last He was awarded the Nobel Prize in physiology and medicine for his discovery concerning protozoa and disease. [777] DARWIN, Sir George Howard English astronomer
1845
Died: Cambridge, December 7, 1912
George Darwin was the second son of Charles Darwin [554], but he avoided being swamped by his father’s biological reputation by going into a different field of science. He studied astronomy and graduated from Cambridge with high honors, including second place in mathe matics. In 1883 he was appointed a pro fessor of astronomy at his alma mater. His best work was done in connection with tides. Although some early scholars had connected the moon with the tides, it remained for Newton [231] to build a satisfactory rationale for them, pointing out the effect of lunar gravitation on earth’s ocean cover. After Newton’s time, Laplace [347], in his general elabo ration of gravitational theory, went into the matter of tides in greater detail. It was left, however, for George Darwin to analyze all the various irregularities of tides created by the interference of land barriers and the frictional effects pro duced by the ocean bottom. Darwin carried the consequences of tidal friction further. In a series of papers dating from 1879, he attempted to use it to forecast the far future and reveal the far past. The effect of tidal friction on the earth was to slow its rota tion and to decrease its angular momen tum. This decrease had to be made up for by an increase elsewhere in the earth-moon system. If the moon were to increase its angular momentum to make
[777] DARWIN
WROBLEWSKI [779] up for earth’s decrease, this could only mean that the moon would have to in crease its distance from the earth. The effect of the tides would be to force a slow retreat on the moon as the day lengthened. This would continue until the earth’s rotation was slowed to the point where its day would be equal to fifty-five times the length of the pres ent day. One side of the earth would then perpetually face the far distant moon and the lunar tides would be fro zen in place. Further changes would take place as a result of the lesser action of solar tides. Working backward, the earth’s period of rotation will have been shorter, and its angular momentum greater, in the past. The moon’s share of angular mo mentum would then have to be less, which meant that it would have to be closer to the earth. Darwin carried this back to the point where the earth rotat ing at six times its present speed would be virtually in contact with the moon. This represented, he believed, the time at which the whirling earth threw off a por tion of its outer crust by centrifugal ac tion, losing angular momentum in that way. This was the first attempt to work out a cosmogony based on known mathe matical principles, rather than on vague generalization. Darwin tried to apply the effects of tidal friction to the evolution of stellar systems, including multiple stars. A generation later, Jeans [1053] was to continue and extend Darwin’s work.
There were attractive points to all this, at least as far as the earth-moon system was concerned. It explained why the moon was less dense than the earth, since it was supposedly produced out of earth’s outer layers, and it also explained why the granite layer that made up the continents was not continuous over the earth’s surface. Some even suggested that the Pacific Ocean, which is free of gran ite, is the vast hole that marks the place where the moon was lost. However, although tidal friction and the slowing of earth’s rotation are mat ters that are still accepted, there is con siderable doubt whether it can be ex trapolated backward in time in such a way as to prove that the moon was ever part of the earth. The feeling is currently more general among astronomers that earth and moon developed indepen dently, although the details are as yet very much in dispute. In 1899 Darwin was made president of the Royal Astronomical Society and in 1905 he was knighted. [778] LIPPMANN, Gabriel Jonas (leep- man')
French physicist Born: Hollerich, Luxembourg, August 16, 1845 Died: aboard ship on the Atlantic Ocean, July 13, 1921 Lippmann, though bom in Luxem bourg, was bom of French parents and the family settled in Paris while he was yet a boy. In 1875 he received his Ph.D. from the Sorbonne, but by then he had al ready developed a capillary electrometer, which was capable of detecting as little as a change of a thousandth of a volt in the electromotive force. He invented a number of other inge nious devices, but the one that made the biggest splash at the time was that of color photography. By using a thick emulsion over a mercury surface that reflected the incident light, he had the incoming light and the reflected light producing stationary waves that repro duced the original colors of the object photographed. It was not really a practical method since a long exposure is required and no copies could be made, and it has no rela tion to modem methods of color photog raphy. Nevertheless, the impression it made was such that Lippmann received the 1908 Nobel Prize for physics for it. [779] WROBLEWSKI, Zygmunt Flo- renty von (vroo-blef'skee) Polish physicist Born: Grodno, Russia, October 28, 1845 Died: Cracow, Poland, April 19, 1888
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