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827 [1338] AMBARTZUMIAN HERSHEY [1341]
in plant pathology at once. He was par ticularly interested in plant viruses. In 1937 Bawden and his associates found that the tobacco mosaic virus, one of the simplest of those super-simple liv ing things whose existence was first made known by Beijerinck [817], contained ribonucleic acid (RNA). This was the first indication that nucleic acids, found in all cells, was found also in subcellular life. Nucleic acids have been found in all clearly identifiable viruses since and are accepted as a universal (and perhaps the most basic) component of life. [1338] AMBARTZUMIAN, Victor Amazaspovich (am'bahr-tsoo'- mee-an)
Soviet astronomer Born: Tiflis (Tbilisi), Georgian SSR, September 18, 1908 Ambartzumian, the son of a teacher of literature, graduated from the University of Leningrad in 1928. He taught at that institution till 1944, when he left for Erivan in the Armenian SSR to head the Byurakan Observatory there. Ambartzumian was interested in the theory of stellar origins and worked out the manner in which gigantic catas trophes might take place in the course of the evolution of stars and galaxies. When Baade [1163] and Minkowski [1179] first identified the radio source in Cygnus as associated with what looked like a closely connected pair of galaxies, it seemed that a galactic collision was taking place there and that this sort of catastrophe might be common enough to account for the numerous extra-galactic radio sources. In 1955, however, Ambartzumian pre sented convincing evidence that this was wrong. He suggested instead vast explo sions within the cores of galaxies— somewhat analogous to supernovas on a galactic scale. With the discovery of ex amples of galaxies that were clearly ex ploding, notably the case of M-82 by Sandage [1469], this hypothesis seems to have become rather firmly established. [1339] WILLIAMS, Robley Cook American biophysicist Born: Santa Rosa, California, Oc tober 13, 1908 Williams graduated from Cornell in 1931 and got his Ph.D. there in 1935. Teaching at the University of Michigan first, he went to the University of Cali fornia in 1950. Greatly interested in astronomy, de spite the fact that he taught in the de partment of biophysics (later renamed as that of molecular biology), Williams noted the manner in which the lunar mountains became much more visible when sunlight struck them obliquely. Their shadows made their heights and shapes plain. It occurred to him that if tiny objects were sprayed with a thin film of opaque metal from an oblique direction, they would cast shadows of metal-free regions and they too would gain three-dimensional visibility. Working with the electron micros- copist Wyckoff [1202], Williams devel oped this technique and the electron mi croscope became a much more versatile and information-yielding instrument. [1340] FRANK, Dya Mikhaylovich Soviet physicist Born: St. Petersburg (now Lenin grad), October 23, 1908 Frank, the son of a professor of math ematics, graduated from Moscow Uni versity in 1930 and in 1944 received a professorial post at that institution. His explanation (with Tamm [1180]) of the cause of Cherenkov [1281] radiation earned him a share in the 1958 Nobel Prize in physics. [1341] HERSHEY, Alfred Day American microbiologist Born: Owosso, Michigan, Decem ber 4, 1908 Hershey obtained his Ph.D. in 1934 from Michigan State University, taught at Washington University till 1950, then 828
[1342] LIBBY
LIBBY [1342]
went on to Cold Spring Harbor, New York, from which he retired in 1975. His interest lay in bacteriophages. In 1945, he demonstrated the occurrence of spontaneous mutations both in bac teriophages and the bacterial cells on which they preyed, something that Luria [1377] also accomplished independently. In 1946 he showed that the genetic ma terial of different viruses could sponta neously combine to produce the effects of a mutation, something that Delbriick [1313] showed independently. In 1952 he showed that it was the nucleic acid of the bacteriophage that entered the cell, which indicated that it was the nucleic acid, and not the protein associated with it, that carried the ge netic message. This pointed up the revo lutionary importance of the findings of James Dewey Watson [1480] and Crick [1406] the following year on nucleic acid replication. For their work, Hershey, Delbriick, and Luria shared the 1969 Nobel Prize for physiology and medicine. [1342] LIBBY, Willard Frank American chemist Bom: Grand Valley, Colorado, December 17, 1908 Died: Los Angeles, California, September 8, 1980 Libby, the son of a farmer, attended the University of California, graduating in 1931 and obtaining his Ph.D. in 1933. He then joined its faculty. During World War II, Libby was at Columbia University working on the atomic bomb project under Urey [1164], developing methods for separating ura nium isotopes, and that shifted his atten tion toward nuclear physics. In 1945, after he had transferred to the Institute of Nuclear Studies at the University of Chicago, a thought occurred to him in connection with the isotope carbon-14. That isotope had been isolated in 1940 and had been found to have an unex pectedly long half life of over five thou sand years. It had just been shown that carbon-14 was continually being formed by cosmic rays colliding with atmospheric nitrogen, which meant that traces of carbon-14 should always be found in the carbon dioxide of the air. Libby reasoned that since carbon dioxide was continually being incorporated into plant tissues, plants ought always to contain tiny amounts of carbon-14; tiny, but enough to detect by modern devices. Further more, since animal life depended on plant life in the last analysis, carbon-14 should also be found in animals; indeed, in all living creatures and in all the car bon-containing products of life. After an organism died, no more car bon-14 would be incorporated into its tissues, and what was already present would begin to break down without re placement, and at a known rate. From the amount of carbon-14 left in old pieces of wood and textile, in mummies and parchment, as compared with the amount in living (or recently dead) sam ples of similar objects, the age (up to as much as 45,000 years) could be deter mined. By 1947 Libby had perfected the technique. Using the carbon-14 dating method, much can be deduced about the earth’s very recent history. Archaeological re mains, being dated, show that the last re treat of the ice-age glaciers occurred more recently than anyone had suspected — 10,000 years ago rather than 25,000. The date of the coming of the Indians to the Americas has been studied; such ob jects as the Dead Sea Scrolls have been dated without guesswork, and so on. It was a sparkling display of what physical science could do for archaeology, and by and large such dating bore out what ar chaeologists had deduced by their own more laborious methods. In 1946 Libby showed that cosmic rays also produced tritium (radioactive hydrogen-3). Traces of this were always present in the atmosphere and therefore in water. Techniques involving the mea surement of tritium concentration could be used in dating well water, wine, and so on. Libby served as a member of the United States Atomic Energy Commis sion from 1954 to 1959, then returned to the University of California. He was 829
[1343] ARTSIMOVICH GREENSTEIN [1345]
awarded the 1960 Nobel Prize in chem istry for his carbon-14 dating technique. In the early 1960s Libby, along with Teller [1332], was in the news as a strong advocate of homemade fallout shelters for use in case of a nuclear war. He maintained, further, that these could be built easily and cheaply. He built a model shelter of his own as an object les son, but the lesson boomeranged when an ordinary fire made it necessary for him to evacuate both house and shelter. [1343] ARTSIMOVICH, Lev Andre evich
Soviet physicist Born: Moscow, February 25, 1909 Died: USSR, March 1, 1973 Artsimovich graduated from the Uni versity of Minsk in 1928. After World War II he worked on isotope separation in connection with the nuclear bomb. This, in turn, led him into work on con trolled nuclear fusion, which occupied him during the last third of his life. His work was instrumental in the de velopment of the Tokamak, which is now the favored instrument for the confinement of ultra-high temperature plasma in the United States as well as the Soviet Union; and it is the possible route whereby controlled fusion may be at tained in the next decade or so. [1344] LAND, Edwin Herbert American inventor Born: Bridgeport, Connecticut, May 7, 1909 Land attended Harvard College and in the mid-1930s, while still an under graduate, came up with an ingenious idea. It was known that certain organic crystals polarized light passing through them, just as Bartholin’s [210] Iceland spar did. The trouble was that it was difficult to get an organic crystal large enough to be useful. It struck Land that a large crystal was not necessary, but that myriad tiny crystals would do the trick if all were lined up in the same di rection. Land left school to work at this idea. He never obtained his degree, but, on the other hand, he collected half a dozen honorary ones. In 1932 he devised methods of align ing the crystals and of then embedding them in clear plastic, which, when set, served nicely to keep them from drifting out of alignment. The result was given the trade name Polaroid, and in 1937 Land organized the Polaroid Corpora tion. Polaroid quickly replaced Nicol [394] prisms in polarimeters and came in handy, too, in safety glass, in spectacles, and wherever it was desirable to cut down the transmission of reflected sun glare. (Such reflections are largely po larized, as Malus [408] had discovered a century earlier.) Other inventions followed, including a system of viewing objects so as to yield a three-dimensional effect. Land developed a new system of color photography which produced a full range of color effects out of two different colors (one of which may be white). This seemed to call for a modification of the Young [402]-Helmholtz [631] theory of color vi sion, which called for three basic colors out of which the total range might be built. Land’s most ingenious and successful invention was the Polaroid Land Camera in 1947. This is a device that produces developed photographs within seconds after snapping. The camera has a double roll of film, consisting of ordinary nega tive film and a positive paper, with sealed containers of chemicals between. The chemicals are released at the proper moment and develop the positive print automatically. [1345] GREEN STEIN, Jesse Leonard American astronomer Born: New York, New York, Oc tober 15, 1909 Greenstein was educated at Harvard University, gaining his Ph.D. in 1937. He then worked at Yerkes Observatory. During World War II he worked on spe cialized optical instruments for military use and afterward traveled westward to 830
[1346] TATUM
SHOCKLEY [1348]
the California Institute of Technology, where, by 1965, he was chairman of the Division of Physics, Mathematics and Astronomy. He was particularly interested in the constitution of stars and in the variations from one to another. The variations, which make one star rich in a particular element or isotope and another poor, must reflect differences in the composi tion of the original clouds out of which the stars were formed, or differences in subsequent histories, and Greenstein’s studies have helped deepen knowledge of stellar evolution. He worked with M. Schmidt [1488] in elucidating the nature of the quasars. [1346] TATUM, Edward Lawrie American biochemist
ber 14, 1909 Died: New York, New York, No vember 5, 1975 Tatum attended the University of Wis consin, where his father was head of the Department of Pharmacology. He gradu ated in 1930 and obtained his Ph.D. in 1934. He joined the faculty of Stanford Uni versity in 1937 and there worked on Neurospora with Beadle [1270], this work earning him a share of the 1958 Nobel Prize in medicine and physiology. In 1957 he joined the staff of the Rocke feller Institute for Medical Research (now Rockefeller University) in New York, where he worked with Lederberg [1466], [1347] MONOD, Jacques Lucien (moh- noh') French biochemist Born: Paris, February 9, 1910 Died: Cannes, May 31, 1976 Monod, whose mother was an Ameri can, obtained his doctorate at the Uni versity of Paris in 1941 and remained on its faculty till 1945 when he joined the Pasteur Institute. There he was as sociated with Lwoff [1253] and Jacob [1438], and for work done on regulatory gene action shared with them the 1965 Nobel Prize for medicine and physiol ogy. In 1970 he published Chance and Ne cessity, in which he insisted, uncom promisingly, on chance as the architect of all things. [1348] SHOCKLEY, William Bradford English-American physicist
ary 13, 1910 Shockley, the son of a mining engi neer, graduated from the California In stitute of Technology in 1932 and ob tained his Ph.D. from the Massachusetts Institute of Technology in 1936. In the latter year he joined the technical staff of Bell Telephone Laboratories. There, Shockley and his co-workers Bardeen [1334] and Brattain [1250] came across an interesting fact in the course of their researches. It had long been known that certain crystals could act as rectifiers; that is, they would allow current to pass in one direction but not in the opposite. Alternating current, passing through such crystals, was rectified, and only the surges in one di rection were transmitted, so that what emerged was a varying direct current. Such rectification is needed if radios are to run on alternating current. Crys tals were first used for the purpose, which is why early radios were known as crystal sets. The development of the radio tube by Fleming [803] and De Forest [1017] gave radio men a much more efficient and less troublesome rectifier and crystals went out of fashion. But now the wheel turned full circle and Shockley discovered that germanium crystals containing traces of certain im purities were far better rectifiers than the crystals used a generation earlier, and had definite advantages over the tubes used since. The impurities either contributed addi tional electrons that would not fit in the crystal lattice and drifted toward the positive electrode under an electric po tential (but not toward the negative); or 831
[1348] SHOCKLEY
WALTER [ 1 3 4 9 ] else the impurities were deficient in elec trons, so that the “hole” where an elec tron ought to be, but was not, would drift toward the negative electrode under an imposed potential (but not toward the positive). In either case, current would pass through in only one direc tion.
In 1948 Shockley found how to com bine “solid-state rectifiers” of these two types in such a way as to make it possi ble not only to rectify but also to am plify a current; in short, to do all that a radio tube could do. The device was called a transistor, because it transferred current across a resistor. During the 1950s, as techniques for the manufacture of transistors were stan dardized and the product was made more uniform and reliable, transistors began to replace tubes. They were much smaller than tubes, so that radios could be reduced in size and would begin oper ating without a preliminary warm-up. (Transistors, unlike the filaments within tubes, did not have to be brought to a high temperature before operation could start.)
Giant computers, after being “transis torized,” also shrank drastically in size. This process of miniaturization was strongly motivated through the latter half of the 1950s by the necessity of cramming as much instrumentation as possible into artificial satellites whose mass had to be reduced to a minimum if they were to be lifted into space without prohibitive expenditure of fuel and en ergy. Solid-state devices continued to shrink until, as the 1980s opened, the equiva lent of the huge computers of the 1950s could be fit into a shirt pocket and were correspondingly inexpensive. The intense computerization of society came to seem inevitable, and it all began with the tran sistor. Shockley, Bardeen, and Brattain were awarded the 1956 Nobel Prize in physics for their discovery of the transistor. In 1955 Shockley became director of re search for the Weapons Systems Evalua tion Group in the United States Depart ment of Defense and, in 1963, became professor of engineering science at Stan ford University. In the 1970s he won a certain notori ety by maintaining the importance of ge netic factors in intelligence in such a way as to imply the innate mental inferi ority of blacks. This was greeted by a storm of disapproval from many quar ters. In 1980 Shockley laid himself open to some ill-natured jests when he revealed he had contributed some of his seventy- year-old sperm cells for the purpose of freezing them for eventual use in the in semination of women of high intelli gence.
[1349] WALTER, William Grey American-British neurologist Born: Kansas City, Missouri, February 19, 1910 Walter was educated in England, grad uating from Cambridge University in 1931. He grew particularly interested in the electroencephalographic measure ments—the “brain waves” first demon strated by Berger [1014]—and found one that he suggested is associated with the learning process. More spectacularly, he developed an automatic device that is so wired as to react in fashions that one usually associ ates with living creatures. It is a small turtlelike object, which he calls a “tes tudo” (Latin for “turtle”) with a pho toelectric cell for an eye, a sensing de vice to detect touch, and motors that en able it to turn, to move forward, and to move backward. In the dark, it wheels about. When it touches an obstacle, it backs off a bit, turns slightly, and moves forward again; repeating the process till it gets around the obstacle. When its photoelectric eye sees a light, it moves straight toward it until the light gets too bright and then it backs away. When its batteries run down, however, the now “hungry” tes tudo can crawl close enough to the light to make contact with a recharger placed near the light bulb. Once recharged, it becomes more sensitive to the light and backs away again. 832
[1350] MARTIN
PIERCE [1351]
This “robot animal” seems to presage the more elaborate robotic imitations of humanity so beloved by science fiction writers.
As the 1980s opened, in fact, devices are used in industry that are so comput erized they can carry through complex operations that, until very recently, re quired human beings. These are termed “robots,” although they are not yet in the least either animal or human in ap pearance. The study of “robotics” (a term first used by Isaac Asimov in 1942) is now well established. [1350] MARTIN, Archer John Porter English biochemist Born: London, March 1, 1910 Martin, the son of a physician, was educated at Cambridge University, where he earned all his degrees, through a Ph.D. in 1936. During the 1930s he worked in the nutritional laboratories at the university and through that his atten tion turned to the proteins. The fact that the protein molecule was made up of a connected chain of amino acids had been demonstrated by Emil Fischer [883], but the characterization of a particular protein by breaking down the molecule to fragments and then de termining the precise number of each amino acid present, was a difficult matter indeed. It had defeated a generation of biochemists. The amino acids were so alike that a complete separation by ordi nary chemical methods was impractical. Chromatography as developed by Will- statter [1009] had sufficed to separate the very similar plant pigments, but some thing on a smaller scale was desperately needed for the amino acids. It occurred to Martin and his co-worker, Synge [1394], that chromatography might be tried on porous filter paper. A drop of amino acid mixture could be allowed to dry near the bottom of a strip, and a particular solvent (into which the bottom edge of the strip could be dipped) could then be allowed to creep up the strip by capillary action. As the creeping solvent passed the dried mixture, the various amino acids would creep up with the solvent but at varying rates, depending on the solubility of each amino acid in the solvent and in water. In the end, the amino acids would be separated. Their position could be de tected by some suitable physical or chemical means and matched against the position of samples of known amino acids treated in the same way. The quan tity of amino acid in each spot could also be determined. This technique of paper chroma tography was developed in 1944, proved an instant success, and was fruitfully ap plied to all varieties of mixtures. It was paper chromatography that determined the number of particular amino acids in protein molecules and even allowed Sanger [1426] to work out the exact order in which they occurred in the insu lin molecule. It was paper chroma tography, combined with the use of iso topic tracers, that enabled Calvin [1361] to work out the scheme of pho tosynthesis. Martin and Synge were awarded the 1952 Nobel Prize in chemistry for the development of this technique. Meanwhile, for some years Martin had been speculating on the possibility of separating gases by chromatographic means and in 1953 perfected such gas chromatography. This has already proved itself to be as useful as paper chromatography and as powerful a tool for the chemist. [1351] PIERCE, John Robinson American electrical engineer Born: Des Moines, Iowa, March 27, 1910 Pierce, the son of a businessman, grad uated from the California Institute of Technology in 1933 and obtained his Ph.D. there in 1936, passing on at once to the Bell Telephone Laboratories, where he was put to work on vacuum tubes. During World War II he devel oped at Bell a klystron-oscillator univer sally used in American radar receivers. Pierce, like Wemher von Braun [1370] and some other spacemen of their gener ation, is a science fiction enthusiast (and, 833
[1352] HODGKIN
COUSTEAU [1353]
in fact, has written for science fiction magazines under the pseudonym J. J. Coupling). The concept of satellites gir dling the earth and acting as reflectors for radio waves was first proposed by the astronomer and science fiction writer Arthur C. Clarke in 1948, and Pierce found the concept not too strange a one to work toward, even at a time when artificial satellites existed only in science fiction. If such satellites succeeded, com munication could become worldwide under conditions that would make a transoceanic telephone call as simple as a local call. In 1957 satellites began to be placed in orbit and on August 12, 1960, Pierce’s efforts paid off when Echo I was sent up. It was an aluminum balloon, one hundred feet in diameter, which was inflated only after it had settled safely into its orbit. It served as a passive reflector for radio waves and, as such, performed its function perfectly. Since then, the matter has progressed rapidly and communications satellites are now routinely used in television and in long-distance communication. In 1971 Pierce accepted a position on the faculty of the California Institute of Technology. [1352] HODGKIN, Dorothy Crowfoot English biochemist
parents), May 12, 1910 Dorothy Hodgkin, daughter of an ar chaeologist, was bom abroad while her father was on his travels, and she and her family continued this tradition of visiting odd corners of the world in the course of their professional life. Of her three children, one was teaching in Al geria, one in Zambia, while another was working in India at the time Hodgkin reached the climax of her career with a Nobel Prize award. Hodgkin herself was then in Ghana. Her education, however, was in En gland. where she graduated from Somer ville College, Oxford, in 1932 and where Robert Robinson [1107] was one of her teachers. She went on then to obtain her Ph.D. at Cambridge University in 1937. For her doctoral labors, she studied the X-ray diffraction of crystals of the digestive enzyme pepsin. That fixed the direction of her interests and she spent her later professional life on the determi nation of complex organic structures through X-ray diffraction. During World War II she tackled the structure of penicillin in this fashion at a time when Florey [1213] and Chain [1306] were desperately trying to work out its structure. Hodgkin made use of an electronic computer in working out the X-ray data and this helped materially in the final structure determination, which was accomplished by 1949. It was the first use of the electronic computer in direct application to a biochemical problem. Hodgkin went further. In the early 1950s she tackled the molecular struc ture of cyanocobalamin (vitamin B12), recently isolated by Folkers [1312]. Its molecule was four times as large as that of penicillin and its structure was, in some ways, unique. Again, an electronic computer was called into play, but even so, it took years, for computer work, combined with the more ordinary chemi cal evidence concerning the breakdown products of cyanocobalamin, to work out the structure in full detail. By 1955 the back of the problem had been broken and in 1964 Hodgkin was awarded the Nobel Prize for chemistry. [1353] COUSTEAU, Jacques-Yves (coo-stoh') French oceanographer Bom: St. Andre-de-Cubzac, June 11, 1910 Cousteau was educated at the Brest Naval Academy and throughout his life seems to have been much more at home underwater than on land. He was with the French underground during World War II, and even during that hard time Cousteau managed to work at his life’s absorption and to in vent the Aqualung. This was a device that supplied air under pressure for the 8 3 4
[1354] FLORY
FRAENKEL-CONRAT [1355]
diver. It was self-contained and did not require the heavy suit and the lifeline that the armored diver needed. Equipped with an Aqualung, men with finned devices on their feet could probe the water under the surface with freedom and mobility. This makes possi ble the modern sport of scuba diving. “Scuba” stands for “self-contained un derwater breathing apparatus.” Cousteau has used the device for exploration and has produced dramatic motion pictures of underwater life, which millions have seen on television. He has also designed underwater structures that can house men for pro longed periods of time. Men have stayed in such devices, forty feet below the sur face, for weeks, and some optimists fore cast man’s colonization of the conti nental shelf before very long. [1354] FLORY, Paul John American chemist
1910
Flory obtained his Ph.D. at Ohio State University in 1934. He then worked with Carothers [1190] and helped develop nylon and the artificial rubber neoprene. He taught at Cornell University and at the Mellon Institute (now Carnegie- Mellon University), and in 1961 moved to Stanford University as professor of chemistry. He retired in 1975. He worked on the analysis of “macro molecules,” the large molecules made up of repeated units, and studied the ways in which the repetitions could be con trolled so that new plastics and other synthetics could be manufactured and so that desired properties could be designed into them, so to speak. For his work he received the 1974 Nobel Prize for chem istry. [1355] FRAENKEL-CONRAT, Heinz (freng'kel-kon'rat) German-American biochemist Born: Breslau, Germany (now Wroclaw, Poland), July 29, 1910 Fraenkel-Conrat, son of a famous gy necologist, obtained his medical degree at the University of Breslau in 1933, then left Germany with the advent of Hitler. In 1936 he obtained a Ph.D. in biochemistry at the University of Edin burgh and went to the United States, which he made his permanent home, becoming a naturalized citizen in 1941. He was at the University of California after 1951. Fraenkel-Conrat’s most startling piece of research was in connection with the viruses. In the 1940s it had been shown that viruses were nucleoprotein in char acter, containing, that is, both protein and nucleic acid. It had also been shown that solutions of nucleic acid alone could change certain physical characteristics of bacterial strains. This rather startled bio chemists, who for the first time turned their attention to nucleic acids as the possible carriers of genetic information. In 1955 Fraenkel-Conrat, working with bacteriophages, developed gentle techniques for teasing apart the nucleic acid and protein of a virus, without seriously damaging either portion, and then putting them together again. At least some of the virus molecules, thus reformed, retained their infectivity and were, therefore, as alive as they ever were by the only criterion by which sci entists could judge viral life. This work strengthened the evidence accumulated in the early 1950s that viruses consisted of a hollow protein shell with a nucleic acid molecule within. Fraenkel-Conrat further showed that whereas the isolated protein was com pletely dead and showed no properties that could be associated with life, the isolated nucleic acid retained a faint in fectivity. The protein, in other words, might be instrumental in getting the nu cleic acid into the cell, but it was the nucleic acid itself that was the infective agent—a point strongly supported by other evidence. Within the infected cell, the nucleic acid (which entered alone, and without its encompassing protein shell) not only brought about the manufacture of addi tional molecules of nucleic acid like it self, but also the manufacture of protein 835
[1356] CHANDRASEKHAR ROBERTS [1357]
shells characteristic of itself and not like the proteins naturally produced by the invaded cell. The manner in which the fine structure of the nucleic acid dictated the production of protein molecules of a particular fine structure is termed the “genetic code.” There was no doubt by the late 1950s that the basic properties of life were the consequence of the activity of nucleic acid molecules, and the detailed chemis try of nucleic acids therefore became the prime target of biochemists. It is because of this that the breakthrough by Wilkins [1413], Crick [1406], and James Dewey Watson [1480], two years before Fraenkel-Conrat’s experiments, assumed such overwhelming importance. [1356] CHANDRASEKHAR, Subrah manyan (chan-drah-seekhahr) Indian-American astronomer
Pakistan), October 19, 1910 Chandrasekhar was educated at Madras University in India, graduating in 1930. He obtained his Ph.D. at Cam bridge University in 1933 where he stud ied under Dirac [1256], He went to the United States in 1936 and was natural ized in 1953. In the United States he joined the faculty of the University of Chicago and worked at Yerkes Observa tory under Otto Struve [1203], Chandrasekhar was chiefly interested in the structure of the white dwarf stars, whose unusual properties were first dis covered by Adams [1045]. In these stars most of the constituent atoms have bro ken down into collections of subatomic particles—plasma—and the whole com pressed to the point where the overall density is thousands of times that of or dinary matter. (Even ordinary stars con tain limited quantities of such degenerate matter, as it is also called, in their inte rior. Plasma received its name from Langmuir [1072] in 1923. He came across it in his study of neon lights.) Chandrasekhar showed that the more massive a white dwarf star, the more compactly it must be compressed by its own gravitational field. Since it could only be compressed to a certain amount (the subatomic particles having a finite volume of their own), such a star could not be more massive than a certain amount, an amount which turned out, according to his calculations, to be 1.5 times the mass of the sun. This is known as Chandrasekhar’s limit. It has been shown by Hoyle [1398] and others that when the ordinary nu clear processes that power a star fail, the star collapses into a white dwarf. (This collapse, it was suggested in 1961, is brought about by the loss of energy through massive emission of neutrinos, which builds up very suddenly in the super-hot interior of stars in the pre white dwarf stage.) Chandrasekhar suggested that when a star with a mass greater than 1.5 times that of the sun reaches that stage and col lapses, it could do so only by exploding and blowing off some of its excess mass. It was this that resulted in supernovas of the type being studied by Zwicky [1209], This means that our sun can never go supernova, being insufficiently massive. This is cold comfort, however, since if it were to become a red giant (as it would have to before collapsing) life on Earth would be wiped out in short order even if there were no explosion. [1357] ROBERTS, Richard Brooke American biophysicist
December 7, 1910 Died: April 4, 1980 Roberts received his Ph.D. at Prince ton in 1937, then joined the faculty of Carnegie Institution in Washington. He worked both on cellular compo nents and on nuclear physics, but his most important finding came in 1939, when he contributed most to the discov ery that uranium fission did not release all the neutrons it produced at one time. Some came off at measurably later times as “delayed neutrons.” This was crucial because it meant that when a fission reactor reached the criti cal point where it might go out of con trol, enough of the neutrons were 836
[1358] SHEMIN
CALVIN [1361]
delayed to keep the rate of fission small enough to give time for the insertion of the control rods. In other words, delayed neutrons are an important element of safety in nuclear reactors, and without them, nuclear reactors might not be practical at all. [1358] SHEMIN, David American biochemist
March 18, 1911 Shemin graduated from the City Col lege of New York in 1932, then went on to Columbia University for graduate work, getting his Ph.D. in 1938. He spent most of his professional career on the Columbia faculty, but shifted to Northwestern University in 1968. He was one of those who made use of carbon-14, after its discovery by Kamen [1385] to follow the pathway of chemi cals as they changed within the body in response to the many reactions talcing place there. The carbon-14 left a trail of energetic particles wherever it went. By following that trail, Shemin worked out the scheme of synthesis of heme, the im portant iron-containing compound that gives blood its red color and (in combi nation with a protein—the whole being hemoglobin) serves to carry oxygen from lungs to tissues. [1359] KATZ, Sir Bernard German-British physiologist
26, 1911 Katz obtained his M.D. at the Univer sity of Leipzig in 1934, but by that time Hitler was in control of Germany, and Katz very wisely left for Great Britain. He continued his education at the Uni versity of London and received his Ph.D. in 1938. He worked on the electrical im pulses that moved along nerves and, in particular, on the transmission of those impulses from nerve to muscle. He showed the manner in which this was mediated by the diffusion of sodium and potassium ions into and out of nerve and muscle cells in such a way as to set up and remove electrical potentials. For this work he shared the 1970 Nobel Prize for physiology and medicine with Axelrod [1374], He was knighted in 1969. [1360] LYNEN, Feodor (lee'nen) German biochemist Born: Munich, Bavaria, April 6, 1911
Died: Munich, August 6, 1979 Lynen studied at the University of Munich, obtaining his Ph.D. in 1937 under Wieland [1048], The connection became even closer when he married Wieland’s daughter that year. He joined the faculty at Munich in 1941 and in 1956 became head of the Institute of Cell Chemistry there. Lynen’s most important work was in connection with coenzyme A, which Lip- mann [1221] had postulated as the car rier of the two-carbon fragment. Lynen’s work helped elucidate the rather compli cated structure of the coenzyme. He was the first to isolate “acetylcoenzyme A,” the combination of the coenzyme A and the two-carbon fragment. As a result, he shared with K. Bloch [1369] the 1964 Nobel Prize for medi cine and physiology. [1361] CALVIN, Melvin American biochemist
8, 1911
Calvin, the son of Russian immigrants, graduated from the Michigan College of Mining and Technology in 1931 and earned his Ph.D. at the University of Minnesota in 1935. He spent two years at the University of Manchester in En gland, then in 1937 joined the faculty of the University of California and re mained there afterward, becoming direc tor of the Lawrence Radiation Labora tory in 1946. In 1949 he became interested in work ing out the chemical details of the pro cess of photosynthesis, whereby the green plant takes carbon dioxide out of 837
[1362] GOLDHABER ALVAREZ [1363]
the air, combines it with water, and forms starch, discharging molecular oxy gen (a by-product of the reaction) into the air. This is the most important single biochemical process on earth, since it is on the food thus formed by the plant that all animal life (including man) lives, and it is the oxygen formed that all animal life (including man) breathes. Unfortunately the reaction cannot so far be imitated in the test tube, with nonliving substances, so that fragments of the process cannot be studied in de tail. Instead, living cells must be used and the process studied as a whole. Fur thermore, the photosynthetic reactions proceed so rapidly that it is almost im possible to stop the process midway. Cal vin and his group made use of radioac tive carbon dioxide, containing the iso tope carbon-14, in order to get around these difficulties. They allowed plant cells to make use of this carbon dioxide for no more than seconds of time, then mashed up the cells and separated the contents by means of the paper chromatographic method worked out earlier in the decade by Martin [1350] and Synge [1394], Those substances containing radioactive carbon (easily detected) must represent compounds manufactured in the very earliest stages of photosynthesis. Progress was slow; but little by little, Calvin and his group discovered and iso lated the intermediate products, deduced how they must fit together, and built up a scheme of photosynthesis that made sense, thus capping a line of research that had begun with Helmont [175] three centuries earlier. By 1957 the main strokes were filled out with detail and Calvin was awarded the 1961 Nobel Prize in chemistry as a result. [1362] GOLDHABER, Maurice Austrian-American physicist Born: Lemberg, Austria (now Lvov, USSR), April 18, 1911 Goldhaber studied at the University of Berlin till 1933. The advent of Hitler made a further stay there highly un desirable and he went to England where, at Cambridge University, he obtained his Ph.D. in 1936. While there, he collaborated with Chadwick [1150] in the determination of the structure of the deuteron (the nu cleus of the atoms of Urey’s [1164] deu terium). It turned out to consist of a proton and a neutron. He went on to study a number of neutron-bombard ment reactions, a type of study similar to that which led Fermi [1243] in the direc tion of the atomic bomb. In doing so, he supplied evidence for the neutron’s being slightly more massive than the proton. In 1938 Goldhaber went to the United States where he joined the faculty of the University of Illinois (becoming an American citizen in 1944). While there he discovered, in 1940, that beryllium would function as a “moderator”; that is, it would slow fast neutrons and make it more readily possible for uranium to un dergo fission. The atomic bomb project had not yet begun and secrecy had not yet been clamped down. Entirely volun tarily, however, Goldhaber felt the ne cessity of keeping his discovery quiet, and voluntarily withheld publication till after World War II. In 1950 Goldhaber joined Brookhaven National Laboratory. [1363] ALVAREZ, Luis Walter American physicist
June 13, 1911 Alvarez, the son of a well-known phy sician, attended the University of Chi cago for both his undergraduate and graduate work, obtaining his Ph.D. in 1937. He then moved on to the Univer sity of California, where he achieved professorial status in 1945. He remained there throughout his career. During World War II he worked on radar and on the atomic bomb. His most important labors involved the use of Glaser’s [1472] bubble chamber, which Alvarez developed to enormous sizes and with which he detected and studied extremely short-lived “resonance particles.” There were numbers of these 838
[1364] MUELLER
STEIN [1365]
and the necessity for explaining their ex istence led to the theories of Gell-Mann [1487] and Ne’eman [1465], For this work Alvarez was awarded the 1968 Nobel Prize in physics. In 1980, quite by accident, he noted an unusually high concentration of irid ium at a certain layer of a sedimentary core studied in Italy. It turned out the layer had been laid down 65 million years ago at the end of the Cretaceous and the time of the disappearance of the dinosaurs. This high concentration of iridium (and other metals) has turned up in widely different places on Earth and has led to the speculation that the dinosaurs, and all large animals, were wiped out in the wake of the collision with Earth of an asteroid ten kilometers wide, an oc currence that released so much dust into the stratosphere as to block all radiation of the sun for three years. As a result, vegetation was so reduced as to plunge animals into extinction. [1364] MUELLER, Erwin Wilhelm German-American physicist
1977
Mueller graduated from the Technical University at Berlin in 1935, working under Gustav Hertz [1116]. He worked in Berlin for nearly two decades thereaf ter, but in 1952 came to the United States and has since been at Pennsyl vania State University. He was natural ized in 1962. Mueller is best known for his field- emission microscope, which he first con ceived in 1936. Essentially this involves a very fine needle tip in a high vacuum. This tip can be made to emit electrons, which shoot outward in straight lines (radiating from the curved needle tip) and strike a fluorescent screen. What ap pears on the screen, then, is a vastly magnified picture of the needle tip. Magnifications of up to one million di ameters are achieved so that the field- emission microscope is the most power ful ever built, an unimaginably far cry from the days of Malpighi [214] and Leeuwenhoek [221]. Ions rather than electrons can also be made to shoot off the needle tip. For this purpose the needle is kept at liquid hy drogen temperatures and helium, ab sorbed on the needle surface, is emitted as helium ions. The image produced by the ions on the screen can distinguish individual atoms; some of these images, taken as early as 1955, are already classics in scientific photography. By 1967 not only could atoms be seen in this way but chemicals could be identified. Through them the atoms first postulated by Democritus [20] twenty- three centuries earlier and first intro duced to modern chemistry by Dalton [389] a century and a half earlier have finally been seen, at least to the extent that their orderly positions in certain substances can be made out. So far, field-emission microscopy is ap plicable only to a limited number of high-melting metals and alloys, but it is of great use in studying gas adsorption and crystal imperfections. A few fairly large organic molecules, such as that of phthalocyanine, have been made visible. [1365] STEIN, William Howard American biochemist Born: New York, New York, June 25, 1911 Died: New York, New York, February 2, 1980 Stein graduated from Harvard Univer sity in 1933 and obtained his Ph.D. from Columbia University in 1938. He then joined the Rockefeller Institute (now Rockefeller University), where he achieved the status of full professor in 1955. He is best known for devising chro matographic methods for analyzing amino acids and small peptides in the complex mixture resulting from the hydrolysis of proteins. He developed an automatic amino acid analyzer and used his methods for the determination of the complete structure of the enzyme ribo nucléase. In this he was assisted by 839
[1366] WHEELER
REBER [1368]
Moore [1379] and, as a result, Stein and Moore shared the 1972 Nobel Prize for chemistry. [1366] WHEELER, John Archibald American physicist
9, 1911
Wheeler obtained his Ph.D. at Johns Hopkins University in 1933, spent two years at Copenhagen, and joined the fac ulty of Princeton in 1938, where he remained until he retired. After World War II he participated in the theoretical work that finally led to the explosion of the first hydrogen bomb in 1952. He then grew interested in those aspects of general relativity that seemed to suggest the possibility of grav itational collapse. To Wheeler it seemed that, under certain conditions, the col lapse could not be stopped and would continue until any mass, however large, would shrink down to a point, or “singu larity.” In the course of such shrinkage the gravitational field at the surface of the shrinking mass would become so in tense that the escape velocity would be greater than the velocity of light, which would mean that nothing, not even light, could escape. Wheeler invented the term “black hole” for such a collapsed mass. Black holes have become one of the most fascinating aspects of astrophysics and Wheeler has remained in the fore front of theoretical thinking on the sub ject, matched only by Hawking [1510]. [1367] KERST, Donald William American physicist
1, 1911
Kerst obtained his Ph.D. in 1937 at the University of Wisconsin, then joined the faculty of the University of Illinois. His main achievement involved the ac celeration of electrons. The electrons are so much lighter than protons that to give them sufficient momentum to induce nu clear transformations, they must be whirled at velocities that would produce so great a relativistic mass increase that an ordinary cyclotron would not work. For that reason, some new method of acceleration had to be devised for elec trons.
The result was the betatron, first put to successful use by Kerst in 1940. In it the speeding electrons (or beta particles, whence the name) were whirled in cir cles rather than in spirals, while the magnetic field was increased in time to the increasing mass of the particles. During World War II Kerst worked at Los Alamos on the atomic bomb project, but afterward he returned to the beta tron, building a huge one for the Univer sity of Illinois in 1950. [1368] REBER, Grote American radio engineer Born: Wheaton, Illinois, Decem ber 22, 1911 Reber entered radio astronomy as a hobby. At fifteen he was already an en thusiastic radio “ham.” When he heard of Jansky’s [1295] discovery, he, and he alone, fired up. Even as a student at the Illinois Institute of Technology, he tried to take up where Jansky left off. For in stance, he tried to bounce radio signals off the moon. (He failed, but the Army Signal Corps, with far more resources at its disposal, managed to do this after World War II.) In 1937 he built the first radio tele scope, in his back yard. The reflector (or “dish”) receiving the radio waves was thirty-one feet in diameter. In 1938 he began to receive and for several years was the only radio astronomer in the world. He discovered points in the sky that emitted stronger-than-background radio waves. Such “radio stars,” he found, did not coincide with any of the visible stars. One of them was later identified by Baade [1163] a decade later as what seemed to be a distant pair of colliding galaxies. Reber published his findings in 1942. Oort [1229] in the Netherlands grew in terested, and once World War II was 8 4 0
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