Mathmatican and inventor, born in London. He studied at Cambridge, where he became professor of mathematics (1828-39), and spent most of his life attempting to build two calculating machines. His "difference engine" was intended for the calculation of tables of logarithms and similar functions by repeated addition performed by trains of gear wheels. An unfinished portion of the machine is now in the Science Museum, London. His "analytical engine" was designed to perform many different computations, using punched cards. The idea was too ambitious to be realized by the mechanical devices available at the time, but can now be seen to be the essential germ of the electronic computer of today, and Babbage is thus regarded as the pioneer of modern computers.
Anthropologist, born in Grantchester, Cambridgeshire, son of biologist William Bateson. Studied physical anthropolgy at Cambridge, but made his career in the USA. With Margaret Mead he was involved in the culture-and-personality movement, publishing Balinese Character in 1942. Influenced by cybernetics, he went on to study problems of communication and learning among aquatic mammals and human schizophrenics. Later works include Mind and Nature (1978).
Mathematician, born in Groningen, the son of Jean Bernoulli. He studied medicine and mathematics, and became professor of mathematics at St. Petersburg in 1725. In 1732 he returned to Basel to become professor of anatomy, then botany, and finally physics. He worked on trigonometric series, mechanics, vibrating systems, and hydrodynamics (anticipating the kinetic theory of gases), and solved a differential equation proposed by Jacopo Riccati, now known as Bernoulli's equation.
Mathematician, born in Basel, Switzerland, the brother of Jean Bernoulli. He became professor of mathematics at Basel in 1687. He investigated infinite series, the cycloid, transcendental curves, the logarithmic spiral, and the catenary. In 1690 he applied Gottfried Leibniz's newly discovered differential calculus to a problem in geomtry, first using the term integral. His Ars conjectandi (1713) was an important contribution to probability theory.
Physicist, born in Vienna. He studied at Vienna, where he became professor in 1895. He did important work on the kinetic theory of gasses and established the principle of the equipartition of energy (Boltzmann's law). He laid the foundations fo statistical mechanics by applying the laws of mechanics and the theory of probability to the motion of atoms, and his name was given to the Boltzmann constant, a fundamental constant of physics.
Mathematician, born in Cluj, Romania. After attempting to prove Euclid's parallel postulate, he realized that it was possible to have a consistent system of geometry in which this postulate did not hold, and so became one of the founders of non-Euclidean geometry.
Biochemist and educator, born in New Haven, CT. He created at Yale the first American course in physiological chemistry (later known as biochemistry), remaining there until 1922, and bringing Yale's Sheffield Scientific School into prominence as its directore (1898-1922). He made pioneering studies in the enzymatic degestion of proteins and starch, isolated glycogen ("animal starch") in 1875, and advocated a low-protein diet for humans. He also investigated the toxicology of human alcohol and chemical addiction.
Physicist, born in Warsaw, who worked at Paris with her French husband Pierre Curie (1859-1906) on magnetism and radioactivity, and discovered radium. She emigrated to France in 1891, and studied at the Sorbonne. Her husband, who also studied at the Sorbonne, became professor of physics there in 1901. Pierre and his brother, Jacques, discovered piezoelectricity. For her thesis she studied the 'rays' earlier discoverd by Becquerel. Pierre and Marie Curie shared the Nobel Prize for Physics with Becquerel for the discovery of radioactivity. After her husband's death in a road accident (1906), Mme Curie succeeded to his chair, isolated polonium and radium in 1910, and was awarded the Nobel Prize for Chemistry in 1911. She died of leukaemia, probably caused by long exposure to radiation.
Darwin was born in Shrewsbury, Shropshire. He was the son of Robert Waring Darwin and his wife Susannah; and the grandson of the scientist Erasmus Darwin, and of the potter Josiah Wedgwood. His mother died when he was eight years old, and he was brought up by his sister. He was taught classics at Shrewsbury, then sent to Edinburgh to study medicine, which he hated, and a final attempt at educating him was made by sending him to Christ's College, Cambridge, to study theology (1827). During that period he loved to collect plants, insects, and geological specimens, guided by his cousin William Darwin Fox, an entomologist. His scientific inclinations were encouraged by his botany professor, John Stevens Henslow, who was instrumental, depsite heavy paternal opposition, in securing a place for Darwin as a naturalist on the surveying expedition of HMS Beagle to Patagonia (1831-6).
Under Captain Robert Fitzroy, he visited Tenerife, the Cape Verde Is, Brazil, Montevideo, Tierra del Fuego, Buenos Aires, Valparaiso, Chile, the Galapagos, Tahiti, New Zealand, and Tasmania. In the Keeling Is he devised his theory of coral reefs. During this five-year expedition he obtained intimate knowledge of the fauna, flora, and geology of many lands, which equipped him for his later investigations. By 1846 he had published several works on the geologcial and zoological descoveries of his voyage- works that placed him at once in the front rank of scientists. He developed a friendship with Sir Charles Lyell, became secretary of the Geological Society (1838-41), and in 1839 married his cousin Emma Wedgewood (1808-96).
From 1842 he lived at Down House, Downe, Kent, a country gentleman among his gardens, conservatories, pigeons, and fowls. The practical knowledge he gained there, especially in variation and interbreeding, proved invaluable. Private means enabled him to devote himself to science, in spite of continuous ill-health: it was not realized until after his death that he had suffered from Chagas's diasease, which he had contracted from an insect bite while in South America.
At Down House he addressed himself to the great work of his life- the problem of the origin of species. After five years of collecting the evidence, he began to speculate on the subject. In 1842 he drew up his observations in some short notes, expanded in 1844 into a sketch of conclusions for his own use. These embodied the principle of natural selection, the germ of the Darwinian Theory, but with typical caution he delayed publication of his hypothesis.
However, in 1858 Alfred Russel Wallace sent him a memoir of the Malay Archipelago, which, to Darwin's surprise, contained in essence the main ideas of his own theory of natural selection. Lyell and Joseph Hooker persuaded him to submit a paper of his own, based on his 1844 sketch, which was read simultaneously with Wallace's before the Linnean Society in 1858. Neither Darwin nor Wallace was present on that historic occasion.
Darwin then set to work to condense his vast mass of notes, and put into shape his great work, The Origin of Species by Means of Natural Selection, published in 1859. This epoch-making work, received througout Europe with the deepest interest, was violently attacked because it did not agree with the account of creation given in the Book of Genesis. But eventually it succeeded in obtaining recognition from almost all biologists.
Darwin continued to work at a series of supplemental treatises: The Fertilization of Orchids (1862), The Variation of Plants and Animals under Domestication (1867), and The Descent of Man and Selection in Relation to Sex (1871), which postulated that the human race derived from a hairy animal belonging to the great anthropoid group, and was related to the progenitors of the orang-utan, chimpanzee, and gorilla. In his 1871 work he also developed his important supplementary theory of sexual selection.
Later works include The Expression of Emotions in Man and Animals (1872), Insectivorous Plants (1875), The Effects of Cross and Self Fertilization in the Vegetable Kingdom (1876), Different Forms of Flowers in Plants of the Same Species (1877), and The Formations of Vegetable Mould through the Action of Worms (1881).
Darwin died after a long illness, leaving eight children, several of whom achieved great distinction. Though not the sole originator of the evolution hypothesis, nor even the first to apply the concept of descent to plants and animals, he was the first thinker to gain for that theory a wide acceptance among biological experts. By adding to the crude evolutionism of Erasmus Darwin, Lamarck, and others, his own specific idea of natural selection, Darwin supplied a sufficient cause, which raised it from a hypothesis to a verifiable theory.
"A man who dares to waste an hour of life has not discovered the value of life."
-Darwin
Astronomer, born in Kendal, Cumbria. He studied at Manchester and Cambridge, where he became professor of astronomy (1913) and director of the Cambridge Observatories, working mainly on the internal structure of stars. In 1919 his observations of star positions during a total solar eclipse gave the first direct confirmation of Einstein's general theory of relativity. He became a renowved popularizer of science, notably in The Expanding Universe (1933). He was knighted in 1930.
Einstein was born into a Jewish family at Ulm, Germany. They moved to Munich the following year, where his father Hermann and his uncle Jakob opened a small electrical and engineering works. His mother, Paulina Koch, encouraged him to study music during his youth, and he became an accomplished violinist, but it was Jakob who inspired his fascination for mathematics. Initially an unremarkable student, he was educated at Munich and Aarau, eventually going on to graduate in physics and mathematics from the Federal Polytechnic University in Zürich in 1900. He became a Swiss citizen in 1905, and was appointed examiner at the Swiss Patent Office (1902-09).
He married fellow student Mileva Maríc in 1903, and they had two sons: Hans Albert and Edward (who later had a mental breakdown). However, the outbreak of World War 1 caused him to be separated from his family - he was in Berlin while they were in Switzerland. They were divorced in 1919. A gifted physicist in her own right, Mileva and Albert would work together on the mathematics of his theoretical thinking. In recognition of this he later gave her the money that came with his Nobel Prize. She gave up physics to look after their son Edward. A second marriage, to Elsa, his first cousin (d.1936), took place in 1919.
From 1905 Einstein published papers on theoretical physics in the prestigious monthly Annalen der Physik, including his special theory of relativity, which in its embryonic form was an essay he had written aged 16. Entitled "Zur Elektrodynamik bewegter Körper" (On the Electrodynamics of Moving Bodies), the theory showed that in the case of rapid relative motion involving velocities approaching the speed of light, puzzling phenomena such as decreased size and mass are to be expected. This provided a new system of mechanics which accommodated James Clerk Maxwell's electromagnetic-field theory, as well as the hitherto inexplicable results of the Michelson-Morley experiments (1881, 1887) on the speed of light. He became professor at Prague in 1911, and at Zürich in 1912, then worked in Berlin, where he was director of the Kaiser Wilhelm Physical Institute (1914-33). On accepting the post in Berlin, he reassumed his German citizenship, relinquishing it again in 1933.
"Die Grundlagen der allgemeinen Relativitästheorie" (The foundation of the General Theory of Relativity) was published in 1916. This theory accounted for the slow rotation of the elliptical path of the planet Mercury, which Newtonian gravitational theory failed to do. Fame and recognition came suddenly in 1919, when the Royal Society of London photographed the solar eclipse and publicly verified Einstein's general theory of relativity. In 1921 he was awarded the Nobel Prize for Physics for his photoelectric law and work in the field of theoretical physics, but such was the controversy still aroused by this theories on relativity that these were not specified in the text of the award.
Einstein was regarded suspiciously in Berlin for his outspoken pacifism and socialism, and also for his Jewish background. He was a supporter of Zionism, pulishing About Zionism (Uber Zionismus) in 1931. After Hitler's rise to power, he was deprived of his post at Berlin and his home at Caputh. He left Germany, and form 1934 lectured at Princeton, NJ, took US citizenship, and became professor at Princeton in 1940.
From the 1930s he was increasingly outspoken in support of world peace. In 1933 he joined with Sigmund Freud to write Warum Kreig? (Why War?). However, when it was brought to his attention by German chemists that the splitting of uranium atoms could result in a mammoth explosion, he carried out experiments at Princeton verifying this possibility, and was persuaded in September 1939 to write to President Roosevelt warning him of the possibility that Germany would try to make an atomic bomb. Despite his pacifism, Einstein felt that force should be used to prevent this happening, and in this way he helped to initiate the Manhattan Project (research work led by Robert Oppenheimer into the creation of the atomic bombs dropped on Hiroshima and Nagasaki), although he was not directly involved in it himself.
After the war, Einstein urged international control of atomic weapons, and protested against the proceedings of the Un-American Activities Senate Subcommittee, which had arraigned many scientists. In 1952 he was offered the presidency of Israel, but declined. He spent the rest of his life trying, by means of his unified field theory (1950), to establish a merger between quantum theory and his general theory of relativity, thus bringing subatomic phenomena and large-scale physical phenomena under one set of determinate laws. His attempt was not successful. After many years of deteriorating health, he died in his sleep in hospital at Princeton.
Einstein ranks with Galileo and Newton as one of the great conceptual revisers of our understanding of the universe. He was the originator of completely new ways of looking at space, time, and gravitational forces, as well being a champion of pacifism and liberalism, and the "grand old man" of world peace.
Greek mathematician who taught in Alexandria c.300B.C. and who was probably the founder of its mathematical school. His chief extant work is the 13-volume Elements, which became the most widely known mathematical book of classical antiquity, and is still much used in geometry. The approach which obeys his axioms became known as Euclidian geometry.
Greek geometer and astronomer, born in Cnidus, Aisa Minor. In geometry he established principles that laid the foundation for Euclid, then applied the subject to the study of the Moon and the planets. He introduced an ingenious system of 27 nested spheres in an attempt to explain planetary motion.
Mathematician, born in Basel, Switzerland. He studied mathematics there under Jean Bernoulli, and became professor of physics (1731) and then of mathematics (1733) at the St. Petersburg Academy of Sciences. In 1738 he lost the sight of one eye. In 1741 he moved to Berlin as director of mathematics and physics in the Berlin Academy, but returned to St. Petersburg in 1766, soon afterwards losing the sight of his other eye. He was a giant figure in 18th-c mathematics, publishing over 800 different books and papers, on every aspect of pure and applied mathematics, physics and astronomy. His Introductio in analysin infinitorum (1748) and later treatises on differential and integral calculus and algebra remained standard textbooks for a century and his notations, such as e and (pi) have been used ever since. For the princess of Anhalt-Dessau he wrote Lettres à une princesse d'Allemagne (1768-72), giving a clear non-technical outline of the main physical theories of the time. He had a prodigious memory, which enabled him to continue mathematical work and to compute complex calculations in his head when he was totally blind. He is without equal in the use of algorithms to solve problems.
Chemist, experimental physicist, and natural philosopher, born in Newington Butts, Surrey. Apprenticed to a bookbinder, he devoted his leisure to science. In 1813 he was engaged by Davy as his assistant at the Royal Institution, and in 1827 he succeeded to Davy's chair of chemistry. His research contributed to an extremely broad area of physical science, such as the condensation of gases, the conservation of force, and studies on benzene and steel. His major work is the series of Experimental Researches on Electricity (1839-55), in which he reports a wide range of discoveries about the nature of electricity, notably electrolysis, and the relationship between electricity and magnetism.
Mathematician, born in Philadelphia, PA. He is one of a small group of scientists who in the 1970s were growing more concerned about the inability of science to explain irregular occurrences in everyday life, such as the shape of clouds, the irregular flow from a dripping tap, and many other events that could be described as chaotic. He developed the mathematics of what is now called Chaos Theory, used in fields such as meteorology, aerodynamics, and ecology.
Physicist, born in Paris. He began by studying medicine, but turned to physcis. He determined the velocity of light, and showed that light travels more slowly in water than in air (1850). In 1851, by means of a freely suspended pendulum, he proved that the Earth rotates. He invented the gyroscope (1852), and improved the mirrors of reflecting telescopes (1858). In 1850 he demonstrated the rotation of the Earth by using a 67m/220ft pendulum hung in the dome of the Panthéon, Paris.
Mathematician, born in Auxerre, France. He accompanied Napoleon to Egypt (1798), and on his return (1802) was made prefect of the deparment of Grenoble, and created barron (1808). He then took up his first interest, applied mathematics, and while working on the flow of heat discovered the equation for which it now bears his name, To solve it, he showed that many functions fo a single variable can be expanded in a series of sines fo multiples of the variable (the Fourier series ).
Astronomer and mathematician, born in Pisa, Italy. He entered Pisa University as a medical student in 1581, and became professor of mathematics at Padua (1592-1610), where he improved the refracting telescope (1610), and was the first to use it for astronomy. His bold advocacy of the Copernican theory brought severe ecclesiastical censure. He was forced to retract before the Inquistion, and was sentenced to indefinite imprisonment - though the sentence was commuted by the pope, at the request of the Duke of Tuscany. Under house arrest in Florence, he continued his research, although by 1637 he had become totally blind. Among his other discoveries were the law of uniformly accelerated motion towards the Earth, the parabolic path of projectiles, and the law that all bodies have weight. The validity of his scientific work was formally recognized by the Vatican in 1993.
Astronomer, born in Pabsthaus, Germany. In 1846, at Berlin Observatory, he discovered the planet Neptune, whose existence had been postulated in the calculations of Leverrier.
Mathematican, born in Bourg-la-Reine, France. He was educated privately and at the Collège Royal de Louis-le-Grand. Despite mathematical ability he failed the entrance for the Ecole Polytechnique to study maths, and settled for the Ecole normale Supériure in 1829 to train as a teacher, but was expelled in 1830 for republican sympathies. He engaged in political agitation, was imprisoned twice, and was killed in a duel aged 21. His mathematical reputation rests on original genius in the branch of higher algebra known as group theory.
Physiologist, born in Bologna, Italy. He studied at Bologna, where he became professor anatomy (1762). Investigating the effects of electrostatic stimuli applied to the muscle fibre of frogs he discovered he could also make the muscle twitch by touching the nerve with various metals without a source of electrostatic charge, and greater reaction was obtained when two dissimilar metals were used. He attributed the effect to 'animal electricity'. His worked inspired his friend Volta, leading to the production of the electrical battery, and also initiated research into electrophysiology. The galvonometer is named after him.
Mathematician, born in Brunswick, Germany. A prodigy in mental calculation, he conceived most of his mathematical theories by the age of 17, and was sent to study at Brunswick and Göttingen. He wrote the first modern book on number theory, in which he proved the law of quadratic reciprocity, and discovered the intrinsic differential geometry of surfaces. He also discovered, but did not publish, a theory of elliptic and complex functions, and pioneered the application of mathematics to such areas as gravitation, magnetism, and electricity. In 1807 he became professor of mathematics and director of the observatory at Göttingen, and in 1821 was appointed to conduct the trigonometrical survey of Hanover, for which he invented a heliograph. The unit fo magnetic induction has been named after him.
Theoretical physicist, born in Würzburg, Germany. He studied at Munich and Göttingen. After a brief period working with Max Born (1923) and Niels Bohr (1924-7), he became professor of physics at Leipzig (1927-41), director of the Max Planck Institute in Berlin (1941-5), and director of the Max Planck Institute at Göttingen (and from 1958 at Munich). He developed a method of expressing quantum mechanics in matrices (1925), and formulated his revolutionary principle of indeterminacy (the uncertainty principle) in 1927. He was awarded the 1932 Novel Prize for Physics.
Chemist, born in Geneva, Switzerland. As professor of chemistry at St. Petersburg, he formulated Hess's law (1840), which states that the net heat evolved or absorbed in any chemical reaction depends only on the initial and final stages. It was a forerunner of the more complete law of the conservation of energy.
Physicist, born in Waldstein, Austria. He studied at Graz and Vienna universities, then taught at Vienna. He realized during balloon ascents that high-energy radiation in the Earth's atmosphere originated from outer space. For his work on cosmic radiation he shared the 1936 Nobel Prize for Physics. In 1938 he emigrated to the USA to become professor of physics at Fordham University, New York (1938-56).
Astronomer, born in Gdansk, Poland. He studied at Leyden, built his own obeservatory in Gdansk, and made his own instruments. He catalogued 1564 stars in Prodromus Astronomiae (1690), discovered four comets, and was one of the first to observe the transit of Mercury. He gave names to many lunar features in his atlas of the Moon, Selenographia (1647).
Chemist, born in Budapest, Hungary. He studied at Berlin and Freiberg, worked at Manchester under Rutherford (1911), then with Paneth at Vienna (1912-20). In 1923 he discovered, with the Dutch physicist Dirk Coster (1889-1950), the element hafnium at Copenhage (Hafnia being the Latin name for the city). He was a professor at Freiburg Univeristy from 1926, but during World War 2 went to Sweden, where he became professor at Stockholm. He was awarded the 1943 Nobel Prize for Chemistry for his work on isotopic tracer techniques.
Radio astronomer, born in Fowey, Cornwall. He studied at Cambridge and spent his career there, becoming professor of radio astronomy (1971-89). In 1967 he began studies, using a radio telescope of novel design, on the scintillation ("twinkling") of quasars (a class of radio stars). This led him and his student Susan Joycelyn Bell Burnell to discover the first radio stars emitting radio signals in regular pulses; named as pulsars, many others have since been discovered. Hewish shared the Nobel Prize for Physics in 1974 with his former teacher, Sir Martin Ryle.
Mathematician and scientist, born in London. He turned form the law to mathematics, becoming professor of applied mathematics at University College, London, and professor of eugenics. He published The Grammar of Science (1892), and works on eugenics, mathematics, and biometrics. Motivated by the study of evolution and heredity, he was a founder of modern statistical theory, and his work established statistics as a subject in its own right. He also founded and edited the journal Biometrika (1901-36).
Mathematician, born in Nizhny Novgorod, Russia. He became professor at Kazan in 1816, where he spent the rest of his life. In the 1820's he developed a theory of non-Euclidian geometry in which Euclid's parallel postulate did not hold. A similar theory was discovered almost simultaneously and independantly by János Bolyai.
Physicist, born in Arnhem, The Netherlands. He studied at Leyden and became professor of mathematical physics there (1878), and from 1923 directed research at the Taylor Institute, Haarlem. He clarified the electromagnetic theory of James Clerk Maxwell, and introduced the concept of local time while working on the Michelson-Morley experiment. In 1902 he was awarded, with Pieter Zeeman, the Nobel Prize for Physics for his theory of electromagnetic radiation. Their work led to Einstein's theory of special relativity.
Meteorologist, born in West Hartford, CT. Working at the Massachusetts Institute of Technology from 1946, he was the first to describe what is known as "deterministic chaos" as a shaper of weather, and was the originator of the term "the butterfly effect"- the flapping wings of a butterfly in China could alter the weather over America a few days later. Among other major meteorology awards, he received the 1991 Kyoto Prize.
Writer, mathematician, and socialite, the daughter of Lord Byron. She taught herself geometry, and was trained in astronomy and mathematics. She owes much of her fame to her friendship with Charles Babbage, the computer pioneer. She translated and annotated an article on his Analytical Engine written by an Italian mathematican, L F Menabrea, adding many explanatory notes of her own. The high-level universal computer programming language, ADA, was named in her honor.
Mathematician, born in Warsaw. He studied at the Ecole Polytechnique, Paris, and at the California Institute of Technology then became professor of mathematics at Geneva (1955-7) and the Ecole Polytechnique (1957-8). He joined IBM in 1958, and became professor of mathematics at Yale in 1987. A central figure in the development of fractals, his book The Fractal Geometry of Nature (1982) was important in demonstrating the potential application of fractals to natural phenomena.
Mathematician, born in Ryazan, Russia. He studied at St. Petersburg,, where he became professor (1893-1905), before going into self-imposed exile in the town of Zaraisk. A student of Pafnuty Chebyshev, he worked on number theory and probability theory. His name is best known for the concept of the Markov chain , a series of events in which the probability of a given even occurring depends only on the immediately previous event. This has since found many applications in physics, biology, and linguistics.
Chemist, born in Tobolsk, Russia. He became a teacher, then studied at Odessa, St. Petersburg, and Heidelberg, becoming professor of chemistry at St. Petersburg from 1866. He devised the periodic classification (or table) of chemical elements, by which he predicted the existence of several elements which were subsequently discovered. Element No 101 (mendelevium) is named after him.
Mathematician, born in Budapest. He escaped from Hungary during the communist regime (1919), studied at Berlin and Zürich, and emigrated to the USA in 1933, to join the Institute for Advanced Study, Princeton. Equally at home in pure and applied mathematics, he wrote a major work on quantum mechanics (1932), which led him to a new axiomatic foundation for set theory, and participated in the atomic bomb project at Los Alamos during World War II, providing a mathematical treatment of shock waves. His mathematical work on high-speed calculations for H-bomb development contributed to the development of computers, and he also introduced game theory (1944), which was a major influence on economics.
From the preface to Theory of Self-Reproducing Automata:
Von Neumann was especially intersted in complicated automata, such as the human nervous system and the tremendously large computers he foresaw for the future. He wanted a theory of the logical organization of complicated systems of computing elements and believed that such a theory was an essential prerequisite to constructing very large computers. The two problems in automata theory that von Neumann concentrated on are both intimately related to complexity. These are the problems of reliability an self-reproduction. The reliability of components limits the complexity of the automata we can build, and self-reproduction requires an automata of considerable complexity.
-Arthur W. Burks, 1966
From the late 1940's through the present the von Neumann architecture, named after the mathematician John von Neumann, has been employed in practial general-purpose computers. The hallmark of a von Neumann machine is a large random-access memory. Each cell in the memory has a unique numerical address, which can be used to access or replace the contents of that cell in a single step. In addition to its ability to address memory locations directly, a von Neumann machine also has a central processing unit (the CPU ) that possesses a special working memory (register memory ) for holding data that are being operated on and a set of built-in operations that is rich in comparison with the Turing machine. The exact design of the central processor varies considerably, but typically includes operations such as adding two binary integers, or branching to another part of a program if the binary integer in some register is equal to zero (so-called conditional branching ). The CPU can interpret information retrieved from memory either as instructions to perform particular operations or as data to apply the current operation to. Thus, a portion of memory can contain a sequence of instructions, called a program, and another portion of memory can contain the data to be operated on by the program. The CPU repeatedly goes through a fetch-execute cycle, in which the next operation and its arguments. Althouygh it computes the same class of functions as a universal Turning machine, a von Neumann machine runs efficiently because of its random-access memory and because its architecture can be implemented in electronic circuitry that makes its basic operations extremely fast (currently from millions to tens of millions of instructions per second in desktop computers).
Isaac Newton was born in Woolsthorpe, Lincolnshire, a premature infant not expected to live. His father (of the same name) had died just three months before. His mother, Hannah Ayscough Newton, remarried when he was three, and left him with his grandmother until her second husband died, in 1653, when Newton was 11. He was educated at King's School, Grantham, and it was assumed he would continue in the farming tradition of his family, but finally his mother became convinced that he should be prepared for entry to university, and in 1661 he went up to Trinity College, Cambridge, as a poor scholar who would have to earn his keep by doing menial tasks for the Fellows.
Newton showed no particular promise in his early years at Cambridge, but Isaac Barrow, who held the Lucasian chair of mathematics, gave him much encouragement. Newton took his degree without distinction (in 1665), and would have prepared for his MA, but in 1664 the Great Plague broke out in London, and the university was closed down the following year.
At home during the plague years, he studied the nature of light and the construction of telescopes. By a variety of experiments upon sunlight refracted through a prism, he concluded that rays of light which differ in color differ also in refrangibility - a discovery which suggested that the indistinctness of the image formed by the object-glass of telescopes was due to the different-colored rays of light being brought to a focus at different distances. He concluded (rightly for an object-glass consisting of a single lens) that it was impossible to produce a distinct image, and was thus led to the construction of reflecting telescopes, perfected by William Herschel and the Earl of Rosse. At the same time, he was working out his ideas on planetary motion.
On his return to Cambridge (1667), Newton became a Fellow of Trinity College, and, in 1668, took his MA. In the following year, Isaac Barrow resigned his chair in favor of his young pupil. Newton's lecture series resulted in an essay which later formed Book 1 of Opticks.
A falling apple had posed in Newton's mind the question of whether the force exerted by the Earth in making the apple fall was the same force that made the Moon "fall" towards the Earth, and so pull it in to an elliptical orbit round the Earth. Calculations showed him that it did, but it was not until 1684, after an exchange of letters with Robert Hooke, that Newton was fully in command of the dynamic principles involved. In that same year, Edmund Halley visited Newton to try to work through some planetary questions. To his surprise, Newton told him that the force between Sun and planets, reulting in an elliptical orbit, operated according to an inverse square law and that he had proved it. He later sent a small treatise on the subject to Halley. Halley persuaded Newton to write a book and, after much antagonism between Newton and Hooke, who demanded credit for discovering the inverse-square law of attraction, the book appeared in 1687 under the title Philosophiae naturalis principia mathematica (The Mathematical Principles of Natural Philosophy).
This important work, which had remained unpublished for years, established Newton as the greatest of all physical scientists. Its impact was immense. Newton had rewritten the whole science of moving bodies. He completed what the late mediaeval physicists had begun and Gallileo had tried to bring to fruition; and his three "laws of motion" formed the basis of all further work.
Meanwhile, the part Newton took in defending the rights of the university against the illegal encroachments of James II procured his a seat in the Convention Parliament (1689-90). In 1696 he was appointed Warden of the Mint, at a time when the government had debased the coinage, and a strong, incorruptible man was needed to deal with courterfeiters. He became Master of the Mint form 1699, having shown himself to be a brilliant administrator. He again sat in parliament in 1701 for his university, and in 1704 published Opticks in English, which he had refused to do until Hooke, his old enemy, was dead.
Much of Newton's life was spent in conflict with other scientists, particularly Hooke, Leibnitz, and Flamsteed, and he sought revenge for slights real or imagined by deleting references to their help from his work. He always took criticsm very badly, responding furiously - an anxiety which has often been explained in terms of his abandonment as a child - and showed signs all through his life of a persecution mania. A breakdown in 1693 heralded the end of his scientific work. Knighted in 1705, his last years were spent under the care of his niece. He never married, but was at his happiest in the role of patron to younger scientists and, from 1703, as a tyrannical president of the Royal Society.
Mathematician, physicist, theologian, and man-of-letters, born in Clermont-Ferrand, France. He invented a calculating machine (1647), and later the barometer, the hydraulic press, and the syringe. Until 1654 he spent his time between mathematics and the social round in Paris, but a mystical experience that year led him to join his sister, who was a member of the Jansenist convent at Port-Royal,m where he defended Jansenism against the Jesuits in Lettres provinciales (1656-7). Fragments jotted down for a case book of Christrian truth were discovered after his death and published as the Pensées (1669, Though
Chemist and microbiologist, born in Dôle, France. He studied at Besançon and Paris universities, and held academic posts at Strasbourg, Lille, and Paris, where in 1867 he became professor of chemistry at the Sorbonne. He established that putrefaction and fermentation were caused by micro-organisms, thus providing an impetus to microbiology. In a famous experiment in 1881, he showed that sheep and cows "vaccinated" with the attenuated bacilli of anthrax received protection against the disease. In 1888 the Institut Pasteur was founded at Paris for the treatment of rabies, and he worked there until his death.
Mathematician, born in Cuneo, Italy. He taught at the University of Turin, and was known for his work on mathematical logic. The symbolism he invented was the basis of that used by Bertrand Russell and Alfred Whitehead in Principia mathematica. He also promoted Interlingua, a universal language based on uninflected Latin.
Physicist, born in Minneaplois, MN. He led the team at Bell Telecommunication Laboratories that developed the first practical solar battery in 1954, originally intended for operating communications equipment in remote terrestrial locations. The space programme greatly enhanced thier importance and thier efficiency.
Astronomer, born in Ponte diValtellina, Italy. He became a Theatine monk, professor of theology in Rome (1779), and professor of mathematics at the Academy of Palermo (1780). He set up an observatory at Palermo in 1789, published a catalogue of the stars (1803, 1814) and discovered and named the first minor planet, Ceres.
Theoretical physicist, born in Kiel, Germany. He studied at Munich and Berlin, where he became professor of theoretical physics (1889-1926). His work on the law of thermodynamics and black body radiation led him to abandon classical Newtonian principles and introduce the quantum theory (1900), for which he was awarded the Nobel Prize for Physics in 1918. Several research institutes now carry his name.
Physical chemist, born in Moscow. He moved to Belguim at the age of 12, studied in Brussels, and became a professor there in 1951. He was also founder-director of the Center for Statistical Mechanics and Thermodynamics at Texas (1967). For his contributions to nonequilibruim thermodynamics he was awarded the Nobel Prize for Chemistry in 1977. His popular books include Order out of Chaos (1979) and From Being to Becoming (1980).
Mathematician, born in Breselenz, Germany. He studied at Göttingen and Berlin universities, and became professor of mathematics at Göttingen (1859). His early work was on the theory of functions, but he is best remembered for his development of non-Euclidian geometry, important in modern physics and relativity theory. His profound conjecture (the Riemann hypothesis) about the behavior of the zeta (or Riemann) function, which he showed determines the distribution of the prime numbers, has resisted proof since its publication in 1857.
Physicist, a pioneer of subatomic physics, born near Nelson, New Zealand. He studied at Christchurch University, moved to Cambridge (1895), and in 1898 became professor of physics at McGill, Canada, where with Frederick Soddy he proposed that radioactivity results from the disintegration of atoms (1903). In 1907 he became professor at Manchester, developing the modern conception of the atom. In 1919 he became professor at Cambridge and director of the Cavendish Laboratory. He recieved the Nobel Prize for Chemistry in 1908, was knighted in 1914, and made a peer in 1931.
Physicist, born in Oak Park, IL. He studied at the Massachusetts Institute of Technology and Illinois University, then taught at Chicago, Illinois, Pennslvania, Cornell (1969-75), and California (Santa Barbara) universities. Collaboration with John Bardeen and Leon Cooper led to the BCS (Bardeen-Cooper-Schrieffer) theory of superconductivity, for which all three shared the 1972 Nobel Prize for Physics.
Physicist, born in Vienna. He taught at Stuttgart, Breslau, Zürich, Berlin, Oxford (1933-8), and Dublin (1940-56), after which he retired to Vienna. He originated the study of the wave behaviour of matter within quantum mechanics with his celebrated wave equation (1926), which is as important to science at the subatomic level as Newton's laws of motion are to mechanics in the normal-size world. A versatile scientist, he also made significant contributions to molecular biology, and philosophy. He shared the Nobel Prize for Physics in 1933. His books include What is Life? (1946) and Science and Man (1958).
Nuclear chemist, born in Ishpeming, MI. He studied at the University of California at Los Angeles and Berkeley, becoming professor of chemistry at Berkeley in 1945, and was part of the team which discovered the transuranic elements plutonium (1940), americium, and curium (1944). By bombarding the last two with alpha rays he produced the elements berkelium and calfiornium in 1950. He shared the 1951 Nobel Prize for Chemistry with Edwin McMillan, and later became chariman of the US Atomic Energy Commission (1961-71).
Mathematician and pioneer of communication theory, born in Gaylord, MI. He studied at Michigan and at the Massachusetts Institute of Technology, and in 1938 published a seminal paper on the application of symbolic logic to relay circuits, which helped transform circuit design from an art into a science. He worked at Bell Telephone Labs (1941-72) in the area of information theory, and wrote The Mathematical Theory of Communication (1949) with Warren Weaver.
Radiochemist, born in Eastbourne, East Sussex. He studied in Wales and at Oxford, and held posts at Montreal, Glasgow, Aberdeen, and Oxford, where he was professor of chemistry (1919-36). In 1913 he discovered forms of the same element with identical chemical qualities but different atomic weights (which he called isotopes ), for which he received the Nobel Prize for Chemistry in 1921.
Biochemist, born in Budapest. He studied at Budapest, then lectured at Groningen, Cambridge, and Rochester, MN, where he isolated ascorbic acid. He was professor at Szeged (1931-45) and Budapest (1945-47), discovering actin, which is responsible for muscle contraction. He emigrated the the USA, becoming director of the Institute of Muscle Research at Woods Hole, MA (1947-75), and scientific director of the National Foundation for Cancer Research, MA (1975). He was awarded the Nobel Prize for Physiology or Medicine in 1937 for his work on the function of organic compounds (especially vitamin C) within cells.
Physicist, born in Budapest. He studied at Budapest and Berlin universites, fleeing from Germany in 1933. He worked first in London, then in 1938 emigrated to the USA, where he began work on nuclear physics at Columbia University. In 1934 he had taken a patent on nuclear fission as an energy source, and on hearing of Otto Hahn and Lise Meitner's fission of uranium (1938), he approached Einstein in order to write together to President Roosevelt, warning him of the possibility of atomic bombs. He was a central figure in the Manhattan Project, and after the War became a strong proponent of the peaceful uses of atomic energy.
Szilard, L. (1929) [1983] 'Uber die Entropieverminderung in einem thermodynamischen System bei Eingriffen intelligenter Wesen', Zeitschrift f¸r Physik 53: 840-56. Translated by A. Rapoport and M. Knoller (1969) as 'On the Decrease of Entropy in a Thermodynamic System By the Intervention of Intelligent Beings', Behavioral Science 9: 301-10. Reprinted in Wheeler and Zurek (1983), 539-48.
Physicist and electrical engineer, born in Smiljan, Croatia. He studied at Graz, Prague, and Paris, emigrating to the USA in 1884. He left the Edison Works at Menlo Park to concentrate on his own inventions, which included improved dynamos, transformers, and electric bulbs, and the high-frequency coil which now bears his name. The unit of mangetic induction is named after him.
For a good introduction to Tesla's life and work, check out Margaret Cheney's "Tesla: Man Out of Time". Or, since you're already reading this online, try this very cool Tesla page. His autobiography is also available online.
Mathematician, born in London. He studied at Cambridge and Princeton, worked in cryptography during World War II, then joined the National Physical Laboratory (1945) and the Computing laboratory at Manchester (1948). He provided a precise mathematical characterization of computability, and introduced the theoretical notion of an idealized computer (since called a Truning machine), laying the foundation for the field of artificial intelligence. He committed suicide after being prosecuted for homosexuality.
Mathematician, born in Hull, Humberside. A fellow of Caius College, Cambridge (1857), he developed George Boole's symbolic logic, and in his Logic of Chance (1866) worked on the frequency theory of probability. He is best known for Venn diagrams, pictorially representing the relationships between sets, though similar diagrams had been used by Gottfried Leibniz and Leonhard Euler.
Physicist, born in Como, Italy. He invented the electrophorus, a device to generate static eletricity (1775), discovered methane gas (1778), and was appointed professor of natural philosophy at Pavia (1778-1804). Inspired by the work of his friend Luigi Galvani, Volta investigated reactions between dissimilar metals, and developed the first electric battery (1800), providing future researchers with a constant source ofcurrent electricity. His name is given to the unit of electric potential, the volt.
Mathematical logician, the founder of cybernetics, born in Columbia, MD. A child prodigy, he entered university at 11, studied at Harvard, Cornell, Cambridge, and Göttingen universities, and became professor of mathematics at the Massachusetts Institute of Technology (1932-1960). During World War II he worked on guided missiles, and his study of the handling of information by electronic devices, handled by the feedback principle, encouraged comparison between these and human mental processes in Cybernetics (1948) and other works.
Physicist, born in Budapest. He studied at Berlin Technische Hochshule, moved to the USA, and became a US citizen in 1937. He was professor of mathematical physics at Princeton (1938-71), and came to be known for his many contributions to the theory of nuclear physics, including the law of conservation of parity. His theory of neutron absorption (1936) was used in building nuclear reactors. He shared the Nobel Prize for Physics in 1963.
British mathematician. He studied at Cambridge, and became professor of mathematics at Warwick University in 1964. Early work developing topology and catastrophe theory produced many applications to physics, social sciences, and economics.
Physicist, born in Zonnemaire, The Netherlands. He studied at Leyden under Lorentz, became a lecturer there (1890), and was appointed professor at Amsterdam (1900), and director of the Physical Institute (1908). While at Leyden he discovered the Zeeman effect - when a ray of light from a source placed in a magnetic field is examined spectroscopically, the spectral line splits into several components. This discovery confirmed Lorentz's theory of electromagnetic radiation, and has helped physicists investigate atoms, and astronomers to measure the magnetic field of stars. In 1902 he shared with Lorentz the Nobel Prize for Physics.
Mathematician, born in Berlin. He studied at Berlin, Halle, and Freiburg universities, and was professor at Göttingen (1905-10) and Zürich (1910-16). He gave the first axiomatic description of set theory in 1908. Although later modified to avoid the paradoxes discovered by Bertrand Russell and others, it remains one of the standard methods of axiomatizing the theory. He also first revelaed the importance of the axiom of choice, when he proved in 1904 that any set could be well-ordered, a key result in many mathematical applications of set theory.