The history of science is characterized by the common feature of all great scientific revolutions in that they invariably knock human arrogance off one pedestal after another. Previous convictions about humanity's own self-importance are shaken. The first great revolution was prompted by Copernicus and Galileo; it taught us that we don't live at the center of the universe. Instead, we're off on a pale blue dot of a planet that orbits an ordinary star on the periphery of creation.
The second great revolution was Darwin's. His theory of evolution relegated humanity to descent from the animal world, not to a specially created position somewhere between animals and angels.
Copernicus, Nicolaus
Born on Feb. 19, 1473, in Thorn (Torun), Poland, Nicolaus Copernicus was destined to become, through the publication of his heliocentric theory 70 years later, one of the seminal figures in the history of scientific thought (see HISTORY OF ASTRONOMY). The son of a prosperous merchant, he was raised after his father's death by a maternal uncle, who enabled him to enter the University of Krakow, then famous for its mathematics, philosophy, and astronomy curriculum. This experience stimulated the young Copernicus to study further liberal arts at Bologna (1496-1501), medicine at Padua, and law at the University of Ferrara, from which he emerged in 1503 with the doctorate in canon law. Shortly afterward he returned to Poland and eventually settled permanently at the cathedral in Frauenberg (Frombork), less than 100 miles from his birthplace. Through his uncle's influence he had been elected a canon of the church even before his journey to Italy. Copernicus not only faithfully performed his ecclesiastical duties, but also practiced medicine, wrote a treatise on monetary reform, and turned his attention to a subject in which he had long been interested--astronomy.
By May 1514 Copernicus had written and discreetly circulated in manuscript his Commentariolus, the first outline of those arguments eventually substantiated in De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres, 1543). This classic work challenged the geocentric cosmology [see COSMOLOGY (ASTROLOGY)] that had been dogmatically accepted since the time of Aristotle. In direct opposition to Aristotle and to the 2d-century astronomer Ptolemy, who enunciated the details of the geocentric system based on the celestial phenomena, Copernicus proposed that a rotating Earth revolving with the other planets about a stationary central Sun could account in a simpler way for the same observed phenomena of the daily rotation of the heavens, the annual movement of the Sun through the ecliptic, and the periodic retrograde motion of the planets.
Anticipated in various aspects by the Pythagoreans and ARISTARCHUS OF SAMOS (with whom he was familiar), and by the Muslim astronomer Ibn al-Shatir and certain Christian writers (whose ideas there is no conclusive evidence he knew), the new theory that Copernicus espoused in De revolutionibus exhibits a peculiar mixture of both radical and conservative elements. In the midst of his radical reordering of the structure of the universe, Copernicus still adhered to the ancient Aristotelian doctrines of solid celestial spheres and perfect circular motion of heavenly bodies, and he held essentially intact the entire Aristotelian physics of motion. Moreover, with significant innovations, he clung to the Ptolemaic representation of planetary motion by means of complicated combinations of circles called epicycles. Although Copernicus realized that his theory implied an enormous increase in the size of the universe, he declined to pronounce it infinite.
These aspects of the Copernican treatise do not mitigate the novelty or the impact of the final theory, or the author's firm conviction that his system was an accurate representation of physical reality. Rather, they indicate the scope of the work that lay ahead and that was effectively addressed in the next century when Johannes KEPLER determined the ellipticity of planetary orbits, GALILEO GALILEI formulated his new concept of motion, and Sir Isaac NEWTON espoused his theory of universal gravitation.
The enunciation of the heliocentric theory by Copernicus marked the beginning of the scientific revolution, and of a new view of a greatly enlarged universe. It was a shift away from the comfortable anthropocentrism of the ancient and medieval world. A scientific theory that reflected so profoundly on humanity was not welcomed by the church, and it was only after the publication (1540) of Narratio prima (A First Account), by an enthusiastic supporter named Rheticus, that the aged Copernicus agreed to commit to print the theory already outlined in 1514. An undocumented, but often repeated, story holds that Copernicus received a printed copy of his treatise on his deathbed. He died on May 24, 1543.
Bibliography: Banville, John, Doctor Copernicus (1977); Burtt, E. A., A Critical and Comparative Analysis of Copernicus, Kepler, Galileo, and Descartes (1924; repr. 1987); Koyre, Alexandre, The Astronomical Revolution (1969); Kuhn, Thomas, The Copernican Revolution (1957); Rosen, E., Copernicus and the Scientific Revolution (1984); Westman, Robert S., ed., The Copernican Achievement (1976).
Galileo Galilei
Galileo Galilei, a pioneer of modern physics and telescopic astronomy, was born near Pisa, Italy, on Feb. 15, 1564. In 1581 he entered the University of Pisa as a medical student, but he soon became interested in mathematics and left without a degree in 1585.
After teaching privately at Florence, Galileo was made professor of mathematics at Pisa in 1589. There he is said to have demonstrated from the Leaning Tower that Aristotelian physics was wrong in assuming that speed of fall was proportional to weight; he also wrote a treatise on motion, emphasizing mathematical arguments. In 1592, Galileo became professor of mathematics at the University of Padua, where he remained until 1610. He devised a mechanical calculating device now called the sector, worked out a mechanical explanation of the tides based on the Copernican motions of the Earth, and wrote a treatise on mechanics showing that machines do not create power but_ merely transform it.
In 1602, Galileo resumed his investigations of motion along inclined planes and began to study the motion of pendulums. By 1604 he had formulated the basic law of falling bodies, which he verified by careful measurements.
Late in 1604 a SUPERNOVA appeared, and Galileo became involved in a dispute with philosophers who held (with Aristotle) that change could not occur in the heavens. Applying the mathematics of PARALLAX, Galileo found the star to be very distant, in the supposedly unchangeable regions of the cosmos, and he attacked Aristotelian qualitative principles in science. Returning to his studies of motion, he then established quantitatively a restricted inertial principle and determined that projectiles moved in parabolic paths. In 1609 he was writing a mathematical treatise on motion when news arrived of the newly invented Dutch telescope. He was so excited at the possible scientific applications of such an instrument that he put all other work aside and began to construct his own telescopes.
The Telescope and the Copernican Theory
By the end of 1609, Galileo had a 20-power telescope that enabled him to see the lunar mountains, the starry nature of the Milky Way, and previously unnoted "planets" revolving around Jupiter. He published these discoveries in The Starry Messenger (1610), which aroused great controversy until other scientists made telescopes capable of confirming his observations. The Grand Duke of Tuscany made him court mathematician at Florence, freeing him from teaching to pursue research. By the end of 1610, he had observed the phases of Venus and had become a firm believer in the Copernican HELIOCENTRIC WORLD SYSTEM. He was vigorously opposed in this belief, because the Bible was seen as supporting the opposite view of a stationary Earth. Galileo argued for freedom of inquiry in his Letter to the Grand Duchess Christina (1615), but despite his argument that sensory evidence and mathematical proofs should not be subjected to doubtful scriptural interpretations, the Holy Office at Rome issued an edict against Copernicanism early in 1616.
Trouble with the Church
In 1623, Maffeo Barberini, long friendly to Galileo, became pope as Urban VIII, and Galileo obtained his permission to write a book impartially discussing the Ptolemaic and Copernican systems. This became Galileo's famous Dialogue (1632), for which he was called to Rome for trial by the Inquisition on the grounds that in 1616 he had been personally ordered never to defend or to teach Copernicanism. In June 1633, Galileo was condemned to life imprisonment for "vehement suspicion of heresy." His Dialogue was banned, and printers were forbidden to publish anything further by him or even to reprint his previous works. Outside Italy, however, his Dialogue was translated into Latin and was read by scholars throughout Europe.
Galileo's sentence was swiftly commuted to house arrest, at first under custody of the friendly archbishop of Siena and then at his own villa in Arcetri, near Florence. There Galileo resumed and completed his Paduan studies on motion and on the strength of materials, published at Leiden as Discourses and Mathematical Demonstrations Concerning Two New Sciences (1638). He rightly regarded this as containing the elements of a new physics that would be carried further by his successors. Galileo died at Arcetri on Jan. 8, 1642.
Influence
Among Galileo's students was Benedetto Castelli, founder of the science of hydraulics and teacher of both Bonaventura CAVALIERI and Evangelista Torricelli. Cavalieri formulated principles that were important to the development of the calculus, and TORRICELLI devised the barometer and explained phenomena of atmospheric pressure. Outside Italy, Galileo's influence was not great, except in making scientists conscious of the need for freedom of inquiry. As he had seen, not only religious but philosophical tradition had to yield to observation and measurement if science were to prosper.
Bibliography: Allan-Olney, Mary, The Private Life of Galileo (1970); Butts, R. E., and Pitt, J. C., eds., New Perspectives on Galileo (1978); Drake, Stillman, Discoveries and Opinions of Galileo (1957); Galileo Studies: Personality, Tradition and Revolution (1970); and Galileo at Work--His Scientific Biography (1978); Geymonat, Ludovico, Galileo Galilei: A Biography (1965); Redondi, Pietro, Galileo: Heretic (1987); Santillana, Giorgio de, The Crime of Galileo (1955); Wallace, W. A., Galileo and His Sources (1984) and Galileo's Logical Treatises (1992).
Darwin, Charles
Charles Darwin, a British naturalist, revolutionized biology with his theory of EVOLUTION through the process of NATURAL SELECTION. He also made significant contributions to the fields of natural history and geology. The theory of evolution, which held that all living species have evolved from preexisting forms, aroused great controversy and brought about a reevaluation of the position of humans in relation to all other living forms.
Darwin was born in Shrewsbury, England on Feb. 12, 1809, the son of Robert Waring Darwin, a physician, and of Susannah Wedgwood, the daughter of porcelainware manufacturer Josiah WEDGWOOD. He was also the grandson of Erasmus DARWIN, who combined the careers of poet, philosopher, and naturalist. Darwin showed little interest in his early education at Shrewsbury School and in medical studies at Edinburgh University (1825-27). He turned away from becoming a physician after witnessing several operations performed without anesthesia. At the same time he began to be interested in geology and natural history. He was finally sent to study for the holy orders for the Church of England at Christ Church College, Cambridge University (1828), but had no inclination for the ministry.
Instead, he became more and more interested in natural history. After he received his B. A. degree in 1831, a Cambridge professor and friend, John Stevens Henslow, recommended him for an unpaid position as naturalist on a scientific expedition. Darwin embarked on a 5-year voyage on the H. M. S. Beagle, a turning point in his life. The Beagle set sail on Dec. 27, 1831, to study the Pacific coast of South America and some Pacific islands as well as to set up navigational stations in the area. Darwin's duties were to study the geology and biology of these areas.
DARWIN'S RESEARCH
Geology
Although not a trained geologist, Darwin made important discoveries, many of which later provided geological support for some of his ideas on evolution. He noted that sedimentary rock crystallizes when metamorphosed by overlying rock and saw evidence of how volcanoes (see VOLCANO) and EARTHQUAKES change the lay of the land, uplifting some areas and sinking others. These and other observations led him to formulate a theory about coral reef formation. Darwin believed the platforms for existing coral reefs were built up from the skeletal remains of coral organisms that died as their home reefs around oceanic mountains gradually sank far below sea level. Darwin's geological observations and theories had one thing in common--the idea that things in nature change with time. He published his observations and conclusions in three books: Coral Reefs (1842), Volcanic Islands (1844), and Geological Observations on South America (1846).
Darwin's Finches
Darwin's biological findings gave him a lasting place in history. The GALAPAGOS ISLANDS were probably the scene of Darwin's most important and best-known research. On these islands, Darwin found a dazzling array of animal life and found that related but different species lived on different islands even though all the islands were very similar in geological, climatic, and other physical conditions. He found, for example, an array of ground finches with beaks ranging from large and powerful to small or fine. He correlated these differences not with physical conditions on the islands but with the birds' feeding habits. Those with powerful beaks ate large seeds; those with smaller beaks ate small seeds; those with fine beaks primarily fed on insects. He postulated that each finch was particularly suited to the food that was available in its environment--an example of what later became known as adaptation. These birds are known today as DARWIN'S FINCHES.
Along the Pacific coast of South America, Darwin observed that closely related species often lived in adjacent geographic areas and that species found on isolated oceanic islands often resembled species found on the nearest continent. Established biological thinking held that all species were unchanging and specially created; however, Darwin found that similar species were always present in adjacent geographic areas. When he found, at a given location, fossils of extinct species that were similar to living species, he began to question why similar species existed in successive geologic time periods.
Darwin collected many geologic and biologic specimens, studied many fossils, and made observations of the form, numbers, diversity, and living habits of different forms of life. From his meticulous research he arrived at the idea that species descend, with modifications, from other species, or, in other words, that species evolve from other species.
Darwin's grandfather Erasmus previously had hinted at the idea of evolution, and some geologists contemporary to Darwin had explored the idea that the face of the earth changes over periods of time, but Darwin waited for years after his return to England (1836) to present his conclusions. Even so, he reported on some of the vast amount of data he had accumulated during his trip in the Journal of Researches (1839). He also wrote a brief summary of his ideas on evolution that became known to a few scientists, but for the most part Darwin turned to other work, including detailed study of barnacles.
He married a cousin, Emma Wedgwood, in 1839, and lived in London for a while, at which time he was admitted to the Royal Society. In 1842, he settled in Downe, Kent, plagued by ill health since the Beagle voyage. During his lifetime, with symptoms of fatigue and intestinal trouble, he was dismissed as a hypochondriac. In Argentina, however, he had been frequently bitten by an insect that transmits TRYPANOSOMIASIS, and his illness resembled that of similarly infected people. Other theories about his chronic ill health also exist.
ON THE ORIGIN OF SPECIES
In 1856, Darwin began to write his theory of evolution by natural selection, but before he had finished (1858), he received a paper from naturalist Alfred Russel WALLACE outlining a theory similar to his own. Friends arranged for the two men to present a joint paper before the Linnaean Society of London in 1858. On Nov. 24, 1859, an abstract of Darwin's theory was published under the weighty title of On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (see ORIGIN OF SPECIES, ON THE).
Darwinism
In this book, Darwin presented his idea that species evolve from more primitive species through the process of NATURAL SELECTION, which works spontaneously in nature. In his account of how natural selection occurs, known as Darwinism, he pointed out that not all individuals of a species are exactly the same but, rather, that individuals have variations and that some of these variations make their bearers better adapted to particular ecological conditions. He pointed out that most species produce more eggs and offspring than ever reach maturity. He theorized that well-adapted individuals of a species have more chance of surviving and producing young than do the less adapted, and that over the passage of time the latter are slowly weeded out. The accumulation of adaptations to a particular ecological way of life leads--if there is a geographic split of the population--into the development of separate species, each adapted to its own particular ecological living space. It remained for the later science of GENETICS to provide an explanation for this process.
Impact
The effect of On the Origin of Species was immediate and widespread. The book upset many established patterns of thought, contradicted firmly held religious tenets, and brought into focus the concept that humans are one species among many that had evolved from a more primitive one. Controversies and debates on the theory raged all over England, Europe, and the United States. Even as recently as 1925, Darwin's theory of evolution created such furor that it culminated in the famous SCOPES TRIAL in Tennessee. Though the evidence Darwin presented was strong, some scientists aligned themselves with orthodox churchmen and others who opposed the theory. Other scientists enthusiastically embraced it.
Darwin himself did not become deeply involved in the defense of his theory, leaving that to others, notably English biologist Thomas Henry HUXLEY. One of the book's greatest effects was the spur it gave biological research. Scientists in all fields of biology pursued research to substantiate or refute Darwin's ideas. Darwin's basic ideas spread to other disciplines, too, although sometimes in a form not true to the original concept, such as the so-called SOCIAL DARWINISM that encouraged a ruthless interpretation of "survival-of-the-fittest" ideas. EUGENICS, a term coined by Darwin's relative Sir Francis GALTON to describe controlled improvement of species, including humans, was also based on Darwin's premises.
Darwin continued to write and do research, expanding on ideas he had presented in On the Origin of Species. In The Descent of Man and Selection in Relation to Sex (1871), Darwin provided evidence for human evolution from more primitive species and discussed the role of sexual selection in evolution. His later studies were devoted to the investigations of plants. Among his botanical works were Insectivorous Plants (1875), in which he described how the sundew traps and digests insects, and The Power of Movement in Plants (1880), in which he wrote how light influences the direction of plant growth. His last work, Formation of Vegetable Mould through the Action of Worms (1881), detailed the manner in which earthworms enrich and aerate soil, benefiting agriculture. Darwin died in Downe on Apr. 19, 1882 and was buried in Westminster Abbey. He has been praised as one of the greatest figures in the history of biology.
Bibliography: Alland, Alexander, Jr., Human Nature: Darwin's View (1985); Appleman, Philip, ed., Darwin (1970); Barzun, Jacques, Darwin, Marx and Wagner, rev. ed. (1958); Clark, R. W., The Survival of Charles Darwin (1985); Darwin, Charles, The Correspondence, ed. by F. Burkhardt and S. Smith, 4 vols. (1985-1989) and Collected Papers, ed. by P. H. Barrett (1980); Darwin, Charles, The Life and Letters of Charles Darwin, 3 vols.,_ ed. by Francis Darwin (1888; repr. 1969); De Beer, Gavin, Charles Darwin: A Scientific Biography (1965; repr. 1976); Desmond, Adrian, and Moore, James, Darwin (1992); Eisely, Loren, et al., Darwin's Century (1958); Farrington, Benjamin, What Darwin Really Said (1966); Gruber, H. E., Darwin on Man (1981); Hull, David L., Darwin and His Critics (1973); Irvine, William, Apes, Angels and Victorians (1972); Keynes, R. D., ed., Charles Darwin's Beagle Diary (1988); Mayr, Ernst, One Long Argument: Charles Darwin and the Genesis of Modern Evolutionary Thought (1992); Moorehead, Alan, Darwin and the Beagle (1969); Nicholas, F. W. and J. M., Charles Darwin in Australia (1989); Russett, Cynthia Eagle, Darwin in America: The Intellectual Response, 1865-1912 (1976); Wichler, Gerhard, Charles Darwin: The Founder of the Theory of Evolution and Natural Selection (Eng. trans., 1961).