space science, body of scientific knowledge as it relates to space exploration; it is sometimes also called astronautics. Space science draws on the conventional sciences of physics, chemistry, biology, and engineering, as well as requiring specific research of its own. The particular disciplines that are relevant depend on the type of mission being planned. There are four basic categories of space mission. The sounding rocket is restricted to suborbital flights with maximum altitude between 35 and 1,300 mi (55-2,100 km). Artificial satellites orbit the earth at altitudes between one hundred and several thousand miles. Space probes travel to the moon and planets. The final and most complex category is human spaceflight, of which the Apollo moon landings, the space shuttle, and the Skylab, Mir, and International space stations are the outstanding examples. The problems that space science must deal with include prediction and control of trajectories and orbits, telecommunications between spacecraft and earth, spacecraft design and fabrication, and life-support systems for human spaceflight.

Trajectories and Orbits

The key contribution of physics is celestial mechanics, the laws that govern the motions of bodies moving under the influence of gravitation. By combining Newton's law of universal gravitation and his laws of motion, the path of a rocket in the earth's vicinity can be calculated. This path, known as the trajectory, is strictly determined by the initial thrust imparted to the rocket, the gravitational field of the earth, and the atmospheric drag encountered. Although the manner in which these factors interact is highly complex, it is possible to determine accurately in advance the trajectory of any rocket and even to alter its course by remote control. If a satellite or unpowered spacecraft is close to the earth, the effects of other heavenly bodies can be ignored and its orbit will be a conic section: circular or elliptical for a satellite that remains in a closed orbit around the earth, and parabolic or hyperbolic for a spacecraft or space probe that escapes the earth's gravitational field into an open orbit.

The criterion that separates the closed and open orbits is the escape velocity, which for the earth is 7 mi (11.3 km) per sec. If the initial thrust provided by a rocket gives the object a speed greater than the escape velocity, it will move away from the earth in an open orbit; if the final velocity is smaller than the escape velocity, it will remain at finite distance from the earth in a closed orbit; if the final velocity is less than 5 mi (8 km) per sec, the flight will be suborbital and the object will follow an arc that returns it to earth.

A satellite in orbit around the earth typically travels at a height of several hundred miles with a velocity of about 5 mi (8 km) per sec and a period of revolution of 90 min. For certain satellites, however—such as communications satellites—synchronous orbits are desirable; at a distance of 22,300 mi (35,900 km), a satellite's period is exactly 24 hours, so it appears to hover over the same point on the earth's surface. Circular orbits are usually the most desirable but are the hardest to achieve. If a satellite is launched eastward near the equator, it receives a boost from the earth's rotation, but the resulting orbit necessarily lies in the earth's equatorial plane. For some applications, polar orbits, which pass near both of the earth's poles, are preferred. In a polar orbit, a satellite will periodically pass directly over every point on the earth's surface. Translunar and interplanetary trajectories are highly complex, because no simplifying assumptions can be made; the gravitational influences of the sun, moon, and other planets must be considered. Such gravitational forces can be exploited advantageously; for example, in the slingshot effect, a space probe is accelerated as it swings past a planet on the correct trajectory.

Telecommunications

Control over unmanned space probes and artificial satellites is maintained from the ground at control centers, where huge electronic computers analyze data and determine the exact moment when a change should be made. These instructions are relayed to the spacecraft by signals carried on certain radio frequencies. Instruments inside the craft also use radio signals to send data back to earth. Radio contact with spacecraft divides naturally into three categories: tracking, telemetry, and control. Tracking is the continuous reporting of a satellite's or space probe's position in space. Telemetry is the transmission of data back to earth by an on-board instrument (e.g., camera, Geiger counter, or magnetometer). Control includes the overall direction of a spacecraft to achieve the intended trajectory. Commands are specific control signals that order execution of a specific maneuver, such as turning on a camera or firing a retro-rocket

Spacecraft Design and Fabrication

Spacecraft employ booster rockets for propulsion and small adjustable retro-rockets for changing the orientation of the craft. Rocket propulsion systems vary from the tiny Aerobee sounding rocket to the giant Saturn V used in the Apollo project. For interplanetary flights, propulsion by nuclear or solar energy may be possible. Also being considered are ion and photon engines, which very efficiently provide low thrust that can build up very high velocity during a long flight. Landing on the earth or any planet with a significant atmosphere raises the problem of atmospheric friction, which can instantly burn up any spacecraft. In the manned space program, shielding that comes apart is used to absorb the frictional energy as the material of the shielding vaporizes. Also, a spacecraft enters the atmosphere at a shallow angle to avoid the friction produced by excessively high velocities.

Without the development of modern electronics based on miniaturized transistor circuitry, space exploration would have been practically impossible. Unmanned space probes and satellites carry on-board computers of varying degrees of sophistication, and even on manned missions, maneuvering the spacecraft requires the rapid calculation and response available only through computerized devices. The instruments carried on spacecraft measure almost every conceivable physical parameter. Devices for measuring micrometeorite density, cosmic rays, magnetic fields, and solar wind were aboard even the early artificial satellites. Television cameras for both visible and infrared light are carried by most space probes. In addition, many spacecraft carry telescopes for different wavelengths of the spectrum, ranging from infrared to X rays and gamma rays. An important technique in space science is called multispectral scanning. Images are formed using only certain selected wavelengths; the data can be used to compile a single, detailed color photograph, or can be studied separately. Certain space probes carry more specialized devices, such as ultraviolet spectrographs for studying stars, and coronographs and spectroheliographs for studying the sun.

Life Support for Human Spaceflight

Long-range life support must be provided in manned spaceflight. This includes oxygen, food, and recycling of waste material. Shielding is also provided against encounters with micrometeorites and cosmic radiation that could damage the spacecraft or be a health hazard for its occupants. The spacesuit is a miniature life-support system for the individual astronaut; it provides sufficient oxygen at the correct pressure to sustain normal body functioning. In more advanced projects like Apollo, the space shuttle, Skylab, Mir, and the International Space Station, a "shirt-sleeve" environment, in which the astronauts do not have to wear any life-support equipment, is provided in a large capsule. Space biology (or exobiology) and space medicine study the reactions of human, animal, and plant life to the physical stresses encountered in space, such as weightlessness and radiation exposure. Attention is also given to the psychological effects on a group of people working together in confined quarters under demanding conditions.

social science, term for any or all of the branches of study that deal with humans in their social relations. Often these studies are referred to in the plural as the social sciences. Although human social behavior has been studied since antiquity, the modern social sciences as disciplines rooted in the scientific method date only from the 18th cent. Enlightenment. Interest at first centered on economics, but by the 19th cent. separate disciplines had been developed in anthropology, political science, psychology, and sociology. The 19th cent. was characterized by the development of wide-ranging theories (e.g., the work of Auguste Comte, Karl Marx, and Herbert Spencer). Developments in the 20th cent. have moved in these directions: the improvement and increased use of quantitative methods and statistical techniques; increased use of the empirical method, as opposed to general theorizing; and the direct practical application of social science knowledge. Social science departments are now firmly established in universities, and social scientists are increasingly called upon to advise industries and governments for future planning.

science fiction, literary genre in which a background of science or pseudoscience is an integral part of the story. Although science fiction is a form of fantastic literature, many of the events recounted are within the realm of future possibility, e.g., robots, space travel, interplanetary war, invasions from outer space.

Science fiction is generally considered to have had its beginnings in the late 19th cent. with the romances of Jules Verne and the novels of H. G. Wells. In 1926, Hugo Gernsback founded the pulp magazine Amazing Stories, devoted exclusively to science fiction, particularly to serious explorations into the future. Good writing in the field was further encouraged when John W. Campbell, Jr., founded Astounding Science Fiction in 1937. In that magazine much attention was paid to literary and dramatic qualities, theme, and characterization; Campbell "discovered" and popularized many important science fiction writers, including Isaac Asimov, Frederic Brown, A. E. van Vogt, Lewis Padgett, Eric Frank Russell, Clifford Simak, Theodore Sturgeon, Fritz Leiber, Murray Leinster, Robert Heinlein, Raymond F. Jones, and Robert Sheckley.

Science fiction has established itself as a legitimate branch of literature. C. S. Lewis's Out of the Silent Planet (1938) used science fiction as a vehicle for theological speculation, and works such as Aldous Huxley's Brave New World (1932), George Orwell's Nineteen Eighty-four (1949), Ray Bradbury's Fahrenheit 451 (1953), and Kurt Vonnegut, Jr.'s Cat's Cradle (1963) demonstrate the particular effectiveness of the genre as an instrument of social criticism. Science-fiction literature anticipates and comments on political and social concerns, and a variety of science-fiction subgenres have emerged: feminist science fiction; disaster novels and novels treating the world emerging from a disaster's wake; stories postulating alternative worlds; fantastic voyages to "inner space"; and "cyberpunk" novels set in "cyberspace," a realm where computerized information possesses three dimensions in a "virtual reality."

The rich variety of notable science-fiction writing to emerge since the "classic" work of Asimov, Heinlein, Arthur C. Clarke, and Ray Bradbury includes Frank Herbert's Dune (1965) and its sequels, which conjured up a desert world where issues of ecology, ethics, and human destiny and evolution were played out; Philip K. Dick's satirical and philosophical vision of postnuclear war southern California in novels such as Do Androids Dream of Electric Sheep? (1968) and Valis (1981); the apocalyptic disaster fiction of J. G. Ballard, including The Crystal World (1966) and Vermilion Sands (1971); the rigorously science-based works of Poul Anderson, such as Tau Zero (1970) and The Boat of a Million Years (1989); Michael Crichton's best-selling science-fiction suspense novels, particularly The Andromeda Strain (1969) and Jurassic Park (1990); William Gibson's evocations of urban "cyberpunk" desolation in novels such as Count Zero (1986) and Mona Lisa Overdrive (1988); Doris Lessing's Canopus in Argos: Archives, a series of four novels (1979-83) that explores the possibilities of a feminist utopia; and the writing of Ursula Le Guin, who has imagined ecological utopias in works such as Always Coming Home (1985) and The Word for World is Forest (1986).

Over recent decades, science fiction has become popular in the nonliterary media, including film, television, and electronic games. Star Wars (1977) and its sequels and prequel, Close Encounters of the Third Kind (1977), and E.T.: The Extra-Terrestrial (1982) were among the most financially successful motion pictures ever produced.

science [Lat. scientia=knowledge]. For many the term science refers to the organized body of knowledge concerning the physical world, both animate and inanimate, but a proper definition would also have to include the attitudes and methods through which this body of knowledge is formed; thus, a science is both a particular kind of activity and also the results of that activity.

The Scientific Method

The scientific method has evolved over many centuries and has now come to be described in terms of a well-recognized and well-defined series of steps. First, information, or data, is gathered by careful observation of the phenomenon being studied. On the basis of that information a preliminary generalization, or hypothesis, is formed, usually by inductive reasoning, and this in turn leads by deductive logic to a number of implications that may be tested by further observations and experiments (see induction; deduction). If the conclusions drawn from the original hypothesis successfully meet all these tests, the hypothesis becomes accepted as a scientific theory or law; if additional facts are in disagreement with the hypothesis, it may be modified or discarded in favor of a new hypothesis, which is then subjected to further tests. Even an accepted theory may eventually be overthrown if enough contradictory evidence is found, as in the case of Newtonian mechanics, which was shown after more than two centuries of acceptance to be an approximation valid only for speeds much less than that of light.

Role of Measurement and Experiment

All of the activities of the scientific method are characterized by a scientific attitude, which stresses rational impartiality. Measurement plays an important role, and when possible the scientist attempts to test his theories by carefully designed and controlled experiments that will yield quantitative rather than qualitative results. Theory and experiment work together in science, with experiments leading to new theories that in turn suggest further experiments. Although these methods and attitudes are generally shared by scientists, they do not provide a guaranteed means of scientific discovery; other factors, such as intuition, experience, good judgment, and sometimes luck, also contribute to new developments in science.

Branches of Specialization

Science may be roughly divided into the physical sciences, the earth sciences, and the life sciences. Mathematics, while not a science, is closely allied to the sciences because of their extensive use of it. Indeed, it is frequently referred to as the language of science, the most important and objective means for communicating the results of science. The physical sciences include physics, chemistry, and astronomy; the earth sciences (sometimes considered a part of the physical sciences) include geology, paleontology, oceanography, and meteorology; and the life sciences include all the branches of biology such as botany, zoology, genetics, and medicine. Each of these subjects is itself divided into different branches—e.g., mathematics into arithmetic, algebra, geometry, and analysis; physics into mechanics, thermodynamics, optics, acoustics, electricity and magnetism, and atomic and nuclear physics. In addition to these separate branches, there are numerous fields that draw on more than one branch of science, e.g., astrophysics, biophysics, biochemistry, geochemistry, and geophysics.

All of these areas of study might be called pure sciences, in contrast to the applied, or engineering, sciences, i.e., technology, which is concerned with the practical application of the results of scientific activity. Such fields include mechanical, civil, aeronautical, electrical, architectural, chemical, and other kinds of engineering; agronomy, horticulture, and animal husbandry; and many aspects of medicine. Finally, there are distinct disciplines for the study of the history and philosophy of science.

The Beginnings of Science

Science as it is known today is of relatively modern origin, but the traditions out of which it has emerged reach back beyond recorded history. The roots of science lie in the technology of early toolmaking and other crafts, while scientific theory was once a part of philosophy and religion. This relationship, with technology encouraging science rather than the other way around, remained the norm until recent times. Thus, the history of science is essentially intertwined with that of technology.

Practical Applications in the Ancient Middle East

The early civilizations of the Tigris-Euphrates valley and the Nile valley made advances in both technology and theory, but separate groups within each culture were responsible for the progress. Practical advances in metallurgy, agriculture, transportation, and navigation were made by the artisan class, such as the wheelwrights and shipbuilders. The priests and scribes were responsible for record keeping, land division, and calendar determination, and they developed written language and early mathematics for this purpose. The Babylonians devised methods for solving algebraic equations, and they compiled extensive astronomical records from which the periods of the planets' revolution and the eclipse cycle could be calculated; they used a year of 12 months and a week of 7 days, and also originated the division of the day into hours, minutes, and seconds. In Egypt there were also developments in mathematics and astronomy and the beginnings of the science of medicine. Wheeled vehicles and bronze metallurgy, both known to the Sumerians in Babylonia as early as 3000 B.C., were imported to Egypt c.1750 B.C. Between 1400 B.C. and 1100 B.C. iron smelting was discovered in Armenia and spread from there, and alphabets were developed in Phoenicia.

Early Greek Contributions to Science

The early Greek, or Hellenic, culture marked a different approach to science. The Ionian natural philosophers removed the gods from the personal roles they had played in the cosmologies of Babylonia and Egypt and sought to order the world according to philosophical principles. Thales of Miletus (6th cent. B.C.) was one of the earliest of these and contributed to astronomy, geometry, and cosmology. He was followed by Anaximander, who extended Thales' ideas and proposed that the universe is composed of four basic elements, i.e., earth, air, fire, and water; this theory was also taught by Empedocles (5th cent. B.C.) in Sicily. The philosophers Leucippus and Democritus (both 5th cent. B.C.) held that everything is composed of tiny, indivisible atoms. In the school founded at Croton, S Italy, by the Greek philosopher Pythagoras of Samos (6th cent. B.C.) the principal concept was that of number. The Pythagoreans tried to explain the workings of the universe in terms of whole numbers and their ratios; in addition to contributions to mathematics and philosophy, they also made notable studies in the area of biology and anatomy, e.g., by Alcmaeon of Croton (fl. c.500 B.C.). The most important developments in medicine were made by Hippocrates of Cos (4th cent. B.C.), known as the Father of Medicine, who formulated the science of diagnosis based on accurate descriptions of the symptoms of various diseases. The greatest figures of the earlier Greek period were the philosophers Plato (427-347 B.C.) and Aristotle (384-322 B.C.), each of whom exerted an influence that has extended down to modern times.

Influence of the Alexandrian Schools

The later Greek, or Hellenistic, culture was centered not in Greece itself but in Greek cities elsewhere, particularly Alexandria, Egypt, which was founded in 332 B.C. by Alexander the Great. The so-called first Alexandrian school included Euclid (fl. c.300 B.C.), who organized the axiomatic system of geometry that has served as the model for many other scientific presentations since then; Eratosthenes (3d cent. B.C.), who made a remarkably accurate estimate of the size of the earth; and Aristarchus (3d cent. B.C.), who showed that the sun is larger than the earth and suggested a heliocentric model for the solar system. Archimedes (287-212 B.C.) worked at Syracuse, Sicily, and made contributions to mathematics and mechanics that were surprisingly modern in spirit. The second Alexandrian school flourished in the first centuries of the Christian era, after Rome had become the leading power in the Mediterranean; it included Ptolemy (2d cent. A.D.), who presented the geocentric system of the universe that was to dominate astronomical thought for 1400 years, and his contemporary Heron, who contributed to geometry and pneumatics. Galen (2d cent. A.D.) studied at Pergamum and Alexandria and later practiced medicine and made important anatomical studies at Rome. The Romans assimilated the more practical scientific accomplishments of the Greeks but added relatively little of their own. With the collapse of the Roman Empire in the 5th cent. and the coming of the Dark Ages, science ceased to develop in the West.

Scientific Progress in China and India

In the East some accomplishments in science had been made paralleling the early developments in the West. However, although many societies were quick to adopt the fruits of technology, they tended to discourage the development of science on the classical model, which is based on the unbiased interaction of theory and experiment.

In China scientific theories were largely subservient to the main schools of philosophy and theology, particularly those of Confucianism, Taoism, and, later, Buddhism. The agricultural society, which endured until modern times, encouraged the separation of theory and experiment, the former falling to the educated, scholar classes and the latter to the lower, craftsman classes. Astronomy and mathematics were used for practical purposes, such as calendar determination, and there was little interest in theory in these fields. Theories of metallurgy, alchemy, and medicine were all tied to the prevailing religious and philosophical doctrines. Nevertheless, many important practical discoveries were made. Paper was invented in the 2d cent. A.D.; block printing was known in the 7th cent. A.D., with movable clay type by the 11th cent. and cast-metal type in Korea by the beginning of the 15th cent.; gunpowder was invented in the 3d cent. A.D. and firearms were in use by the 13th cent.; and the magnetic compass came into use during the 11th and 12th cent.

In India an alphabetic script was developed, as well as a numeral system based on place value and including a zero; this latter Hindu contribution was adopted by the Arabs and combined with their numeral system. Important Hindu scientists flourished in the 6th and 7th cent. A.D. and also in the 12th cent., making contributions to astronomy and mathematics. Many of these early Indian works showed the influence of Greek science, as in the geocentric systems of astronomy, or of Babylonian science, as in their development of algebraic methods for solving many problems.

Science in the Middle Ages

Muslim Preservation of Learning

With the eclipse of the Greek and Roman cultures, many of their works passed into the hands of the Muslims, who by the 7th and 8th cent. A.D. had extended their influence through much of the world surrounding the Mediterranean. All of the Greek works were translated into Arabic, and commentaries were added. Important developments from the East were also transmitted, and the Hindu numeral system was introduced, as well as the manufacture of paper and gunpowder, learned from the Chinese. Scholars gathered at cities like Damascus, Baghdad, and Cairo, at one end of the Mediterranean, and at Cordova and Toledo, in Spain, at the other end. Many astronomical observations were made at different locations, but there was little effort to improve or modify the Greek model of Ptolemy. In medicine important contributions were made by Al-Razi (Rhazes, 865-925) and Ibn-Sina (Avicenna, 980-1037), and in alchemy and pharmacology by Jabir (Geber, 9th cent.), whose work was expanded in the 10th cent. by a mystical sect aligned with the Sufi tradition. At Cairo, Al-Hazen (965-1038) studied optics, particularly the properties of lenses, and Maimonides (1135-1204), the Jewish philosopher, came there from Spain to practice medicine as physician to Saladin, the Sultan. The Arabs thus preserved the scientific works of the Greeks and added to them, and also introduced other contributions from Asia. This body of learning first began to be discovered by Europeans in the 11th cent.

The Craft Tradition and Early Empiricism in Europe

Certain technical innovations during the Dark Ages, e.g., development of the heavy plow, the windmill, and the magnetic compass, as well as improvements in ship design, had increased agricultural productivity and navigation and contributed to the rise of cities, with their craft guilds and universities. These changes were more pronounced in N Europe than in the south. The introduction of papermaking (12th cent.) and printing (1436-50) made possible the recording of craft traditions that had been handed down orally in previous centuries. This served to reduce the gap between the artisan classes and the scholar classes and contributed to the development of certain individuals who combined elements of both traditions—the artist-engineers such as Leonardo da Vinci, whose studies of flight and other technological problems were far beyond their time, and the artist-mathematicians, such as Albrecht Dürer, who examined the laws of perspective and wrote a textbook on geometry. Many artists came to study anatomy in detail.

Beginning in the 12th cent. the Arabic versions of Greek works were translated into Latin, an edition of Ptolemy's Almagest being translated at Toledo, and one of Aristotle's biological works in Sicily. Leonardo da Pisa (Fibonacci) presented some of the new Hindu-Arabic mathematics in the early 13th cent., and the medical and alchemical works were also translated. Also in the 13th cent., a trend toward empiricism was promoted by Roger Bacon and others, but this was short-lived. The dominant philosophy of science and other fields was the Christianized version of Aristotelian philosophy created by Albertus Magnus and Thomas Aquinas in the 13th cent. This view tended to treat scientific theories as extensions of philosophy and, for example, postulated the existence of angelic agents to account for the movements of the heavenly bodies. Even so, the craft traditions continued to develop in an independent manner, particularly medieval alchemy, and certain schools grew up that were not dominated by the main scholastic philosophy. The rebirth, or Renaissance, of learning spread throughout the West from the 14th to the 16th cent. and was further enhanced by the great voyages of discovery that began in the 15th cent.

The Scientific Revolution

Science, in the modern sense of the term, came into being in the 16th and 17th cent., with the merging of the craft tradition with scientific theory and the evolution of the scientific method. The feeling of dissatisfaction with the older philosophical approach had begun much earlier and had produced other results, such as the Protestant Reformation, but the revolution in science began with the work of Copernicus, Paracelsus, Vesalius, and others in the 16th cent. and reached full flower in the 17th cent.

The Rejection of Traditional Paradigms

Copernicus broke with the traditional belief, supported by both scientists and theologians, that the earth was at the center of the universe; his work, finally published in the year of his death (1543), proposed that the earth and other planets move in circular orbits around the sun. Paracelsus rejected the older alchemical and medical theories and founded iatrochemistry, the forerunner of modern medical chemistry. Andreas Vesalius, like Paracelsus, turned away from the medical teachings of Galen and other early authorities and through his anatomical studies helped to found modern medicine and biology. The philosophical basis for the scientific revolution was expressed in the writings of Francis Bacon, who urged that the experimental method plays the key role in the development of scientific theories, and of René Descartes, who held that the universe is a mechanical system that can be described in mathematical terms. The science of mechanics was established by Galileo, Simon Stevin, and others. The astronomical system of Copernicus gained support from the accurate observations of Tycho Brahe; the modification of Johannes Kepler, who used Tycho's work to show that the planetary orbits are elliptical rather than circular; and the writings of Galileo, who based his arguments on his own mechanical theories and observations with the newly invented telescope. Other instruments were also of major importance in the discoveries of the scientific revolution. The microscope extended human knowledge of living things just as the telescope had extended human knowledge of the heavens. The mechanical clock was perfected in the late 16th cent. by Christian Huygens, who also made improvements in the telescope, and thus events, both celestial and terrestrial, could be timed with greater precision—an essential factor in the development of the exact sciences, such as mechanics. The 17th cent. also saw the discovery of the circulation of the blood by William Harvey and the founding of modern chemistry by Robert Boyle.

Improved Communication of Scientific Knowledge

Another important factor in the scientific revolution was the rise of learned societies and academies in various countries. The earliest of these were in Italy and Germany and were short-lived. More influential were the Royal Society in England (1660) and the Academy of Sciences in France (1666). The former was a private institution in London and included such scientists as Robert Hooke, John Wallis, William Brouncker, Thomas Sydenham, John Mayow, and Christopher Wren (who contributed not only to architecture but also to astronomy and anatomy); the latter, in Paris, was a government institution and included as a foreign member the Dutchman Huygens. In the 18th cent. important royal academies were established at Berlin (1700) and at St. Petersburg (1724). The societies and academies provided the principal opportunities for the publication and discussion of scientific results during and after the scientific revolution.

The Impact of Sir Isaac Newton

The greatest figure of the scientific revolution, Sir Isaac Newton, was a fellow of the Royal Society of England. To earlier discoveries in mechanics and astronomy he added many of his own and combined them in a single system for describing the workings of the universe; the system is based on the concept of gravitation and uses a new branch of mathematics, the calculus, that he invented for the purpose. All of this was set forth in his Philosophical Principles of Natural Philosophy (1687), the publication of which marked the beginning of the modern period of mechanics and astronomy. Newton also discovered that white light can be separated into a spectrum of colors, and he theorized that light is composed of tiny particles, or corpuscles, whose behavior can be described by the laws of mechanics. A rival theory, holding that light is composed of waves, was proposed by Huygens about the same time. However, Newton's influence was so great and the acceptance of the mechanistic philosophy of Descartes and others so widespread that the corpuscular philosophy was the dominant one for more than a century.

The Age of Classical Science

The history of science during the 18th and 19th cent. is largely the history of the individual branches as they developed into the traditional forms by which they are still recognized today.

The Evolution of Mathematics and Physics

In mathematics the calculus invented by Newton and G. W. Leibniz was developed by the Bernoullis, Leonhard Euler, and J. L. Lagrange into a powerful tool that was to be used not only in mathematics but also in physics and astronomy. Newtonian physics spread to the Continent slowly, its acceptance being hindered by adherents of the older Cartesian philosophy and by disputes over priority in the invention of the calculus. However, by the late 18th cent. it was firmly established. Other branches of physics came into their own during this period. The study of electricity expanded to include electric currents and magnetism, and it was finally synthesized in the theory of electromagnetic radiation of J. C. Maxwell in the second half of the 19th cent. These discoveries provided the foundation for the technological advances in communications and in other fields using electrical energy. The wave theory of light was revived at the beginning of the 19th cent. by Thomas Young and developed by others; Maxwell's theory showed that light was one form of electromagnetic energy. In the 18th cent. scientists thought that heat was a kind of fluid called caloric. However, by the early 19th cent. it became apparent that heat is a form of motion—the motion of the particles of which substances are composed. The classical theory of heat and thermodynamics was developed by J. P. Joule, Lord Kelvin, R. J. E. Clausius, and others, who showed the relation between heat and other forms of energy and formulated the law of conservation of energy. Maxwell, Ludwig Boltzmann and others developed statistical mechanics, which treats matter as a large aggregate of many particles and applies statistical methods to the prediction of its behavior.

Innovations in Chemistry

Chemistry became increasingly quantitative and experimental during the 18th cent. Joseph Priestley and other English scientists made a number of discoveries which served as the basis for A. L. Lavoisier's explanation of the role of oxygen in combustion and respiration. John Dalton proposed the modern version of the atomic theory in the early 19th cent. and Dmitri Mendeleev, in his periodic table, showed how the chemical elements described by the atomic theory could be arranged in a systematic way. In the mid-19th cent. R. W. Bunsen and G. R. Kirchhoff developed spectroscopy as a tool for chemical analysis. Also in the 19th cent., the synthesis of urea by Friedrich Wöhler (1828) established that organic substances are composed of the same kinds of atoms as inorganic substances, thus opening a new era in the study of organic chemistry.

Advances in Astronomy

Astronomy progressed on the theoretical level through the contributions to celestial mechanics of P. S. Laplace and others, and on the observational level through the work of many scientists. They included William Herschel, who built telescopes and discovered Uranus (1781), the first planet found in modern times, and his son John Herschel, who extended his father's observations to the Southern Hemisphere skies and pioneered in astrophotography, which in modern astronomy is the chief method of observation. Another tool that found important application in astronomy was the spectroscope. Increasingly astronomers made use of the instruments, techniques, and theories of other fields, particularly physics.

Birth of Modern Geology

Modern geology may be said to date from the work of James Hutton, who postulated (1785) that the geologic processes and forces that had shaped the earth were still in operation and could be observed directly. Georges Cuvier, the French naturalist, founded the field of comparative anatomy and applied its principles to geology in the study of the fossil remains of animals of the distant past, thus also founding the field of paleontology.

New Ideas in Biology

In biology Carolus Linnaeus instituted a system of classification of animals and plants, and improvements in this system helped scientists to arrange different forms of life according to complexity, suggesting to some that organisms may evolve from simple to complex forms. In the 19th cent. K. E. von Baer founded the field of embryology, the study of the earliest stages of different forms of life, and Matthias Schleiden and Theodor Schwann identified the cell as the basic unit of living matter. In medicine the treatment of disease was furthered by the introduction of smallpox vaccination by Edward Jenner and the recognition of the role of germs and viruses in causing diseases. A number of ways of reducing the growth of such organisms were introduced, including pasteurization of foods and antiseptic surgery. Anesthetics were introduced in the 19th cent. by several scientists, and, through chemistry, new medications were developed that aimed at treatment of specific ailments.

Science and the Industrial Revolution

Some of the greatest changes were in the area of technology, in the development of new sources of energy and their application in transportation, communications, and industry. Among the important aspects of the Industrial Revolution were the invention of the steam engine by James Watt and its use in factories, mines, ships, and railroad engines; the development of the internal-combustion engine and the companion growth of petroleum technology to provide fuel for it; the invention of many different kinds of agricultural machinery and the resulting enormous increase in productivity; the improvement of many metallurgical processes, particularly those involving iron and steel; and the invention of the electric generator, electric motor, and numerous electric devices that are now commonplace.

Revolutions in Modern Science

The enormous growth of science during the classical period engendered an optimistic attitude on the part of many that all the major scientific discoveries had been made and that all that remained was the working out of minor details. Faith in the absolute truth of science was in some ways comparable to the faith of earlier centuries in such ancient authorities as Aristotle and Ptolemy. This optimism was shattered in the late 19th and early 20th cent. by a number of revolutionary discoveries. These in turn attracted increasing numbers of individuals into science, so that whereas a particular problem might have been studied by a single investigator a century ago, or by a small group of scientists a few decades ago, today such a problem is attacked by a virtual army of highly trained, technically proficient scholars. The growth of science in the 20th cent. has been unprecedented.

In much of modern science the idea of progressive change, or evolution, has been of fundamental importance. In addition to biological evolution, astronomers have been concerned with stellar and galactic evolution, and astrophysicists and chemists with nucleosynthesis, or the evolution of the chemical elements. The study of the evolution of the universe as a whole has involved such fields as non-Euclidean geometry and the general theory of relativity. Geologists have discovered that the continents are not static entities but are also evolving; according to the theory of plate tectonics, some continents are moving away from each other while others are moving closer together.

The Impact of Elementary Particles

Physics in particular was shaken to the core around the turn of the century. The atom had been presumed indestructible, but discoveries of X rays (1895), radioactivity (1896), and the electron (1897) could not be explained by the classical theories. The discovery of the atomic nucleus (1911) and of numerous subatomic particles in addition to the electron opened up the broad field of atomic and nuclear physics. Atoms were found to change not only by radioactive decay but also by more dramatic processes—nuclear fission and fusion—with the release of large amounts of energy; these discoveries found both military and peaceful applications.

Quantum Theory and the Theory of Relativity

The explanation of atomic structure required the abandonment of older, commonsense, classical notions of the nature of space, time, matter, and energy in favor of the new view of the quantum theory and the theory of relativity. The first of these two central theories of modern physics was developed by many scientists during the first three decades of the 20th cent.; the latter theory was chiefly the product of a single individual, Albert Einstein. These theories, particularly the quantum theory, revolutionized not only physics but also chemistry and other fields.

Advances in Chemistry

Knowledge of the structure of matter enabled chemists to synthesize a sweeping variety of substances, especially complex organic substances with important roles in life processes or with technological applications. Radioactive isotopes have been used as tracers in complicated chemical and biochemical reactions and have also found application in geological dating. Chemists and physicists have cooperated to create many new chemical elements, extending the periodic table beyond the naturally occurring elements.

Biology Becomes an Interdisciplinary Science

In biology the modern revolution began in the 19th cent. with the publication of Charles Darwin's theory of evolution (1859) and Gregor Mendel's theory of genetics, which was largely ignored until the end of the century. With the work of Hugo de Vries around the turn of the century biological evolution came to be interpreted in terms of mutations that result in a genetically distinct species; the survival of a given species was thus related to its ability to adapt to its environment through such mutations. The development of biochemistry and the recognition that most important biological processes take place at the molecular level led to the rapid growth of the field of molecular biology, with such fundamental results as the discovery of the structure of deoxyribonucleic acid (DNA), the molecule carrying the genetic code. Modern medicine has profited from this explosion of knowledge in biology and biochemistry, with new methods of treatment ranging from penicillin, insulin, and a vast array of other drugs to pacemakers for weak hearts and implantation of artificial or donated organs.

The Abstraction of Mathematics

In mathematics a movement toward the abstract, axiomatic approach began early in the 19th cent. with the discovery of two different types of non-Euclidean geometries and various abstract algebras, some of them noncommutative. While there has been a tendency to consolidate and unify under a few general concepts, such as those of group, set, and transformation, there has also been considerable research in the foundations of mathematics, with a close examination of the nature of these and other concepts and of the logical systems underlying mathematics.

Astronomy beyond the Visual Spectrum

In astronomy ever larger telescopes have assisted in the discovery that the sun is a rather ordinary star in a huge collection of stars, the Milky Way, which itself is only one of countless such collections, or galaxies, that in general are expanding away from each other. The study of remote objects, billions of light-years from the earth, has been carried out at all wavelengths of electromagnetic radiation, with some of the most notable results being made in radio astronomy, which has been used to map the Milky Way, study quasars, pulsars, and other unusual objects, and detect relatively complex organic molecules floating in space. The latter, coupled with the discovery of extrasolar planetary systems and possible microscopic fossils in meteorites of Martian origin, have raised new questions about the origin of life and the possible existence of intelligent life elsewhere in the universe.

Modern Science and Technology

The technological advances of modern science, which in the public mind are often identified with science itself, have affected virtually every aspect of life. The electronics industry, born in the early 20th cent., has advanced to the point where a complex device, such as a computer, that once might have filled an entire room can now be carried in an attaché case. The electronic computer has become one of the key tools of modern industry. Electronics has also been fundamental in developing new communications devices (radio, television, laser). In transportation there has been a similar leap of astounding range, from the automobile and the early airplane to the modern supersonic jet and the giant rocket that has taken astronauts to the moon. Perhaps the most overwhelming aspect of modern science is not its accomplishments but its magnitude in terms of money, equipment, numbers of workers, scope of activity, and impact on society as a whole. Never before in history has science played such a dominant role in so many areas.

Promise and Problems of Modern Science

Modern science holds out a number of promises, as well as a number of problems. In the foreseeable future researchers may solve the riddle of life and create life itself in a test tube. Most diseases may be brought under control. Science is also working toward control over the environment, e.g., dispersing hurricanes before they can endanger life or property. New sources of energy are being developed, and these together with the capacity to manipulate alien environments may make life possible on the moon or other planets.

Among the challenges faced by modern science are practical ones such as the production and distribution of enough energy to meet increased demands and the elimination or reduction of pollutants in the environment. Some of these problems are political and sociological as well as scientific, as are such problems as control over nuclear and other forms of weapons (biological, chemical) and regulation of the use of computers and other electronic devices that may seriously infringe on individual privacy and freedom. Some have profound ethical implications, e.g., those associated with gene manipulation, organ transplantation, and the capacity to sustain life beyond the point at which it once would have ended. There are also philosophical problems raised by science, as in the uncertainty principle of the quantum theory, which places an absolute limit on the accuracy of certain physical measurements and thus on the predictions that may be made on the basis of such measurements; in the quantum theory itself, with its suggestion that at the atomic level much depends on chance; and in certain paradoxical discoveries in mathematics and mathematical logic. Even a detailed account of the history of science cannot be complete, for scientific activity is not isolated but takes place within a larger matrix that also includes, for example, political and social events, developments in the arts, philosophy, and religion, and forces within the life of the individual scientist. In other words, science is a human activity and is affected by all that affects human beings in any way.

sanitary science, principles of health preservation, embracing hygiene, on an individual level, and public health, on a communal level. Those who specialize in sanitary science are sanitary engineers. They endeavor to eliminate or reduce health hazards associated with the supply of water and milk, the collection and disposal of sewage and refuse, and the prevalence of rodents and insects. Conditions of noise, air pollution, and improper food handling that threaten the well-being of the public are also their concern. Sanitary engineers have had to develop methods for safely disposing of radioactive waste material at sea and on land. See solid waste.

political science, the study of government and political processes, institutions, and behavior. Government and politics have been studied and commented on since the time of the ancient Greeks. However, it is only with the general systematization of the social sciences in the last 100 years that political science has emerged as a separate definable area of study. Political science is commonly divided into a number of subfields, the most prominent being political theory, national government, comparative government, international relations, and special areas shared with other social sciences such as sociology, psychology, and economics. In practice, these subfields overlap. Political theory encompasses the following related areas: the study of the history of political thought; the examination of questions of justice and morality in the context of the relationships between individuals, society, and government; and the formulation of conceptual approaches and models in order to understand more fully political and governmental processes. The study of national government focuses on the political system of the researcher's particular country, including the legal and constitutional arrangements and institutions; the interaction of various levels of government, other social and political groups, and the individual; and proposals for improving governmental structure and policy. Comparative government covers many of the same subjects but from the perspective of parallel political behavior in several countries, regions, or time periods. International relations deals both with the more traditional areas of study, such as international law, diplomacy, political economy, international organizations, and other forms of contact between nation states, and with the development of general, scientific models of international political systems. None of the political science subfields can be clearly separated. All of them, for example, deal with questions closely associated with political theory. Valuable and sophisticated discussions of almost all the areas of political science, including the areas now generally classified under such titles as political sociology, can be found throughout intellectual history as far back as Plato and Aristotle. Through the centuries, the questions of political science have been discussed in contexts varying with the changing perspectives of the time. During the Middle Ages, for example, the major concerns revolved around the problem of where the state stood in relation to man and his God. Karl Marx, on the other hand, viewed political questions in the context of society's economic structure. Modern political science stresses the importance of using political concepts and models that are subject to empirical validation and that may be employed in solving practical political problems.

planetary science or planetology, study of planets and planetary systems as a whole. Planetary science applies the theories and methods of traditional disciplines such as astronomy, geology, physics, chemistry, and mathematics to the study of the origin, composition, and distribution of matter in planetary systems, especially the evolution and structure of planets and their natural satellites. The study of planetary systems initially focused on the earth and moon. It was extended to include the other solar planets and their satellites with advances in astronomy, and increased in significance as the lunar and planetary probes of the last half of the 20th cent. returned more and more data. Planetary science burst out of the confines of the solar system with the discovery of extrasolar planets in 1995, of extrasolar multiple-planet systems in 1999, and of an extrasolar planet nearly as old as the universe in 2003. Planetary science is also concerned with the study of life on other planets (see exobiology).

philosophy of science, branch of philosophy that emerged as an autonomous discipline in the 19th cent., especially through the work of Auguste Comte, J. S. Mill, and William Whewell. Several of the issues in philosophy of science concern science in general. David Hume raised a problem of induction, namely that of the grounds people have for believing that past generalizations, i.e., scientific laws, will be valid in the future. Sir Karl Popper and Nelson Goodman have made influential contributions to issues concerning induction in science. Another issue centers around the relations of scientific theories to the interpretation of the world. An additional general issue concerns the way science develops. Contemporary philosophers such as Thomas Kuhn have denied the thesis of the logical positivists (see logical positivism) that scientists choose between competing theories in a purely rational fashion, i.e., by appealing to theory-neutral observations. The philosophy of science also focuses on issues raised by the relations between individual sciences and by individual sciences themselves. An example of the former is the issue of whether the laws of one science, e.g., biology, can be reduced to those of a supposedly more fundamental one, e.g., physics. An example of the latter sort of issue is that of the implications of quantum mechanics for our understanding of causality.

naval science: see strategy and tactics.

museums of science, institutions or buildings where collections relevant to science and technology are preserved and displayed to promote education and research. While the preponderance of these museums are in North America and Europe, the chief cities of Australia, New Zealand, Africa, and Latin America are known for outstanding collections in local natural history and ethnology. See also botanical garden; planetarium.

Development of the Science Museum Concept

Many early museums of science, e.g., the Ashmolean Museum (1683) at Oxford, the first public museum in the Western world, originated from gifts of private collections. At first most exhibits consisted of classified and labeled geological or biological specimens. Later exhibition techniques have emphasized the grouping of specimens to illustrate origins, associations, and interrelationships. Exhibition devices include habitat groups, restorations, murals, dioramas, models, and key installations in feature exhibits. The illustration of abstract ideas in biology, e.g., evolution and heredity, was extended to physics and chemistry, long neglected in science museums. A pioneer in showing the principles of mechanics, light, heat, and sound was the Buffalo Museum of Natural Science.

The modern science museum has a threefold function—exhibition of collections, sponsoring of research, and education. Many museums provide cataloged reserve collections for students and undertake research and the publication of results; some participate in expeditions for research or for enlarging collections. Provisions for adult education include guided tours, lectures, and classes; museums cooperate with schools by providing loan exhibitions, special exhibits and tours for children, and story hours. A growing trend has been the use of computer terminals and "hands-on" models to enhance the learning experience. Many museums now also attempt to educate the public in the principles of ecology and wildlife and resource conservation.

North American Museums

Outstanding in developing educational functions are the American Museum of Natural History, New York City, and the Field Museum of Natural History, Chicago. Although most science museums cover the general field, there are many, including a number of university and college teaching museums, that specialize, notably in anthropology; one of these is the National Museum of the American Indian, Washinton, D.C., and New York City. The establishment of the Adler Planetarium, Chicago (1930), the Fels Planetarium (1933) of the Franklin Institute, and the Hayden Planetarium (1935) of the American Museum of Natural History have stimulated science museums to deal with astronomy. The Museum of Science and Industry, Chicago, and the Franklin Institute, Philadelphia were pioneers in the field of applied sciences. The growth of local trailside museums, most of them in national parks, was stimulated by the success of Yosemite Museum (1921). The 1980s and 90s saw a number of new science and technology museums constructed in U.S. cities, and aquariums, which increasingly emphasized ecology in their exhibits, experienced a resurgence in popularity. Canada has notable museum collections, especially in Toronto, Ottawa, and Quebec.

The Smithsonian Institution, the national museum of the United States and the largest museum in the world, includes several constituent museums that specialize in particular areas of science and technology. There are many municipal and state museums of science. Universities and colleges that have notable museums include Harvard, with the Museum of Comparative Zoology (est. 1859 by Louis Agassiz, the earliest such collection in the United States) and the Peabody Museum of Archaeology and Ethnology; the Univ. of Chicago, with the Oriental Institute; and the Univ. of Pennsylvania, specializing in ethnology and archaeology, especially of the Americas and of Asia. In addition to those already mentioned, the Academy of Natural Sciences of Philadelphia (est. 1812) and the Boston Society of Natural History (now the Museum of Science) are outstanding among American museums.

There are also many small special museums centering on limited fields of science or technology. Some are privately supported, others have been established by government agencies. Among them is the Robert C. Williams American Museum of Paper Making, Atlanta, Ga., which includes the Dard Hunter Collection (see Hunter, Dard); it embraces all aspects of papermaking and of the use of paper. The American Museum of Atomic Energy (now the American Museum of Science and Energy) opened in 1949 in Oak Ridge, Tenn. Many private companies have established their own museums. Such private museums often have unique collections, e.g., the glass museum in Corning, N.Y.

European Museums

Pioneers in the field of applied science include the Conservatoire des Arts et Métiers (the first industrial museum, est. 1799) and the Palais de la Découverte, both in Paris; the Science Museum, London; and the Deutsches Museum, Munich, Germany. Many private museums with unique collections have been established. The first of these, dating from 1916, was a button museum in Prague. Other notable specialized museums are the museums of oceanography in Monaco and in Berlin and the Jurassic Museum of Asturias in Colunga, Spain. Most of the principal countries have national science museums or strong science collections in general museums. In London are the great natural history collection of the British Museum, housed in South Kensington, and the Museum of the Royal College of Surgeons, with its Hunterian Collection. Other noted science museums in Europe include Norway's Bergen Museum; the Swedish Museum of Natural History, Stockholm; the National Museum, Copenhagen; the Rijks Museum, Leiden, Netherlands, noted for its departments of geology, mineralogy, and zoology; the University Museum, Amsterdam; the Natural History Museum, Vienna; the Natural History Museum (Jardin des Plantes), Paris; and the Kunstkammer of the Russian Academy of Sciences, St. Petersburg. Germany has many excellent science museums in its cities and universities, and many Italian universities are noted for their science collections.

military science: see strategy and tactics.

domestic science: see home economics.

creation science: see creationism.

United States National Science Foundation: see National Science Foundation.

Pugwash Conferences on Science and World Affairs: see Rotblat, Sir Joseph.

National Science Foundation (NSF), an independent agency in the executive branch of the U.S. federal government concerned with promoting a national science policy by supporting basic research and education in science. The National Science Board is the policy-making body of the NSF. It consists of 25 members appointed by the president with the consent of Congress. Founded in 1950, the NSF does not conduct research of its own but makes support grants to qualified educational and nonprofit institutions and awards fellowships to individual scientists, teachers, and students. The foundation supports projects in the mathematical, physical, medical, biological, social, and engineering sciences, including the U.S. Antarctic Program, the Ocean Drilling Program, and programs in global geoscience. It supports the development of improved science curriculum materials and fosters the interchange of scientific ideas nationally and internationally. Among the more important permanent NSF-supported facilities are: National Center for Atmospheric Research (Boulder, Colo.), National Radio Astronomy Observatory (Green Bank, W.Va.), Kitt Peak National Observatory (Tucson, Ariz.), National Astronomy and Ionosphere Center (Arecibo, Puerto Rico), and Cerro Tololo Inter-American Observatory (La Serena, Chile).

London School of Economics and Political Science, at London, England; founded 1895, recognized as a school of the Univ. of London (see London, Univ. of) in 1900. It publishes many periodicals, including the British Journal of Sociology, the British Journal of Industrial Relations, and the International Bibliography of the Social Sciences. The Centre for Economic Performance and the Centre for International Studies are affiliated.

Iowa State University of Science and Technology, at Ames, commonly known as Iowa State University; land-grant with state and federal support; coeducational; chartered 1858, opened 1868 as an agricultural college; called Iowa State College of Agriculture and Mechanic Arts from 1896 to 1959. It has schools of agriculture, business, design, education, engineering, family and consumer sciences, liberal arts and sciences, and veterinary medicine as well as graduate faculties. The Ames Laboratory of the U.S. Dept. of Energy is there.

Cooper Union for the Advancement of Science and Art, accredited institution of higher education; in New York City; coeducational; chartered and opened in 1859. Founded by Peter Cooper, it pioneered in evening engineering and art schools; day schools were added in 1900. Today it includes schools of engineering, art, and architecture, a division of adult education, and a faculty of humanities and social sciences. There are no tuition, application, matriculation, or graduation fees for U.S. residents. The Cooper-Hewitt, National Design Museum, was founded in 1897 as part of Cooper Union by Sarah, Eleanor, and Amy Hewitt, granddaughters of Peter Cooper. Since 1967 the museum, still located in New York City, has been a division of the Smithsonian Institution.

Christian Science, religion founded upon principles of divine healing and laws expressed in the acts and sayings of Jesus, as discovered and set forth by Mary Baker Eddy and practiced by the Church of Christ, Scientist. The church teaches that God is good and the only reality, and that sin, evil, and illness are overcome on the basis of this understanding. Adherents rely on spiritual, rather than medical or material, means for healing. The occasion of Mary Baker Eddy's discovery of divine healing was her immediate recovery of life and health when in 1866 she read an account of healing by Jesus in the New Testament. In 1875 her Science and Health (later published as Science and Health, with Key to the Scriptures) was published. In 1879 she established the Church of Christ, Scientist. In Boston in 1892 was organized the First Church of Christ, Scientist—the Mother Church, of which Christian Science churches throughout the world are branches. Each individual church is self-governing and self-supporting, but all accept the tenets framed by the founder and incorporated in the Church Manual. Upon Eddy's death in 1910, the administrative power was assumed, as laid down in the Manual, by the Christian Science Board of Directors. An extremely active organization, the board enabled Christian Science to grow steadily in numbers and scope of activity during the first third of the 20th cent. Of the numerous publications the church issues, the most important include the Christian Science Monitor, a daily newspaper; the Christian Science Quarterly; the Christian Science Sentinel; and the Christian Science Journal. These are published by the Christian Science Publishing Society. Other activities are conducted by a board of education and a board of lectureship. The churches have no individual pastors. Services are conducted by two readers, one reading from the Scriptures, the other from Science and Health. All churches use the same lessons at the same time. The teachings are drawn from the life and words of Jesus. Although most Christian Scientists are in the United States, the religion is found in 70 countries with large Protestant populations. A great percentage of its adherents are women.

American Association for the Advancement of Science (AAAS), private organization devoted to furthering the work of scientists and improving the effectiveness of science in the promotion of human welfare. The association was founded in 1848; it presently includes some 143,000 individual members, as well as 296 scientific societies, professional organizations, and state and city academies. AAAS actively promotes science education, and many junior academies of science are affiliated with it. Separate sections of the association represent the various physical and biological sciences, as well as many of the social sciences. It publishes the journal Science.

Medical field dealing with animals and with diseases that are transmissible between animals and humans. It was practiced as a specialty in ancient Egypt and Babylonia; the first veterinary schools in Europe were founded in the mid-18th century. Veterinarians practice internal medicine, surgery, and preventive medicine, using the same techniques used on humans. They serve worldwide in private and corporate clinical practice, academic programs, private industry, government service, public health, and military services. Many specialize in either small animals (pets) or large ones (livestock); a few specialize in wild animals.

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or unity-of-science view

In the philosophy of logical positivism, the doctrine holding that all sciences share the same language, laws, and method. The unity of language has been taken to mean either that all scientific statements could be restated as a set of protocol sentences describing sense-data or that all scientific terms could be defined using physics terms. The unity of law means that the laws of the various sciences must be deduced from some set of fundamental laws (e.g., those of physics). The unity of method means that the procedures for supporting statements in the various sciences are basically the same. The unity-of-science movement that arose in the Vienna Circle held to those three unities, and Rudolf Carnap's “physicalism” supported the notion that all the terms and statements of empirical science could be reduced to terms and statements in the language of physics.

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A branch of soil science focusing on the formation, morphology, and classification of soils as bodies within the natural landscape. Pedology seeks to understand how the properties and distribution patterns of soils worldwide (collectively called the pedosphere) have developed along with broader landforms, biogeochemical environments, and habitats of living organisms. Through their understanding of the causes and magnitudes of soil variations, pedologists help to broaden knowledge of the surface of the Earth.

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Any discipline or branch of science that deals with the sociocultural aspects of human behaviour. The social sciences generally include cultural anthropology, economics, political science, sociology, criminology, and social psychology. Comparative law and comparative religion (the comparative study of the legal systems and religions of different nations and cultures) are also sometimes regarded as social sciences.

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Branch of philosophy that attempts to elucidate the nature of scientific inquiry—observational procedures, patterns of argument, methods of representation and calculation, metaphysical presuppositions—and evaluate the grounds of their validity from the points of view of epistemology, formal logic, scientific method, and metaphysics. Historically, it has had two main preoccupations, ontological and epistemological. The ontological preoccupations (which frequently overlap with the sciences themselves) ask what kinds of entities can properly figure in scientific theories and what sort of existence such entities possess. Epistemologically, philosophers of science have analyzed and evaluated the concepts and methods employed in studying natural phenomena, both the general concepts and methods common to all scientific inquiries and the specific ones that distinguish special sciences.

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Fiction dealing principally with the impact of actual or imagined science on society or individuals, or more generally, literary fantasy including a scientific factor as an essential orienting component. Precursors of the genre include Mary Shelley's Frankenstein (1818), Robert Louis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde (1886), and Jonathan Swift's Gulliver's Travels (1726). From its beginnings in the works of Jules Verne and H.G. Wells, it emerged as a self-conscious genre in the pulp magazine Amazing Stories, founded in 1926. It came into its own as serious fiction in the magazine Astounding Science Fiction in the late 1930s and in works by such writers as Isaac Asimov, Arthur C. Clarke, and Robert Heinlein. A great boom in popularity followed World War II, when numerous writers' approaches included predictions of future societies on Earth, analyses of the consequences of interstellar travel, and imaginative explorations of intelligent life in other worlds. Much recent fiction has been written in the “cyberpunk” genre, which deals with the effects of computers and artificial intelligence on anarchic future societies. Radio, film, and television have reinforced the popularity of the genre.

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Academic discipline concerned with the empirical study of government and politics. Political scientists have investigated the nature of states, the functions performed by governments, voter behaviour, political parties, political culture, political economy, and public opinion, among other topics. Though it has roots in the political philosophies of Plato and Aristotle, political science in the modern sense did not begin until the 19th century, when many of the social sciences were established. Its empirical and generally scientific orientation is traceable to the work of Henri de Saint-Simon and Auguste Comte. The first institution dedicated to its study, the Free School of Political Science, was founded in Paris in 1871.

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Study of the properties of solid materials and how those properties are determined by the material's composition and structure, both macroscopic and microscopic. Materials science grew out of solid-state physics, metallurgy, ceramics, and chemistry, since the numerous properties of materials cannot be understood within the context of any single discipline. With a basic understanding of the origins of properties, materials can be selected or designed for an enormous variety of applications, from structural steels to computer microchips. Materials science is therefore important to many engineering fields, including electronics, aerospace, telecommunications, information processing, nuclear power, and energy conversion. Seealso mechanics, metallography, strength of materials, testing machine.

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Scientific discipline concerned with all aspects of the world's oceans and seas, including their physical and chemical properties, origin and geology, and life forms. Research entails sampling seawater and marine life, remote sensing of oceanic processes with aircraft and satellites, and exploration of the seafloor. Oceanography aids in predicting weather and climate, in exploitation of the Earth's resources, and in understanding the effects of pollutants. Seealso marine geology.

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Principles and practices of library operation and administration, and their study. It emerged as a separate field of study in the second half of the 19th century. The first training program for librarians in the U.S. was established by Melvil Dewey in 1887. In the 20th century, library science was gradually subsumed under the more general field of information science. Today's graduate programs in library and information science are accredited by the American Library Association (founded 1876) and prepare students for professional positions in other areas of the information industry as well.

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Discipline that deals with the processes of storing and transferring information. It attempts to bring together concepts and methods from such varied disciplines as library science, computer science and engineering, linguistics, and psychology to develop techniques and devices to aid in the handling of information. In its early stages in the 1960s, information science was concerned primarily with applying the then-new computer technology to the processing and managing of documents. The applied computer technologies and theoretical studies of information science have since permeated many other disciplines. Computer science and engineering still tend to absorb its theory- and technology-oriented subjects, and management science tends to absorb information-systems subjects.

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Science of applying medical knowledge to legal questions, recognized as a specialty since the early 19th century. Its primary tool has always been the autopsy, to identify the dead (e.g., plane-crash victims) or determine cause of death, which can significantly affect trials dealing with insurance and inheritance. Forensic psychiatry determines the mental health of an individual about to stand trial. Forensic genetics allows paternity to be determined and can identify blood or other tissue samples as coming from a particular person (see DNA fingerprinting). Forensic toxicology, concerned with such topics as intentional poisonings and drug use, is increasingly important in cases of industrial and environmental poisoning.

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The belief that matter, the various forms of life, and the world were created by God out of nothing. Biblical creationists believe that the story told in Genesis of God's six-day creation of the universe and all living things is literally correct. Scientific creationists believe that a creator made all that exists, though they may not hold that the Genesis story is a literal history of that creation. Creationism became the object of renewed interest among conservative religious groups following the wide dissemination of the theory of biological evolution, first systematically propounded by Charles Darwin in On the Origin of Species (1859). In the early 20th century some U.S. states banned the teaching of evolution, leading to the Scopes Trial. In the late 20th century many creationists advocated a view known as intelligent design, which was essentially a scientifically modern version of the argument from design for the existence of God as set forth in the late 18th century by the Anglican clergyman William Paley.

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Study of computers, their design (see computer architecture), and their uses for computation, data processing, and systems control, including design and development of computer hardware and software, and programming. The field encompasses theory, mathematical activities such as design and analysis of algorithms, performance studies of systems and their components, and estimation of reliability and availability of systems by probabilistic techniques. Because computer systems are often too large and complicated for failure or success of a design to be predicted without testing, experimentation is built into the development cycle.

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Series of international meetings of eminent scientists to discuss problems of nuclear weapons and world security. The first meeting was held in 1957 at the estate of Cyrus Eaton in Pugwash, Nova Scotia. The Pugwash organization was established to convene subsequent conferences to discuss arms control and disarmament; these were held in the Soviet Union, Britain, India, and the U.S., among other countries. The organization and its president and founding member, Joseph Rotblat (born 1908), received the 1995 Nobel Prize for Peace.

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officially Church of Christ, Scientist

Religious denomination founded in the U.S. in 1879 by Mary Baker Eddy. Like other Christian churches, Christian Science subscribes to an omnipotent God and the authority (but not inerrancy) of the Bible and takes the Crucifixion and Resurrection of Jesus as essential to human redemption. It departs from traditional Christianity in considering Jesus divine but not a deity and in regarding creation as wholly spiritual. Sin denies God's sovereignty by claiming that life derives from matter. Spiritual cure of disease is a necessary element of redemption from the flesh and one of the church's most controversial practices. Most members refuse medical help for disease, and members engaged in the full-time healing ministry are called Christian Science practitioners. Elected readers lead Sunday services based on readings from the Bible and Eddy's Science and Health with Key to the Scriptures. At the end of the 20th century, the church had about 2,500 congregations in 70 countries; its headquarters is at the Mother Church in Boston. Seealso New Thought.

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