Science

I

Introduction

Science (Latin, scientia, from scire, “to know”), term used in its broadest sense to denote systematized knowledge in any field, but usually applied to the organization of objectively verifiable sense experience. The pursuit of knowledge in this context is known as pure science, to distinguish it from applied science, which is the search for practical uses of scientific knowledge, and from technology, through which applications are realized. For additional information, see separate articles on most of the sciences mentioned.

II

Origins of Science

Efforts to systematize knowledge can be traced back to prehistoric times, through the designs that Palaeolithic people painted on the walls of caves, through numerical records that were carved in bone or stone, and through artefacts surviving from Neolithic civilizations. The oldest written records of protoscientific investigations come from Mesopotamian cultures; lists of astronomical observations, chemical substances, and disease symptoms, as well as a variety of mathematical tables, were inscribed in cuneiform characters on clay tablets. Other tablets dating from about 2000 bc show that the Babylonians had knowledge of Pythagoras' Theorem, solved quadratic equations, and developed a sexagesimal system of measurement (based on the number 60) from which modern time and angle units stem. (see Number Systems; Numerals.)

From almost the same period, papyrus documents have been discovered in the Nile Valley, containing information on the treatment of wounds and diseases, on the distribution of bread and beer, and on working out the volume of a portion of a pyramid. Some of the present-day units of length can be traced back to Egyptian prototypes, and the calendar in common use today is the indirect result of pre-Hellenic astronomical observations.

III

Rise of Scientific Theory

Scientific knowledge in Egypt and Mesopotamia was chiefly of a practical nature, with little rational organization. Among the first Greek scholars to seek the fundamental causes of natural phenomena was the philosopher Thales, in the 6th century bc, who introduced the concept that the Earth was a flat disc floating on the universal element, water. The mathematician and philosopher Pythagoras, who followed him, established a movement in which mathematics became a discipline fundamental to all scientific investigation. The Pythagorean scholars postulated a spherical Earth moving in a circular orbit about a central fire. In Athens, in the 4th century bc, Ionian natural philosophy and Pythagorean mathematical science combined to produce the syntheses of the logical philosophies of Plato and Aristotle. At the Academy of Plato, deductive reasoning and mathematical representation were emphasized; at the Lyceum of Aristotle, inductive reasoning and qualitative description were stressed. The interplay between these two approaches to science has led to most subsequent advances.

During the so-called Hellenistic Age following the death of Alexander the Great, the mathematician, astronomer, and geographer Eratosthenes made a remarkably accurate measurement of the Earth. Also, the astronomer Aristarchus of Samos espoused a heliocentric (Sun-centred) planetary system, although this concept did not gain acceptance in ancient times. The mathematician and inventor Archimedes laid the foundations of mechanics and hydrostatics (part of fluid mechanics); the philosopher and scientist Theophrastus became the founder of botany; the astronomer Hipparchus developed trigonometry; and the anatomists and physicians Herophilus and Erasistratus based anatomy and physiology on dissection.

Following the destruction of Carthage and Corinth by the Romans in 146 bc, scientific inquiry lost its impetus until a brief revival took place in the 2nd century ad under the Roman emperor and philosopher Marcus Aurelius. At this time the geocentric (Earth-centred) Ptolemaic System, advanced by the astronomer Ptolemy, and the medical works of the physician and philosopher Galen became standard scientific treatises for the ensuing age. A century later the new experimental science of alchemy arose, springing from the practice of metallurgy. By 300, however, alchemy had acquired an overlay of secrecy and symbolism that obscured the advantages such experimentation might have brought to science.

IV

Medieval and Renaissance Science

During the Middle Ages, six leading culture groups were in existence: the Latin West, the Greek East, the Chinese, the East Indian, the Arabic, and the Maya. The Latin group contributed little to science before the 13th century, the Greek never rose above paraphrases of ancient learning, and the Maya had no influence on the growth of science. In China, science enjoyed periods of progress, but no sustained drive existed. Chinese mathematics reached its zenith in the 13th century with the development of ways of solving algebraic equations by means of matrices, and with the use of the arithmetic triangle. More important, however, was the impact on Europe of several practical Chinese innovations. These included the processes for manufacturing paper and gunpowder, the use of printing, and the mariner's compass. In India, the chief contributions to science were the formulation of the so-called Hindu-Arabic numerals, which are in use today, and in the conversion of trigonometry to a quasi-modern form. These advances were transmitted first to the Arabs, who combined the best elements from Babylonian, Greek, Chinese, and Hindu sources. By the 9th century, Baghdad, on the River Tigris, had become a centre for the translation of scientific works, and in the 12th century this learning was transmitted to Europe through Spain, Sicily, and Byzantium.

Recovery of ancient scientific works at European universities led, in the 13th century, to controversy over scientific method. The so-called realists espoused the Platonic approach, whereas the nominalists preferred the views of Aristotle. At the universities of Oxford and Paris, such discussions led to advances in optics and kinematics that paved the way for Galileo and the German astronomer Johannes Kepler.

The Black Death and the Hundred Years' War disrupted scientific progress for more than a century, but by the 16th century a revival was well under way. In 1543 the Polish astronomer Nicolaus Copernicus published De Revolutionibus Orbium Coelestium (On the Revolutions of the Heavenly Bodies), which revolutionized astronomy. Also published in 1543, De Corpis Humani Fabrica (On the Structure of the Human Body) by the Belgian anatomist Andreas Vesalius corrected and modernized the anatomical teachings of Galen and led to the discovery of the circulation of the blood. Two years later the Ars Magna (Great Art) of the Italian mathematician, physician, and astrologer Gerolamo Cardano initiated the modern period in algebra with the solution of cubic and quartic equations.