Overview: Physical Sciences 1450-1699

The Medieval Foundation

Medieval science and intellectual thought were based not on direct observation and experience, but were heavily influenced by the Aristotelian view of nature (such as the four elements), and were further formalized by church teachings. Yet by the mid-thirteenth century Franciscan thinkers plied an observational/empirical logic to question wholesale acceptance of ancient scientific ideas, as in the impressive study of optics and the rainbow by Robert Grosseteste (c. 1175-1253) and others, with important contemporary efforts by Muslim thinkers. The heart of this critical view formalized into the new logic of nominalism, most familiarly recognized in William of Occam (c. 1285-1349) and overall as a late medieval disagreement with ancient, particularly Aristotelian, rationalization of abstractions and universals. More refined methodology resulted most effectively in the Parisian School of physical theorists, headed by Jean Buridan (c. 1297-c. 1358), who developed early theories of impetus as the causal agent of motion. His follower Nicole Oresme (c. 1320-c. 1382) criticized Aristotle's celestial ideas by hypothesizing the realistic logic of Earth rather than the universe rotating, one of Nicolaus Copernicus's later heliocentric theory arguments. These steps led to the physical science of the next 250 years, to the dawn of the eighteenth century, a time of profound transition to and foundation of modern physical science.

Renaissance Science

By the late fourteenth century European thinkers began a process of turning to original Greek thought as a new foundation of critical reappraisal of the ancient legacy. This was the so-called Renaissance, roughly continuing in spirit until 1600. The Renaissance was a period of European transitions, one much more complicated than simply the passing of medieval thought and the beginning of modern thought. It was a time of economic and social upheaval, emphasized by the age of exploration and discovery. In physical science the transition was outwardly noticeable, for without a new systematic base to replace that of ancient Greece, conservative thought mingled with changing views, all laced with a persistent traditional intuitive conception of knowing nature by occult processes, particularly astrology and alchemy. Interestingly, the Renaissance started roughly with one of the greatest gifts to intellectual stimulus, the printing press, which provided a dissemination of knowledge of phenomenal breadth via the printed word.

By the mid-fifteenth century physical science was also finding vision for this new Renaissance. The term "Renaissance Man" was first given to Leonardo da Vinci (1452-1519), an artist, inventor, and scientific polymath who delved at understanding nature with a stubborn brilliance for the thought process itself, rather oblivious of formal learning. Of the more formal variety of thought, the Renaissance spirit was effective in astronomy, initially through the efforts of Johann Müller (a.k.a. Regiomontanus, 1436-1476) and select others emphasizing a base of original ancient astronomical thought along with accurate instruments and observational technique. By the early sixteenth century investigators were poring over other areas of the physical sciences so comprehensively demarcated by Aristotle in physics, the earth sciences, and chemistry. And thinkers such as mathematician Girolamo Cardano (1501-1576) were challenging such ancient tenets as the legitimacy of the so-called four elemental building blocks of the terrestrial world; the delineation of terrestrial and celestial boundaries and the phenomena of each; and the immutability and perfection of celestial space with its curious essence, the "ether."

Nicolaus Copernicus (1473-1543) provided what has popularly become known as the revolutionary heliocentric theory of the universe, with Earth not only revolving around the Sun but rotating on its axis. The theory's relevance for the time was not so definitive, affecting only a modest few thinkers and in more practical aspects of observational astronomy. Still, there were a few scientists who took the heliocentric theory more profoundly. A school of heliocentric thought developed in England under Thomas Digges (c. 1543-1595), who drew from it a infinite cosmos instead of that fixed by the ancients. In Germany a large community of astronomers was greatly influenced by its implications in pro and con arguments. In Italy an unconventional philosopher/priest named Giordano Bruno (1548-1600) used it as part of his personal rebellion to church authority and was burned at the stake for it. This theory provided an impressive backdrop to a century of exploratory physical thought, groping toward systematic knowledge.

A characteristic part of that search was observational conscientiousness, stressing collecting and cataloguing not only physical specimens in natural history, mineralogy, and geology but also recording hard data of everything from comets and appearance of the Milky Way (not considered celestial) to rainbows and the odd shapes of hailstones. Among notable advances in physical science were: Georgius Agricola's (a.k.a. Georg Bauer, 1494-1555) systematic geological thought, William Gilbert's (1544-1603) landmark magnetic and electrical studies, and Tycho Brahe's (1546-1601) accurate astronomical measurements and their implications, one of which was application to the new Gregorian Calendar (1582).

The Seventeenth Century: Fundamental Base of Physical Science

Though Brahe and some astronomers and other thinkers into the seventeenth century were still tied to astrological sympathies, that century's astronomers were fully occupied with accurate planetary and stellar observations. These observations were made possible with new instruments of unparalleled sophistication. Nonetheless, Johann Kepler (1571-1630) conceived his monumental three laws of planetary movement (1609, 1619) partially out of his belief in a mystical geometry of a harmonious cosmos. But occult intuitiveness faded with its failure to compete with empirical and mathematical innovation in explaining nature as the seventeenth century wound toward its end.

As in the previous century, the appearance of comets and a host of variation in the supposed fixed star field continued to cast theoretical doubts about traditional ancient beliefs about the heavens. The introduction of the refracting lens telescope early in the century also opened up a closer look and new perspective on the heavens. Galileo Galilei (1564-1642) was the first to turn it toward the planets and discover the satellites of Jupiter, before he turned to his landmark studies in the physics of mechanics and his later crisis in the controversy over heliocentricity. Telescopic study of sunspots and comets with a clearer vision of the field of stars, resulting in significant advances in star catalogues and atlases through the century, paralleled advances in telescope technology.

The century's experimental science developed a growing methodology of laboratory investigation and instrumentation. At the forefront of this movement was René Descartes (1596-1650), grounding his mechanistic logic in physical and chemical phenomena. The building and testing of various thermometers, barometers, and hygrometers focused on the study of air and its properties. Jan Baptist van Helmont (1577-1644) first defined the term "gas." Galileo devised early forms of thermometers, while several investigators worked on measuring scales, thereby setting the stage for later studies in heat phenomena. Galileo's student Evangelista Torricelli (1608-1647) constructed the first mercury barometer. Robert Boyle (1627-1691) coined the term "barometer" and constructed many instruments, including hygrometers for studying weather changes. He rejected the traditional base of alchemy and promoted analysis of matter and substance by its composition. His experiments with gases culminated in the pressure/volume gas law. His colleague Robert Hooke (1635-1703), adding to a period of conjecture about the structure of Earth, pondered Earth's great age, developed atmospheric instruments, and—in experiments on mechanical elasticity—discovered the law of elastic force (1678).

The scientific thought of the seventeenth century was an arrangement of stepping stones toward a synthesis of ideas, as more outstanding minds provided plausible theories to solve physical problems. After mid-century that importance was made known in the transition of private and limited patronage of science to the government level. The great scientific societies were beginning to appear: the Academia del Cimento (Florence, 1657), the English Royal Society (London, 1662), and the French Académie Royal des Sciences (Paris, 1666). Institutional astronomy followed suit with, for example, the Observatoire de Paris (1667) and the Greenwich Royal Observatory (1675). Paralleling these outward signs of the credence in science were the ideas of some of the best thinkers of the latter part of the century. Christiaan Huygens (1629-1695), in addition to telescopic discovery of Saturn's rings and moon Titan, made important studies and applications in optics. He invented the pendulum clock and presented the mechanistic theory of light (1690) as an impulse (incipient wave theory), explaining light's optical properties. Edmond Halley (1656-1742) concluded that comets moved in closed orbits and appeared to be periodic. His theoretical base in this was a mathematical assurance in physical motion courtesy of Isaac Newton's (1643-1727) method of calculating a comet's apparent orbit.

Newton, who invented the reflecting telescope and derived calculus (1671) along with theorizing light behavior based on the corpuscular (particle) theory, had been developing a unifying mechanical theory for both celestial and terrestrial motion based on mathematical principles. This theory was a monumental culmination of the century's cumulative scientific experience, a long-awaited systematic plan for delving into nature. Newton's mathematical concept was really a synthesis of the two basic scientific trends of the seventeenth century. The one was a mathematical rationalism, basically a deductive method seen in Descartes or Galileo, while the other was a mathematical empiricism, the inductive method of experimentation, declared by Francis Bacon (1561-1626) and carried out by this experimental century, a significant representation being the body of the Royal Society's work.

"Newtonian" science was a secularized freedom from centuries of religious stricture on scientific thought, for it meant the discovery of independent and fundamental laws to the universe that were mathematically derived, one of its most essential being his universal law of gravitation between bodies. Newton's principles of scientific method were the immediate legacy of what would become physical science, what Newton himself termed natural philosophy "discovering the frame and operations of nature" in established rules and laws based on observation and experiment. These rules and laws became the now-defined classical physics thread that bound the fabric of physical science for the next two hundred years.

WILLIAM MCPEAK