Overview: Physical Sciences 2000 B.C. to A.D. 699
Overview: Physical Sciences 2000 b.c. to a.d. 699
When did the study of physical science begin? The Sumerians, who created the first civilization in Mesopotamia around 3200 b.c., were ruled by a relatively complex government, yet considered the natural world to be ruled by a variety of gods. By 2000 b.c., however, Mesopotamia had become Babylonia, and mathematics and astronomy became legitimate fields of study. Egypt, influenced by Babylonian thought, had similar levels of scientific sophistication at the same point in history. Records from India indicate complex astronomical thought before 1500 b.c. In China, long overlooked by historians of science, artifacts from between 1600 and 1400 b.c. indicate observations of comets, nova, and star positions, as well as an elaborate system of mathematics.
Astronomy had its crude beginnings as astrology, when pagan religions sought to interpret the movement of the stars and planets and determine the influences of the heavens on human events. It began in ancient Mesopotamia, and eventually spread to Egypt, Greece, India, and the Orient. This required a keen observation of the stars and planets, and served as a springboard for the science of astronomy and the development of calendars.
Early Greek Philosophy
Eventually astronomy split from astrology, marking the birth of physical science. This was precipitated by the Greeks, beginning with Thales (c. 640-546 b.c.). Later philosophers such as Eudoxus (c. 400-347 b.c.), Apollonius of Perga (c. 240-170 b.c.), and Hipparchus (c. 130 b.c.), studied astronomy by observing the heavens, predicting events, and verifying the results. Two Greek mathematicians, Heraclides of Pontus (387-312 b.c.) and Aristarchus of Samos (c. 310-230 b.c.) proposed a heliocentric universe, with planets revolving around the sun. Greek thought also divided the physical world into two realms, the superior celestial and inferior terrestrial. This division of nature also divided physics into two branches: earth science and astronomy.
This division of nature was further elaborated by Pythagoras (d. c. 497 b.c.) and Plato (c. 427-347 b.c.), who saw perfection in the circular cycles of celestial motion. Terrestrial motion on the other hand, was viewed as rectilinear, imperfect, and corruptible, as was everything in that sphere. Aristotle (384-322 b.c.), one of the greatest ancient Greek philosophers, believed that the cosmos was divided into 55 concentric spheres, with Earth at the center.
Aristotle also defined, arranged, and compartmentalized the natural sciences in four separate branches: the celestial (De caelo et mundo), the terrestrial, the earth sciences, and chemistry (Meteorologica), physics (De physica), and organic nature (De generatione and corruptione). Like Empedocles (c. 492-c. 432 b.c.), he believed that the four elements of fire, earth, air, and water were the basis of all matter, rejecting Leucippus's (fifth century b.c.) and Democritus's (c. 470-380 b.c.) theory that atoms (from the Greek atomos, meaning "indestructible") were the building blocks of nature.
Theophrastus (c. 372-287 b.c.), a Greek philosopher and devoted student of Aristotle, succeeded his teacher as head of the Lyceum in Athens. Although much of his work has been lost, several of his works have survived, either in whole or in part, including his History of Physics and nine treatises on physical science, such as On Stone, On Fire, and On Wind.
Greek cosmology reached its apogee in Ptolemy's (c. 100-170) He mathematike syntaxis (The mathematical compilation), or Almagest as it came to be known over the centuries. Ptolemy expanded Aristotle's vision, positing that the planets traveled in "epicycles," circular orbits that followed that paths of the spheres; sometimes the epicycles themselves were thought to follow epicycles.
Like the other earth sciences, geodetics (the science of calculating the size and shape of the earth and determining the position of points on its surface) and geography began with the Greeks. Both Plato and Aristotle espoused a spherical earth. Eratosthenes (c. 276-c. 196 b.c.), the first to calculate the circumference of the earth, also wrote a systematic treatise on geography. Ptolemy's second great work, the Geography, contained contemporary maps of the ancient world and questioned the possibility of life at the equator and in the southern hemisphere (the antipodes), an idea that was not universally held at the time.
Terrestrial physics were less studied than celestial mechanics, but two areas did receive considerable attention: optics (or perspective) and statics. Euclid (c. 300 b.c.), Aristotle, and Archimedes (c. 287-212 b.c.) all wrote on optics; Archimedes also laid the foundations of hydrostatics, an event immortalized by his apocryphal revelation in the bathtub.
Roman and Medieval Science
As the centuries progressed, Greek science was filtered through Roman practicality of thought, which combined incomplete Greek science with curiosity about nature. Among the more important works of this type are the writings of the poet Marcus Manilius (fl. 40 b.c. to a.d. 20), Ambrosius Theodosius Macrobius (395-423), Martianus Capella (c. 410-c. 429), and Gaius Julius Hyginus, curator of the Palatine Library in Rome (c. 64 b.c.-a.d. 17). A more general science compilation, Noctes Atticae, written by Aulus Gellius (c. 123-c. 170) contains fragments from many lost works. Several original works on physical science came from the notable Romans Lucius Annaeus Seneca (c. 4 b.c.-a.d. 65), who wrote Natural Questions, and Pliny the Elder (23-79), author of Natural History, the first encyclopedic sourcebook of ancient science, which was very influential up through the sixteenth century.
The rise of Christianity in the fourth century heightened suspicions about Greek science and its ties to pagan astrology. By the end of the fifth century, knowledge of the Greek language and science faded away with the Roman Empire. But Christian Neoplatonists provided something of a stopgap in this situation. Representing the last vestiges of seminal Greek philosophy, they borrowed from the spectrum of Greek philosophy, focusing on Aristotle's method and logic. Both Christian and non-Christian schools developed in the second century a.d.. Neoplatonism lent itself well to Christian theology, a preference that would continue through the seventeenth century.
The first important Neoplatonic disciple in the Christian integration of ancient science with Christian theology was a theologian and biblical scholar named Origen (c. 185-c. 254), who was well acquainted with current Greek astronomical knowledge, including precession of the equinoxes and other Greek science. Around 300, a Greek scholar named Chalcidius translated the Platonic dialogue Timaeus into Latin; it would be the only one of its kind for the next 800 years. Saint Augustine (354-430), who defended empirical science against biblical articles of literal faith, was a profound Neoplatonic influence during the Middle Ages, paving the way for medieval church acceptance of Greek science, particularly Aristotle.
A few other early century thinkers kept ancient Greek works from disappearing, translating scientific works and compiling encyclopedic commentaries on them. One of the most important of these was the Christian Neoplatonist Anicius Manlius Severinus Boethius (c. 480-524), who attempted to translate all of Aristotle's and Plato's works into Latin. Boethius was followed by Cassiodorus (480-575) and Isidore of Seville (560-636), a monk and archbishop, respecitvely. These men were encyclopedic compilers who preserved many ancient texts at a time when civilization was collapsing around them. Sixth-century Neoplatonists such as Ammonius (fl. 522), Johannes Philoponus (c. 490-570), and Olympiodorus (fl. 530) wrote commentaries on Aristotle's meteorology, astronomy, and physics, displaying their acquaintance with Greek observational sophistication, and adding some much-needed common sense to their commentary and criticism.
Near and Far Eastern Science
Scientific thought appeared much later in the East, around the first century a.d., but fortunately was free of the upheaval that disrupted progress in the West. Chinese science, furthermore, exhibited an orderly regimentation very different from the disputational Greek tradition. An important scientist from this period is Zhang Heng (or Chang Heng or Hong, 78-139) who plotted stars and comets, and constructed what may be the first seismographic instrument. Another important personality is astronomer Tsai Yung (c. 190) who constructed the Chinese calendar. In India astronomy began to flourish around 300 b.c. Hindu astronomers included Aryabhata (476-550) who taught the rotation of the earth, Varahamihira (505-587) who gathered a compendium of Egyptian, Greek, Roman, and Indian astronomy, and Brahmagupta (598-668) who developed algebraic methods for calculating motions and conjunctions of planets and eclipses of the sun and moon.
During nearly three thousand years of development, both West and East, in seminal concepts of physical nature ultimately provided the foundation for all physical science to follow. This was a rich legacy which to this day is marveled over and studied as an epochal continuum of intellectual endeavor unique in the annals of civilization.
WILLIAM MCPEAK