Physical Science in India

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Physical Science in India

Overview

Though there remain essential questions concerning the age of Indian literature, a timeframe of sophisticated ideas from about 1500 b.c. indicates that Indian astronomy and physical thought were on a par with that of Babylonia and Egypt. Some historians have pushed this date back to 6000 b.c. and earlier based on claims that the oral transmission of such ideas far precede written records. Ancient Hindu sources from around 1500 b.c. indicate the existence of advanced concepts of basic astronomical awareness of movement for five planets and the Sun and Moon, and their application to cosmological time cycles, or solar calendars. Other claims suggest an understanding of relative astronomical motions (specifically rotation of the Earth and the Sun as center of the planets), sphericity of Earth, flattened poles of the Earth, and the concept of fundamental matter as atoms.

Some of these ideas require a validated chronology of dating to be considered legitimate. On the other hand, the traditional historical claims that Indian science was dependent on Greek science after 326 b.c. are inaccurate and fail to account for the native evolution of science and mathematics in India for thousands of years b.c. By the fifth century a.d., important Indian astronomers and mathematicians, such as Aryabhata (476-550) and Brahmagupta (598-668), developed advanced physical thought, providing continuity with seminal ancient Indian conceptions in astronomy and other sciences.

Background

Based on interpretation of early Indian Hindu religious literature, which was orally composed well before being committed to writing, some scholars have claimed that a high level of sophistication and innovation existed early in Indian science, perhaps in rudimentary form from 3000 b.c., though more likely 1500 b.c. It remains suspect, however, that oral information alluding to scientific ideas would be exactly transmitted thousands of years later to the written word without cumulative revisions based on improved scientific conceptions and techniques. Early, essentially nonscientific literature has been long accepted as a legitimate source for very early scientific ideas where scientific literature had not yet developed formally. The earliest sources in India are the Hindu Vedas, four Vedic texts (Rig, Yajur, Sama, and Atharva) that are sources of prayers, hymns, magic, and sacrificial formulae with many astronomically advanced suggestions dating from about 1500 b.c., though perhaps earlier.

The Rig Veda is referred to the most regarding claims of advanced scientific concepts in India, and these conceptions are largely presented under astrological references that had great significance in Hindu religion. This was also the case with other ancient religions in an effort to understand the heavens and its influence on terrestrial nature. Veda concepts entailed the use of a 12-month lunar calendar, knowledge of the precession of the equinoxes, a solar day ritually divided into 3, 4, 5, or 15 equal divisions, and a rather modest 27-star catalog of names.

Another assemblage of early literature, based on the text fragments and oral traditions of the Jain (a religion independent from Hinduism), were recomposed much later (probably about 350 b.c.). Ardha-Magadhi Prakrit, consisting of approximately 50 texts that entail more specific mathematical and astronomical information. These texts also imply that the scientific concepts included were updated over time. Of these writings, two of the books known as the Angas deal with astronomy and mathematics. In the set known as the Upangas there are references to astronomy and the concept of time, asankhyata, meaning "inscrutable infinitesimal time," and sirsaprahelika, meaning "millions of years." The Culikasutra is a treatise on astronomy and mathematics. A post-Jain work from the second century a.d. called Tattvarthadhigma Sutra was composed by the astronomer Umavati (185-219) and deals with astronomy and Indian cosmology. Additionally, there are other works on Jain theoretical and observational astronomy written up until the seventh century.

Jain cosmology featured the conception of Mount Meru in India as the central axis of the Earth, a motionless planet, surrounded by the Sun, Moon, planets, and constellations of the stars. The Jain cosmographical diagram showed Mount Meru at the center (the pole star above it) with the 12 months, planetary cycles, and the movements of the Sun and Moon wrapped congruently around it. A major city or area considered the center of the Earth was a typical conception of most ancient cultures. The Indians, like other early cultures, were also interested in understanding worldly phenomena such as the terrestrial water cycle, the tides, and the change of seasons.

Claims that the Indian conception of the sphericity of the Earth is earlier and significantly different than that of the ancient Greeks remain suspect, as they are dependent on the validation of unrevised-by-time passages in ancient Indian literature, such as the Rig Veda, to predate that of Greece. Though some claim that the term "bowl," which appears in early Vedic texts and the Puranic works Markandeya Purana and Vishnu Purana, alludes to the sphericity of the Earth, it was actually quite common among ancient cultures to envision the cosmos as a flat or hollow bowl-shaped Earth, or sometimes an inverted bowl, with the heavens stretched over it. These are typical ancient interpretations based on the perspective of one standing on Earth and observing and interpreting what he or she saw at face value around them. But these texts do have interesting anticipations of later physical thought that suggest the cause of twilight, the blue of the sky, the phases of the Moon, allusions to some notion of gravity, and perhaps the Sun as center of the Solar System. A group of texts called the Vaiseshika Sutras (dating from as early as the second century to as late as the fifth century) entail an elaborate analysis of matter as atoms, even in combination (the idea of molecules), under the influence of time and direction.

Impact

Aside from considerations of the religious and astrological origins of Indian cosmology and astronomical thinking, the more historically precise textual proof of the advances of Indian astronomy and its ancient foundation begins with the fifth century, particularly the astronomer Aryabhata (476-550). His Aryabhatiya, a multi-disciplinary work of mathematics and astronomy, was composed in about 498 and is an enlightening source for observing the advance of Indian science from its foundation in ancient times. It contains a discussion of spherical astronomy (an application for astronomy) along with calculations of planet mean positions and rules for calculating solar and lunar eclipses. Most importantly, it contains his view that Earth rotated on its axis, though it is uncertain whether or not this concept was the result of Greek influence on Indian astronomy.

Aryabhata was perhaps the earliest astronomer to begin a continuous counting of solar days by revolutions of the Earth (rather than the usual conception of orbits of the Sun around the Earth)—that is, determining the length of the year. He also used this data with that on orbits of the Moon (the ratio of the former to the latter) to provide a mathematical rendering of the month, and thus an early astronomical ratio. His methods of calculating planetary motions would be adopted by astronomers in his native Kerala, a state in southern India, who by 683 agreed to modify this method with a revision to be known as the Parahita system.

The Siddhantas texts of the sixth and seventh centuries reveal more sophisticated astronomical calculations, indicating an advance from Aryabhata. And indeed a few of the these are in fact technical in nature, one being written by astronomer and mathematician Varahamihira (505-587), who came from the area of Ujjain, where a famous astronomical observatory would arise. As a philosopher as well, Varahamihira made a thorough study of Western and Middle Eastern astronomical rudiments, including those of the Egyptians, Greeks, Romans, and Indians, and compiled a comparative and comprehensive work called Five Treatises. Though an example of intellectual exchange, Varahamihira's work might have provided a source for the inaccurate traditional Western view that Indian astronomy was dependent on other cultures.

The Ujjain school of astronomy produced another significant astronomer in the person of Brahmagupta (598-668), who wrote a comprehensive revision of an old text of astronomy, the Brahma Siddhanta, called the Brahma Sphuta Siddhanta. Brahmagupta's revision included pure math and astronomical applications. Essentially, he provided a systematized rendering of rules for algebra, geometry, other mathematics, and astronomy. Brahmagupta may have been the first astronomer to apply algebraic techniques to astronomical problems and, evidently, also came up with the concept of using zero and a solution to the indeterminate equation, a significant advance in numerical theory before the eighteenth century. His methods of astronomical calculations were thorough and included discussion of the motions, positions, rising and setting, and conjunctions of planets, and eclipses of the Sun and Moon. He believed the heavens and Earth were round or spherical, but he did not believe that Earth rotated or moved. He also took a hand at geodetics, resulting in a fairly good approximation of the circumference of the Earth as 5,000 yojanas (about 4.5 miles [7.2 km] per the ancient unit of yojanas or 22,369 miles [36,000 km]).

Another area in which some historians theorize that Indian scientists made very early innovations concerns the understanding of gravity and heliocentrism, as understood by the major Indian astronomers already noted. Varahamihira might have been the first Indian thinker to suggest a force holding the Earth and the celestial bodies in place. Brahmagupta had said: "Bodies fall toward the earth as it is in the nature of the earth to attract bodies, just as it is the nature of water to flow." Yet earlier claims point to some Sanskrit words found in Vedic literature that are interpreted as dealing with attraction in the gravitational sense, suggesting to some that some idea of gravity was known at an early date. And again, the Vedic literature is held up as the earliest source, as well as an ultimate reference, to the central place of the Sun as gravitational source and center of the universe—thus, its heliocentric implication. However, heliocentrism was arrived at later in Indian astronomy, first by Aryabhata, as already noted.

Some historians assert this early Indian concept of heliocentrism, based on the Vedic sources, predates the Greek concept of heliocentrism that appeared in about the mid-fourth century b.c. However, this claim is highly interpretative since, after all, the Sun's importance as a light and heat source, whether as a deity or natural influence, is primary in all ancient civilizations, thus casting doubt on such a purported gravitational or heliocentric view. Additionally, words relating to the prominence of the Sun would be subjective in meaning and could be interpreted as anticipating such scientific ideas in other ancient cultures as well. At the same time, Aryabhata's applications of heliocentric astronomy in his calculations would logically point to perhaps some earlier tradition of heliocentrism as a foundation for his ideas. But a more exacting, objective analysis of scientific meaning in Indian literature will have to validate what would otherwise be interpreted as only subjective claims.

Nonetheless, the credit due to Indian scientific thinkers from 1500 b.c. to the end of the seventh century a.d. has been long in coming. Indian historians and other interdisciplinary international historians have proceeded with important research in Indian source translation and commentary that is necessary to properly interpret India's scientific past and its place in the larger framework of intellectual history.

Certainly, in the more than 2,000 years leading up to the seventh century Indian thinkers provided a progression from sophisticated religious refinement of the ordering of the physical cosmos to important practical developmental concepts in observational astronomy, mathematical application to astronomy, and various physical theories centering on the perception of the Sun and planets. As with other ancient peoples, India holds a unique place by virtue of its cultural characteristics and innovative intellectual endeavors, as well as its contributions to foundational thought and legacy of physical scientific knowledge.

WILLIAM J. MCPEAK