Hindu Achievements in Exact Science: A Study in the History of Scientific Development c15: IX. Physics
Hindu Achievements in Exact Science: A Study in the History of Scientific Development c15
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IX. Physics
c15.2
PLAYFAIR makes the following remarks with regard to Greek physics: "Nothing like the true system of natural philosophy was known to the ancients. There are nevertheless to be found in their writings many brilliant conceptions, several fortunate conjectures, and gleams of light, which were afterwards to be so generally diffused."
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The same remarks may be made, generally speaking, about Hindu physics. Both in methodology and achievements it exhibits almost the same strength and limitations as the Greek. But probably the attempts of the Hindu physicists were more comprehensive, and more coordinated with investigations in other branches of knowledge than those of the Greeks.
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Some hypothesis of nature, i.e., of matter and energy, constituted the positive basis of each of the principal schools of Hindu philosophy, including metaphysics. The idea of a real "natural philosophy" was never absent from the intellectual horizon even of those who believed that "the proper study of mankind is man." There was no system of thought without its own physico-chemical theory of atoms, its own "laws of nature," and so forth. The most idealistic school had thus its own "materialistic" background. And the method of investigation, if not fully that of Baconian "experimental" induction, was not less fruitful and "experiential" than that of Aristotelian speculative logic.
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The problems in natural philosophy, which engaged the attention, more or less, of every thinker in India, were of the kind described below:
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1. The theory of atoms and molecular combinations. It is generally associated with the name of Kanada, the founder of Vaishesika philosophy. He has therefore been called the Democritus of India. Strictly speaking, there were almost as many atomic theories as the schools of Hindu thought. One or two may be mentioned:
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(1) Vaishesika system: Atoms cannot exist in an uncombined state in creation. "The doctrine of atomism did not take its rise in Greece, but in the East. It is found in the Indian philosophy. Kanada . . . could not believe matter to be infinitely divisible. (Fleming's "Vocabulary of Philosophy.")
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(2) Jaina system: The atoms are not only infinitesimal, but also eternal and ultimate. Atomic linking, or the mutual attraction (or repulsion) of atoms in the formation of molecules was analyzed by Umasvati (A.D. 50) with a most remarkable effect. The Jainas hold that the different classes of elementary substances are all evolved from the same primordial atoms. "The intra-atomic forces which lead to the formation of chemical compounds do not therefore differ in kind from those that explain the original linking of atoms to form molecules."⁵⁹
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2. General properties of matter: These were analyzed and defined not only by Kanada and his school, but also by the Jainas, Buddhists, and other rivals and contemporaries. A few such concepts were elasticity, cohesiveness, impenetrability, viscosity, fluidity, porosity, etc. Capillary motion was illustrated by the ascent of the sap in plants from the root to the stem, and the penetrative diffusion of liquids in porous vessels. Upward conduction of water in pipes was explained by the pressure of air.⁵⁹
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3. The doctrine of motion: Motion was conceived in almost every school of thought as underlying the physical phenomena of sound, light, and heat. This motion was known to be not only molar and molecular, but also the subtle motion lodged in the atoms themselves, i.e., the very principle of matter-stuff.
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4. Time and Space: In order to be precise and definite in their calculations the Hindus conceived infinitesimally small magnitudes of time and space. The instruments of measurement were crude. The attempt to distinguish from one another the varying grades of "least perceptible" sound, light, heat, time, etc., has therefore to be taken for what it is worth. An atom (*truti*) of time was regarded as equal to 1/33750th of a second. The thickness of the minimum visible (*trasa-renu*), e.g., the just perceptible mote in the sunbeam, was known to be 1/349525th of an inch. The size of an atom was conceived to be less than π.3.5⁻¹.2⁻⁶² of a cubic inch. "Curiously enough, this is fairly comparable (in order of magnitude) with the three latest determinations of the size of the hydrogen atom."⁵⁹ No unit of velocity seems to have been fixed upon. But average velocity was measured in accordance with the formula v = s/t. These measurements were not arbitrary poetic guess-works. It is on the basis of these that a remarkably accurate measurement of the relative pitch of musical tones was made, and the instantaneous motion of a planet determined (and thus the "principle" of the differential calculus discovered).
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5. The doctrine of conservation: Both matter and energy were known to be indestructible. But though constant, they were known to be liable to addition and subtraction, growth and decay, i.e., to changes in collocation. This transformation was known to be going on constantly.
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The following ideas about matter and energy may be gleaned from the writings of the Hindus.⁵⁹ Some of these should be regarded as real contributions to knowledge, though not demonstrated according to the modern methods:
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⁵⁹ 59
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(*a*) Heat:
(1) Light and heat were known to Kanada as different forms of the same substance.
(2) Solar heat was known to Udayana as the source of all the stores of heat.
(3) Heat and light rays were believed by Vachaspati (A.D. 850) to consist of very minute particles emitted rectilineally by the substances.
(4) Rarefaction in evaporation and the phenomenon of ebullition were correctly explained by Shamkara Mishra.
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(*b*) Optics:
(1) The phenomena of translucency, opacity, shadows, etc., were explained by Udyotakara.
(2) The angle of incidence was known to be equal to the angle of reflection. This was known to the Greeks also.
(3) The phenomenon of refraction was known to Udyotakara.
(4) The chemical effects of light rays were known to Jayanta.
(5) Lens and mirrors of various kinds, spherical and oval, were used for purposes of demonstration. Light rays were focussed through a lens on a combustible like paper or straw. (The making and polishing of glass was a great industry in India. According to Pliny the best glass was that made by the Hindus.)
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(*c*) Acoustics:
(1) Physical basis of sound: Two theories were held about the vehicle or medium of propagation. Shabara Swami knew it correctly to be the air. But Udyotakara and others knew it to be ether.
(2) Wave-motion: The sound-waves were understood by both schools. But Prashastapada knew them to be transverse; and Udyotakara and Shabara Swami understood the transmission of sound to be of the nature of longitudinal waves.
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(3) Echoes were analyzed by Vijnana-bhiksu.
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(4) Sounds were distinguished according to their tones and over-tones, volume or massiveness, and quality or timbre, by Batsyayana, Udyotakara, and Vachaspati (*c* A.D. 850).
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(5) Musical notes and intervals were analyzed and mathematically calculated in the treatises on music,¹⁴ e.g., Sharamgadeva's "Samgita-ratnakara" ("Ocean of Music") (1210-47), Damodara's "Samgita-darpana" ("The mirror of music") (1560-1647), etc. The relative pitch of the notes of the diatonic scale was, according to Krishnaji Ballal Deval, accurately determined.
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(6) The so-called Pythagorean law ¹² of the vibration of stretched strings was known to the Hindus, viz., the number of vibrations (pitch of a note) varies inversely as the length of the string.¹⁰
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(7) The Hindus knew that the octave above a note has twice as many vibrations as the note itself. They had thus arrived at the octave on which modern Eur-American music is based.
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(*d*) Magnetism:
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(1) Elementary magnetic phenomena could not but be observed. The attraction of grass, straw, etc., by amber, and the movement of the iron needle towards the magnet, were explained by Shamkara Mishra as due to *adrista*, i.e., unknown cause.
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(2) Bhoja (*c* A.D. 1050) in his directions for shipbuilding gave the warning that no iron should be used in holding or joining together the planks of bottoms intended to be sea-going vessels. The fear was entertained lest the iron should expose the ships to the influence of magnetic rocks in the sea, or bring them within a magnetic field and so lead them to risks.³⁴
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(3) Mariner's compass: Mookerji points out a compass on one of the ships in which the Hindus of the early Christian era sailed out to colonize Java and other islands in the Indian Ocean. The Hindu compass was an iron fish (called in Sanskrit *matsya-yantra* or fish machine). It floated in a vessel of oil and pointed to the north.
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(*e*) Electricity: Most rudimentary electrical phenomena may have been noticed by Umasvati (a.d. 50). His theory of atomic linking was based on the idea that the two atoms to be combined must have two opposite qualities. He believed that atoms attracted and repelled each other according as they were heterogeneous (i.e., unlike), and homogeneous (i.e., like), respectively.⁵⁹
Linked texts (1)
- Saṅgītaratnākara — Śārṅgadeva, Sanskrit