A Living Portrait of India
A Living Portrait of India |
India Heritage:Science:Physics |
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The link between energy generation or disappearance and the creation of heat was a connection missed by most of the ancients. Prasatapada recognized parispanda (molecular/atomic motions), be they whirling, circling, or harmonic. Also, that kriya (action) was the consequence of these. The Nyaya-Vaisesikas believed that all matter except akasa (ether) contained parispanda, and that all atoms are in a state of constant activity. Akasa alone was non-atomic and niskriya (non-active). Clearly, kinetic energy was perceived. Sankara Misra in his Upaskara dwelt on the properties of heat, but once again, the absence of instruments prevented any measurement of heat. In the tenth-eleventh century AD, Udayana recognized solar heat as the heat-source of all chemical changes. Vijnanabhiksu (seventeenth century AD) discussed heat as being a latent factor in the earth element. However, it was accepted that heat was responsible for physico-chemical reactions. The taijasa element discussed by Prasastapada referred to the heat particles that affected molecular groupings (vyuhas), i.e. causing chemical changes. The process itself was called paka, and different modes of action were assumed - corresponding to the pilupakavada and the pitharapakavada theories. Both theories are best explained through the baking of an earthen pot. Pilupakavada theory : Pilu refers to isolated atoms. The Vaisesikas held that first, the fire particles reduce the molecules of the earthen pot into atoms; next, continued action of fire upon the atoms changes the colour from black to red; third and last, the fire particles cause the conjunction of the recently altered atoms, thereby creating diads, triads, and higher aggregates. Hence the term pilupakavada - action of fire particles on isolated atoms. Pitharapakavada theory : Pithara refers to the whole (body of the pot). The Naiyayikas (of the Nyaya school) disagreed with the Vaisesikas - they pointed out that if the fire particles were to reduce molecules into their atomic state, the pot should vanish! Clearly, the fire particles were acting upon the pot as a whole, resulting in atomic conjunctions and disjunctions. Thus, there was no change in the shape of the pot - only in the colour. SOURCES : The Cultural Heritage of India History of Science & Technology in India Concise Encyclopedia of Science and Technology Masters of the Millennium - 100 Indians who
shaped the century |
