Talk:Physical Sciences
By Shishir Thadani
The physical sciences were quite developed in ancient times and their theories were very close to the modern scientific theories. For instance, the earliest application of chemistry took place in the context of medicine, metallurgy, construction technology (such as manufacturing of cement and paints) and in textile production. Concomitant to furthering applications, there was also an interest in attempting to describe the basic elements of matter - what they were composed of, and how they interacted with each other to produce new substances. Natural phenomenon were studied in the context of tides, rainfall, appearance of the sun, the moon and stellar formations, changes in season, weather patterns and agriculture. (For instance, Vedic literature mentions the condensation of water vapor from seas and oceans due to evaporation caused by the Sun's heat and the subsequent formation of clouds and rain.)
The Vaisheshikas, some of the earliest available scientific literature available today, describe basic information on the physical properties of different types of plants and natural substances and also provide a classification scheme for the same. Intuitive formulations and approximate theories about the composition of matter and physical behavior are also provided.
Particle Physics[edit]
Though particle physics is one of the most advanced and most complicated branches of modern physics, the earliest atomic theories are at least 2,500 years old. Virtually every school of philosophy had something to say on the nature of elementary particles. Various schools promoted the idea that matter was composed of atoms that were indivisible and indestructible. Later philosophers further elaborated on this notion by positing that atoms could not only combine in pairs (dyads) but also in threes (triads) - and that the juxtaposition of dyads and triads determined the different physical properties of the substances seen in nature.
Atomic/molecular theories were also utilized in explanations of chemical changes caused by heat. Prasastapada, a Vaisheshika scholar, proposed that the taijasa (heat) factor affected molecular groupings (vyuhas), thus causing chemical changes. Two competing theories attempted to provide a more detailed explanation of the process (as applied to the baking/coloring of a clay pot through firing):
- The Pilupakavada theory, as proposed by the Vaisheshikas, held that the application of heat (through fire, for instance) reduced the molecules of the earthen pot into atoms and the continued application of heat caused the atoms to regroup creating new molecules with a different color.
- The Pitharapakavada theory, offered by the Nyayikas (of the Nyaya school), disagreed suggesting that the molecular changes/transformations took place without the breakdown of original molecules into basic atoms. This theory argued that if atoms regrouped due to heat, there would also have to be a disintegration of the pot itself but pot remained intact. It only changed the color.
An intuitive understanding of kinetic energy appears common in the texts of both Praśastapada and the Nyaya-Vaisheshikas. In both the texts it has been mentioned that all atoms were in a state of constant activity. The concept of parispanda was propounded to describe such molecular/atomic motion whether this activity was whirling, circling, or harmonic.
Optics and Sound[edit]
The rationalists of the earlier times also attempted to provide theories on the nature of light and sound. Cakrapani suggested that both sound and light traveled in waves, but light traveled at a much higher speed. Suśruta posited that it was light arriving from an external source at the retina that illuminated the world around us. The Mimamsakas imagined light to be comprised of minute particles, known as photons. These photons were consistently in motion and spread light through radiations and diffusion from the original source.
The wave character of sound was elaborated on by Praśtāpada who hypothesized that sound was borne by air in increasing circles similar to the movement of ripples in water. Sound was understood to have its own reflection - pratidhvani (echo). Musical pitches (śruti) were seen to be caused by the magnitude and frequency of vibrations. A svara (tone) was believed to consist of a śruti (fundamental tone) and some anuranana (partial tones or harmonics). Musical theory was elaborated on the basis of concepts such as jativyaktyoriva tadatamyam (genus and species of svara), parinama (change of fundamental frequency), vyanjana (manifestation of overtones), vivartana (reflection of sound), and karyakaranabhava (cause and effect of the sound).
Varahamihira[1] discussed reflection as being caused by the light particles arriving on an object and then scattering back (kiranavighattana, murcchana). Vatsyayana referred to this phenomenon as rasmiparavartana, and the concept was adapted to explain the occurrence of shadows and the opacity of materials. Refraction was understood to be caused by the ability of light to penetrate to the inner spaces of translucent or transparent materials and Uddyotakara drew a comparison with fluids moving through porous objects.
Astronomy and Physics[edit]
Just as the study of Mathematics received an impetus from the study of astronomy, so did the study of Physics. Aryabhatta[2] made pioneering discoveries in the realm of planetary motion. This led to advances in the definition of space and time measuring units. Due to which a better comprehension of concepts such as gravitation, motion and velocity emerged.
For instance, Yativrasabha's work Tiloyapannatti[3] gives various units for measuring distances and time and also describes a system of infinite time measures. Vacaspati Misra[4] anticipated solid (co-ordinate) geometry eight centuries before Descartes proposed. In his Nyayasuchi-nibandha, he states that the position of a particle in space could be calculated by assuming it relative to another particle and measuring along the three (imaginary) axes.
The study of astronomy also led to a great interest in quantifying very large and very small units of time and space. According to the Nyaya-Vaisheshikas, a solar day was considered to be made up of 1,944,000 kśana (units of time). Each kśana thus corresponded to .044 seconds. The truti was defined as the smallest unit of time i.e. 2.9623*10-4. The Silpasāśtra records the smallest measure of length as the paramanu i.e. 1/349525 of an inch. This measurement corresponds to the smallest thickness of the Nyaya-Vaisheshika school - the trasarenu, which was the size of the smallest dot visible on a sunbeam as it shone into a dark room. Varahamihira [5] posited that 86 trasarenu were equal to one anguli i.e. three-fourths of an inch. He also suggested that 64 trasarenu were equal to the thickness of a hair.
The Laws of Motion[edit]
The Vaisheshikas made the earliest attempts to classify different types of motion. These were further developed by Praśtāpada[6] who described four kinds of motion.
- Linear motion
- Curvilinear motion (gamana)
- Rotary motion (bhramana)
- Vibratory motion
Praśtāpada also differentiated motion that was initiated by some external action from the action which initiated as a result of gravity or fluidity. He also described motion that resulted from elasticity or momentum, or as an opposite reaction to an external force. He noted that some types of actions result in like motion and some other type of action resulted in opposite motion or no motion at all. These different types of motions were due to variations arising from the internal and inherent properties of the interacting objects. He also noted that at any given instance, a particle was capable of only a single kind of motion (although a body such as a blowing leaf composed of multiple particles may experience a more complex pattern of motion due to different particles moving in different ways).
Sridhara[7] reiterated and expanded on Praśtāpada's work.
Bhaskaracharya[8], in his Siddhanta Śiromani and Ganitadhyāya measured average velocity v=d/t (where d is distance covered, and t is time).
Bhoja[9] referred to magnetism in his era.
Sankara Misra[10] noted the phenomenon of electrostatic attraction after he had observed how grass and straw were attracted by amber. He also brought some awareness in the concept of kinetic energy and in his Upaskara dwelt on the properties of heat, and tried to relate the process of boiling to evaporation. In the same treatise, he also gave examples of capillary motion citing the ascent of sap from root to stem in a plant and the ability of liquids to penetrate through porous vessels. He also wrote about surface tension, and posited sandrata (viscosity) as the cause behind the cohesion of water molecules and the smoothness of water itself. Magnetism was later on mentioned by him.
Udayana[11] recognized solar heat as the heat-source of all the chemical changes. He also mentioned that air had weight in a discussion of balloons in his Kiranawali.
Vallabhacharya [12] in his Nyaya-lilāvati pointed out the resistance of water to a sinking object.
Raja Bhoja's Somarangana-sutradhara[13] describes many useful mechanical inventions.
Notes & References[edit]
- ↑ Varahamihira is dated to the 6th century CE
- ↑ Aryabhatta lived from 476 to 550 CE
- ↑ Tiloyapannatti is tentatively dated between 5th and 6th century CE
- ↑ Vacaspati Misra is tentatively dated circa AD 840
- ↑ Varahamihira is tentatively dated circa 6th century CE
- ↑ Praśtāpada is dated to the 7th century CE
- ↑ Sridhara lived from 870 CE to 930 CE
- ↑ Bhaskaracharya is dated to the 12th century CE
- ↑ Bhoja lived circa 10th-11th century CE
- ↑ Sankara Misra is dated to 15th-16th century CE
- ↑ Udayana lived circa 10th-11th century CE
- ↑ Vallabacharya is dated to 13th century CE
- ↑ Raja bhoja's Somarangana-sutradhara is dated circa AD 1100
- The Positive Sciences of the Ancient Hindus (Brajendranath Seal)
- Concise History of Science in India (Bose, Sen, Subarayappa, Indian National Science Academy)
- Studies in the History of Science in India (Anthology edited by Debiprasad Chattopadhyaya)
- Causation in Indian Philosophy (Mahesh Chandra Bhartiya, Vimal Prakashan, Ghaziabad)