India’s civilization created some of the most extraordinary conceptual advances. These include a cosmos with many solar like systems, the earliest astronomy, geometry, number theory, the ten-digit number system, the idea of physical laws and invariance, the earliest formal system to describe a complex natural phenomenon (as in Pāṇini’s computer program-like grammar that was not rivaled for 2,500 years), a very subtle Yoga psychology, the idea of immunization in medicine, and above all a framework that includes consciousness.
PHYSICAL LAWS AND MOTION
The history of Indian physics goes back to Kaṇāda (~ 600 BCE) who asserted that all that is knowable is based on motion, thus giving centrality to laws and their operational analysis in the understanding of the universe.20
There are nine classes of substances: ākāśa, space, and time that are continuous; four elementary substances (or particles) called earth, air, water, and fire that are atomic; and two kinds of mind, one omnipresent and another which is the individual.
Let the basic atoms of pṛthvi, āpaḥ, tejas, and vāyu be represented by P, Ap, T, and V, respectively. Every substance is composed of these four kinds of atoms. Consider gold in its solid form; its mass derives principally from the P atoms. When it is heated, it becomes a liquid and therefore there should be another kind of an atom already in gold which makes it possible for it to take the liquid form and this is Ap. When heated further it burns and this is when the T atom gets manifested. When heated further, it loses its mass ever so slightly, and this is due to the loss of the V atoms.
The atoms are eternal only under normal conditions, and during creation and destruction, they arise in a sequence starting with ākāśa and are absorbed in the reverse sequence at the end of the world cycle. The sequence of evolution of the elements is given as V→T→Ap→P. The V and T atoms have little mass (since they do not exist in a substantive form), whereas P and Ap atoms have mass. This sequence also hides within it the possibility of transformation from V and T atoms that are energetic to the more massive Ap and P atoms.
Indian chemistry developed many different alkalis, acids, and metallic salts by processes of calcination and distillation, often motivated by the need to formulate medicines. Metallurgists developed efficient techniques of extraction of metals from ore.21
ASTRONOMY
We know quite a bit about how astronomical science evolved in India. The Yajurvedic sage Yājñavalkya knew of a ninety-five-year cycle to harmonize the motions of the sun and the moon, and he also knew that the sun’s circuit was asymmetric. The second millennium BCE text Vedāṅga Jyotiṣa of Lagadha22 went beyond the earlier calendrical astronomy to develop a theory for the mean motions of the sun and the moon. An epicycle theory was used to explain planetary motions. Given the different periods of the planets, it became necessary to assume yet longer periods to harmonize their cycles. This led to the notion of mahāyugas and kalpas with periods of billions of years.
The innovations of the division of the circle into 360 parts and the zodiac into 27 nakṣatras and 12 rāśis took place first in India. The schoolbook accounts of how these innovations first emerged in Mesopotamia in the 7th century BCE and then arrived in India centuries later are incorrect because both these divisions are described in the Ṛgveda.
The Śatapatha Brāhmaṇa which was compiled soon after the Vedas says: “The sun strings these worlds [the earth, the planets, the atmosphere] to himself on a thread. This thread is the same as the wind…” This suggests a central role to the sun in defining the motions of the planets and ideas such as these must have ultimately led to the theory of expanding and shrinking epicycles.
Astronomical texts called siddhāntas begin appearing sometime in the first millennium BCE.
According to the tradition there were eighteen early siddhāntas, of which only a few have survived. Each siddhānta is an astronomical system with its own constants. The Sūrya Siddhānta speaks of the motion of planets governed by “cords of air” that bind them, which is a conception like that of the field.
The great astronomers and mathematicians include Āryabhaṭa, who took Earth to spin on its own axis and who spoke of the relativity of motion and provided outer planet orbits with respect to the sun. This work and that of Brahmagupta (b. 598) and Bhāskara (b. 1114) was passed on to Europe via the Arabs. The Kerala School with figures such as Mādhava (c. 1340–1425) and Nīlakaṇṭha (c. 1444–1545) came up with new innovations of analysis based on advanced mathematics.23
Read More at https://cisindus.org/2021/07/18/a-brief-history-of-indian-science-from-mathematics-to-medicine/