Ancient Indian Physics (भौतिकविज्ञानम्)

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Ancient Indians contributed to the development of many concepts of modern Physics (Samskrit: भौतिकविज्ञानम्) much earlier than the advent of modern physics. The study of physics involves an understanding of the functioning, interactions and relationships between the fundamental components of the observable universe and the observable cosmos. The field of physics covers all aspects of the natural world, both at macroscopic and microscopic levels. The conception of Panchamahabhutas, or the five gross elements, to explain the diversity of nature, was the foundational aspect of Indian physical shastras. Nature consists of a variety of things – solids, water, gas, fire, and space. Space, or Akasa, is considered eternal and was created to give material objects a positive reference, a substratum, and a medium on which things exist. In modern terms it resembles the concept of an all-pervading ether medium.

Introduction

Physics deals with matter and energy and their interactions. Measurements are central to the growth of physics, and length (space), time, and mass are the three most important physical quantities, called the fundamental quantities. Most other physical quantities are generally expressed in terms of mass, length, and time. For example, speed is measured in miles per hour (or kilometers per hour) and involves a measurement of space (distance) and time.

Electricity, light, heat, mechanics (motion and inertia of things), gravitation, sound and its transmission, and quantum physics, which comprise the subjects of modern physics have been explored in several Indian traditions along with their applications.

Source Texts for Physics in India

There are many sources of knowledge of physics in ancient Indian texts and a wide range of topic they dealt with.

1. Vedas - They were the earliest texts that deal with the concepts of cosmology, creation of the universe and cosmic cycles. Sutra granthas specifically the Shulbasutras gave the fundamentals of mathematics and their application in geometry and architecture.
2. Upanishads - They explain interconnectedness of matter-energy, their relationship and unity, the chemical qualities such as solubility, viscosity etc. Physical
3. Darshanas - They put forth the earliest atomic theory, defined matter, their interactions and attributes. Vaiseshika darshana elaborates the atomic theory (Paramanu), classified reality into seven padarthas and explained their characteristics.
4. Puranas - A great deal of information on light, cosmology is specifically noted in Vishnu, Vayu and Matsya puranas.
5. Vaastu shastra, Shilpa shastra - They discuss the principles of structure, geometry, acoustics, and materials.
6. Siddhanta granthas - Surya siddhanta for example describes the planetary motion, eclipses, calculation of time (concept of cyclic time, yugas, kalpas) and trignometric functions.
7. Commentaries - Astronomical texts such as Aryabhata's Aryabhatiya gave the foundational concepts such as rotational motion of earth, celestial body calculations, correct order of planetary orbits and the infiniteness of the universe. Bhaskara II's Siddhanta Shiromani deals with advanced astronomical principles, mechanics and planetary equations. A commentary of Kamasutra by Visvakarma details design of machines.
8. Other works - Many texts were lost but we find their references in major texts such as Mahabhashya, Mahabharata, Puranas, Arthashastra and Samarangana Sutradhara.
   1. Samarangana Sutradhara - Yantras or contrivances useful in creating mechanical objects such as birds, fountains are described in this text. It also describes yantras used in war machines, water-lifting instruments for agricultural uses, and time devices such as water clocks for astronomical measurements.
   2. Yantrarnava - describes physical concepts such as generation of power/energy or motion through the continuous movement of lever/pulley.
   3. Natyashastra - describes various musical instruments and their acoustical characteristics
   4. Agasthya Samhita - describes electrical cells

Padarthas in Vaiseshika Darshana

In order to define and distinguish matter, Kanāda divides matter, or substance into padarthas or six categories (Vais. Sutr. 1.1.4)

1. Substance (dravya)
2. Quality (guna)
3. Action (karma)
4. Generality (sāmānya)
5. Individuality (viśesa)
6. Inherence (samavāya)

Matter of different materials have different attributes. For example, identical sizes of iron and cotton would have different weights. Apples can have differences in their colours and yet be called apples. It is the assembly of attributes that defines matter. Maharshi Kanada describes seventeen attributes, or gunas, of matter, and each of the bhutas, or elements, has special characteristics:

• रूपरसगन्धस्पर्शवती पृथिवी । वैशेषिक-२,१.१ । Prithvi (Earth) has the attributes of color, taste, touch and smell
• रूपरसस्पर्शवत्य आपो द्रवाः स्निग्धाः । वैशेषिक-२,१.२ । Ap (Water) has the attributes of color, taste, touch, fluidity and viscidity
• तेजो रूपस्पर्शवत् । वैशेषिक-२,१.३ । Tejas or Agni (Fire) has color and touch
• स्पर्शवान् वायुः । वैशेषिक-२,१.४ । Vayu (Air) has touch
• त आकाशे न विद्यन्ते । वैशेषिक-२,१.५ । Akasa (space or ether) has no attribute of touch

Air vs Space

In his attempt to clarify a difference between space and air, Kanāda used the attribute of touch, which is absent in space: “Air has the property of touch, while space does not have such a property.” While analyzing air, Kanāda concludes that "क्रियावत्त्वात् गुणवत्त्वाच्च । वैशेषिक-२,१.१२ । air is substance since it has action and attributes." Air is matter, but its non-perception in spite of being a substance is due to the non-existence of colour in it. With the non-perception of air, Kanāda defines reality beyond appearance. Not all that exists in the world is visible to human eyes. To support that air is matter, Kanāda argued that तृणे कर्म वायुसंयोगात् । वैशेषिक-५,१.१४ । breeze can move the blades of grass. Thus air, though invisible, can exert force and move things.

Dik (Space) and Kala (Time)

Vaisheshika principles approach fundamental scientific concepts in a characteristic manner. In these sutras we find the basic definitions of dravyas or categories of time and space.

तत्त्वम्भावेन । वैशेषिक-२,२.८ ।

Meaning: Time, like Existence, is One (unity), because, in spite of their multiplicity, the marks of Time, namely the cognition (example - "it is slow or late") are the same in all places and because there is no distinguishing mark like the Atman, which is Existence. Time which is said to be One, however, is manifold, hours, moments, days, days and nights, seasons and years. The reason for this is explained as due to the external condition or Upadhi - the indivisible time appears to be different according to the limit set by the movement of the Sun as well as the limit imposed by the effects of sun. The division of time as past, present and future as understood by the observer is said to be a consequence of the fact that time is a function of movement.

इत इदमिति यतस्तद्दिश्यं लिङ्गम् । वैशेषिक-२,२.१० ।

- That which gives rise to such (cognition and usage) as "This (is remote, etc) from this" is the mark of space.

Time, space, Atma and mind are the eternal or nitya dravyas and none of them are perceivable by any of the sense organs is a basic definition in Vaiseshika. Although, these four eternal entities can only be conceived by the mind, they are real existent dravyas or entities. Time, space and akasa are incapable of motion and it is only the earth, water, fire and air (the four dravyas) and mind which are capable of motion.

दिक्कालावाकाशं च क्रियावद्वैधर्म्यान्निष्क्रियाणि । वैशेषिक-५,२.२१ ।

Meaning: Space, time, Akasa and Atman (indicated by the word "Cha") are void of action because of their difference from that which possesses activity.

Space is identified through the fact that it can provide the context to describe objects as being separated spatially.

Universal Vedic Conceptions

Physical concepts in the Vedic texts show some universal features, such as

1. Visvajyoti or Cosmic Light as the principle of life, the essence of devatas and all manifestations
2. Rta or Natural Law as the transcendental and unitary principle of all motions (universal and individual)
3. Yajna as the connective dynamic principle and nucleus of all evolution
4. Ap (primaeval water) as the supra-sensible first cause.

These universal conceptions laid the foundations for newer formulations which are holistic in nature and structure.

Visvajyoti or Cosmic Light

A striking feature of the Rigvedic texts is the attempt to discover the essence or power that is behind all manifestations. In the Rigveda, the concept of the unmanifested is cosmic energy, and the manifested is cosmic light, which is referred to as Visvajyoti, a positive unitary principle, pure and sublime. One can conceive the cosmic light as the principle of life and longevity, and it is the ‘soul of all gods’ and the ‘womb’ of all created things. Sri Aurobindo explains the symbolism of Aditi as 'the boundless' or 'the unbounded'. According to the Rigveda, Aditi is the substratum (pure consciousness of infinite existence) of all that is here and beyond. Aditi is Light-Infinite, and the deities who are born of Aditi are manifestations of the Infinite Light. Mundaka Upanishad (2.20.10) refers to Brahman as the Self-Luminous Light.

Rta

Rta is the cosmic law of harmony. ‘Rta’ means ‘the course of things’, order or law, and the primal principle, which is non-temporal and cohesive. It is a natural law which even the Vedic deities have to follow; they are often described as the "guardians of rta" and "practicers of rta" in the Rigveda (1.23.5). The natural phenomena, such as the flow of rivers, change of seasons, and day and night, are stated to be in accordance with this natural law (Rig. Veda. 4.3.8-12; 5.80.1). Aditya, or Surya, is the all-pervading light extolled as the dweller in eternal law and, eventually, the eternal law itself (Rig Veda 4.40.5). The Rigvedic seers were convinced that nature is not as heterogeneous as it seems to us and that all types of natural motions are traceable to rta, which, according to them, is self-existent and ever extending. Symbolically, rta was also conceived by the Rigvedic seers as Varuna, who was supposed to have determined the laws of the physical universe. Rta helps Indra "light up and energize the whole world" and Ushas to "illumine the universe". As eternal order, it is transcendental, signifying uniformity of nature or an ordered course in a cosmic sense.

The Vedic seers had the instinctive conviction in the natural order. They conceived the external world as an ordered whole and that its dynamic or changing phenomena were regulated by rta. Vedas state that the emergence of ṛta is the initiation of the process of creation. In the context of physical sciences, it is not far-fetched to infer that Prakriti from the state of existence (first attribute) undergoes a change by way of rajas guna (second attribute), or motion. In modern scientific language this would mean that energy at rest changed to kinetic form and thus the Vedic term for modern kinetic energy is ṛta.

The term 'kinetic energy' does not carry the meanings as given in Vedic context. Hence ṛta does not merely mean motion but reveals that its motion is charged with the knowledge of accomplishing some purpose. Rta is all science, divine and is never wrong, rta is always right as Vedic language calls the divergence from rta as anṛta i.e., not ṛta. Rta through its constant motion lays down the pattern of the cosmic law which governs, controls and maintains all creation and the entire activity, actions and re-actions, related with the same. This cosmic law is called dharma by Veda. Dharma is neither any worship or a ritual; science is the knowledge of order and dharma is the order itself.

rtam ca satyam ca (Rig. Veda. 10.190.1)

Rta and satya were the successive manifestations of Prakriti after the commencement of the process of creation. While rta is the cosmic order, Satya, the Sanskrit term, is synonymous with 'Truth' in English, but in physics 'satya' denotes 'reality'. Verma mentions that in Yaskacharya's Nirukta, rta has been stated to denote electricity.

Yajna

Yajna is referred to as the navel of the universe (vishvanabhi) round which the latter turns, and as the unifying principle which expands and contracts in accordance with the happenings in the universe. For, the Rgvedic seers believed that yajna is the instrument for preserving the cycle of cosmic events in harmony. The act of yajna is for the protection of rta. It also has the connotation of dynamism too.

Ap (Water)

The famous Nasadiya Sukta in the tenth Mandala of the Rigveda, speaks of water as the supra-sensible First Cause or the primeval world-ground; and water is the first "element" to be conceived in this manner, without any mythological association. In the Brhadaranyaka Upanishad (5.5.1), it is stated: ‘In the beginning this world was just water.’

Panchamahabhutas

The Indian doctrine of five elements, or Panchamahabhutas, it must be emphasized, is a part of the philosophical ideas. In other words, it does not have an independent standing apart from its being an integrated component of the leading systems of Indian thought. It accounts for the apparently unordered, diverse world of matter and qualities. Also known as Pancabhutas (mahabhutani), the five elements are prthvi, ap, tejas, vayu, and akasa, which are loosely translated respectively as earth, water, fire, air and a non-material ubiquitous substance. Since they are interrelated, they have to be viewed in totality.

Geocentrism and Rotation of Earth

The Indian traditional astronomy is essentially geo-centric and geo-static inasmuch as the Earth is considered to be a stationary sphere at the centre of the solar system. The Sun, the Moon and the planets have a motion of their own from west to east while the asterisms or the stellar sphere is considered to have their motion from east to west, as a result of which the former are supposed to fall behind the latter. This geocentric and geo-stationary view was for the first time modified by Aryabhata I who, while maintaining the geo-centric idea, conceived of a direct rotation of the Earth about its axis, and even gave a precise rate of rotation stating that the Earth rotates through an angle of one second in one prana of time.

Light

The concept of light has been an important part of Indian shastras and is associated with various philosophical, spiritual, and scientific ideas. These include Jyotish (Vedic Astrology), Prakasha (Illumination), Jnana (Knowledge), Surya (Sun), and Tejas (Radiance). The symbol of light has been used in Indian texts to describe knowledge and spiritual practice and as a symbol of enlightenment, inner strength, transformation and energy. Jyotish itself means “light” or “illumination” and refers to the idea that the study of astrology sheds light on the mysteries of the universe and our place within it.

• Jyotish uses the positions of celestial bodies and other astronomical phenomena to understand and interpret human affairs and natural phenomena.
• Prakasha refers to the illuminating aspect of consciousness. Prakasha is the light that illuminates our thoughts, feelings, and experiences and allows us to know and understand the world around us.
• Jnana is often associated with the concept of light in Indian philosophy. Light illuminates and removes the darkness; similarly, jnana illuminates our minds and removes ignorance to reveal the truth of our nature and the nature of the universe.
• Surya is an important symbol of light and illumination in Hinduism. The sun is often associated with knowledge, enlightenment, and the power of consciousness to dispel darkness and ignorance. Rituals and practices are performed at sunrise and sunset, when the light of the sun is believed to be most potent.
• Tejas refers to radiance or brilliance. Tejas is associated with the concept of agni, or fire, and is considered to be a form of energy that fills the universe. It is often associated with the concept of tapas, or spiritual discipline, and is believed to be the source of inner strength, energy, and illumination.