In Lothal (c. 2400 BC), the ancient port city of the Harappan civilization, shell objects served as compasses to measure the angles of the 8–12 fold divisions of the horizon and sky in multiples of 40–360 degrees, and the positions of stars. In the late Vedic era (c. 9th–6th century BC), the astronomer Yajnavalkya, in his Shatapatha Brahmana, referred to an early concept of heliocentrism with the Earth being round and the Sun being the "centre of spheres". He measured the distances of the Moon and the Sun from the Earth as 108 times the diameters of these heavenly bodies, which were close to the modern values of 110.6 for the Moon and 107.6 for the Sun.

Indians in the Vedic era classified the material world into five basic elements: earth, fire, air, water and ether/space. From the 6th century BC, they formulated systemetic atomic theories, beginning with Kanada and Pakudha Katyayana. Indian atomists believed that an atom could be one of up to 9 elements, with each element having up to 24 properties. They developed detailed theories of how atoms could combine, react, vibrate, move and perform other actions, as well as elaborate theories of how atoms can form binary molecules that combine further to form larger molecules, and how particles first combine in pairs, and then group into trios of pairs, which are the smallest visible units of matter. This parallels with the structure of modern atomic theory, in which pairs or triplets of supposedly fundamental quarks combine to create most typical forms of matter. They had also suggested the possibility of splitting an atom, which as we know today, is the source of atomic energy.

The principle of relativity (not to be confused with Einstein's theory of relativity) was available in an embryonic form since the 6th century BC in the ancient Indian philosophical concept of "sapekshavad", literally "theory of relativity" in Sanskrit.

The Samkhya and Vaisheshika schools developed theories on light from the 6th–5th century BC. According to the Samkhya school, light is one of the five fundamental "subtle" elements out of which emerge the gross elements, which were taken to be continuous. The Vaisheshika school defined motion in terms of the non-instantaneous movement of the physical atoms. Light rays were taken to be a stream of high velocity fire atoms, which can exhibit different characteristics depending on the speed and the arrangements of these particles. The Buddhists Dignāga (5th century) and Dharmakirti (7th century) developed a theory of light being composed of energy particles, similar to the modern concept of photons.