SPEED OF LIGHT IN THE VEDIC LITERATURE

Abstract

Speed of light is a universal constant. In the western world, its value was first determined by Roemer in 1676. Prior to that, it was believed that light travels with infinite speed. However, its value was known to Indians since Vedic period ( c. 1500 and 1200 BC). Sayana a Vedic scholar (c. 1315–1387) and a minister in the court of King Bukka I of the Vijayanagar Empire in South India, wrote commentaries on Rigveda. In a hymn addressed to the Sun, he says that “it is remembered that the Sun traverses 2,202 Yojan in half a Nimesh". This value is quite close to the presently measured value of the speed of light in vacuum, i.e., 300 million metre per second or 186,000 mile per second (Vartak, 1995; Kak, 2000). The paper examines Sayana’s shloka that he has decoded from Rigveda hymn 1.50.4 to reveal how speed of light was calculated using unit of time as Nimesh and unit of distance as Yojana. It is argued that the value of speed of light mentioned in Sayana’s shloka was not just a coincidence, it is calculated based on some rational approach.