It is widely a preconceived notion in the world that the concept of measuring the speed of light was first explained by Danish astronomer Ole Roemer (1644–1710). He is believed to be the first person to measure the speed of light in 1676.
Contrary to the shared beliefs the Rig Veda contains the accurate speed of light in one of its shlokas mentioning the sunlight.
Yojananam Sahastra Dwe Dwe Shate Dwe Cha Yojane Aken Nimishardhena Krammana Namostute.
In this hymn, the author ( Sri Sayancharya) pays respect to the one who moves 2202 yojanas in half a nimish.
Sri Sayanacharya was born to Māyaṇācārya and Śrīmatīdevī in Pampakṣetra (modern-day Hampi) in a Brahmin family around 1270CE. He was one of the chief commentators on the Vedas during his time.
Thus it is remembered: [O Sun] you who traverse 2,202 yojanas in half a nimesa.
Here yojana is about 9 miles as in the Arthasaastra (and Mahabharat Adiparva). The measures of time are thus defined in the Puranas:
1 Day-Night = 30 Muhurta = 24 Hours
1 Muhurta = 30 Kala = 24/30 Hours
1 Kala = 30 Kastha = 24/900 hours = 1.6 minute
1 Kastha = 15 Nimesha = (1.6/15) min = 3.2 seconds
1 Nimesh = 3.2/15 = 0.21333… second
A Nimesh is, therefore, equal to 16/75 seconds. (0.21333)
If you calculate the value is,
(2202*9 miles)/((16/75)/2 sec) = 185793.75 miles/sec
The currently agreed value of the speed of light is 186282.397 miles per second, which is an approximation!
We must take note of the fact that acharya Sayana utilizes the term “remembered” in this sentence. This demonstrates unequivocally that Sayanacharya has not “found” the value mentioned above but is recalling a statement that must have been made considerably earlier than his time. This demonstrates unequivocally that Indian sages were conversant in such disciplines thousands of years before Sayanacharya’s commentary.
Even more intriguing is the fact that there was no advanced technology available and sunlight was the only significant light source at the time (due to which the value has been attributed to the sun itself). But even so, our predecessors gave us such a precise value. Even with highly advanced equipment costing millions, scientists can only provide an approximation today.
Sayanacharya was the purvashrama brother of Jagadguru Vidyaranya Mahaswami, the patron saint of the Vijayanagara kingdom and the 12th Jagadguru and Shankaracharya of Sringeri Sharada peetham, with whom most of his writings were produced.