The Contribution of India to Science and Technology

I remember reading somewhere that even the speed of light was calculated to a reasonably good degree of accuracy in ancient India. Is there any truth to that? Srivash Kark has done some work on that. He, perhaps he can explain it. Now, why do you think India's contribution to science is not recognized? Was there a certain decision that was made in Europe about 500, 600 years ago that we're going to expunge all references to India in our history texts?"