Relationship between shining diamonds and cables under the sea !!
At first instance the title would seem to be crazy and lame, but actually the physics involved in both are largely the same. The high speed internet and shine of diamonds both are due to TIR(Total Internal Reflection). This phenomenon is one of the most versatile phenomenon exploited by humans to develop high speed communication devices. The discovery of TIR is kinda controversial but largely attributed to Johannes Kepler(1611). Let me try to explain TIR in most simple and objective manner: Consider a light ray propagating in medium having refractive index n1 and entering a phase having refractive index n2 . As we know when n2>n1 , the light is entering in a denser medium from a rarer, so by Huygens wavefront theory or snells law we can predict it would bend slightly towards normal. But when the light is in n2 and going to n1 it would bend away from normal. Now when we carefully analyze this situation we conclude that at some point of incidence the light ray would bend so much m