Definition that contains city of light
- refractive index the ratio of the velocity of light in a vacuum to that in a medium
- index of refraction the ratio of the velocity of light in a vacuum to that in a medium
- michelson-morley experiment a celebrated experiment conducted by Albert Michelson and Edward Morley; their failure to detect any influence of the earth's motion on the velocity of light was the starting point for Einstein's theory of relativity