Well. If the light is traveling at a certain speed, let’s say the speed of light. And then enters water, it slows down which is what they say refraction is. And then when it comes out it again travels at the speed of light. How? And I may not have the laws right but whatever one says that the transfer of heat is irreversible but clearly the speed is reversible. How did it gain speed from nothing. How can it go faster without anything to cause it? But I don’t believe light travels anyway. Go turn on the bedroom light. The light is traveling? At the speed of light? Nonsense.