Last night my daughter asked me to explain to her in simple words “why the light changes direction when entering the water”, without complicating the explanation with index here and index there…I said think of the photons or elements of light as balls. At the moment a ball enters the water part of it is inside the water and part of it outside the water. The part that is inside the water experiences different forces than the part outside the water. This is the reason why it changes its direction. It is like when you brake in a car. If the car brakes only work, let say, on the left wheels it changes the direction of the car. She was convinced. Then it was discussion why sometimes teachers have difficulties explaining some problems in physics.
Keywords: Confined Quantum Field Theory, Relativity, Squeeze of photon, Super fluidity, Superconductivity
