When light is reflected, how can the photons change the direction of travel instantly with no acceleration time?
Answer A: Photons don’t really change direction instantly. Photons themselves do not accelerate (they have no mass, and always travel at the speed of light). Electrons inside the reflecting material are accelerating as a result of the incident photons. The acceleration rate of the electrons will be a characteristic of the particular material, and will result in a slight time delay for the reflected photon.
