Assuming for now a simple photon particle model for light, where you have a stream of photons traveling with a certain frequency. Picturing this in my head on a number line, with just 3 photons at a time, and lets just say the wavelength is 1 and speed is 1, and at time t=0 we have a photon at x=0, x=1, x=2, then at time t=1 we have a photon at x=1, x=2, x=3, etc So let's say I shine a flashlight with the above setup on a spot. Then I shine another flashlight, which has the same wavelength and speed (and thus the same color), on the same spot. However this 2nd flash light is slightly out of phase from the first one. For this second flash light, at time t=0 the 3 photons are at x=0.5, x=1.5, x=2.5, and at t=1 they are at x=1.5, x=2.5, x=3.5 If I shine both these flash lights at the same spot, and the light reflects back to my eye, both streams of photons overlap, and when they combine there are now more photons per unit of length, so the wavelength has changed, so I would assume that I should see a different color. However, both flashlights I shined on the spot have the same color, so it seems odd. Hopefully I am misunderstanding something here that someone can clarify for me, thanks!