I.e., sine and cosine inherently have different initial phases. For infinitely long sinusoids, a change in is the same as a shift in time, such as a time-delay. But what about light in QM then? Q. Notice that the two waves illustrated differ in phase … If the waves are completely in phase they will combine to make a new waveform with the same frequency but double the amplitude. In physics, the term phase has two distinct meanings. Keeping the idea that waves must travel in mind, here's what happens whenever you figure out a way to build a region in which the energy of such a moving wave cancels out fully: If you look closely, you will find that you have created a mirror, and that the missing … Setup and definitions: Out of phase waves f= 3;H* Frequency *L phase= 0; Plot@Sin@ 2p f t+ phaseD,8t,0,1