0 Our intuition is that if we combine two beams of light into a single beam, traveling in the same direction, the intensities should add. But it is not so obvious how this can be, since the fields should add linearly, and the Poynting vector is proportional to the square of the fields. Suppose we superimpose two plane waves that are traveling in the same direction, but with random polarizations. Show that, on the average, the intensities do add