Destructive Interference: Cancelling Light

Where does the energy go?

This is an interferometer and it has two exit ports. Where’s the other exit for the light?

A Michelson interferometer (more properly a Twyman-Green) demonstrates the cancellation even more dramatically. As the path length difference is changed by 1/2 wavelength of light, the intensity of light on the screen goes from bright to dark to bright to dark again. That’s some real cancel culture.