The Nature of Light
Geometric Optics is consistent with Newton’s theory that light consists of “corpuscles.”
Ray optics implies that a barrier should cast sharp shadows.
Sound exhibits diffraction. For example, a sound source can be heard in spite of a barrier between source and receiver.
Notes:
At first glance it appears that objects cast very sharp shadows when illuminated by a point source of light, as illustrated at lower left. On the other hand sound bends around barriers, so that it’s easy to hear a point source of sound even though the sound has to bend around a barrier. It’s no wonder that even brilliant scientists like Isaac Newton didn’t realize that light, too, is diffracted at a barrier.