Light, and all electromagnetic waves in general, does not necessary follow a straight path; electromagnetic waves can bend around objects. This property is common to all waves, not just electromagnetic waves. For example, consider the propagation of water waves in Figure 14.1.
Figure 14.1 Water waves incident upon a wall with an aperture (opening).
The waves are traveling from left to right through open water. Upon encountering a wall with a small opening, the waves diffract. That is, on the right side of the wall, the waves propagate from the aperture in a circular manner. This behavior is in direct contrast to how particles ...