Figure 6. In image A, a rope is tied between two poles. My assistant oscillates the rope at the center, creating a wave source. Notice that in image A the wave source is not a point-wave source. I drew it with a minimum diameter of ½ a wavelength because a rope tied between two poles in nature could not propagate a wave with any smaller width. This wave source in the middle is emitting pulses in both directions in a one-dimensional medium.

Images B through E represent various stages of waves emerging from the central wave source in image A. Notice that in image B there are two pulses coinciding and moving in opposite directions. In image C, these pulses are now partially coinciding. Finally, in D, they are totally separated. At a later stage, in E, the two outer pulses are separated by ½ a wavelength. And the central wave source is made up of two pulses emerging in opposite directions. This new wave at the center has an upside-down amplitude. It is my contention that all waves in a medium are constructed of pulses, but pulses are one-directional and one-dimensional wave sources.

The wave source in the center of image E is different from this image’s outer wave sources. The center wave source is emitting pulses in all directions in a one-dimensional medium. The outer wave sources are emitting pulses in one direction in this same medium. Hence, they have different constructs. Nonetheless, both are constructed out of pulses.