Figure 5. In nature, a free medium (one that is free of obstructions) never has a wave in it that is any simpler than a single pulse. A pulse is a wave that is one-directional and one-dimensional with a ½ wavelength. Also, a pulse always has a crest or trough straddled by two locations with zero amplitudes. In image A, my assistant whips the end of the rope and creates a pulse moving down this rope. She could not create a wave that is any simpler. Image B is not a pulse, even though it has a ½ wavelength, because it does not have a crest or trough straddled by end points with zero amplitudes. Image C represents two pulses. It is my hypothesis that all waves in a free medium can be constructed by pulses within that medium.