Solid obstacles act as anti-openings, diffracting waves around themselves the same way openings do.

Evidence

As well as occurring through openings, diffraction also happens around solid objects; one could consider them to be anti-openings, as shown in Figures 1.45 and 1.46. Here the wave diffracts around the object and meets behind it. The effect is also a function of the size of the object with respect to the wavelength. When the size of the wavelength is large relative to the object then the wave is diffracted strongly around it and the object has little Figure 1. — David Howard, Jamie Angus, coustics and Psychoacoustics, 422

Categorization

• DEFINE: Introduces the elegant inversion that solid objects can be modeled as anti-openings for diffraction purposes.