25.1 Principle of Relativity Michelson Interferometer Explanation: The video simulates the Michelson Interferometer as discussed in Section 25.1. Referring to the diagram in Figure 25.2, the fixed mirror is on the left; the adjustable mirror is at the bottom next to the spinning wheel; the half-silvered mirror and the path-length compensator are in the middle; the light source is on the right; and the resulting interference pattern is shown at top right. The changes in pattern are due to the motion of the adjustable mirror.    Source: Samantha Shoemake and John T. Foley The Optics Project (TOP) Department of Physics and Astronomy Mississippi State University, Mississippi State, Mississippi 39762.