In the 20th century, the concept of duality played a significant role in various fields of study, including physics, philosophy, and psychology. Physicists found that particles can be understood as either particles or waves, depending on how they are observed.

This wave-particle duality was a cornerstone of quantum mechanics, and it upended traditional physics. This spawned other concepts of two-ness, including complementarity and entanglement. The implications of these two-based discoveries rippled into many other areas, including psychology, philosophy, and literature.

In this course we will look at the power of two in the twentieth century: First through the lens of physics, and then in the way that the physics of two influenced everything else.