For some reason I am fascinated by opposites. When true opposites are combined, they equal nothing. Examples can be seen in the mathematical world, where -5 and 5 are true opposites. In the physical world, particles and their anti-particles are true opposites, since when they collide they annihilate.

Opposites are usually thought of as pairs, but this is not always the case. An example of three-way opposites can be seen in color addition.