The smallest possible wavelength in the electromagnetic spectrum is the Planck length, which is approximately 1.616 × 10^(-35) meters. It is derived from the Planck constant (h) and the speed of light in a vacuum (c) using fundamental physical constants. The Planck length is associated with the scale at which the effects of quantum gravity become significant. Below this scale, our current understanding of physics breaks down, and it is believed that a theory of quantum gravity is needed to describe the behavior of spacetime.