[physics]
Radiant energy that exhibits both particle and wave phenomena. It can be characterized by wavelength or frequency. It ranges from gamma rays and X-rays, through ultraviolet, visible, and infrared light, and out to microwave and radio frequencies. The wave energy model is based on opposing, oscillating electric and magnetic waves that are at 90 degrees to each other and are orthogonal to the direction of propagation. At propagation, in a vacuum, energy waves move at 3 x 108 m/s, the speed of light. The wave energy model was defined by Scottish physicist James C. Maxwell in the nineteenth century. The particle-based model, introduced in the twentieth century by German-born theoretical physicist Albert Einstein, is used to describe how energy interacts with matter, where it is described by behavior of the discrete or quantum nature of the photon.