Light, or Visible Light, commonly refers to electromagnetic radiation that can be detected by the human eye. Light can also be described in terms of a stream of photons, massless packets of energy, each travelling with wavelike properties at the speed of light. Light consists of photons, which are produced when an object's atoms heat up. The wave nature of light was first illustrated through experiments on diffraction and interference. Like all electromagnetic waves, light can travel through a vacuum. In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The absorbed energy of the EM waves is called a photon and represents the quanta of light. Light of nature (uncountable) (archaic) innate wisdom or knowledge.