The form radiation refer both to the transmission of energy in the form of wave, and to the transmission of streams of atomic particles through space. Any energy that transmitted in the form of waves is some kind of electromagnetic radiation. Each kind is distinguished by its wavelength, or frequency. All kind of electromagnetic radiation obey the same physical laws, they all travel at the speed of light, and when they fall on a surface they exert a pressure proportional to the net flux of energy divided by the speed of light. Roughly in the order of decreasing are radio waves, radiant heat energy and microwaves, infrared radiation, light, ultraviolet radiation, X ray, and games rays. Many form of particulate radiation are possible, in the phenomenon of radioactivity, alpha radiation (helium nuclei) and beta radiation (electrons) are observed, along with gamma rays. Very energetic particles from outer space are called cosmic rays. Any particulate or electromagnetic radiation that ca