Does radiation need a phase of matter to travel with?

Radiation has become a frightening word, but there's not necessarily anything dangerous about it. Visible light is radiation. Heat is radiation. Many news channels say that explosions or meltdowns 'leak' radiation into the atmosphere, but few say what exactly this 'radiation' is.

1) when you rub your hands together quickly, the kinetic energy is converted to mechanical energy.2) thermal energy from the sun travels to earth as infrared waves.3) energy is transferred through the matter of space by electromagnetic waves. 4) when a match is burned, chemical potential energy is converted to thermal and radiant energy. 5) seismicwaves are caused by back and forth movement , or vibration, of an object. 6) mechanicalenergy in an engine changes thermal energy into kinetic energy to make a car move.