THE SPEED OF LIGHT. When light travels through a vacuum, it shouldn't really be called light? It should be called Electomagnetic energy, or energy in state of limbo. When this comes in contact with matter it radiates both heat and light. Therefore without a medium, light cannot actually exist as light? Can someone please tell me if heat will travel at the speed of light when it radiates back into space. Also is heat a form of light (black light)? When you light a room with a light bulb, why doesn't all that energy eventually radiate as heat inside the room? When you turn a light off, all the light is gone, so does that mean when the light hits the surfaces of the room, does only a tiny tiny percentage of the light radiate inside as heat and the rest goes straight outside?