Every sound you hear travelled through the air in a wave before entering your ear. And every time you turn on a lamp, you send light waves shooting off. All waves move energy, in fact, a wave is the movement of energy. Some waves can only travel through matter. For example, sound waves need matter in order to travel. They can travel through solid, liquid or gas. Other waves, like light waves, don't need matter to travel. They can journey through empty space. That's how light from the sun reaches us. It travels through empty space.