Why does light travel as a wave through a complete vacuum? What is the force behind this? Michio Kaku said in his book Hyperspace this ... In my studies, I learned that one of the great debates of the nineteenth century had been about how light travels through a vacuum. (Light frow the stars, in fact, can effortlessly can travel trillions upon trillions of miles through the vacuum of out space.) Experiments also showed beyond question that light is a wave. But if light were a wave, then it would require something to be "waving." Sound waves require air, water waves require water, but since there is nothing to wave in a vacuum, we have a paradox. How can light be a wave if there is nothing to wave? So physicists conjurned up a substance called the aether, which filled the vacuum and acted as the medium for light. However, experiments conclusively showed that the "aether" does not exist.* *Surprisingly, even today physicists still do not have a real answer to this puzzle, but over the decades we have simply gotten used to the idea that light can travel through a vacuum even if there is nothing to wave.