New Wave

If you don’t happen to like math, don’t panic. Just visualize stone-generated waves rippling across a pond, and you’ll understand the basic concept of waves. But wait a minute. There is something wrong with our ripples in a pond as a model of electromagnetic radiation.
Water is a medium, a substance, something through which waves are transmitted. Space, we have said, is very nearly a vacuum, nothing. How, then, do waves move through it?
This is a question that vexed physicists for centuries. They understood the concept of waves. But they also understood that sound, a wave, could not travel through a vacuum, whereas light, also a wave, could.
Why?
At first, most scientists believed that the very fact that light is transmitted through space means that space must not be empty. They knew it didn’t have air, as on Earth, but they suggested it was filled with another substance, which they called the ether. But this fictitious substance did not long vex physicists. A series of experiments in the late nineteenth century made it clear that ether didn’t exist and that although light could be studied as a wave, it was a different kind of wave than, say, sound.