How do electromagnetic waves travel with no medium?
A wave generally needs a medium in which to travel, i.e., it is a travelling vibration of the medium. However, an electromagnetic wave (such as light or radio) can travel in a vacuum, i.e., no medium. This is because an electromagnetic wave is composed of interacting oscillating electric and magnetic fields that can also exist in a vacuum. The changing electric field creates (or induces) a changing magnetic field, that in turn creates a changing electric field, and so on. Before 1900, scientists believed that the medium of the electromagnetic wave did exists called ether, a virtual material.
