In classical electromagnetic theory, electromagnetic waves propagate through space at the speed of light and do not naturally come to a complete stop. According to Maxwell's equations, electromagnetic waves travel at a constant velocity in a vacuum, and they continue to propagate until they encounter an object or interact with a medium.
While it is not possible to completely halt or "stop" an electromagnetic wave in its tracks and then release it to continue from where it stopped, certain materials and structures can affect the propagation of electromagnetic waves. For example, materials with high refractive indices, such as certain types of metamaterials, can slow down the speed of light as it passes through them. This phenomenon is known as slow light or electromagnetically induced transparency.
In these cases, the electromagnetic wave's propagation is temporarily delayed as it interacts with the material, but it does not come to a complete stop. Once the interaction is over, the wave continues its propagation, typically with a delay due to the slower speed in the material.
It's important to note that these effects occur within specific experimental setups and are subject to limitations and constraints. The overall behavior of electromagnetic waves is governed by the fundamental principles of electromagnetism, which dictate that they travel at the speed of light in a vacuum and cannot be completely stopped and then restarted at will.