An electric field itself does not move or propagate through space. Instead, changes in the electric field propagate as electromagnetic waves, which do travel at the speed of light. This distinction is important to understand.
When there is a change in the electric field, it generates electromagnetic waves that propagate outward at the speed of light. These waves consist of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation. Electromagnetic waves carry energy and information through space.
The speed at which electromagnetic waves propagate in a vacuum, such as in outer space, is precisely the speed of light, which is approximately 299,792 kilometers per second (186,282 miles per second). This speed is a fundamental constant of nature.
It's worth noting that the speed of light in a medium, such as air, water, or glass, is slightly slower than its speed in a vacuum. This is due to the interaction of light with atoms and molecules in the material, which affects its speed. However, the speed of light in a vacuum is considered the maximum speed at which any information or signal can travel through space.
So, while an electric field itself does not move with a finite speed, the changes in the electric field propagate as electromagnetic waves at the speed of light.