# How does an electromagnetic field oscillate if time does not pass for the speed of light?

As far as I'm aware, traveling at $c$ will prevent time passing due to time dilation. Electromagnetic waves rely upon oscillations to propagate. Since oscillations rely upon the passing of time, how does an electromagnetic wave oscillate if time does not pass?

But the electromagnetic field itself does not 'travel' at $c$ so your reasoning isn't clear to me.