If there is no obstruction, light NEVER stops. Photons keep traveling until they are absorbed. Photons can’t accelerate or decelerate. This is paramount in Einsteins theory of special relativity. But why? Why MUST massless particles travel at the speed of light in a vacuum when they don’t accelerate or decelerate? They have energy but no mass. They have energy programmed within them, a massless program and they can travel infinitely without obstruction.

There is so much to the universe that we take as fact that we actually have no idea what it is, we can only observe what it does.

Don’t confuse observing for knowing. We are great observers, not so sure where we fall on the scale of actual knowledge. Beyond the observation.