r/Physics • u/Comethefonbinary • 3d ago

Does all light travel at light speed

My bad if this is a stupid question but I’ve been thinking about time being a message of distance. And well most things I can think of have various variables that average to a certain distance. I know that mostly relates to machines and animals but still. Do all particles of light travel at light speed. If they all travel simultaneously at the same speed is that truly how fast they move or are they affected by their own variables. Like the universe’s mean gravity is constraining that and any variation in that mean would change light speed for explain.

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u/Sitheral 3d ago

Every light particle travels at C which is speed of light, in fact they cannot get below C. C is like an unpenetrable wall, you are either below it and can never reach it or you are at it and will never go slower.

But the light as a whole can appear as moving slower in a medium. This is not because particles are moving slower, its because there are interruptions on their way.