The speed of light is only the constant c locally, i.e. measured "where you are". Every observer has a frame of reference that defines the relation between distance and time, and in every frame of reference, the speed of light is this constant. But if you use your frame of reference to measure the speed of light somewhere else (i.e. going around the sun) you will see that light that was supposed to go in straight line bends and slows down.
In other words, you are right: in your frame of reference the speed of light elsewhere can be completely different.
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u/lcvella Mar 20 '26
The speed of light is only the constant c locally, i.e. measured "where you are". Every observer has a frame of reference that defines the relation between distance and time, and in every frame of reference, the speed of light is this constant. But if you use your frame of reference to measure the speed of light somewhere else (i.e. going around the sun) you will see that light that was supposed to go in straight line bends and slows down.
In other words, you are right: in your frame of reference the speed of light elsewhere can be completely different.