Final answer:
The perception of simultaneity for light flashes observed by observers on a moving rail car differs due to the constant speed of light and relative motion.
Step-by-step explanation:
The question revolves around the observation of light flashes from two flash lamps on a moving rail car in relation to special relativity and the invariance of the speed of light. Observer A is moving with the rail car, while Observer B is stationary relative to the rail car. When the light flashes are emitted as Observer A passes Observer B, both are equally distant from the lamps. Observer B measures the time intervals of the light flashes and, based on the principle that the speed of light is constant and does not depend on the motion of the source, deduces that the flashes arrive simultaneously.
However, due to relative motion, Observer A perceives the light flash from the right lamp before the left lamp since they've moved closer to the right lamp, shortening the light's travel distance. This is a demonstration of how the constancy of the speed of light, as stated in Einstein's theory of relativity, affects the perception of simultaneous events in different frames of reference. Observer B concludes that the simultaneity of events is relative and depends on the observer's frame of reference.