A woman seated at the center of a moving rail car sees two flash-lamp pulses from opposite ends arrive at different times, while a man standing on the platform sees them arrive together. What physical idea does this illustrate?

1. The man on the platform receives both flashes at the same time, since he is equidistant and at rest relative to the source points. 2. The woman on the moving rail car meets one pulse before the other because she moves toward one lamp and away from the other during the pulses' travel. 3. This difference shows that simultaneity, whether two events happen at the same instant, depends on the observer's frame of reference. 4. Light does not travel faster inside a moving vehicle, and no broken clock is involved. 5. So simultaneity depending on the frame of reference is correct. _Source: OpenStax Physics (CC BY 4.0), Ch 10 "Special Relativity", section 10.1 Postulates of Special Relativity_