Final answer:
The physics concept in question is related to the measurement of time intervals between light flashes as observed from different frames of reference, illustrating the principle that the speed of light is constant for all observers according to the special theory of relativity.
Step-by-step explanation:
The question asks about the measurement of time intervals between two light flashes in a scenario involving two observers and relative motion, which is a concept explored in the field of Physics, specifically related to the special theory of relativity. In the given scenario, Observer A is on a moving rail car, and Observer B is on a platform. Both observers are measuring the elapsed time between two light flashes emitted from lamps on the rail car. According to the second postulate of the theory of relativity, the speed of light is constant for all observers, regardless of their relative motion. Consequently, Observer B sees the light flashes as simultaneous because the light travels equal distances at equal speeds to him.
In another context, the first paragraph refers to a moral dilemma dealing with traffic laws, but this is not relevant to the physics concept being discussed.