Two blinking warning lights are $3000 \mathrm{~m}$ apart along a railroad track. Suppose that in the ground frame the west light blinks (event $W$ ) $5 \mu$ s before the east light blinks (event $E$ ). Now imagine that both lights are observed by a passenger on the train who passes the west light just as it blinks. It is possible for the train to be moving fast enough that the two blinks are observed (not necessarily seen) by the passenger to be simultaneous.

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Quizplus · Accepted Answer

According to the theory of relativity, the simultaneity of events is relative to the observer's frame of reference. If the train is moving fast enough towards the east light, the time it takes for the light from the east blink to reach the observer can be reduced, making it possible for the observer on the train to perceive both blinks as simultaneous. This is due to the relativistic effects of time dilation and length contraction.

Two Blinking Warning Lights Are 3000 m3000 \mathrm{~m}3000 m Apart Along a Railroad Track

Two Blinking Warning Lights Are $3000 \mathrm{~m}$ Apart Along a Railroad Track