Take the traincar thought experiment with light emitted towards front and back of the train. Assume that the train is rigged with mirrors at the wall that will direct the light around the edges of the train wall, ceiling, and then back to the center of the train at the rooftop, where a sensor is located. The sensor is rigged to blow up the train if it receives light from both sides within some small fraction of time. To an observer from the perspective within the train, the light hits both sides of the sensor simultaneously and the train blows up (killing the observer). To an observer outside of the train, the light hits one sensor long before the other, so the train does not blow up, and the person inside the train survives. Is this right?