Commander Einstein, on the Galactic Explorer, sets off bright signal lights at the two ends of his spaceship so that they are flashing simultaneously by Corporal Maxwell, who is watching the ship go by$.$ Corporal Maxwell concludes that he was next to the midpoint of the ship at the instant when the lights flashed in his reference frame. This can only happen if Commander Einstein, at the center of the Galactic Explorer, a$.$ sees the lights flash simultaneously in his coordinate system