わかりました、ありがとう。光の速度で移動できるロケットシップを構築できると仮定しましょう。ヘッドライトの光は、2倍の光の速度で移動しますか？
Ok, thank you. Let's assume we could build a rocketship that could travel at the speed of light and it had headlights that we could turn on. Would the light of the headlights travel at double the speed of light?