A brick could be used to stop a train. But I’ve got a better way to stop a speeding train. Stand firmly on the tracks, stare down the oncoming train, and boldly whisper, “Stop” as you hold out a stiff arm and just stand there. It might feel like you’re waiting your whole life for that train to stop, and quite possibly you will wait your whole life for that train to stop. But from that point your life expectancy has decreased to just a few seconds, so you won’t be waiting very long at all.