How could scientists in the UK hear an underwater explosion 19,000 kilometers away in Australia? It's not an experiment you could reproduce in a pool, even a very large one, because the speed of sound is more variable than you may think, and so are the conditions in different parts of the ocean. MinuteEarth explains. I won't guarantee you'll understand it all, but it does remind us that the world is a very weird place, and there's always more to learn about it. -via Digg