imagine the loudest sound you have heard. And then amplify it. That is exactly what physicists in Virginia, usa , have done. They have bottled up sound waves crammed with 1,600 times more energy than before. This achievement, they claim, will lead to powerful machinery driven by sound in time.

Sound waves are, in many ways, similar to waves on the beach. When a wave contains too much energy it becomes too high and breaks. A shock wave is the equivalent phenomenon with sound. In a shock wave, the energy spreads over a wide band of frequencies and is subsequently lost as heat. Often, some energy from a sound wave leaks into waves of higher frequencies, called overtones. A shock wave is formed when these waves pile up at the same place, causing a sudden