Scientists say that you can break the sound barrier with just your hand, a marble and a bowl of water.

Researchers made the discovery when they were investigating in detail what happens when an object is dropped into water.

If you drop a marble into a bowl of water, it makes a temporary cavity in the liquid. As this cavity gets deeper, the walls start to move closer together because of the pressure of the water.
The air trapped inside the cavity then has to escape somewhere. Since the pressure is much greater there than above the water, it forces the air upwards.

Recent experiments surprised scientists by showing that the jet of air can move faster than the speed of sound (340m/s or 1,224km/h).