What happens when you travel faster than sound?
Sound waves are like ripples in a pond that radiate around the object. An airplane traveling at subsonic speed will travel behind the sound it has made. When the plane reaches the exact speed of sound, the sound it produces will accompany you on your journey. This can be very dangerous. Why? Because while traveling at the speed of sound, there will be a continuous buildup of sound around the aircraft. As new sounds are produced, the aircraft will fly along with those new sounds, and so on. Eventually the racket will break the plane!
Because of this, airplanes discovery the sound barrier. They will travel at subsonic speed for a time and then accelerate rapidly until they have passed and left the buildup of sound behind them. Meanwhile, anyone downstairs will hear the sonic boom as the sound waves radiate to the ground.
Light travels much faster than sound, and a machine has never been built that approaches the speed of light. It is theoretically impossible to reach this speed as it would require infinite energy (or limited energy for an infinite period of time). If the laws of physics could be broken and the speed of light reached or exceeded, the forward momentum would become perpetual.
The difference in the speed of light and sound waves can be demonstrated by observing the firing of a large cannon. If you were to use a powerful telescope to observe the cannon shot from half a mile away (for example), you would actually hear the explosion within a fraction of a second after seeing how it is fired. A more common example is the gap between lightning and thunder. We all know that the time difference between the two represents the distance between the storm and the observer.
A final example is one of our fly killing machines. If you could film an unfortunate fly being attacked by the IND41 Bug with the movie camera and microphone at one end of a large room, slow motion playback would show a distinctive gap between the flash, as the bug is electrocuted and the sound. bubbly it does.
Of course, no one can hear an approaching plane traveling faster than sound. Only after it has passed will you hear anything. Fortunately for us, wasps and flies are not that fast!
