there's nothing particularly spooky about the travelling at speeds above the sound barrier... except of course that you can't hear anything from behind you that isn't moving with you (but travelling at the speed of sound requires enough power that the engine would probably drown out most of that sound anyway). In fact, if you were sitting in a jet moving at a constant speed faster than the speed of sound, but had the windows closed, you wouldn't even no you were moving. the effect on the ground is a little different. The passing jet is emitting a lot of sound in the direction it is moving, but since the jet moves faster than the sound waves, the sound doesn't reach you until it passes you. The sound waves finally reaching you,compressed together through the doppler effect, is what you here as a sonic boom when a plane passes. It mostly seems eary because the plane seems silent until it passes you, at which point there is a loud boom.
methos5000: I think you said the following. Sound has a speed. We can go beyond it by moving at a speed faster than the speed of sound, or we can observe others moving faster than the speed of sound. We hear a sound of an object moving beyond the sound barrier later than the sound is made and later than we observe the object. So it is all an explicable phenomenon, nothing spooky. You may correct me if I am wrong.
Pretty much, yes. I did leave out one point though. the speed of sound is the speed at which vibrations can normally be transmitted through the air(or whatever medium you are in). moving through air obviously means that you have to push the air out of the way... but air doesn't want to move out of the way faster than the speed of sound. Don't get me wrong, it will move, otherwise we wouldn't be able to go faster than sound, but it does take some engineering skill to design a plane strong enough. This is why you can't just strap a really powerful engine onto any plane to make it supersonic. it is also why, at one point, people thought it might not be possible to travel faster than sound.
but anyway, the direct answer to your question is that there's nothing really spooky about travelling faster than the speed of sound except that you won't hear anythign behind you (unless it's moving with you) and you will pass a point before any of your sound can be heard at that point (at which time anyone at that point will hear a sonic boom).
