I know it comes from breaking the sound barrier, but why a boom instead of complete silence?
I have the understanding it creates a physical wave too.
Bonus questions: Does the pilot hear it?
Can the same thing be achieved underwater?
Related: I know the speed of sound is faster under water, does any reaction happen theoretically at the air speed of sound underwater?
In: 310
For every inch a jet (or anything really) moves forward, it pushes the air in front of it forward in the form of a small wave of higher pressure air. Similar to shaking a slinky, that wave travels forward in front of the jet at the speed of sound, since that small wave of pressure is *the sound of the jet itself*.
What happens then when a jet travels faster than the speed of sound? The wave in front of it can’t move faster than the jet, so instead of a sound wave which is comprised of a bunch of “ripples,” all the ripples bunch up on top of each other and we get one massive “shock wave,” which is essentially one really big and loud wave of pressure. It’s basically the same thing that happens when an explosion goes off. You can visualize this yourself in a swimming pool: Place your arm vertically through the surface of the water, and then move your arm very slowly and you’ll see ripples moving in front of your arm, however if you move your arm very quickly, the ripples instead bunch up and form a big wave form a big wave.
Since the jet keeps moving, it keeps pushing air out of the way and therefore continues to make a shock wave as it travels through the air. The “boom,” you hear is simply the sound from the jet passing in front of you at that moment (or in reality a few moments ago) and the people further along the jet’s path will hear the shock wave later, since the jet is constantly making the noise.
As for underwater, it would technically be possible and the exact speeds would be dictated by the speed of sound in water, though actually getting something to those speeds would be difficult without the object destroying itself.
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