The fact that an extremely strong frequency of sound can crack, and even shatter glass isn’t a scientific revelation, but newly resurfaced video of Brazilian Air Force planes destroying windows at the country’s supreme court building gives gritty weight to the idea.
Watch as the windows fracture and break at the Praça dos Três Poderes, as if throttled by an atomic explosion. As you’d expect with a video of capturing massive glass windows breaking, it’s loud:
The video is originally from 2012, and is enjoying renewed-life on a Reddit thread that’s earned 1363 comments and over 5,000 upvotes. It shows the rapid flight of two Mirage 2000s — formerly the chief aircraft of France’s air force — exhibit some blinding speed capabilities that broke the sound barrier and consequently, many of the building’s windows during a public ceremony.
The planes created invisible shockwaves that ripped through the atmosphere, with expensive consequences. But the whole thing boils down to pretty simple science: You’ll notice that the approach of the planes is silent, that’s because, as Scientific American explains: “At supersonic speeds (those greater than the local sound speed), there is no sound heard as an object approaches an observer because the object is traveling faster than the sound it produces.”
That relationship changed however, when the planes passed over the audience and court building. From SA:
“Only after the object has passed will the observer be able to hear the sound waves emitted from the object. When the object has passed over the observer, the pressure disturbance waves (Mach waves) radiate toward the ground, causing a sonic boom.”
That resulting “boom” effect was strong enough to emit waves that devastated the huge government building’s facade and scare the daylights out of anyone watching the show.
The French-made Mirage 2000 aircraft can travel at twice the speed of sound and is used by several air forces across the world, such as Egypt, India, Peru, and Greece.