a broadband strike — not a drive · every frequency at once, the object answers with its own · the tang purifies to a pure tone, the survivor is the mode with a node at the zero
verdict
booting — raising the hammer...
conductor — purification vs frozen
the struck sphere (soft-GL)
strike it: the whole sphere shudders (all elastic modes at once — the tang), then the surviving mode emerges — a clean two-lobe antiphase shape (magenta) with a still node at the mount. the messy overtones die; the pure tone remains. drag to rotate.
the tang purifying — spectrum + purity
top: the spectrum just after the strike (all modes, the tang) fading to one line (the fundamental). bottom: the purity meter — energy fraction in the fundamental, climbing from 0.65 to 1.0 as the overtones die. the strike settles to a pure tone.
drive vs strike — the two ways to ring it
left: DRIVE (the photon climb) — you tune to the mode and pump; narrowband; you must know the frequency. right: STRIKE — broadband impulse; the object answers at its own frequency; you discover the modes. one pumps a known note; one asks every note at once.
toddler corner
ELI5: before, we filled the sapphire ring with a careful stream of light tuned to exactly the right note — slow and precise. Now we just WHACK it, like flicking a tuning fork. A whack contains every note at once, so for a split second the sphere makes a messy "tang" — all its notes jumbled together. But then something clean happens: the ugly notes fade fast and one pure note is left ringing, clear as a bell. Why that note? Because it's the one that holds perfectly still right at the spot where the sphere is held — it doesn't tug on its own mounting, so it doesn't leak away, so it lasts. The whack asks the sphere every question at once, and the sphere answers with the single note that costs it nothing to keep singing. That's why a tuning fork gives ONE clean pitch: hit it messy, it cleans itself up.