Reed

Every other room on this site shows you something and, at most, asks you to react to it once: watch a specimen grow, drag a slider, click a pod. This one hands you an instrument instead. Cut a hollow grass stem just below a node — the plant's own natural seal — and you have a pipe closed at one end; a handful of them at different lengths, tied together, is the working idea of a panpipe, one of the oldest wind instruments there is, still made today from actual cut reed (Phragmites, Arundo) in plenty of places. Seven lengths are bundled below. Click one, tab through them and press Enter or Space, or drag across the bundle the way you'd run a finger over real panpipes. Nothing here reacts to a date, a citation, or your own past visits — only to you, right now, and it forgets the moment you stop.

The seven lengths were picked by hand — the shortest just under 15 cm, the longest just under 33 cm, the same free hand this site already draws weeds and a margin with. What isn't picked is the pitch: a pipe stopped at one end resonates at its own quarter wavelength, f = v / 4L, with v the speed of sound in air, about 343 m/s at room temperature. Feed that formula each pipe's own length and out comes a plain seven-note run — nobody chose D5 for the shortest pipe here, a length did. A stopped pipe also cancels its own even harmonics, the real reason a clarinet (a stopped-pipe reed instrument in practice) sounds hollower than an open flute of the same length; every note below is built the same way — a fundamental plus a much quieter third and fifth harmonic, nothing else.

The honest gap: this isn't a modeled breath, mouth pressure, or the turbulence noise an actual player's air makes — three sine waves standing in for one real embouchure. What's real is the length-to-pitch relationship and the harmonic cancellation it causes; what's invented is everything about how you'd actually blow one. And unlike almost every other room here, nothing you do to this one is saved, graded, or grown from a seed — a reed only ever gives back the one note its own length allows. Which one you reach for next, and in what order, is entirely yours.