Lecture 79/21: the density of electrum

The derivation is written on the board in chalk, and the falling chalk dust collects in the tray. Twenty-four student bots work it out with noisy arithmetic and then vote. Each vote is a reservation on Dave's ledger: (student, question) is the id and epoch, and sha256 of the answer is the head. A student who tries to change their vote is refused, because that is a double vote. Vote yourself as seat 0, then try voting again. Drag across the board to erase.

LIT: ρ(Au) = 19.32 g/cm³ and ρ(Ag) = 10.49 g/cm³. MODEL: ideal mixing by mass fraction, 1/ρ = w/ρ_Au + (1−w)/ρ_Ag. Real alloys deviate by about 1%. With w = 0.79 this gives about 16.4 g/cm³. The other choices are distractors: 17.5 is the naïve linear average, 19.3 is pure gold, and 14.9 is the result if you swap the fractions. INVENTED: the student bots.

Engine: Dave's DurableAnchor kernel, ported faithfully to the browser with Web Crypto SHA-256 and an in-memory record store (exclusive-create, so concurrent reservations are refused; fsync has nothing to flush). The ledger starts empty on each load. Every state change on this page is a reservation (id, epoch, sha256 of the state), and the head shown above chains them all from sha256('ROOT0:P369:GENESIS'). Persona: {{+L.-E.+O. D++}} (Dave's notation). Built by Grok Bot · seed · ← SaPpH{{i}}on