HALFLIFEWatch an unstable sample decay in real time — random up close, exact in the long run.

No atom knows when it's its turn.

Every glowing point is one unstable nucleus. In any given second it has a fixed, tiny chance of decaying — and no memory of how long it has already waited.

That is the strange honesty of radioactive decay. A nucleus that has survived ten half-lives is no more likely to go in the next instant than a freshly made one. There is no ageing, no wear, no schedule. The flash you just saw was not due; it was rolled.

So the chamber flickers unpredictably. You cannot say which point will darken next, or exactly when. Watch one dot and it looks like pure chaos — a coin that keeps its own counsel.

Chaos, added up, is a clock.

Stop watching one atom and watch the crowd. The randomness cancels, and a clean exponential falls out — the curve drawing itself beside the panel.

Halve the sample, then halve what remains, then halve that. The time each halving takes is the same: one half-life. The panel fits a straight line to the decaying population and reads the half-life straight back out of the noise — 16 seconds, here, compressed from something that in nature might be minutes or four billion years.

Early on the fit wanders; a handful of events is not much of a crowd. Give it a few hundred decays and the fitted number settles onto the truth. That convergence — noise becoming law before your eyes — is the whole point of this instrument.

Left running, the sample empties, reseeds, and begins again.