Whole, half, quarter, eighth, ... – anything that goes away at a constant fractional rate fades in the same pattern. Whatever the starting point, after one half-life there's half as much left, after two half-lives it's down to a quarter, and so forth.

That's negative feedback, radioactive decay, exponential decline, ...

(LOOPY is an ultralight tool for thinking in systems ©2021 MITRE Corporation; cf LOOPY - Learn, Work, Save (2021-06-19), LOOPY - Throw a Ball (2021-08-17), LOOPY - Revolution vs Stability (2021-08-19), ...) - ^z - 2021-08-21