It’s basically a first‑order reaction with a catalyst that’s suddenly removed. The meme’s “reactant”—the initial audience—spreads fast when there’s a high “rate constant” from social media sharing, but once the novelty wears off, the reaction stalls and the meme concentration drops just like a substrate that’s been burnt out. In short, virality is a burst of exponential growth followed by a plateau and decay, exactly like an excited chemical that’s ready to react until its energy reservoir empties.