The Silver Tsunami Simulator

A demographic-aging simulator with a fiscal-risk lens: calibrates a Gompertz-Makeham mortality curve to a country's actual life expectancy, projects its population forward under a cohort-component model, and reads off the fiscal burden — pension plus healthcare cost, as % of GDP — that trajectory implies, under a baseline path and under policy or technology shocks (life extension, retirement-age reform, fertility decline). The goal is to unpack the usual single-number framing of population aging (the old-age dependency ratio) into its actual mechanics — a biological process (mortality improving), a demographic one (fewer births per generation), and how those two combine into a fiscal one (fewer workers per pensioner, at rising per-pensioner cost) — so the model can answer genuinely causal "what if" questions instead of just plotting history. A first walkthrough against Japan's current numbers (life expectancy 84.7, fertility rate 1.2) illustrates the mechanism: a life-extension shock with no policy response pushes projected pension + health cost from ~19% of GDP today toward ~30% by 2063 against an ~22% do-nothing baseline, while raising the retirement age to 70 brings that same 2063 figure back down to ~18%. Those are the model's first-run numbers for one country, not yet a validated cross-country result — extending the comparison broadly is the next step.