Why now?

The Show HN post hit 608 points, showing strong organic appetite for intuitive, human-scale physics explainers right now, and the whole thing is a pure client-side visualization with no backend or API costs.

The gap

Existing relativity explainers tend to be abstract equations or dry textbook diagrams; this proves people want to feel relativistic effects with everyday objects, but the current version is a single-purpose demo rather than a reusable teaching tool.

Main competitor

Generic physics simulation platforms and YouTube explainer channels; no direct competitor is named in the signals, and the HN traction suggests this specific human-scale framing is not well served.

Execution plan

1. Ship a polished v1 with adjustable c values, preset scenarios (walking, driving, orbiting), and shareable permalinks so each demo is a linkable teaching artifact.
2. Add a lightweight 'classroom mode' with guided questions and a worksheet export, since physics educators are the recurring audience.
3. Open-source the renderer and publish a small embeddable widget so other sites and teachers can drop it into lessons, driving distribution.
4. Build a small library of related human-scale visualizations (time dilation, length contraction, Doppler) to turn a one-off into a series.
5. Instrument usage to see which scenarios get shared most, then double down on those before considering any paid tier.

Monetization

No paid tier is evident from the signals; the realistic path is free with optional support (Patreon/Ko-fi) or paid classroom worksheet packs, but demand for payment is unproven and educators expect free demos.