The Gifted Amateur

A QED reverse-engineering game.

Somewhere, a universe is running on a Lagrangian you cannot see. You have a cloud chamber, an e⁺e⁻-style collider, a decay observatory, and a finite grant. Read the tracks, find the bumps, measure the lifetimes — then write down the one line of physics that explains everything, and get it past Reviewer 2.

Open the-gifted-amateur.html in any browser. That single file is the whole game.

The loop

1. Expose the cloud chamber — charged particles leave droplet trails that curve in the magnetic field (r = p/QB, droplet density ∝ 1/β²). Kinks are decays in flight; pairs opening from nowhere are photons converting.
2. Run the collider — collide the lightest stable charged particle with its antiparticle. Steps in σ(√s) are pair-production thresholds (each step is a mass); bumps are s-channel resonances (position = mass, width = 1/lifetime).
3. Measure decays — lifetimes and branching fractions. A slow decay is hiding something: a feeble coupling or a heavy virtual mediator (Γ ∝ g⁴Δm⁵/m⁴_φ — the muon's own story).
4. Build ℒ and publish — pick terms (Dirac fermions with minimal coupling, the Maxwell term, a real scalar, Yukawa couplings), set masses and couplings, and submit to the Annals of the Pocket Universe. The referees enforce gauge invariance and charge conservation before they even look at your data.

Campaign

Six universes: pure QED (First Light), a stable heavy lepton (The Heavy Cousin), a scalar resonance (A Fifth Force), flavor-changing decays through a too-heavy-to-produce mediator (Alchemy), missing energy (The Dark Sector), and a randomly drawn universe (Publish or Perish).

What's real and what's simplified

The structure is honest: gauge invariance forbids the photon mass term, every vertex conserves charge, minimal coupling is flavor-diagonal, the lightest charged particle is stable, thresholds and Breit–Wigner resonances sit where they should, and three-body decay rates carry the Fermi-style 1/m⁴ mediator suppression. The rates are tree-level and qualitative; there is no renormalization, no loops (beyond a decorative φ→γγ), one U(1) gauge group, and no detector backgrounds. See the in-game Field Guide for the full honesty section.

Development

node build.js            # concatenates src/ into the-gifted-amateur.html
node test/physics.test.js  # physics engine unit tests
node test/smoke.js       # headless browser playthrough (requires playwright)

Source layout: src/physics.js (universe generation, processes, decays, peer review), src/chamber.js (cloud chamber canvas sim), src/render.js (Lagrangian typography, Feynman SVG, charts), src/ui.js (game shell), src/style.css, src/shell.html.

Named for Lancaster & Blundell's Quantum Field Theory for the Gifted Amateur, the book that started this.