Atom_Sim: Physics Simulator Dev Log

An atom simulator built on one rule: Every number has a label (exact, numerical, approximation, counterfactual, or visual_liberty). Unlabeled numbers are treated as bugs.

Stack: Python physics engine -> React + Three.js frontend.

Phase Logs

Phases 1–3: The Hydrogen Foundation

• Hydrogen Core: Uses exact math for energies and wavefunctions. Validates its electron clouds using statistical KS tests.
• Numerical Solver: Solves the Schrödinger equation for custom shapes. It calculates its own accuracy by halving the grid spacing.
• Constants Lab: Allows changing fundamental constants (hbar, e, c). It proves that changing individual units changes nothing if the ratio between them stays the same.
• Classical Ghost: Shows old Bohr orbits collapsing, proving why classical physics cannot explain atoms.

Phases 4–6: Altered Potential & Real Atoms

• Fake Physics: Simulates universes with non-standard forces (like Yukawa or power laws) under a clear warning banner.
• Screened Atoms: Models elements from Helium to Argon using historic 1974 data. If an element (like Sulfur or Chlorine) lacks clean data, it is left out entirely rather than guessed.

Phases 7–12: Fields, Relativity & Nuance

• Dirac Math: Tracks exact relativistic shifts and highlights what the math misses (the Lamb shift).
• External Fields: Simulates atoms splitting under magnetic fields (Zeeman effect) and electric fields (Stark effect).
• Hyperfine: Models the 21 cm hydrogen line using the precise electron-to-proton mass ratio.

Phases 13–17: Light, Speed & Thermodynamics

• Fast Math: Uses a custom integration trick to calculate atomic lifetimes exactly and 13x faster.
• Doublet Ratios: Proves via quantum math (Wigner 6j) why certain spectral lines are twice as bright as others.
• Heat Sliders: Combines Saha and Boltzmann equations to turn raw rates into actual visible light. Dragging the temperature slider smoothly hands Lyman lines over to Balmer lines.

Phase 18: Line Profiles (Current Work)

Replaces infinitely sharp lines with realistic Voigt profiles using three combined factors:

1. Natural Width: A Lorentzian shape caused by how fast an excited state decays.
2. Doppler Width: A Gaussian shape caused by thermal motion. Works perfectly for normal hydrogen, positronium, and muonic hydrogen.
3. Instrumental Width: A Gaussian blur based on the user’s chosen telescope or sensor resolution.

Note on Missing Physics: Collision/pressure broadening is not simulated. Instead of a text disclaimer, the app calculates how large that missing effect would be and prints the raw margin of error right next to the chart.

Core Development Rules

• No Smoke Tests: Every physics feature must pass an automated math test.
• No Live Fetches: All reference data is saved locally with a hard citation.
• No Silent Approximations: If the code cannot calculate something honestly, it stops and prints exactly what data is missing.