Codex — Physics Plan

Drafted 2026-05-17. Per-domain plan for the Physics axis of the five-domain expansion. Sibling of (forthcoming) CHEMISTRY_PLAN.md, BIOLOGY_PLAN.md, PHILOSOPHY_PLAN.md. Subordinate to BIBLE_EXPANSION_PLAN.md for cross-domain mechanics. Companion to FASTTRACK_COVERAGE_ROADMAP.md — that plan tracks Fast Track booklist coverage on the math/physics axis; this plan structures the physics-proper namespace it feeds into.

Status: Draft. Locks the five-branch structure, section numbers, tier anchors, mastery endpoints, math prereq cone, and the seed-unit slate. Does not produce units (production happens after the validator + UNIT_SPEC patches in BIBLE_EXPANSION_PLAN.md §10 land).

Read in this order before this plan: OVERVIEW.md (canonical); BIBLE_EXPANSION_PLAN.md (cross-domain contract); FASTTRACK_COVERAGE_ROADMAP.md (math/physics depth push). This plan does not restate them — it builds on them.

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§1 What this plan does

Three things and only three:

1. Locks the five-branch decomposition of physics-proper into top-level sections §09–13, with internal ordering, tier anchors, mastery endpoints, math prereq cones, and outbound-hook taxonomies to chem/bio/phil per branch.
2. Defines the first wave — five seed units, one per branch — to validate the cross-domain link contract (hooks_out, cross-domain pending prereqs) on real material before chem and bio plans are drafted.
3. Specifies the relationship between this plan's physics-proper namespace and (a) the existing math-physics border units in §03, (b) the existing math-flavor §08 stat-mech section, and (c) the Fast Track coverage push.

It does not:

• Produce units (production gated on BIBLE_EXPANSION_PLAN.md §10 patches).
• Choose specific anchor editions or chapter-level reading lists — that's per-unit work in production.
• Decide whether §08 math-stat-mech eventually merges with §11 physics-stat-mech (deferred to §8 below).
• Override OVERVIEW.md invariants 1–5, 7, 8. All carry forward.

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§2 Physics scope

2.1 In scope (v1)

Mainstream physics covering: classical mechanics (Newtonian → Lagrangian → Hamiltonian → symplectic), electromagnetism (Maxwell + classical EM applications), special relativity (kinematics, dynamics, covariant formulation), statistical mechanics and thermodynamics (kinetic theory → ensembles → phase transitions → RG), quantum mechanics (non-relativistic + relativistic + many-body), quantum field theory (canonical + path-integral + gauge theory + intro renormalization), general relativity (manifold-based + Einstein eq + Schwarzschild + cosmological models).

Subareas treated as advanced extensions of the above, in v1:

• Condensed matter physics — as an application stack on top of QM + stat mech (e.g., band theory, Fermi liquid, BCS, topological phases). Lives in §12 (QM extensions) and §11 (stat-mech extensions) with cross-refs, not its own §.
• Plasma physics, classical fluid dynamics — as applications of classical mech + EM. Lives in §09 / §10 with cross-refs.
• Cosmology — as an application of GR. Lives in §13.
• Particle physics — as an application of QFT + gauge theory. Lives in §12.
• Optics — as an application of EM (and QM for quantum optics). Lives in §10 and §12.

2.2 Out of scope (v1)

• Experimental technique pedagogy (lab methods, instrumentation, measurement uncertainty as a craft) — physics-as-laboratory-practice is its own teaching tradition; not what this curriculum is doing.
• Engineering physics (specific applications to specific industries — aeronautics, nuclear engineering, semiconductor device physics as engineering).
• Astrophysics-as-survey (stellar structure, galactic dynamics, etc., as observational catalogs). The physics methods behind these are in scope (radiation transport in §10, stellar structure derivations in §11–13); the catalog itself is not.
• Geophysics, atmospheric physics, oceanography — out of v1 entirely.
• History of physics as primary content — historical context appears in unit prose where useful, but no dedicated history units.

2.3 Exclusions (lives in another domain)

• Chemical thermodynamics → chem (the apparatus comes from physics §11; the application is chem).
• Spectroscopy methods applied to molecules → chem.
• Biomechanics applications → bio.
• Quantum biology, biological electrochemistry → bio (the underlying physics → §10, §12).
• Philosophy of physics (interpretation, simultaneity, time, determinism) → phil (with hooks_out from the physics units to it).
• Materials science as applied condensed-matter chemistry → chem (boundary is fuzzy; default rule: if the question is "what does this material do?" → chem; if the question is "what governs the underlying many-body state?" → physics).

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§3 The five branches

Each branch gets one top-level section in §09–13. Branch entries below specify: section number, internal ordering, math prereq cone, anchor literature per tier, mastery endpoints per tier, and the dominant hooks_out targets to chem / bio / phil.

3.1 §09 Classical Mechanics (variational + symplectic)

Internal ordering (chapters):

Chapter	Topic
09.01	Newtonian mechanics — kinematics, forces, conservation laws
09.02	Lagrangian mechanics — variational principle, Euler-Lagrange
09.03	Symmetries and conservation — Noether's theorem
09.04	Hamiltonian mechanics — Legendre transform, Hamilton's eq, Poisson brackets
09.05	Canonical transformations and Hamilton-Jacobi theory
09.06	Integrable systems and action-angle variables
09.07	Continuum mechanics and field theory (warm-up to §10, §12)
09.08	Chaos, KAM theorem, modern dynamical systems
09.09	Geometric mechanics — symplectic / Poisson manifolds, momentum maps

Math prereq cone:

From math	Why
§00 precalc	basic functions
§02 analysis	ODEs, calculus of variations, vector calculus
§03 modern geometry	manifolds, tangent / cotangent bundles (for ch 09 onward)
§05 symplectic	symplectic forms, Poisson structures, momentum maps (for 09.04 onward)

Anchor literature:

Tier	Anchor
Beginner	Susskind & Hrabovsky The Theoretical Minimum: Classical Mechanics; Feynman Lectures Vol I (selected chapters)
Intermediate	Taylor Classical Mechanics; Marion-Thornton Classical Dynamics (alt)
Master	Arnold Mathematical Methods of Classical Mechanics; Marsden-Ratiu Mechanics and Symmetry; Abraham-Marsden Foundations of Mechanics

Mastery endpoints:

Tier	Endpoint
Beginner	Explain conservation of energy / momentum / angular momentum in plain language; predict qualitatively the motion of a planet / pendulum / collision system
Intermediate	Derive the Lagrangian for a mechanical system; solve Hamilton's equations for standard problems (oscillators, central forces, rigid bodies) from Taylor's exercise sets cold
Master	Prove integrability of a Hamiltonian system using Liouville-Arnold; apply geometric-mechanics framework (momentum maps, symplectic reduction) to a problem with continuous symmetry; follow a paper in modern geometric mechanics or KAM theory

Outbound hooks (taxonomy, not exhaustive):

• → Chemistry: molecular dynamics simulation foundations (e.g., classical Hamiltonians for force-field methods); classical limit of quantum molecular dynamics
• → Biology: biomechanics (e.g., muscle as a mechanical system); classical population-dynamics models that share the Hamiltonian / dissipative structure
• → Philosophy: determinism, free will, classical vs quantum boundary, the nature of time in Hamiltonian flow, the role of the action principle

Math-physics border units already in §03 that this branch should cross-ref: Yang-Mills action (03.07.05), Hamiltonian formulation pieces inside Chern-Weil / Bott periodicity territory.

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3.2 §10 Electromagnetism + Special Relativity

Internal ordering:

Chapter	Topic
10.01	Electrostatics — Coulomb, Gauss, Laplace eq, boundary value problems
10.02	Magnetostatics — Biot-Savart, Ampère, vector potential
10.03	Electrodynamics — Faraday, Maxwell's equations (integral form)
10.04	Maxwell's equations in differential form; wave equation; EM radiation
10.05	Special relativity — postulates, Lorentz transformations, kinematics, dynamics
10.06	Covariant electrodynamics — Faraday tensor, four-potential, gauge invariance
10.07	Radiation reaction, Liénard-Wiechert, Larmor formula
10.08	Macroscopic media — polarization, dielectrics, magnetic materials, optics
10.09	Classical field theory — Lagrangian for EM, conservation laws via Noether
10.10	Plasma physics primer (application stack)

Math prereq cone:

From math	Why
§02 analysis	vector calculus, PDE, Green's functions
§03 modern geometry	differential forms (10.04 onward), Minkowski geometry (10.05 onward)
§07 rep theory	Lorentz group reps (10.06 onward, soft prereq — most intro books skip)

Anchor literature:

Tier	Anchor
Beginner	Susskind & Friedman Special Relativity and Classical Field Theory; Feynman Lectures Vol II (selected)
Intermediate	Griffiths Introduction to Electrodynamics; Purcell-Morin Electricity and Magnetism (alt)
Master	Jackson Classical Electrodynamics; Landau-Lifshitz Vol 2 The Classical Theory of Fields; Zangwill Modern Electrodynamics (alt)

Mastery endpoints:

Tier	Endpoint
Beginner	Explain Maxwell's equations in plain language; identify what each one says physically; explain why c is invariant and what time dilation / length contraction mean
Intermediate	Solve boundary-value problems from Griffiths (capacitors, waveguides, antennas); work problems on relativistic kinematics and dynamics from a standard SR problem set
Master	Work Jackson chapter problems; derive radiation patterns for arbitrary charge distributions; treat radiation reaction with the full Abraham-Lorentz-Dirac apparatus; read a paper in classical plasma physics or accelerator physics

Outbound hooks:

• → Chemistry: spectroscopy foundations (light-matter interaction at the classical level); ionic systems; dielectric response of molecular media
• → Biology: vision (the EM signal side; the photo-receptor biochem belongs to bio); photosynthesis (the EM input side); medical imaging physics (MRI is QM, EEG/ECG are bioelectromagnetic); bioelectric signaling
• → Philosophy: simultaneity (the canonical SR problem); ontology of fields (are fields "real"? — the long-running debate); causality in relativistic settings

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3.3 §11 Statistical Mechanics + Thermodynamics (physics-flavor)

Important boundary note. Math has §08 stat-mech already (Onsager, RG, lattice gauge, path integrals, mean field, etc.) — that section's flavor is mathematical physics: rigorous treatments, exact solutions, theorems. This new §11 is physical: phenomenological derivations, computation, predictions, applications. Cross-references go both ways heavily. The §11 chapters below should cite into §08 wherever §08 has the rigorous version of the result.

Internal ordering:

Chapter	Topic
11.01	Thermodynamics — laws, state functions, free energies, thermodynamic potentials
11.02	Kinetic theory — equation of state, Maxwell-Boltzmann distribution, transport
11.03	Statistical ensembles — microcanonical, canonical, grand canonical
11.04	Partition functions and thermodynamic quantities
11.05	Quantum statistics — Bose-Einstein, Fermi-Dirac, photon gas, electron gas
11.06	Phase transitions — Ising model (phenomenological), Landau theory
11.07	Critical phenomena and the renormalization group (physics-side; cross-refs §08 RG)
11.08	Non-equilibrium stat mech — linear response, fluctuation-dissipation, Onsager (cross-refs §08)
11.09	Statistical biophysics primer — polymer chains, membrane mechanics (cross-refs bio)

Math prereq cone:

From math	Why
§02 analysis	probability theory, measure theory, complex analysis (for saddle-point methods)
§07 rep theory	for symmetry classification of phases (soft prereq)
§08 math-stat-mech	rigorous results that §11 cites

Anchor literature:

Tier	Anchor
Beginner	Schroeder Introduction to Thermal Physics (Beginner-tier sections); Susskind & Hrabovsky Statistical Mechanics: Theoretical Minimum (forthcoming/selected lectures)
Intermediate	Schroeder Introduction to Thermal Physics; Reif Fundamentals of Statistical and Thermal Physics (alt)
Master	Landau-Lifshitz Vol 5 Statistical Physics Part 1; Reichl A Modern Course in Statistical Physics; Goldenfeld Lectures on Phase Transitions and the RG

Mastery endpoints:

Tier	Endpoint
Beginner	Explain entropy and the second law in plain language; predict qualitatively whether a process is spontaneous
Intermediate	Derive partition function for systems in Schroeder; solve problems on Bose / Fermi gases; compute thermodynamic quantities from a Hamiltonian
Master	Work Landau-Lifshitz problems; apply RG to a non-trivial system (cross-cites §08); read a paper in modern stat mech (e.g., active matter, glass transition, biophysics of folding) and identify the technique used

Outbound hooks:

• → Chemistry: chemical thermodynamics (Gibbs free energy in reactions, equilibrium constants, phase equilibria); statistical mechanics of solutions; partition functions for molecular systems
• → Biology: entropy production in living systems; statistical biophysics of biopolymers / membranes / molecular motors; kinetic models of metabolism
• → Philosophy: arrow of time, second-law universality, the question of fluctuations and Boltzmann brains, time-reversal symmetry vs observed irreversibility

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3.4 §12 Quantum Mechanics + Quantum Field Theory

The deepest branch. Hosts the longest internal ordering because QM → QFT spans more conceptual ground than any other branch.

Internal ordering:

Chapter	Topic
12.01	Foundations — Stern-Gerlach, two-state systems, complex amplitudes
12.02	Hilbert-space formalism — states, operators, observables, measurement
12.03	Schrödinger / Heisenberg / interaction pictures; time evolution
12.04	One-dimensional problems — well, barrier, harmonic oscillator
12.05	Angular momentum and spin — rep theory of SU(2), Clebsch-Gordan
12.06	Central force problems — hydrogen atom
12.07	Perturbation theory — time-independent, time-dependent
12.08	Scattering theory — Born approximation, partial waves, Lippmann-Schwinger
12.09	Identical particles, second quantization, many-body QM
12.10	Path integrals — formulation, free particle, oscillator, semiclassical limit
12.11	Relativistic QM — Dirac equation, Klein-Gordon (cross-refs §03 Dirac operator)
12.12	Canonical QFT — scalar field, Dirac field, photon field
12.13	Interactions and Feynman diagrams — QED at tree level
12.14	Renormalization — divergences, regularization, RG (cross-refs §08, §11)
12.15	Non-Abelian gauge theory — Yang-Mills, Higgs mechanism (cross-refs §03.07.05)
12.16	Effective field theory primer
12.17	Condensed-matter applications (band theory, Fermi liquid, BCS, topological matter)

Math prereq cone:

From math	Why
§01 foundations	linear algebra (Hilbert spaces at finite-dim level)
§02 analysis	functional analysis, distributions, Lebesgue integration
§03 modern geometry	manifolds, principal bundles (for 12.15)
§07 rep theory	reps of Lie groups (SU(2), Lorentz, SU(N)) — central to 12.05, 12.12 onward
§08 math-stat-mech	path integral / RG rigor (cross-refs 12.10, 12.14)

Anchor literature:

Tier	Anchor
Beginner	Susskind & Friedman Quantum Mechanics: Theoretical Minimum; Feynman Lectures Vol III
Intermediate	Griffiths Introduction to Quantum Mechanics; Sakurai Modern Quantum Mechanics (mid-to-upper intermediate)
Master	Sakurai Modern (advanced sections) + Sakurai Advanced Quantum Mechanics; Peskin & Schroeder Introduction to QFT; Weinberg Quantum Theory of Fields Vols I–III; Polchinski String Theory (selected QFT background); Coleman Aspects of Symmetry

Mastery endpoints:

Tier	Endpoint
Beginner	Explain superposition, measurement, and the uncertainty principle in plain language; trace what happens in a two-slit / Stern-Gerlach experiment
Intermediate	Solve Griffiths and Sakurai problems including angular momentum, hydrogen atom, perturbation theory, scattering; do simple second-quantized many-body problems
Master	Compute amplitudes from Peskin-Schroeder; renormalize a non-trivial diagram; treat gauge theory at the level of Coleman or Weinberg; read a recent QFT or condensed-matter theory paper and identify the EFT structure / RG flow / symmetry-breaking pattern

Outbound hooks:

• → Chemistry: atomic structure (hydrogen + multi-electron atoms); molecular orbital theory; bonding; spectroscopy mechanisms; reaction barriers and tunneling
• → Biology: quantum biology (photosynthesis coherence, magnetoreception, vision at the photoreceptor); NMR foundations
• → Philosophy: interpretation (Copenhagen, many-worlds, Bohmian, QBism, etc.); measurement problem; quantum nonlocality and Bell inequalities; ontology of quantum fields

Math-physics border units in §03 that this branch should cross-ref heavily: Clifford algebra (03.09.02), Spin structure (03.09.04), Dirac operator (03.09.08), Fredholm operators (03.09.06), Yang-Mills action (03.07.05), Atiyah-Singer (03.09.10), CFT basics (03.10.02).

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3.5 §13 General Relativity + Cosmology

Internal ordering:

Chapter	Topic
13.01	From SR to GR — equivalence principle, why curved spacetime
13.02	Manifold formalism — metric, connection, geodesics, parallel transport
13.03	Curvature — Riemann tensor, Ricci, Einstein tensor
13.04	Einstein field equations — vacuum solutions, with matter
13.05	Schwarzschild solution — orbits, light bending, gravitational redshift
13.06	Black holes — Kerr, charged solutions, horizons
13.07	Linearized GR and gravitational waves
13.08	Cosmological models — FLRW, expansion, dark energy / dark matter at the field-eq level
13.09	Modern cosmology — inflation, CMB physics, structure formation
13.10	Singularity theorems and global structure (Penrose-Hawking)

Math prereq cone:

From math	Why
§02 analysis	calculus of variations (for the action principle approach to GR)
§03 modern geometry	manifolds, tensor calculus, Riemannian geometry, connections — this is where §03 most directly powers physics

Anchor literature:

Tier	Anchor
Beginner	Susskind General Relativity: Theoretical Minimum; Hartle Gravity (Beginner-tier sections)
Intermediate	Schutz A First Course in General Relativity; Hartle Gravity; Carroll Spacetime and Geometry (mid sections)
Master	Wald General Relativity; MTW Gravitation; Carroll Spacetime and Geometry (advanced sections); Weinberg Gravitation and Cosmology (alt for cosmology emphasis)

Mastery endpoints:

Tier	Endpoint
Beginner	Explain why mass curves spacetime; describe time dilation in gravitational fields; explain what an event horizon is qualitatively
Intermediate	Solve standard GR problems (Schwarzschild orbits, gravitational redshift, geodesics on simple metrics); derive the Friedmann equations
Master	Work Wald problems; treat the singularity theorems and global structure; read a current paper in modern cosmology (CMB analysis, inflation models, dark-sector physics) or numerical relativity and identify the technique used

Outbound hooks:

• → Chemistry: minimal (gravity is too weak to matter at chemical scales; one possible hook is to philosophy-of-chemistry questions about supervenience)
• → Biology: minimal direct hooks; cosmological / planetary conditions appear as boundary conditions for origin-of-life questions (which live in bio §17 or phil §20)
• → Philosophy: spacetime ontology (substantivalism vs relationalism); the hole argument; fine-tuning of cosmological constants; eternal vs evolving universe; whether time exists fundamentally; observational cosmology and the limits of empirical access

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§4 Existing physics-adjacent units already shipped

Inventory (snapshot 2026-05-17) of units that are physics-flavored but live outside the §09–13 namespace. These are accessed by physics readers via cross-domain hooks, not by relocation. From the 313-units count in FASTTRACK_COVERAGE_ROADMAP.md, the physics-relevant ones cluster here:

4.1 §03 modern-geometry math-physics border (from pilot + waves)

Unit ID	Title	Branch served
03.07.05	Yang-Mills action	§12 QFT (gauge theory)
03.09.02	Clifford algebra	§12 QM (spin), §13 GR (spinors)
03.09.04	Spin structure	§12 QM, §13 GR
03.09.06	Fredholm operators	§12 QM (functional-analytic foundations)
03.09.08	Dirac operator	§12 (relativistic QM, QFT)
03.09.10	Atiyah-Singer index theorem	§12 QFT (anomalies, instantons)
03.10.02	CFT basics	§12 QFT (conformal field theory)
03.06.04	Pontryagin and Chern classes	§12 QFT (topological field theory)
03.06.06	Chern-Weil homomorphism	§12 QFT (gauge invariants)
03.08.07	Bott periodicity	§12 (K-theory in physics)

Rule: these stay in §03. The first physics unit in each affected §09–13 chapter that needs one of these declares the cross-ref via prerequisites (the math-side units are the prereq for the physics-side context).

4.2 §08 stat-mech (mathematical flavor)

Subdirectories (per existing tree): critical, gaussian, lattice-gauge, mean-field, onsager, partition, path-integral, rg, wick. These are the rigorous mathematical treatments. §11 chapters cross-cite into them where the rigorous version of a result is the canonical reference.

4.3 No physics-proper units exist yet in §09–13

The five branches are empty in content/. This plan's job is to seed them.

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§5 First wave — five seed units, one per branch

Purpose: validate the cross-domain link contract on real physics material before chem and bio plans are drafted. Each seed is chosen for:

1. Well-defined math prereq — exercises cross-domain prereqs against the existing math corpus.
2. Plausible hooks_out to at least two of {chem, bio, phil} — exercises the new field.
3. Standard textbook anchor at all three tiers — low content risk; pilot stress-tests the system, not the material.
4. Self-contained scope — each fits the 20–50 min Master-tier window cleanly.

Branch	Seed unit ID	Title	Why this one
§09	09.04.02	Hamilton's equations	Clean cite to §05 symplectic; hooks out to chem (MD foundations), phil (determinism in Hamiltonian flow); anchored in Taylor + Arnold
§10	10.04.01	Maxwell's equations in differential form	Clean cite to §03 differential forms; hooks out to chem (light-matter), bio (vision/photosynthesis), phil (field ontology); anchored in Griffiths + Jackson
§11	11.04.01	Canonical ensemble and partition function	Clean cite to §02 probability + §08 partition; hooks out to chem (chemical thermo), bio (statistical biophysics), phil (arrow of time); anchored in Schroeder + Landau-Lifshitz
§12	12.01.02	Stern-Gerlach and spin-1/2	Clean cite to §01 linear algebra and §07 SU(2) reps; hooks out to chem (atomic spin), phil (measurement); anchored in Sakurai + Griffiths; cross-refs 03.09.02 Clifford algebra
§13	13.05.01	Schwarzschild solution	Clean cite to §03 Riemannian geometry; hooks out to phil (event horizons, time dilation); anchored in Schutz + Wald

Sequence: §09 → §13 → §10 → §11 → §12.

Rationale for the order:

• §09 first because classical mech is the most concretely anchored to existing math (symplectic §05) and the link-contract check is cleanest there.
• §13 second because GR's math dependence is on §03 (already heavily populated by the pilot) and the unit set is small enough to stress-test a different math axis quickly.
• §10 third because EM introduces a new math dependence (differential forms in §03) that the prior two don't.
• §11 fourth because it stress-tests the cross-cite to another physics section (§08), not just math → physics.
• §12 last because QM's prereq footprint is the largest (foundations + analysis + rep theory + sometimes §03), and putting it last lets the link contract be calibrated on simpler cases first.

5.1 Success criteria (Wave 1 physics)

The wave succeeds if, by end of production:

• All 5 units exist in content/0{9..13}-<slug>/ per UNIT_SPEC.md with full frontmatter including hooks_out.
• All hooks_out entries have kind: proposed (no confirmations expected on wave 1 because chem/bio/phil aren't producing yet).
• All prerequisites resolve to shipped math units OR to math units explicitly registered as pending_prereqs: true in manifests/deps.json. Cross-domain pending prereqs are allowed per BIBLE_EXPANSION_PLAN.md §3.4.
• All reference citations resolve to real files in reference/. Where no reference/ material covers a topic, the citation may be pending+pointer: to a future addition per UNIT_SPEC.md §5 (existing convention).
• Validator passes (existing 19 automated checks + new hooks_out validation).
• At least one hooks_out → chem and one hooks_out → bio exist across the wave (otherwise the link contract has not actually been exercised against non-existent target domains).
• At least one hooks_out → 20.essays.NN exists across the wave (validates the philosophy-essay-ID retrofit).
• Pilot-lessons style retro written into docs/pilot-lessons.md — what worked, what didn't, what the chem/bio/phil plans should change as a result.

The wave fails (not "succeeds with caveats") if:

• Any unit ships without a populated hooks_out field (even an empty list counts as populated; the validator should require the key, not non-empty content — but the wave's purpose is to exercise the field, so each wave-1 unit should have ≥ 2 outbound hooks).
• Any cross-domain hooks_out target uses a section number outside the locked prefix table.
• The validator's hooks_out extension is buggy enough to require a hotfix during the wave (suggests the spec needs revision before wave 2).
• Production time per unit exceeds 1.5× the math-pilot median (current ~2 min agent-drafted, ~2.5 h manual) — would suggest physics production has unanticipated friction worth investigating before scaling.

5.2 Production strategy per unit

Unit	Strategy	Notes
09.04.02 Hamilton's eq	Manual first	Establishes the physics-side production pattern; one human-hand pass before scaling
13.05.01 Schwarzschild	Agent-drafted + LM-editorial pass	Math dependence is on §03 (already shipped), so RAG should be productive
10.04.01 Maxwell-forms	Agent-drafted + LM-editorial pass	Same as above
11.04.01 Canonical ensemble	Agent-drafted + LM-editorial pass	Cross-cite to §08 stress-tests RAG retrieval against the math-side §08 content
12.01.02 Stern-Gerlach + spin-1/2	Agent-drafted + LM-editorial pass	Cross-ref to 03.09.02 Clifford stress-tests pre-existing-unit citations in a new section

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§6 Reviewer roster sketch

Per REVIEWER_PLAN.md's convention, each unit needs a named mathematical / domain reviewer. Inferred from Tyler's known competencies (gauge theory, spin geometry, classical math-physics border, RG); flagged where outside reviewer recruitment will be needed.

Branch	Tyler-solo confidence	Outside reviewer needed for
§09 classical mech	Green at intermediate; Yellow at master (geometric mechanics depth)	Master-tier geometric-mechanics units (09.09) if Marsden-Ratiu coverage is required
§10 EM + SR	Yellow (radiative reaction, plasma); Green elsewhere	Master-tier 10.07 (radiation reaction) and 10.10 (plasma primer)
§11 stat mech (phys)	Green for foundational chapters (11.01–11.04); Yellow for 11.07 RG crossing § 08; Red for 11.09 statistical biophysics	Master-tier 11.09 (biophysics overlap) needs a biophysics reviewer; cross-domain recruit
§12 QM + QFT	Green for foundations; Yellow for QFT renormalization at master; Red for advanced gauge / EFT / condensed matter	Multiple outside reviewers: one for renormalization / EFT, one for condensed-matter applications (12.17)
§13 GR + cosmology	Green for GR foundations; Yellow for singularity theorems; Red for modern cosmology / numerical relativity	Master-tier 13.09 (modern cosmology), 13.10 (singularity theorems if Penrose-Hawking depth)

Recruitment priority (before §12 wave starts):

1. QFT / renormalization reviewer — single highest-leverage outside reviewer; covers most Yellow / Red in §12 and the 11.07 / 11.08 crossings.
2. Condensed-matter theorist — covers §12.17 and the application stack.
3. Cosmologist / numerical relativist — covers §13.09–10.

Cross-domain reviewer attestation for hooks_out to chem/bio (per BIBLE_EXPANSION_PLAN.md §3.2 — the confirmed_by: field) is not the same as the physics-side mathematical reviewer; the cross-domain confirmation comes from a reviewer credentialed on the receiving side. For Wave 1 we don't expect any confirmed hooks because the receiving domains aren't producing yet — all hooks stay at proposed.

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§7 Coverage strategy and Fast Track integration

Physics coverage in v1 has two complementary tracks:

7.1 Track A: Fast Track equivalence (depth on canonical anchors)

FASTTRACK_COVERAGE_ROADMAP.md governs depth. Per current memory, Fast Track §2 Quantum is the biggest gap with Chatterjee 2.03 as the lowest-friction next audit. The §12 branch of this plan is where the §2-Quantum push lands — chapters 12.01–12.16 are the physics-proper home for everything FT §2 audits will produce. FT auditing produces units that go into the §12 (and §11) namespace; PHYSICS_PLAN.md gives those units a structural home.

7.2 Track B: Coherent branch-completion (breadth across all five branches)

Independent of Fast Track. The point of Track B is that physics in v1 should not be "100% of §12 Quantum, 0% of §09 Classical Mech because FT happens to weight quantum." The five branches should fill in roughly proportionally so that the cross-domain link contract has hooks-out from all of physics into chem/bio/phil, not just from the deepest branch.

Target ratio for v1: at least 5 units in every branch before any branch exceeds 50 units. Soft target, revisited every wave.

7.3 What gets done first

Phase	Track A (FT depth)	Track B (branch coverage)
Wave 1 (this plan)	none — wave 1 is link-contract validation	1 seed unit per branch (5 total)
Wave 2	Resume FT §2 Quantum push (Chatterjee 2.03 + downstream)	Each branch grows by 3–5 units
Wave 3+	Continue FT booklist march	Continue branch fill

Track A and Track B will overlap: a single physics unit can simultaneously satisfy "audited from Chatterjee" and "fills branch §12 chapter 4." The two tracks are bookkeeping views of the same physical unit production, not separate work streams.

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§8 Open questions (deferred)

Question	Deferred to	Why now is wrong
Does §08 math-stat-mech eventually merge with §11 physics-stat-mech, or do they stay parallel forever?	After Wave 2 completes, when cross-cite frequency between them is measurable	Premature to decide before we see the actual citation pattern
Does §03 math-physics border get reorganized once §09–13 are populated? (E.g., do Yang-Mills / Dirac operator move to §12?)	Probably never — BIBLE_EXPANSION_PLAN.md §3.1 already locked "no renumber"	Listed here for completeness; the answer is no
Should "condensed matter" become its own §14 section?	After §12 reaches ~30 units and §11 reaches ~15 — if condensed-matter weight justifies it	Premature; treat as application stack inside §11 + §12 for now
Whether to introduce a "computational physics" subsection or units	After Wave 3 at earliest	Tooling pedagogy is a different teaching mode; decide later
How to handle physics topics that have no mainstream textbook at master tier (e.g., research-frontier topological QFT, holography)	Per-unit, when those units come up	Most v1 production won't hit this — the apex Codex pilot already explored that territory in §03

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§9 Risks

Risk	Mitigation
Physics production stalls on the math prereq cone (an §09 unit needs an §02 math unit that doesn't exist yet)	Cross-domain prereqs can be pending_prereqs: true per BIBLE_EXPANSION_PLAN.md §3.4. Production continues; math axis catches up; pending edges resolve.
QFT renormalization and condensed-matter content stalls on reviewer recruitment	Recruitment is sequenced (§6) — start before §12 wave, not after the wave stalls.
Wave 1 produces 5 units but none has meaningful hooks_out because authors default to "I don't know what chem cares about"	§5.1 success-criteria-as-failure-criterion: minimum 2 outbound hooks per unit, ≥ 1 to chem AND ≥ 1 to bio across the wave. Reviewers enforce.
Physics-side stat-mech (§11) duplicates math-side stat-mech (§08) without enough cross-cite, creating a parallel curriculum problem	§3.3 locks §11 as physical-flavor with explicit cross-cites into §08. Wave-1 §11 seed unit (canonical ensemble) must demonstrate this.
Production rate slows compared to math axis because physics units have no Lean equivalent — every unit needs human reviewer attestation	Acknowledged in BIBLE_EXPANSION_PLAN.md §5; physics reviewer-bandwidth is the throughput constraint at master tier. No mitigation other than reviewer roster expansion.
Five branches of physics share so much (e.g., the action principle threads through 09, 10, 12, 13) that the namespace allocation creates a unit-redundancy problem (Noether's theorem in §09.03 and §12.12 and §10.09 and §13.04?)	One canonical unit per concept; the other locations cross-ref it. The unit "lives" in the branch whose internal ordering needs it first — likely §09.03 for Noether. The other branches prerequisites: [09.03.NN] rather than restating.
Potential prereq cycle: physics §12 declares math §07 rep theory as a prerequisite (for SU(2), Lorentz, gauge group reps); but math §07 rep theory pedagogy often uses spin-1/2 / QM as motivating examples and may declare hooks_out back to §12. If a math §07 unit ever upgrades its motivation into a prerequisites edge, the DAG cycles	The discipline is one-way: §07 rep theory is mathematically self-contained (Lie groups → reps → characters); QM examples in math §07 are motivational only and must stay as hooks_out (informational), never prerequisites (blocking). Reviewers enforce this asymmetry on math §07 units.

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§10 Decision log entries (to be added to OVERVIEW.md §12 on the same date)

Date	Decision	Rationale
2026-05-17	Physics branches locked: §09 classical mech, §10 EM+SR, §11 stat-mech (phys), §12 QM+QFT, §13 GR+cosmology	Five branches cover the "all mechanisms of physics needed to understand the universe" goal; further subdivision (e.g., condensed matter as §14) deferred until usage warrants.
2026-05-17	Physics-side §11 stat-mech created parallel to math-side §08 stat-mech; the two cross-cite rather than merge	§08 is rigorous-mathematical-stat-mech; §11 is phenomenological / applied / computational. Merging would either lose rigor (§08 flavor) or lose accessibility (§11 flavor).
2026-05-17	Math-physics border units in §03 stay in §03; physics branches cite into them rather than relocating	Per BIBLE_EXPANSION_PLAN.md §3.1 routing rule. ~10 already-shipped units, ~50+ cross-refs, not worth the churn.
2026-05-17	Two-track coverage strategy: Track A (Fast Track depth push, especially §2 Quantum) + Track B (proportional branch breadth)	Avoids "all of §12, none of §09" pathology that pure Fast Track ordering would create. Tracks are bookkeeping views of the same production.
2026-05-17	Wave 1 physics: 5 seed units (one per branch) in order §09 → §13 → §10 → §11 → §12	Each unit chosen for clean math prereqs, plausible cross-domain hooks, low content risk. Order escalates from cleanest math dependence to deepest prereq footprint.
2026-05-17	Wave 1 success requires ≥ 2 outbound hooks per unit and ≥ 1 hook each into chem, bio, phil across the wave	Without minimum-hook requirements, "validate the link contract" degrades to "we shipped some physics."
2026-05-17	One canonical unit per cross-cutting physics concept (e.g., Noether's theorem in §09.03 only; other branches cross-ref)	Prevents quadruple-duplication across branches that all use the action principle. Branch where concept first appears in internal ordering owns the canonical version.

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§11 Next immediate actions

Gated on BIBLE_EXPANSION_PLAN.md §10 actions 1–4 (UNIT_SPEC + validator + OVERVIEW patches + philosophy essay ID retrofit) being complete. Once unblocked:

1. Produce 09.04.02 Hamilton's equations manually — the physics-side equivalent of pilot-unit-#1 Clifford algebra. Establishes the production pattern; surfaces spec gaps before scaling.
2. Retro on 09.04.02 — what worked, what's missing in the spec, what needs to change for agent-drafted units in this branch. Update docs/pilot-lessons.md.
3. Produce the remaining 4 seed units (13.05.01, 10.04.01, 11.04.01, 12.01.02) — agent-drafted with LM-editorial pass.
4. Cross-domain audit on Wave 1 — review manifests/connections.json for the proposed hooks_out edges. Are the hooks plausible? Are any glaringly missing?
5. Write the chem and bio plans informed by Wave-1 retro. Cross-domain audit feeds into them (each per-domain plan absorbs its hooks_out → its domain proposals as backlog per BIBLE_EXPANSION_PLAN.md §3.6).
6. Begin Wave 2 physics — Fast Track resume + branch breadth fill, in parallel with chem/bio plan drafting.

This plan is the canonical reference for the physics axis. When uncertain about physics-section structure, branch ordering, or seed-unit selection, check here. When updating, propagate to OVERVIEW.md §12 and BIBLE_EXPANSION_PLAN.md §6 the same day.