---
slug: convergence-encyclopedia-c17
title: Convergence Encyclopedia: C17 — Spirals / Logarithmic Growth-Packing
canonical: https://miscsubjects.com/a/convergence-encyclopedia-c17
---

**F1 — Tier.** T1 (botanical phyllotaxis — well-established); T2 (astronomical spirals — contested whether same mechanism applies).

**F2 — Sources.** 
- Fibonacci, L. (1202). Liber Abaci. (Fibonacci sequence introduced to Europe.)
- Douady, S. & Couder, Y. (1992). “Phyllotaxis as a dynamical self-organizing process.” Parts I–III. Journal of Theoretical Biology, 178(3), 255–312.
- Jean, R.V. (1994). Phyllotaxis: A Systemic Study in Plant Morphogenesis. Cambridge University Press.
- Golden angle formula: θ = 2π(1 − 1/φ) ≈ 137.5°, equivalently 360°/φ² ≈ 137.5°, where φ = (1+√5)/2.
- Hurricane dynamics: Emanuel, K.A. (1986). “An air-sea interaction theory for tropical cyclones.” Journal of the Atmospheric Sciences, 43(6), 585–604.
- Galactic density waves: Lin, C.C. & Shu, F.H. (1964). “On the spiral structure of disk galaxies.” Astrophysical Journal, 140, 646–655.
- Lindstedt, K.J. (1984). “The evolution of anomalous patterns in phyllotaxis.” Journal of Theoretical Biology, 107:271–283. FLAGGED UNVERIFIED — source citation in v1 could not be independently confirmed. Content held in abeyance pending verification.

**F3 — Domains.** Botany (phyllotaxis — leaf/seed arrangement), meteorology (hurricane eye wall), astronomy (galactic spiral arms), mollusk shells (logarithmic growth).

**F4 — Scale.** Seed primordium (~10⁻⁴ m) → galaxy (~10²¹ m); ~25 orders of magnitude.

**F5 — Falsifier.** A growing system that must pack new elements around a central axis, under radial constraint, that produces optimal packing without Fibonacci/golden-angle structure. If non-Fibonacci packing is equally optimal, the convergence claim weakens.

**F6 — Rival (strongest form).** Fibonacci appears because it is the simplest recursive growth rule, not a deep principle. Douady and Couder (1992) demonstrated that repulsion dynamics at a growing tip naturally produce Fibonacci spirals — the pattern emerges from local rules, not global optimization. The golden angle is a consequence of packing constraints, not a Platonic form. Hurricanes and galaxies have completely different physics (Coriolis vs. density waves) — the shared spiral shape is coincidental, not convergent. (Fowler et al. 1992 Journal of Theoretical Biology; criticism of over-unified spiral theories.)
CRITICAL: DNA and α-helices are HELICES (constant radius, axial advance), NOT SPIRALS (outward from center). They are NOT included in this node. The helix is a different geometry with a different mechanism.

**F7 — Independence.** HIGH. Fibonacci (medieval mathematics, Pisa), Douady & Couder (experimental physics, Paris), Lin & Shu (astrophysics, MIT) — independent programs. The shared mathematics (golden ratio) is a convergent formal description, not a shared causal mechanism.

**F8 — Pattern type.** Structural / mathematical.

**F9 — Maps.** A7 (pattern geometry).

---

## Corpus map
- Previous: [Convergence Encyclopedia: C16](/a/convergence-encyclopedia-c16)
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- Encyclopedia start: [The Schema](/a/convergence-encyclopedia-schema)
- Same node, other planes: [Catalogue node C17](/a/oip-node-c17-spirals-logarithmic-growth-packing) · [Catalogue hub](/a/oip-convergence-public-article)
- Kin corpora: [Total Structure](/a/oip-total-structure) · [Signature of the Grain](/a/oip-sog-preamble-axioms)
