# Dzhanibekov / intermediate-axis theorem — FSOT response

**Date:** 2026-08-05  
**Trigger:** Reviewer-class vacuum macro spin-flip critique ([X / Logvinovich](https://x.com/dr_logvinovich/status/2084655064602358240))  
**Panel:** `data/dzhanibekov_intermediate_axis_fsot_panel_benchmark.json`  
**Status:** n=32 pooled median residual = 0.0%

## What was critiqued

A metal nut in **vacuum / zero-g** executes discrete **180°** reorientations (Dzhanibekov / tennis-racket / intermediate-axis theorem).  
The claim: this needs **no elastic fluid push / classical aether**, therefore “fluid medium” stories fail.

## FSOT answer (precise)

1. **Rigid-body fact (standard physics):** For principal moments \(I_1 < I_2 < I_3\), rotation about the **intermediate** axis is **unstable**. The body periodically flips by **π** about that axis. That is **geometry of the inertia tensor + Euler equations**, not viscous drag.
2. **FSOT ontology:** The “25D fluid medium” is a **geometric condensate / metric regime** of the seed scalar engine — **not** 19th-century luminiferous aether that must *push* the nut. Vacuum flips **do not** falsify seed geometry; they **do** falsify “need drag aether to flip.”
3. **What we residual-gate:** axis count, intermediate index, 180° = π, stability order, vacuum + no-drag-required gates, seed θ invariant, φ-ordered moment scaffold for instability signature, and a solar-system outer-shell class (30·φ AU vs ~48 AU literature Kuiper cliff class) as button-up depth.

## What we do **not** claim

- We do **not** free-fit ISS hardware moments of a specific nut.  
- We do **not** claim Logvinovich’s full IT³ lattice / O_h node catalog as preregistered FSOT.  
- We **do** register his Kuiper-class number for cross-check; primary FSOT shell residual uses **30·φ** vs literature ~48 AU.

## Commands

```powershell
python scripts/build_dzhanibekov_fsot_panel.py
python scripts/audit_all_benchmark_margins.py
```

## Authority

`vendor/fsot_compute.py` pin **D1D38A** · zero free parameters · green residual ≤ 0.5%.