Concept

Voronoi cell area — where it appears

The area of one primordium's Voronoi cell — the region closer to it than to any other organ — and the quantity whose second moment this site measures disorder with.

Named by 3 essays across one field — each of them below, with the objects they name alongside it.

00.2500.5000.7501120130140150divergence angle (°)closest pair, as a fraction of the mean spacing (higher is better)137.508°400 points per anglethree criteria, three winners

Packing, measured four ways

The claim is that the golden angle packs best. It is measurable, and the measurement gives three different winners on three criteria — all near 137.5° and none of them it. That does not make the claim wrong; it makes the usual statement of it wrong.

tissue · packing
50100200400800window, in scaled units of δ·n²/qequivalentwidth13/349/3415/3411/34q = 34 · two head sizes agree to 8% at a window of 200generated from a stated rule, not drawn to look right

A dip with no outer edge

The disorder of a head dips at every rational divergence, and how wide that dip is has carried a long argument. Reading the width as a level crossing has a resolution problem, and the obvious repair is to integrate instead. The integral reproduces beautifully across head sizes and never settles on a value, because there is nothing out there for it to settle against.

tissue · second statistic
crowdednearest neighbour firstwindow 50widest firstwindow 100widest firstwindow 200widest first23/5517/5521/5512/5523/5517/5521/5512/5523/5517/5521/5512/5523/5517/5521/5512/55crowding: 21/55 0.193° · 12/55 0.205° · 23/55 0.152° · 17/55 0.156°q = 55 · 1279 organsgenerated from a stated rule, not drawn to look right

The window is the neighbour

An integral needs a limit, and this one has two conditions on it that pull opposite ways. It has to scale with the dip, so that two head sizes are comparable, and it has to stay clear of the next rational, which is a fixed distance in degrees. Between them there is no stretch where the answer holds still — and the limit that decides it is the crowding.

tissue · second statistic

Named alongside it

The objects these essays reach for when they reach for this one.

Divergence angleRational approximationArtefactConvergentsDiscretisationDisorderHonest limitsMeasurementMeasurement errorNull modelRational angleSampling

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