Phyllotaxis
the spirals are counted, not admired
Concept

Drift — where it appears

A disturbance that changes slowly, so that neighbouring organs are displaced together. It is the part of an error a placement rule cannot correct, because correcting means comparing an organ with its neighbours and a drift moves them all.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

02550750102030how many organs the disturbance stays correlated overwander at a block of 64182 organs120 organs30 organs8 organs3 organsneighbourhood measured as the organs carrying 90% of the profileno crossover at any depth

The drift goes the other way

A rule that corrects what its neighbourhood shares should let through any disturbance slower than its own reach, and should suppress anything faster — a crossover, tracking the depth. Swept over a neighbourhood that changes by a factor of sixty, there is no crossover anywhere, and the deep rule passes nearly four times as much as the shallow one. The prediction is not weakly supported; it is backwards.

mechanism · noise colour 012342.262.081.480.9030.477organs in the neighbourhoodagainst the shallowest rulewanderscatterdrift througha drift correlated over 33 organs · 3 seeds a pointdrift through: 1.52° to 1.82°

What the ratio was hiding

The statistic that says a rule sharpens a drift rises by a factor of nearly four across a sweep of the rule's depth. Undo the normalisation and ask instead how many degrees of drift actually reach the divergences, and the answer changes by a fifth. Nearly all of the effect was in the denominator, and the denominator is the thing the rule is good at.

mechanism · noise colour

Named alongside it

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

AutocorrelationDiscriminationFalsifiabilityHonest limitsMeasurementNegative resultNeighbourhood depthNoiseThe placement ruleRepulsionSelf correctionArtefact

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