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Vagelis Plevris

Vagelis Plevris⁠

Structural engineer, professor and science communicator exploring engineering, mathematics, AI and science through clear, useful and engaging stories.

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MATHEMATICAL MYSTERIES

Why Does Nature Love the Angle 137.5°?

How changing an angle by a single degree creates 13 spiral arms, revealing a surprising connection between the golden ratio, Fibonacci numbers, and nature.

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Imagine placing 700 tiny seeds on a circular surface, one after another. Each new seed is rotated by exactly the same angle relative to the previous one, while its distance from the center gradually increases.

You begin with an angle of 137.5°. The result is remarkable. The seeds spread across the surface in a dense, almost uniform arrangement. There are no obvious straight spokes or large empty sectors. Instead, an intricate pattern of interlacing spirals appears, resembling the center of a sunflower.

Now change the angle to 138.5°. Just one degree. The arrangement transforms dramatically. Instead of filling the disk almost uniformly, the points organize into 13 conspicuous curved arms, separated by large empty regions.

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Two panels of 700 dots each. On the left, at 137.5 degrees, blue dots fill a disk almost uniformly in a sunflower-like pattern of interlacing spirals. On the right, at 138.5 degrees, terracotta dots gather into 13 curved arms radiating from the center, separated by wide empty gaps.
The same 700 seeds placed by the same rule. Only the angle between successive seeds differs: 137.5° on the left, 138.5° on the right.

Nothing else has changed. The number of seeds is identical, and so is the rule governing their radial positions. Only the angle between successive seeds has been modified.

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Structural engineer, professor and science communicator exploring engineering, mathematics, AI and science through clear, useful and engaging stories.