The electron's fast heartbeat: the vortex oscillates between a tightly-wound core at
reff ≈ 150 fm and its expanded partner at the reduced Compton wavelength
ħ/mec ≈ 386 fm, once per Compton period TC = 8.1 × 10⁻²¹ s. This is the
Zitterbewegung — the Nambu particle/hole exchange — with energy swapping between core rotation
and the expanded breath, their sum the rest mass energy. (The slow journey out to ξ ≈ 100 μm is a
separate coherence-dress mode at ω₁, roughly 10⁸× slower — see the scale-separation figure.)