Each firefly has a phase oscillator. When it peaks, it flashes. Each flash nudges nearby fireflies toward the same phase. Drag the density slider. Watch what happens above the threshold.
Sync order measures global coherence (0 = random phases, 1 = perfect sync). The critical transition appears around 0.6–0.7. Period is detected from collective flash bursts — it emerges, not from any individual. Based on Photinus carolinus research (Science Advances, 2021).