pink noise

Neither regular nor random: a fractal fluctuation that looks the same at every zoom, found in the variability left after you subtract the average. Its presence indicates a system whose parts interact so densely you cannot say which component did what — how you walked twenty paces ago still affects the next stride. This is why sorter/sorted can be measured rather than only described, why interaction-dominance has evidence behind it, and why the fluctuation is the finding rather than what obscures it.