α=0: white α=1: pink (1/f) α=2: brown
1/f noise appears throughout nature: heart rate variability, neural activity, music, finance, geophysics. Generated via spectral shaping in Fourier space:
Filter white noise: X̃(f) = G(f) · f^{−α/2} where G is Gaussian white noise. Inverse FFT gives the time series. α=1 is the boundary between stationary (α<1) and non-stationary processes.