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Discovering the mechanism underlying the ubiquity of 1=α noise has been
a long-standing problem. The wide variety of systems showing such long-ranged temporal correlations suggests the existence of some simple and general mechanism. I will argue that memory-less nonlinear response suffices to explain the observed non-trivial values of &#945;: If an input signal S(t) with a power spectrum varying as 1=&#61606; &#945;&#61602;, is fed to a non-linear device with response function R, the output R(S(t)) can have a power spectrum 1&#61604;&#61606;&#945; with &#61472;&#945; < &#945;&#61602;.
As an illustrative example, a bounded Brownian noise (&#945;&#61602; = 2), fed to a device with a sigmoidal response function R(S) = sgn (S)&#61564; S&#61564;x, with x < 1, produces an output with power spectrum exponent &#945; = 3&#61604;2 +&#61604;x, for 0&#61603; x &#61603; 1/2. The argument is easily extended to more general input noise and response functions.