A form of this phenomenon studied by Aldert van der Ziel that occurs in the abelian sandpile model is sometimes named for the fact that it obeys an inverse power law with an exponent between 1 and 2. So-called “dark current” occurs due to a type of this phenomenon discovered via experiments in vacuum tubes. A form of this phenomenon is modelled as a Poisson process and occurs due to electric charge (10[1])quantization. (10[2])Thermal agitation (10[1])produces a form of this phenomenon named for Johnson and Nyquist. A form (10[1])of this phenomenon (10[1])has a constant power spectral density across all frequencies and is called its “white” form. For 10 points, name this random fluctuation of a signal, which in audio devices is responsible for the sound of static. ■END■