“Like the roulette wheel, a computer can produce a sequence of numbers that is random in the same sense. In fact, using a mathematical model, the computer could simulate the physics of the roulette wheel and throw a simulated ball at a slightly different angle each time in order to produce each number in the sequence. Even if the angles at which the computer throws the simulated ball follow a consistent pattern, the simulated dynamics of the wheel would transform these tiny differences into what amounts to an unpredictable sequence of numbers. Such a sequence of numbers is called a pseudorandom sequence, because it only appears random to an observer who does not know how it was computed. The sequence produced by a pseudorandom number generator can pass all normal statistical tests of randomness.”