Consider a system that undergoes a continuous phase transition at the critical value λ λ = λ λ c = 0 of a control parameter. The theory of critical phenomena states that, as the control parameter is tuned closer and closer to its critical value, the correlation length ξ ξ and the relaxation time τ τ of the system tend to diverge algebraically with the critical exponent ν ν as ξ ξ ∼ ∼ λ λ − − ν ν , τ τ ∼ ∼ λ λ − − z ν ν , respectively. z is the dynamic exponent which relates spatial with temporal critical fluctuations.