Dynamical Scaling and Critical-Point Universality of Fluids

The hypothesis of dynamical scaling asserts that, sufficiently close to the critical temperature, the decay rate Γ of the order-parameter fluctuations assumes the form Γ=qᶻΩ(qξ), where q is the wave number and ξ the correlation length. A new accurate experimental study of this decay rate in 3-methylpentane-nitroethane yields the value 3.06 ±{} 0.02 for the dynamical scaling exponent z, in excellent agreement with the theoretical predictions for the dynamic universality class of fluid systems.