Experimental measurement of the persistence exponent of the planar Ising model

Using a twisted nematic liquid crystal system exhibiting planar Ising model dynamics, we have measured the scaling exponent θ. which characterizes the time evolution p(t) - t^-θ, of the probability p(t) that the local order parameter has not switched its state by the time t. For 0.4 sec-200 sec following the phase quench, the system exhibits scaling behavior and. measured over this interval. θ=0.19±0.03, in good agreement with theoretical analysis and numerical simulations.