CRITICAL SPEEDING UP OBSERVED

The extreme compressibility of a fluid near its liquid-vapor critical point significantly alters its dynamic response to temperature changes. Adiabatic processes allow a fluid of constant volume to thermalize in a matter of seconds, compared with the hours or days that thermal diffusion would require. Moreover, the adiabatic transient is faster as the temperature of the fluid approaches the critical temperature. We present experimental measurements of turbidity in critical xenon which show the fast time scale of the adiabatic transient and the phenomenon of critical speeding up. © 1990 The American Physical Society.