Recently, the extrema of classically-defined thermophysical properties such as thermal diffusivity 𝜄 thermal [m 2 /s], kinematic viscosity (i.e., momentum diffusivity) 𝜄 fluid [m 2 /s], and the speed of sound 𝑢 sound [m/s] were shown to be bounded by fundamental constants of nature . The lower bounds for kinematic viscosity and thermal diffusivity of a fluid, for instance, can be related through the inequality given as