Paper published in Nature Communications

In chemistry and physics, it is well known that cooling a fluid to its liquid-vapor critical point will cause a striking transformation called critical opalescence -- at this special set of conditions, the fluid suddenly appears cloudy. The hard-earned explanation for this phenomenon is that as it is cooled, the fluid practices splitting into liquid and gas by forming regions of low and high density. Fluctuations and correlations in these regions grow precipitously to macroscopic length scales and scatter light, making the fluid appear opaque. This statistical description has sufficed for towering advances in statistical physics including universal scaling laws and the powerful theoretical machinery of the renormalization group (for which K. Wilson was awarded the Nobel Prize in 1982). Less understood, however, is what impact this critical phenomenon has on the motion of individual molecules. Missing is a complete understanding of the mechanical instability driving the anomalous statistical features of this singular state. That is, we do not currently have an understanding worthy of Gibbs' name for this program -- statistical mechanics. Using theory and computer simulations, we have shed new light on this problem. We have shown that the degree of chaos in the molecular motion is suppressed as the fluid approaches the critical point and begins to practice splitting into liquid and gas.