Scientists from London’s Queen Mary University and the Institute of high pressure physics named after L. F. Vereshagin RAS found a limit to how much can be a viscous liquid. Created by physicists, the equation restricts the figure with the help of fundamental constants. About their work, the researchers reported in the journal Science Advances.

Viscosity is a measure of how much resistance having a liquid or gas when you move one part relative to another. We know that during cooling the viscosity of the substance increases, and decreases when heated. This interval is in reality limited by the temperatures of freezing and boiling liquids. But is there a fundamental limit on how viscous can be fluid? It is believed that viscosity is almost impossible to calculate from theoretical calculations, since it is very difficult depends on the structure, composition and interactions of fluids.

To solve this problem tried two researchers from Russia and the UK. They amounted to an equation describing the minimum value of viscosity. The authors showed that how much liquid can be the liquid, is determined by only two fundamental physical constants — Planck constant and electron mass. In addition, the equation contains the constant PI and the value of the mass of the molecules of a substance, the viscosity of which is a limit.

“This result is astounding. The viscosity is a complex property, greatly varied for different liquids and conditions. However, our results show that the minimum viscosity of all fluids is a simple and versatile size, says lead author, Professor at London Queen Mary University of Constantine Trachenko. The lower fundamental limit shows us how fundamental constants have an impact on our lives — from making a Cup of tea to the operation of hydroelectric power plants”.

There are practical consequences of the discovery of this limit. It can be used where required in the synthesis of liquid for chemical, industrial or biological process with a low viscosity. For example, it can be important when using supercritical fluids for environmentally friendly methods of processing difficult waste. In this case, the minimum limit of viscosity shows to which you can aspire. According to him, the minimum viscosity depends only on the mass of the molecule, and thus in any way it cannot be artificially lowered below this value.