Physicists First Calculated The Yield Point Of A Liquid
Russian and British scientists have derived one of the fundamental equations of physics, which allows us to theoretically calculate the limit to which a liquid remains a liquid for the first time. The equation is based on fundamental natural constants. The results are published in the Science Advances magazine.
It is known that liquids become thicker when cooled and more liquid when heated. If they continue to heat, the liquids begin to boil and pass into a gaseous state. At the transition point, which depends not only on temperature but also on pressure, the liquid has a minimum viscosity. This is the yield point.
Traditionally, it is considered that the viscosity cannot be calculated theoretically, because it depends in a complex way on the structure of the liquid, its composition, chemical interactions, as well as on external conditions. Nobel laureate Steven Weinberg compared the complexity of calculating the viscosity of water to the problem of calculating the fundamental physical constants that underlie the structure of our Universe.
Despite all the difficulties, Kostya Tkachenko from the Queen Mary University of London and Vadim Brazhnik, a Russian scientist and Director of the Institute of high-pressure physics of the Russian Academy of Sciences, succeeded.
At the same time, the yield strength equation obtained by scientists uses two fundamental physical constants-measurable properties of physical nature that does not change the minimum value of elementary viscosity, which is the product of viscosity and volume per molecule, and Planck's constant, which governs the quantum world the dimensionless ratio of the mass of a proton to an electron.
"This result is striking," Professor Kostya Trachenko said in a press release from the Queen Mary University of London. Viscosity is a complex property that varies greatly for different liquids and external conditions. However, it turned out that the minimum viscosity value for all liquids can be simple and universal."
The discovery has a real practical application. First, the new equation will be useful in creating new ultra-low viscosity fluids for various chemical, industrial, or biological processes. It will show the limit beyond which it makes no sense to strive, wasting resources. One example where this is important is the recent use of supercritical liquids for environmentally friendly ways to process and dissolve the complex waste.
Second, since the resulting restriction is fundamental, that is, based on basic physical constants, the discovery can be used to describe the processes that occur in the Universe as a whole, for example, to determine the so-called "habitable zone," where stars and planets can form, and vital molecular structures can arise.
"There are indications that the fundamental lower limit of liquid viscosity may be related to very different areas of physics: black holes, as well as a new state of matter, quark-gluon plasma, which appears at very high temperatures and pressures. Studying and evaluating these and other connections is what makes the research so exciting," says academician Brazhkin.