Physicist Kostya Trachenko at Queen Mary University of London identified a new constraint on fundamental physical constants. The constants must permit liquids to flow in ways that support life within and between cells, according to research published in Science Advances.
Viscosity, the resistance of fluids to flowing, depends on fundamental physical constants. Water flows easily because it has low viscosity, while honey and tar move slowly due to high viscosity. Trachenko's work showed that a lower limit on liquid viscosity connects directly to the basic constants governing the universe.
Living cells require molecules to move through fluids. Nutrients must reach where they are needed, waste products must be transported away, and diffusion must occur for chemical reactions to proceed. If viscosity changed significantly, these processes would break down.
Trachenko explained the connection: "If fundamental constants change, viscosity would change too impacting life as we know it. For example, if water was as viscous as tar life would not exist in its current form or not exist at all."
He suggested the range of constants compatible with cellular life could be narrow. "Any change in fundamental constants including an increase or decrease would be equally bad news for flow and for liquid-based life. We expect the window to be quite narrow: for example, viscosity of our blood would become too thick or too thin for body functioning with only a few per cent change of some fundamental constants such as the Planck constant or electron charge."
A follow-up study published in January 2025 in The European Physical Journal E examined how fundamental constants influence blood viscosity. Despite blood's complexity containing plasma, red blood cells, and platelets, its viscosity remains surprisingly close to a theoretical value derived from basic physical constants.
The findings raise a question about why the universe's fundamental laws have values suited to supporting life.