ABSTRACT
In a Darwinian environment where organisms compete for limited resources, the ability to consume, grow, and reproduce more rapidly than one’s rivals may lead to a selectable advantage. Water plays an important part in the living world on scales ranging from a single cell to groups of organisms swimming in schools. Its physical and chemical properties are of direct relevance to the structure and function of biomolecules. The chapter investigates the properties of fluids with regards to their motion by developing the model of the Newtonian fluid. The microscopic origins of the viscosity can be traced back to thermal diffusion of the molecules of the liquid. If a velocity gradient is set up in a fluid, then diffusion of molecules from regions of space characterized by a smaller fluid velocity to ones where the velocity is higher, and vice versa, will result in transfer of momentum and consequently a force.
