Nonequilibrium Physics of Molecules and Cells

Abstract

AbstractA thermodynamic system consists of particles and/or fields that are bound in space. The rest is the environment. The system can be open in which case the system can exchange matter and radiation with the environment as well as heat and work can be done on the system. A closed system can exchange heat and work can be done on it, but no matter or radiation is exchanged with the environment. An isolated system cannot exchange anything with the environment and work cannot be done on it. A fundamental concept in thermodynamics is the state of a system and its thermodynamic variables. Thermodynamic variables are macroscopic variables like number of particles, pressure, volume, and temperature. A state of a thermodynamic system is specified by the values of these variables. A system is said to be in equilibrium if all thermodynamic variables are constant in time and all macroscopic flows are zero. If the thermodynamic variables are constant, but there are macroscopic constant flaws, the system is in a steady state. If the thermodynamic variables or flaws vary in time the system is nonequilibrium. The zeroth law of thermodynamics states that two systems in thermodynamic equilibrium with a third system are in thermodynamic equilibrium with each other. Thus, we can introduce a small system called thermometer that will equilibrate fast with big systems and measure the temperature of other systems by putting the thermometer in touch with the measured system. Historically, the equilibration of the temperature of two objects in contact was characterized by the heat that flows from the warmer to the colder body.