Systems and Processes in Thermodynamics

Systems and processes play a vital role in understanding physics, chemistry, and biology. Systems may be of different sizes and they are characterized by their structure, stability, properties, bonding, reactivity, interactions, etc. The state of a classical N -particle system is defined in a 6 N -dimensional phase space, while a related wave function is generated in a 3 N -dimensional configuration (or equivalently momentum) space for a corresponding quantum system. On the other hand, a process takes a system from one state to another, like going from ‘being’ to ‘becoming’. Depending on the different length scales for the former and time scales for the latter, one needs to resort to appropriate theoretical frameworks like classical mechanics, quantum mechanics, molecular mechanics, statistical mechanics, molecular simulation, multi scale-modeling, etc.