In the history of science, the study of celestial motions led to the development of Newtonian mechanics, a framework that can be understood by anyone who has taken a basic physics course. By contrast, the effort to convert heat into motion—an issue far more closely connected to everyday life—gave rise to thermodynamics, a field that has evolved over more than two centuries and whose full implications are still not universally understood, even among those who work with it.
Initially, thermodynamics focused on heat and its potential to produce mechanical work. It later expanded to encompass the broader concept of energy and its transformation from one form to another. Over time, thermodynamics became a general theory of transformations of the states of matter, with motion generated by heat appearing as a particular consequence of these transformations. At its foundation lie two fundamental laws: one concerned with energy and the other with entropy.
Every system possesses both energy and entropy. When matter transforms from one state to another, the total energy of the system and its surroundings is conserved, whereas the total entropy can only increase or, in ideal cases, remain constant. These statements appear simple, yet they lead to far-reaching consequences. Max Planck (1858–1947) was deeply impressed by the scope of what could be derived from them and devoted a substantial part of his scientific life to the study of thermodynamics.
Albert Einstein (1879–1955) captured the intellectual power of nineteenth-century thermodynamics in a frequently cited remark:
“A theory is the more impressive the greater the simplicity of its premises, the more different kinds of things it relates, and the wider its range of applicability. Therefore the deep impression which classical thermodynamics made upon me. It is the only physical theory of universal content which I am convinced will never be overthrown, within the framework of applicability of its basic concepts.”
The thermodynamics that so impressed Planck and Einstein was the thermodynamics of equilibrium. It described stationary systems and was formulated to calculate entropy differences between initial and final equilibrium states. In this classical framework, there was no direct link between natural processes—such as chemical reactions or heat transfer—and the rates at which these processes unfold.
In the twentieth century, Lars Onsager (1903–1976), Ilya Prigogine (1917–2003), and others extended the formal structure of classical thermodynamics by explicitly relating entropy production rates to the rates of irreversible processes such as chemical reactions, transport phenomena, and heat flow. Thermodynamics thus became not only a theory of equilibrium states, but also a theory of irreversible processes.
Modern thermodynamics, equipped with a formalism that allows entropy production rates to be quantified, offers a fundamentally new perspective on the role of irreversibility in nature. Importantly, this perspective is not merely of conceptual or philosophical interest. It has become essential for addressing practical engineering challenges in the contemporary world.
Many of today’s critical engineering problems—ranging from energy conversion and storage technologies to climate-responsive systems, multiphase processes, and biologically inspired applications—operate far from equilibrium and are dominated by irreversible dynamics. Approaches based solely on equilibrium or quasi-equilibrium assumptions often fail to capture the mechanisms that govern efficiency, stability, and control in such systems.
From an engineering standpoint, non-equilibrium thermodynamics provides the appropriate language for analyzing and designing systems that operate under continuous fluxes of matter, energy, and information. A process-based framework enables engineers to identify limiting mechanisms, optimize performance under realistic operating conditions, and design systems that remain robust in fluctuating environments. In this sense, irreversibility should not be viewed merely as a source of loss, but as an active element shaping functionality, adaptability, and organization.
Engineering thermodynamics, therefore, need not—and in the context of the twenty-first century cannot—remain confined to classical equilibrium formulations. In an era where engineers increasingly shape not only machines but complex socio-technical and biological systems, a thermodynamic understanding grounded in irreversible processes is indispensable. Thermodynamics beyond equilibrium is not an abstract extension of classical theory; it is a practical necessity for engineering practice in an open, evolving, and uncertain world.
Yorumlar
Yorum Gönder