codziennosc: Second law of thermodynamics

Evidence: 100 • authority: 72

The second law of thermodynamics is a physical law based on universal empirical observation concerning heat and energy interconversions. A simple statement of the law is that heat always flows spontaneously from hotter to colder regions of matter (or 'downhill' in terms of the temperature gradient). Another statement is: "Not all heat can be converted into work in a cyclic process." These are informal definitions, however; more formal definitions appear below. The second law of thermodynamics establishes the concept of entropy as a physical property of a thermodynamic system. It predicts whether processes are forbidden despite obeying the requirement of conservation of energy as expressed i…

Evidence: 54 • authority: 72

Entropy is a thermodynamic state variable that quantifies the probabilistic distribution of accessible microstates in a system. The term and the concept are used in diverse fields, from classical thermodynamics (where it was first recognized), to the microscopic description of nature in statistical physics, and the principles of information theory. It has far-ranging applications in chemistry and physics, in biological systems and their relation to life, in cosmology, economics, and information systems including the transmission of information in telecommunication. Entropy is central to the second law of thermodynamics, which states that the entropy of an isolated system left to spontaneous…

Evidence: 54 • authority: 92

Universal Foundations of Thermodynamics: Entropy and Energy Beyond Equilibrium and Without Extensivity.. Thermodynamics is commonly presented as a theory of macroscopic systems in stable equilibrium, built upon assumptions of extensivity and scaling with system size. In this paper, we present a universal formulation of the elementary foundations of thermodynamics, in which entropy and energy are defined and employed beyond equilibrium and without assuming extensivity. The formulation applies to all systems-large and small, with many or few particles-and to all states, whether equilibrium or nonequilibrium, by relying on carefully stated operational definitions and existence principles rathe…

Evidence: 54 • authority: 72

In thermodynamics, the thermodynamic free energy is one of the state functions of a thermodynamic system. The change in the free energy is the maximum amount of work that the system can perform in a process at constant temperature, and its sign indicates whether the process is thermodynamically favorable or forbidden. Since free energy usually contains potential energy, it is not absolute but depends on the choice of a zero point. Therefore, only relative free energy values, or changes in free energy, are physically meaningful. The free energy is the portion of any first-law energy that is available to perform thermodynamic work at constant temperature, i.e., work mediated by thermal energy…

Evidence: 48 • authority: 88

The Second Law of Thermodynamics. We have seen that the first great principle of energy transfers is that energy is conserved. The essence of the second principle or law has to do with energy availability, or with the "directionality" of these transfers (processes). In other words, it is observed that once the constraints on the beginning and ending states are decided upon, processes can only proceed spontaneously in one direction between these states and are never observed to proceed in the other direction unless they are "pushed" with an external energy source. For example, a brick can fall off a table onto the floor. The potential energy it has on the table is converted to kinetic energy…

Evidence: 48 • authority: 88

Application of the second law of thermodynamics to industrial processes. An extensive industrial energy data base was developed at the four-digit and sub four-digit Standard Industrial Classification (SIC) level. The data base contains information defining 108 industrial processes which represent the top sixty energy consuming four-digit SIC industries and account for approximately 72 percent of the industrial manufacturing sector energy consumption in the United States. Each process contained in the data base is characterized by a process configuration (i.e., flow diagram) representing a nationally typical plant, and energy and mass balances for each of the unit operations which comprise t…

Evidence: 48 • authority: 72

Entropy is one of the few quantities in the physical sciences that requires a particular direction for time, sometimes called an arrow of time. As one goes "forward" in time, the second law of thermodynamics says, the entropy of an isolated system can increase, but not decrease. Thus, entropy measurement is a way of distinguishing the past from the future. In thermodynamic systems that are not isolated, local entropy can decrease over time, accompanied by a compensating entropy increase in the surroundings; examples include objects undergoing cooling, living systems, and the formation of typical crystals. This idea has been first proposed by Ludwig Boltzmann in 1877. Much like temperature,…

Evidence: 42 • authority: 80

Work, Energy, and Heat: First Law of Thermodynamics

Evidence: 42 • authority: 92

Econophysics and the Landauer Principle: A Redefinition of Economic Temperature.. A redefinition of key notions in econophysics based on the Landauer principle is proposed. Marginal economic temperature is defined via the economic Landauer principle and is proportional to the minimal monetary cost associated with erasing or transmitting one bit of information in a given economic system. The actual economic temperature is defined as the effective monetary cost per irreversibly processed bit in a given economic system. The introduced definitions are particularly relevant for high-frequency trading environments. The Clausius formulation of the Second Law is reformulated for economic systems as…

Evidence: 42 • authority: 72

The concept entropy was first developed by German physicist Rudolf Clausius in the mid-nineteenth century as a thermodynamic property that predicts that certain spontaneous processes are irreversible or impossible. In statistical mechanics, entropy is formulated as a statistical property using probability theory. The statistical entropy perspective was introduced in 1870 by Austrian physicist Ludwig Boltzmann, who established a new field of physics that provided the descriptive linkage between the macroscopic observation of nature and the microscopic view based on the rigorous treatment of large ensembles of microscopic states that constitute thermodynamic systems.

Evidence: 36 • authority: 80

The first and second law of thermodynamics

Evidence: 36 • authority: 92

A principled basis for nonequilibrium network flows.. The great power of equilibrium statistical physics comes from its principled foundations: its First Law (conservation), Second Law (variational tendency principle), and its Legendre Transforms from observables (U, V, N) to their driving forces (T, p, μ). Here, we generalize this structure to nonequilibria in Caliber Force Theory, replacing state entropies with path entropies; and replacing (U, V, N) with dynamic observables (node probabilities, edge traffics, and cycle fluxes). Caliber Force Theory derives dynamical forces and a complete set of conjugate relations: (i) It yields generalized Maxwell-Onsager relations and fluctuation-respo…