Sometimes when people argue, they make the mistake of not defining their terms. Two people will argue in both directions, and barely an hour later, they will realize that they are really arguing about the meaning of the words. The zero law of thermodynamics is a bit like these arguments – it`s not deep or extremely important, but you have to dismiss it, otherwise everything else becomes a waste of time. But before we talk about the zero law, we must first define thermodynamics. A thermodynamic system, by definition, is in its own state of internal thermodynamic equilibrium, that is, there is no change in its observable state (i.e. macro-state) over time and no current occurs in it. A precise statement of the zero law is that the thermal equilibrium relation is an equivalence relation on pairs of thermodynamic systems. [7]: 52 In other words, the set of all systems, each in its own state of internal thermodynamic equilibrium, can be divided into subsets in which each system belongs to a single subset and is in thermal equilibrium with all other members of that subset and is not in thermal equilibrium with a member of another subset. This means that each system can be assigned a unique “tag”, and if the “labels” of two systems are the same, they are in thermal equilibrium with each other, and if they are different, they are not.
This property is used to justify the use of empirical temperature as a marking system. Empirical temperature provides other thermally balanced system relationships, such as order and continuity with respect to “heat” or “cold”, but these are not implicit in the standard statement of the zero distribution. Well, heat always spontaneously transfers from warm places to cold places. It turns out that this is a way of formulating the 1st law of thermodynamics. However, this means that both objects or systems must be at the same temperature so that heat does not circulate when it can. With the three laws, the need for a law formalizing the concept of temperature became obvious. Since the concept of temperature is fundamental to understanding any law of thermodynamics, the British mathematician Ralph H. Folwer (1889-1944) treated temperature as: This law is important for the mathematical formulation of thermodynamics, which requires the assertion that the thermal equilibrium relation is an equivalence relation. This information is necessary for a mathematical definition of temperature compatible with the physical existence of valid thermometers.
If it is defined that a thermodynamic system is in thermal equilibrium with itself (i.e. thermal equilibrium is reflexive), then the law of zero can be given as follows: The zero law of thermodynamics defines temperature and makes thermometers possible. However, for a thermometer to be useful, it must first be calibrated. All other basic units of measurement — such as length, mass, time, etc. — are each defined according to a specific standard. In this case, scientists need to define not only a unit of measurement, but also the starting point of the scale. Taking into account the three objects A, B and C, the zero law of thermodynamics states: As an example of thermodynamics in action, placing a pot of water on a heated oven causes the pot to heat when heat is transferred from the oven to the pot. This in turn causes the water molecules to jump into the pot. The faster movement of these molecules is observed in the form of warmer water. It is the function of this statement in the article, which is not called the zero law here, not only to foresee the existence of a transfer of energy in a way other than by labor or the transfer of matter, but further to provide that such a transfer is unique in that there is only one type of wall of this type. and a kind of transfer of that kind. This is pointed out in the postulate of this work by Carathéodory that exactly a non-deformation variable is necessary to complete the specification of a thermodynamic state, beyond the necessary strain variables, which are not numerically limited.
It is therefore not entirely clear what Carathéodory means when he writes in the introduction to this article that temperature is a property that distinguishes thermodynamics from other sciences. This property makes it possible to distinguish hot from cold. When two or more bodies are brought into contact with different temperatures, they reach a common temperature after a certain time and are assumed to exist in thermal equilibrium. Written this way, suddenly Law Zero becomes really obvious. Of course, if object A has the same temperature as B and C, then B and C have the same temperature as each other. So why are we talking about something so obvious? This statement may seem trivial, but it is necessary because without this law, the other laws of thermodynamics cannot be properly defined. The zero law of thermodynamics is observed in many everyday situations. Two systems in thermal contact eventually reach a state of thermal equilibrium. This state is clearly defined by temperature, which is a universal function of state properties and internal energy. If system 1 is in equilibrium with system 2 and if system 2 is in equilibrium with system 3, then system 1 is in equilibrium with system 3. This is called the zero law of thermodynamics and involves the construction of a universal temperature scale (first given by Joseph Black in the 18th century and named much later by Guggenheim).
If a system is in thermal equilibrium, it is assumed that the energy is clearly distributed over the volume. As the system energy increases, the system temperature also increases (dU/dT> 0). In other words, the zero law means that all three bodies have the same temperature, according to NASA (opens in a new window). James Clerk Maxwell (opens in a new window) put it perhaps more simply when he said, “All heat is the same.” (Longmans, Green et Cie, 1875). Most importantly, the zero law states that temperature is a fundamental and measurable property of matter. Nevertheless, the most common application of the zero law of thermodynamics can be seen in thermometers. We can observe the zero law in action by taking a very ordinary thermometer with mercury in a tube. When the temperature rises, this mercury expands because the surface of the tube is constant.
This extension increases the height. Now, increasing the height of the mercury label shows the temperature changes and basically helps us measure them. You yourself do not use the expression “zero law of thermodynamics” here. There are many statements of the same physical ideas in the physical literature long before this text, in very similar language. The only novelty here was the law of thermodynamics. Simply put, the zero law states that if object A has the same temperature as B and C, B and C have the same temperature. It may seem really obvious, but our understanding of temperature is the foundation on which the rest of thermodynamics is built. Fowler & Guggenheim (1936/1965)[17] wrote about the zero law as follows: Similarly, in accordance with the zero law, we find that from Fig. 14.11 we conclude that the zero law of thermodynamics states that if two bodies are each in thermal equilibrium with a third body, they are also in equilibrium with each other. This essentially explains that if objects A and B are each in thermal equilibrium with object C, A and B are in thermal equilibrium with each other. In addition, we can note that the first and second laws were well established as supplementary laws and could not be renumbered in the first and second laws, hence its name of law zero.
According to Sommerfeld, Fowler coined the term zero law of thermodynamics[15] while discussing the 1935 text by Meghnad Saha and B.N. Srivastava. [16] Some examples of everyday life that illustrate the zero law of thermodynamics are: The zero law of thermodynamics takes into account that temperature is something worth measuring because it predicts whether or not heat will be transferred between objects. This is true regardless of how objects interact. Even if two objects are not in physical contact, heat can flow between them through the radiant heat transfer mode. While the zero law of thermodynamics states that when systems are in thermal equilibrium, there is no heat flow. Lieb and Yngvason (1999)[7] are of the opinion that the derivation of the law of increasing entropy from statistical mechanics is an objective that has so far eluded the deepest thinkers. [7]: 5 Thus, the idea remains open that the existence of heat and temperature are necessary as coherent primitive concepts for thermodynamics, as expressed for example by Maxwell and Planck.
