定律的英文

First lawMain article: First law of thermodynamics“ In any process, the total energy of the universe remains constant. ” More simply, the First Law states that energy cannot be created or destroyed; rather, the amount of energy lost in a steady state process cannot be greater than the amount of energy gained.This is the statement of conservation of energy for a thermodynamic system. It refers to the two ways that a closed system transfers energy to and from its surroundings - by the process of heating (or cooling) and the process of mechanical work. The rate of gain or loss in the stored energy of a system is determined by the rates of these two processes. In open systems, the flow of matter is another energy transfer mechanism, and extra terms must be included in the expression of the first law.The First Law clarifies the nature of energy. It is a stored quantity which is independent of any particular process path, i.e., it is independent of the system history. If a system undergoes a thermodynamic cycle, whether it becomes warmer, cooler, larger, or smaller, then it will have the same amount of energy each time it returns to a particular state. Mathematically speaking, energy is a state function and infinitesimal changes in the energy are exact differentials.All laws of thermodynamics but the First are statistical and simply describe the tendencies of macroscopic systems. For microscopic systems with few particles, the variations in the parameters become larger than the parameters themselves, and the assumptions of thermodynamics become meaningless. The First Law, i.e. the law of conservation, has become the most secure of all basic laws of science. At present, it is unquestioned.Second lawMain article: Second law of thermodynamics“ There is no process that, operating in a cycle, produces no other effect than the subtraction of a positive amount of heat from a reservoir and the production of an equal amount of work. ” This version is the so-called Kelvin-Planck Statement. In a simple manner, the Second Law states that energy systems have a tendency to increase their entropy (heat transformation content) rather than decrease it.The entropy of a thermally isolated macroscopic system never decreases (see Maxwell's demon), however a microscopic system may exhibit fluctuations of entropy opposite to that dictated by the Second Law (see Fluctuation Theorem). In fact, the mathematical proof of the Fluctuation Theorem from time-reversible dynamics and the Axiom of Causality, constitutes a proof of the Second Law. In a logical sense the Second Law thus ceases to be a "Law" of Physics and instead becomes a theorem which is valid for large systems or long times.Stephen Hawking described this using time as an entropy base. For example, when time moves in a forward direction and one, say, breaks a cup of coffee on the floor, no matter what happens, in our universe, one will never see the cup reform. Cups are breaking all the time, but never reforming. Since the Big Bang, the entropy of the universe has been on the rise, and so the Second Law states that this process will continue to increase. Third lawMain article: Third law of thermodynamics“ As temperature approaches absolute zero, the entropy of a system approaches a constant. ” The Third Law says that constant is in fact zero. As the temperature approaches zero, the probability that the system, however complex, sits in its unique quantum ground state approaches one. The entropy of any unique state is zero, so the entropy approaches zero. More rigorously, if the system happens to have half-integer net spin, there are two degenerate ground states, related by time-reversal symmetry, so the dimensionless entropy approaches the natural log of two. However, that is the entropy for the whole system, and is negligible on the scale of any macroscopic system. Basically, no system can reach absolute zero.