Interesting Facts About Laws of Thermodynamics

• Zeroth law: Although the concept of thermodynamic equilibrium is fundamental to thermodynamics, the need to state it explicitly as a law was not widely perceived until Fowler and Planck stated it in the 1930s, long after the first, second, and third law were already widely understood and recognized. Hence it was numbered the zeroth law. The importance of the zeroth law as a foundation to the earlier laws is that it defines temperature in a non-circular logistics without reference to entropy, its conjugate variable. • First law is nothing but a connotation of Energy Conservation • Second Law of Thermodynamics has been formulated differently by many scientists like Kelvin, Planck, Clausius and Caratheodory. But this law is the outcome of a very basic fact that Entropy of a spontaneous system always increases. Entropy is also defined qualitatively as Disorder of state. This is a common experienced fact that if let on its own, the disorder of a system always increases and work has to be done to bring it back in order. • According to the second law the entropy of any isolated system, such as the entire universe, never decreases. If the entropy of the universe has a maximum upper bound then when this bound is reached the universe has no thermodynamic free energy to sustain motion or life, that is, the heat death is reached. • The famous theory of evolution violates our Second Law of thermodynamics. Second law states that the entropy (disorder) of an isolated system always increases. Considering the Universe is an isolated system, various stages in Theory of evolution like Big Bang, or even our improvement in all respects since ever clearly goes against the law that disorder always increases. eg. Plants would have never evolved and started converting useless solar energy to useful form of energy (food) if the entropy was supposed to increase. Snowflakes, sand dunes, tornadoes, stalactites, graded river beds, and lightning are just a few examples of order coming from disorder in nature. • But even more enticing fact is that both theory of evolution and second law of thermodynamics are philosophical. Second law is a blend of experience and sense. Though there is no exception yet found practically to second law, there is no guarantee that none will be found in future. • In fact second law has always been marred with controversies. The famous Maxwell Demon Paradox attempts to prove 2nd law wrong.
Maxwell imagines one container divided into two parts, A and B. Both parts are filled with the same gas at equal temperatures and placed next to each other. Observing the molecules on both sides, an imaginary demon guards a trapdoor between the two parts. When a faster-than-average molecule from A flies towards the trapdoor, the demon opens it, and the molecule will fly from A to B. The average speed of the molecules in B will have increased while in A they will have slowed down on average. Since average molecular speed corresponds to temperature, the temperature decreases in A and increases in B, contrary to the second law of thermodynamics.

One of the most famous responses to this question was suggested in 1929 by Leó Szilárd, and later by Léon Brillouin. Szilárd pointed out that a real-life Maxwell's demon would need to have some means of measuring molecular speed, and that the act of acquiring information would require an expenditure of energy. Since the demon and the gas are interacting, we must consider the total entropy of the gas and the demon combined. The expenditure of energy by the demon will cause an increase in the entropy of the demon, which will be larger than the lowering of the entropy of the gas.