The Principle of Entropy and Erosion of Material Structures

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From experience, anyone knows that inanimate objects always tend to reach stabler states. We consider quite natural to see a book fall from a shelf, a brick from a wall, or a shingle to the ground, but we do not expect the fallen book, brick, or shingle to go back to their original positions on the shelf, wall, or roof, respectively. Such miracles could happen in the world of myth and fiction but not in the real world ruled by the rigorous laws of nature. We consider the above objects to have found their stabler or more probable, although less-ordered, states. All the above-mentioned examples are unidirectional and less-ordered states, and the spontaneous return to the original ordered state is impossible. But exceptions exist. Nests of birds and beaver dams are ordered structures, artifacts that cannot arise naturally. Termites build mounds, which clearly are structures that cannot occur spontaneously  They build their mounds above their subterranean multichambered nests, and the mounds may be of different sizes, shapes, and heights, with complex mazes of tunnels and shafts used for ventilation. But whether a bird’s nest, a beaver dam, or a termite mound, left under natural conditions, sooner or later all of them are doomed to lose their order and break down.

Over centuries, human civilizations around the globe have added order and created naturally highly ordered structures by investing work and information. Yet observe what remains of Athens’s ancient Acropolis, or of thousands of remnants of ancient and prehistoric works of art, inhabited centers, fortifications, and castles. No one could expect that under natural conditions, the heads of the US presidents carved in granite on Mount Rushmore will remain as originally sculpted by Gutzon and Lincoln Borglum  60 years ago. In fact, fractures in the granite have already occurred. No spontaneous process or event can improve the structure or function of a Porsche; only the opposite is possible. Since the probability of occurrence of less-ordered states is infinitely greater than the ordered state, less-ordered states are more probable, and hence statistically more stable. This explains the observation that all objects in nature tend to reach stabler states: stabler states are statistically more likely to occur.

Such observations of the natural trend of the loss of order in nature, which goes as far back as the origins of humanity, found a theoretical explanation only around the second half of the nineteenth century with the discovery of the second law of thermodynamics, which, in the opinion of many scientists, may be the most universal law governing the universe. Central to the second law of thermodynamics is the principle of entropy. For the purpose of this discussion, a simple and classical definition of the law is:

 

In an isolated system, only processes that are associated with increase of entropy can occur.
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