What is entropy?
Entropy describes the tendency for systems to go from a state of higher organization to a state of lowest organization on a molecular level. In your day-to-day life, you intuitively understand how entropy works whenever you pour sugar in your coffee or melt an ice cube in a glass. Entropy can affect the space into which a substance spreads, its phase change from solid to liquid to gas, or its position. In physics, entropy is a mathematical measurement of a change from greater to lesser potential energy, related to the second law of thermodynamics. Entropy comes from a Greek word meaning, “transformation.” This definition gives us insight into why things seemingly transform for no reason. Systems can only maintain organization on a molecular level as long as energy is added. For example, water will boil only as long as you hold a pan over flames. You’re adding heat, a form of kinetic energy, to speed up the molecules in the water. If the heat source is removed, we all can guess that the
Entropy is one of the most fundamental concepts of physical science, with far-reaching consequences ranging from cosmology to chemistry. It is also widely mis-represented as a measure of “disorder”, as we discuss below. The German physicist Rudolf Clausius originated the concept as “energy gone to waste” in the early 1850s, and its definition went through a number of more precise definitions over the next 15 years. Wikipedia has an interesting “history of entropy” page.
“, is to reiterate something I said in the introduction: Entropy is what the equations define it to be. You can interpret those equations to come up with a prosey explanation, but remember that the prose & the equations have to match up, because the equations give a firm, mathematical definition for entropy, that just won’t go away. In classical thermodynamics, the entropy of a system is the ratio of heat content to temperature (equation 1), and the change in entropy represents the amount of energy input to the system which does not participate in mechanical work done by the system (equation 3). In statistical mechanics, the interpretation is more general perhaps, where the entropy becomes a function of statistical probability. In that case the entropy is a measure of the probability for a givem macrostate, so that a high entropy indicates a high probability state, and a low entropy indicates a low probability state (equation 6). Entropy is also sometimes confused with complexity, the
