If you sat down at a poker table with seven people to play five-card stud and dealt a brand new deck right out of the box, the results are a foregone conclusion because new cards are inserted in the box in order. This means that the number of possible states in which the system could be found increases over time. Since heat flows from warm to cold, a system not in equilibrium is in flux it is changing. Entropy is a measure of the number of possible states in which you might find the system if you checked.

Hence, those behind Clausius had a deep disdain for mere probabilistic principles, while those in line with Boltzmann argued that the number of interactions was far too large to be handled by normal means and that probabilistic claims were the best we could make for such large collections.īoltzmann eventually won the day, and entropy is best thought of in terms of what physicists call “ensembles,” the set of all possible states of a thermal system. Physicists traditionally were wedded to mechanistic pictures of point masses bouncing off of each other in accordance with well-structured Newtonian principles. The word “tends” sparked a firestorm with physicists divided between those who took Clausius’ view that, like every other physical quantity, it was subject to absolute deterministic rules and therefore must increase and those who took Boltzmann’s position that thermodynamic quantities were statistical averages, so we have to talk about the probability that entropy most likely increases. They found that “in any process in which a thermally isolated system goes from one macrostate to another, the entropy tends to increase (Reif 1965, 122).” It measures the “disorder” of a system in terms of the number of microstates-arrangements of molecules-accessible to a system in a given macrostate-having a particular temperature, pressure, and volume.

That explanation led them to posit a strange quantity, one not directly observable: entropy. Given its well behaved sibling, the first law of thermodynamics (that energy is always conserved, neither created nor destroyed), researchers sought a means of quantifying and explaining this energy transaction fee. So if we changed money back and forth, we would eventually go broke even with a fixed exchange rate. Whenever we exchange money, say from dollars to Euros, the bank charges a transaction fee.

Scientists and engineers discovered that, when trying to convert one form of energy, e.g., heat, into another form of energy, e.g., motion, we were never able to make the transfer complete, there was always some energy lost.

The second law is best known as the principle that rules out perpetual motion, something resulting from its origin in the question “how efficient can we make steam engines?”-a strangely pragmatic starting point for such an esoteric principle. This is a common misunderstanding of one of the more baffling principles in physics, which has a long and contentious history, having been formulated in different ways by Sadi Carnot, Rudolf Clausius, William Thomson (Lord Kelvin), Ludwig Boltzmann, and Max Planck. The anti-evolutionists’ argument is based on an understanding of the second law of thermodynamics, according to which disorder always increases.

Entropy biology