Everyone in the west has heard of the Second Law of Thermodynamics, but very few can quote it accurately and even fewer actually understand it. Mathematically, it’s very simple to state:
ΔS = ΔH/Tabs
In words, the change in entropy equals the change in enthalpy (another hard-to-grasp subject, but it’s got the units of energy) over the absolute temperature. This, incidentally, is why the Carnot limit for thermal efficiency is (Tsource
) / Tsource
; the entropy of the heat coming from the source equals the entropy of the heat going to the sink, so there is no net increase in entropy. No heat engine can achieve anything as good as the Carnot limit, and most are much worse. You can generate
electricity, which has almost zero entropy, from heat, but you have to throw out lots of waste heat carrying all the entropy in the inputs, plus more entropy generated in the process, with it.
There are many, many natural processes in which local entropy decreases. Consider the freezing of water. Liquid water is a highly disordered substance, while ice is largely organized into 6-molecule rings; ice has far less entropy than the water does. So where does this entropy go? The answer is, it goes with the heat. The heat of fusion of 80 calories per gram, divided by the freezing point of 273.15 K, equals the difference of entropy between water and ice. If the temperature is lower than the freezing point, the heat which seeps into the environment from the freezing water has more entropy than the water loses in forming ice, so net entropy increases; if the temperature is higher than the freezing point, the heat coming from the environment to thaw the ice has less entropy than the ice gains in forming water, so net entropy increases. The Second Law is obeyed in both cases.
What happens to this entropy? It doesn’t accumulate on earth; it gets radiated out into space along with the escaping heat. The entropy of the universe in general increases, but the entropy of earth is DECREASING as e.g. heat from the core and mantle seeps up to the surface and is lost.
This applies to more complex processes as well. Consider the bete noir of all “2LOT makes evolution impossible” zealots: the green plant. A plant takes high-entropy CO2 and water and turns it into low-entropy sugars and amino acids and phenols and lipids, from which it builds even lower-entropy cellulose, lignin and cells. Since we don’t have any processes which can decrease entropy in general, where is it going? It’s expelled from the plant as low-entropy sunlight (effectively temperature of about 5700 K) is converted into high-entropy ambient heat. Every step from photon to excited chlorophyll molecule to ATP to splitting water to reducing CO2, making sugars, etc. is irreversible; it generates entropy. But the plant and its environment becomes MORE orderly as gas and water is assembled into organized molecules and larger units; the entropy is dissipated as heat and ultimately radiated off to space.
The Miller-Urey experiment, repeated many times over, is more proof that the 2LOT is no obstacle to local decreases in entropy. Converting water and light gases into a soup of sugars, amino acids and nucleotides is most definitely a decrease in entropy, but it’s far outweighed by the entropy generated as the electricity for the spark or UV light is converted to ambient heat. The key take-home fact is that entropy doesn’t stay inside the reaction vessel.
The contents can become more orderly over time.
I’ve never encountered a single anti-evolutionist who can address these facts. It’s a mind-killer for them; it threatens their entire concept of self. They’re as bad as social justice warriors in that regard, and that’s saying something. When irrefutable facts are rejected as a moral issue, that’s a problem.
Labels: 2nd Law, entropy, evolution, Miller-Urey