Entropy as Disorder: History of a Misconception

Before reading this essay, go to your kitchen and find a bottle of Italian salad dressing. Get one that\u27s been sitting still for a while at a fixed temperature-that is, one in thermal equilibrium. You\u27ll find an oil-rich layer at the top of the bottle and a vinegar-rich layer at the bottom (see Fig. 1). But think for a moment before spreading it over a delicious salad and eating up. That bottle\u27s in thermal equilibrium, so it\u27s in a state of maximum entropy. Doesn\u27t entropy mean disorder ? No one would call a stack of 50 pennies and 50 dimes disordered if all the dimes were on the top and all the pennies at the bottom. So why is this salad dressing at thermal equilibrium segregated like an ordered stack of coins