24 Aug 2018

Caffeinated entropy

Often I wonder why people stir the milk in their coffee or tea for more than ten times. Cling cling cling cling cling. How annoying.

That's overstirring. A good mixing can probably be achieved in less than ten stirs. That is, the distribution of milk particles in the coffee quickly becomes uniform over time and plateaus after just a few stirs.

Funny. A uniform distribution of milk particles is then the goal of coffee stirring. I couldn't help but imaging what happens to the milk particles when you cease stirring. Well, assuming the latte as ideal fluid and a closed system, do the milk particles perform Brownian movement? If so, then the distribution of milk particles over time becomes...random? Maximum entropy?

Hang on. There's a reason to keep stirring then. To keep the milk particles from becoming randomly distributed. To keep them uniformly spaced in the coffee, or tea. To ensure each sip are consistent in taste and texture.

Can't really blame the old man next table for clinging clinging and clinging now, can I?