DYNAMICS

A steaming cup of coffee is sitting on my desk. Aside from the steam, there is little else that would suggest any other activity is present. The cup and it contents appear to be “at rest”. But a little closer examination reveals a small ripple of waves on the surface of the liquid caused by a mechanical pump in the room next door. Indeed, if I rest my finger gently on the lip of the cup, I can feel the vibration. I can also feel the heat that has developed in the cup, now several minutes since I poured the coffee from the pot and added some creamer.

If I could examine this evenmore closely Iwould actually see that nothing is truly “at rest”. The particles of the liquid are jostling about incessantly. The particles of the creamer that I added have clearly taken flight and diffused rapidly out into all regions of the coffee. The cup itself is also in motion. Its particles are undergoing incessant vibrations that are ultimately responsible for the heat I feel when I hold it.

Perhaps most interesting is that all this microscopic motion appears to be driven entirely by thermodynamics. The coffee and cup are sitting in a climatecontrolled office and there is a constant flux of thermal energy (heat) entering and exiting both the coffee and the cup to keep things moving.