A day without me

The first thing to understand about the 2nd Law of Thermodynamics is that energy changes are what keep the universe going. And what keeps energy going is its tendency of flowing from high concentrations to lower concentrations. The total amount of energy doesn't change, but it becomes less useful every time it moves, this is the second thing to understand.

When it comes to doing useful work like running, highly concentrated energy is easier to use and more efficient. Foods like carbs and fats have highly concentrated energy and it is efficient for us to use it to fuel our bodies. Cellular respiration is the process by which humans convert concentrated food energy into muscule work, but most of it converts in heat making us hot and sweaty.

In conclusion, the 2nd Law describes how energy always and eventually runs down until it's not useful because it becomes heat, hence the principle of entropy.

A thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system

I didn't know, until recently, that the lines in a red Solo plastic cup could be used to measure the amount of liquid you pour into it. It makes a lot of sense to me but I haven't been able to try it myself. I think I'm going to throw a party just to see if that really works.