Quick refresher regarding the four laws of thermodynamics:

Zeroth Law: If A = B and B = C, then A = C

Mnemonic: “You must be in balance to measure temperature.”

Explanation: If two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other. This law helps define temperature.

First Law: Energy cannot be created or destroyed

Mnemonic: “You can’t get more energy than you put in.”

Explanation: Energy is conserved. The total energy in a closed system is constant—energy can only be transferred or transformed (e.g., heat to work).

Second Law: Entropy always increases

Mnemonic: “You can’t even break even unless it’s absolute zero.”

Explanation: In any energy transfer, some energy becomes unavailable to do work, increasing the system’s overall disorder (entropy).

Third Law: Absolute zero is unattainable

Mnemonic: “You can’t get out of the game.”

Explanation: As the temperature approaches absolute zero, the entropy of a perfect crystal approaches zero, but absolute zero cannot be reached in a finite number of steps.

Summary:

Zeroth Law: Think of it as “defining temperature.”

First Law: “Energy is conserved” (no free lunch).

Second Law: “Disorder (entropy) always increases” (you can’t break even).

Third Law: “You can’t reach absolute zero” (you can’t get out of the game).