Note from Oleksandr: Please scroll down after you finished reading this article and give us your opinion on which law of thermodynamics is the most important according to you.
The second law of thermodynamics, in my opinion, is the most important one to understanding the others. It states that the entropy of a closed system is always increasing. Our universe being a closed system because no particles come in or leave, tells us that the law is true for our universe too. Entropy is a measure of chaos and disorder in the universe. An exaple is a cube of sugar. When you drop it into tea it will dissolve, and you will never be able to stick it back the same way again. Humans, and other complex beings seem like they arent realistic if you take the law into consideration, but we are not a close system, as we exchange heat and energy with our surrounding. Something terrifying that you can find out from the law is that ultimately thermal equilibrium will lead to the universes heat death. Thermal equlibrium is something that needs to be explained on an example. Take a refrigerator – it is cold at all times, but if you leave the door open, in some time it will take the same temperature as the room it is in. The same can happen to our universe – it will become all the same temeprature, and therefore no spontaneous actions – like an ice-cube melting won’t happe anymore. At least the universe wont experience the heat death In a long time so theres nothing to worry about. Now you should have a basic understanding of the second law of thermodynamics and the basis to future learning.