“The second law of thermodynamics states that the total entropy of an isolated system always increases in time. (or remains constant in ideal cases)”
You’ve never heard of entropy? Ok, let me explain it simply: Entropy is a measure of the disorder of a system. And according to this law, the disorder of an isolated system always increases. Well, let’s say, you dropped a cup and broke it into pieces. Have you ever seen those pieces coming back together? Or have you ever managed to unscramble an egg? I guess not. Well, that’s because entropy never decreases.