The answer
Think of your room. Left to itself, it gets messier, not tidier. That's entropy. It's not a force; it's just probability. There are far more ways to be messy than tidy. So, naturally, systems move to more probable states—messy ones. For a gas, molecules spread out because that's statistically likely. Energy disperses. This is the second law: in an isolated system, total entropy (disorder) always increases until equilibrium. It explains why heat flows from hot to cold, and why time feels one-way. Simple rule: disorder wins unless you put in energy (like cleaning) to fight it.
