How does the entropy in the universe always increase?
Take this as an example. Connect two bulbs via a tap of some sort. Have one bulb filled with a gas and the other a vacuum. When the tap is closed there is a finite number of ways to arrange the gas molecules. Now open the tap and gas rushes through to equilibrate the pressure. This results in a greater number of ways of arranging the molecules. To see this consider just one molocule passing through and place it randomly inside the second bulb. This is exaclty one more way of arranging the molecules than when the tap is closed, put is somewhere else in the second tube or move two molecules through and the combinations get very much bigger very rapidly. Entropy is a measure of the level of disirder in the system, the number of available states open to it. All spontaineous processes lead to an increase in entropy of the system as a whole. The entropy of water which has ice put in it goes down but the entropy of the ice goes up a disproportionately large amount resulting in a net increase
