When you drop an egg on the floor, it breaks. But dropping a broken egg on the floor doesn't cause it to become whole.A new deck of cards comes with all the cards in order. Shuffling them mixes up the cards. Now take a deck of cards that's mixed up and shuffle them. The cards do not come back to their original order.
Pick up a can of air freshener and push down the button. The air freshener spews out of the can and spreads out around the room. Now try gathering up the air freshener and putting it back in the can. Doesn't work, does it?
You put ice in a drink to make it colder. You trust that when you do this, your drink will get colder while the ice gets warmer, and eventually melts. Pouring water into a cold drink won't cause the reverse of this process to occur. That is, when you pour water into a cold drink, the water doesn't freeze while the rest of the drink gets warmer.
The shuffling of a deck of cards, the spray of an aerosol can, the flow of heat from warm things to cold things, the breaking of an egg; these are all examples of what physicists call " irreversible processes" . They occur very naturally, but all the king's horses and all the king's men can't undo them.
Practically everything that goes on in the universe is irreversible. (In the technical, "physics" sense, that is. Don't read anything politcal, philosophical, or sociological into that last statement!) But why are all these processes irreversible?
The answer is entropy!
Entropy and poker
The Page of EntRoPy
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