Quantum Mechanics

When you try to understand how very small things work, you realize that you can't use the same kind of ideas which you used to explain how bigger things like cars and balls work. So one of the things you realize is that very small things care about how you look at them. Suppose you have a room with two doors. With big things, if you opened one door and saw a red ball inside and then you opened the other door, you would also see a red ball. But with small things, it could happen that you open one door, see a red ball, open the other door see a blue ball and then open the first door again and now see a blue ball! Also, two very small things that are far away can know much more about each other than two big things that are far away. This is what makes small things much weirder than big things, but also can be used to make better computers and phones. But big things are always made of small things; so why do big things also not work like small things? Well, this is one of the most important questions that people who think about small things are thinking about, but the answer seems to be that when you put a lot of small things together the weird things always seem to kill each other off.