Many adults experience the same suffering, confusion, and joy that quantum physicists have every day. These are the parents of small children — they go through a hard time trying to understand the young, much like a physicist struggling to understand the tiny quantum mechanical systems.
To start, you never know what children are thinking about. In those tiny brains, there could be the idea of pulling a naughty deed or the thought of entertaining a cute dance. Until you go and interact with them, you simply don’t know whether they will do one or the other. Children are therefore simultaneously lovely angels and evil devils. Trying to figure out what’s going on in their head is just like trying to figure out whether the cat in the box is alive or not in Schrödinger’s thought experiment. Until you open that box, the cat is in a superposition of the two states—both dead and alive.
But kids will become devils for sure if you explicitly “tell” them what to do. For example, you might be making a beef stew for dinner. You get a phone call, and in doing so you leave the pot on the stove. You then tell your kids not to touch the pot because it is hot, but they go and touch it anyways. In effect, if you had not bother to tell them of the pot in the first place, these children might not have even notice its existence. Or put another way, the act of ordering them affects their behavior. This is much like measuring a quantum mechanical system — the act of measuring it will affect the behavior of the system and in turn affects the result a physicist will obtain.
It is also impossible to tell children to sit still. Kids can never sit still; they will start moving around randomly after sitting for only a few seconds. Quantum mechanics can explain this: Heisenberg’s Uncertainty Principle tells us that tiny things, which apparently includes children, will never have both a definite position and a definite momentum. This uncertainty drives both parents and physicists crazy.
Children go even crazier when you supply them with toys and candies. Transformer robots and Kit-Kats to them are much like energy to electrons. Both kids and electrons will go into an excited state. And similar to an electron’s quantized energy levels, children are either sad or happy, and are never in a mood that is mediocre. When supplied with toys and candies, kids will most likely become over-excited and start causing troubles, be it playing water gun in the living room or sewing your favorite jeans together. In that case, you as parents might want to “ground” them.
But these excited, troublesome children will eventually get tired. They will fall asleep with a big smile on their face, all the while dreaming about the toys and the candies they just had fun with. Much like electrons emitting various colours when they fall back from the excited state, the sleepy children’s big smiles are probably the most beautiful emission spectrum you will ever see in your life.
And that is why parents still love them despite their confusing thoughts and their diabolic pranks. You realize how pure and beautiful your babies are, just like a physicist who loves the beauty that lies at the heart of quantum mechanics.