Nobody wonders, in the hurricane’s aftermath, whether her home will be in better shape than it was before: stacks of books straightened; skewed pictures righted; clothing back up on its hangers; dust bunnies shepherded into tidy, sweep-able piles; the contents of the neighbor’s dilapidated barn reconfigured into a lovely second bathroom. No, with nature or just the passing of time, energy undoes, disperses, homogenizes, until there’s nothing left to do or undo because little quantities of everything are everywhere. This is entropy in its favorite state, one of absolutely perfect disarray.
Our modern understanding of entropy is less than 200 years old. (And by our I mean physicists who are not me.) But an intuitive understanding of the phenomenon—in Henry Adams’s phrase, “chaos [is] the rule of nature; order [is] the dream of man”—comes part and parcel with navigating this world. When does this understanding emerge? About as early, it would seem, as psychologists know how to test.
In 1981, researchers Thomas Shultz and Marilyn Coddington had children draw pictures of what a small box of marbles arranged by color might look like after the box was shaken. Nine-year-olds accurately predicted that the arrangement of marbles would become more random with each shake, but a group of six-year-olds showed no such understanding. (Nor, according to the researchers, did the younger children’s facial expressions appear sufficiently “puzzled” if the marbles remained neatly in place.) Huge leaps in obtaining an intuitive understanding of entropy occur between the ages of six and nine, Shultz and Coddington concluded.
Then two decades later, William Friedman revisited the question. Instead of asking children to predict the outcome of an event, he asked them to identify, using simple yes-no responses, whether a given outcome was possible. In one study, for instance, children were shown “before” and “after” pictures of scenes. One of the pictures might show table settings arranged neatly for a picnic, while the other showed the plates and silverware strewn haphazardly. Children were asked whether an act of nature could have turned “before” into “after”: That looks different, doesn’t it? Somebody said that maybe the wind did it. Do you think the wind can make this happen? Friedman found that even four-year-olds were likelier to say that an act of nature could disrupt a neatly arranged scene than to agree that a gust of wind could clean up and organize an untidy one.
In recent years, new studies have shown that even infants possess an intuitive understanding of entropy. Take this one, published earlier this year by researchers Lili Ma and Fei Xu, which uses an even simpler task: watch.
Under the infants’ attentive gaze, a group of red and yellow balls was ordered—either randomly or in a regular pattern. The infants were then allowed to see who, exactly, was responsible for the ordering. Sometimes, they saw a human hand; other times a claw. At just nine months old, the infants looked longer at the claw than the human hand, but only if the balls appeared in a regular pattern. In other words, the babies were intrigued when a claw—but not a human—was responsible for the nifty patterns that were highly unlikely to occur by chance.
Humans are agents, these infants understood, capable of controlling their environments. Of course they’d want the balls just so. But the claw contraption threw them for a loop—at least until they understood how it worked. Babies weren’t surprised in the least when the curtain was pulled back to reveal a claw so long as, back in the waiting room, they’d witnessed the claw being manipulated by a human.
