Mother: “How many times do I have to tell you to clean your room?”

Teen: “I can’t help it. It looks like this because of entropy!”

Ah, entropy, the innocent scapegoat of messy rooms and so much more. But is it to blame? Let’s go through and find out what entropy is, what it applies to, and why high-entropy systems occur more naturally than lower-energy ones.


Entropy in action.

By: Dr. Jennifer Marlone

Entropy is broadly defined “the degree of disorder or uncertainty in a system.” Entropy, though, is more than just whether some objects are arranged in a logical order or not.

Think of a pool table before a game, with the white cue ball sitting on its marker and a triangle of fifteen striped and solid-colored balls perfectly placed on the other side of the table. There’s only one arrangement for the pool balls at the beginning of a game; any change in the position of the balls, and the table must be reset for the next game to begin. It takes input of energy to put the balls into their starting position; they don’t simply roll themselves into place. In the organized starting scenario, the system would have low entropy- this system has little tolerance for randomness – and any misalignment of balls leads to a higher entropy system, wherein more energy would have to be input in order to return the system to a lower-entropy starting arrangement.

However, once the game begins and the cue ball breaks the triangle open, there are many, many more possible ways to arrange the balls. Theoretically, each ball could be anywhere within the pool table, and there are an infinitely large number of arrangements in which all balls are somewhere on the green felt. Here, entropy is high, since it’s generally uncertain which of the many arrangements of balls one will end up when the triangle is split.

Now, suppose you had a bucket which contained an enormous number of cards, each of which had a ball arrangement drawn on it, so that all possible arrangements of balls on the table were displayed by a card in the bucket. There is only one card with a single ball on one side and a triangle on the other, but there are many, many cards with the pool balls scattered around the table. Thus, it’s far more likely for someone to draw a random arrangement of balls than the perfect, aligned starting arrangement of balls. This is why, when the triangle is split open, the balls assume a random position on the table and do not coalesce into another neat triangle arrangement- the high entropy system is much, much more likely

So, how does this apply to the messy room? Well, there is one possible way in which a room is clean: every object in the room is put in its rightful place. However, this requires energy on the part of the teen who lives in the room, and such a process requires much motivation, or activation energy, to complete. The number of messy room arrangements, though, is quite large, with many easily executed processes (soccer practice! A pillow fight!) leading to the messy state. So, the messy state is much more likely at any given point. Clean rooms, then, are indeed unnatural; however, this author encourages both the occasional battle against entropy and the fight for a clean room.

About The Author

Ariel Chen