A Different Kind of Three-body Problem

June 22nd, 2024

The three-body problem in classical physics is about taking the initial positions and velocities of three masses that orbit each other in space and then using Newton’s laws of universal gravitation and motion to determine their trajectories. Newton tried to predict the movements of the sun, moon, and earth as their masses affected each other. He didn’t do very well with that. The difficulty lies in the fact that even tiny changes in the initial conditions result in wildly diverging trajectories. The movements and relationships between the three bodies are part of a chaotic system.

If three unconscious physical masses in motion are unpredictable, then how much more chaotic are the movements of three sentient beings. As a case in point, Karin and I visited our three grandchildren in Texas recently, and they were never objects at rest. Weston, Madeline, and Wyatt are five, three, and one year old respectively. They are all energetic preschoolers. They are always in motion, and their movements seem to be completely random. They are constantly interacting, but in unforeseeable ways.

Their mom, Gabby, does a remarkable job of keeping track of them. She too, by necessity, is always in motion. Somehow Gabby is able to satisfy, at least temporarily, to their insatiable needs and desires, and still get other things done. She has an intuitive sense of where and when to respond. She might have to comfort a crying child, or clean up a messy one, or seek out the kid is silently getting into mischief. While she is tracking the three bodies in her care, Gabby is also cooking supper, doing laundry, or attending any number of other chores. It’s rather impressive.

When Karin and I came to visit for a week, we brought little Asher along with us. Asher played with his cousins and effectively created a four-body problem. I’m not sure if our presence in the household was helpful. In some ways we just caused more chaos by upsetting the family routines. On the other hand, Karin and I could herd the four youngsters to give Gabby some breathing space. Decades ago, we raised three kids of our own, so we are familiar with chaotic systems. They tend to be loud, and emotionally intense. Currently, Karin and I are Asher’s fulltime caregivers, so we understand Gabby’s situation. It’s strange, but even though he is one child, Asher still outnumbers us.

Gabby’s household contains smaller nonhuman bodies in motion. There are two cats in the house. Cats are by their very nature inscrutable. There is also a not-quite-housebroken puppy named Bella who explores the premises. Gabby has a handheld carpet shampooer. She gets plenty of use out of that. The floor always has a coating of cracker crumbs, bits of apple, pet food, and toys. This is unavoidable. Since the actions of the various moving bodies cannot be anticipated, there is a constant battle to tidy up after them. I am a compulsive cleaner, so I kept very busy. Gabby asked me once,

“If I told you that you did not need to clean up, would you stop?”

“No.”

She sighed and said, “I wish Hans (her husband) had that compulsion.”

“And the train it won’t stop going
No way to slow down” – from Locomotive Breath by Jethro Tull

This multi-body system is like a runaway train in some ways. It won’t ever stop, but it does actually slow down occasionally. Even the most intensely active children eventually crash. In the early afternoon, little Wyatt conks out and takes a nap with his mama. Weston gets absorbed into the world of Minecraft. Maybe I read a book to Madeline. Asher plays with all of his cousins’ toys and scatters them around the house. It is a temporary respite, but welcome, nonetheless.

Although the thought of predicting the movements of four preschoolers is attractive, there is also some pleasure in just being part of the show. Weston crawls all over his “Oma” as she tries to teach him German verses from when she was a young girl. Madeline breaks out a smile that shines like the sun at high noon. Wyatt consents to me picking him up and rocking him in my arms. It’s a maelstrom of motion, noise, and love.

It’s not really a problem after all.