For Christmas this year, I bought my son a Newton’s Cradle, or as he described it, “that metal ball thing that goes back and forth.” Also described as “Executive Balls Desk Toy,” this gadget wasn’t the first thing I would have thought of when selecting a gift for my ten-year-old. Nevertheless, considering that the other items on his list included a paper shredder and a reclining, vibrating massage chair, the Newton’s Cradle seemed like a great choice.
When he opened the present, he was so happy with it. I was, too, noting that it was almost educational.
Imagine how pleased I was when he exclaimed, “Look mom, this illustrates the Law of the Conservation of Momentum!”
Actually he just smiled and laughed as the balls crashed into each other. But I knew he was thinking in physics and was on the verge of postulating his own therom.
The regular tic-toc motion of the toy was at once predictable and surprising. You pull one ball on the left, let go, watch it strike the other balls at rest, and it launches the outer most ball on the right. The right one swings out and falls back to relaunch the one on the left. It was soothing. It was entertaining. It was proof that I was an excellent parent.
I noted smugly, as I watched the spheres click back and forth, a good mom pulls back, let’s go, and at the point of contact she launches her child into the world for a time. Then, without any more influence from her, the child comes back to deliver his own impact. Two spheres exchange influence, relaunching each other back and forth before finally coming to rest. How great this?! So glad I didn’t get the paper shredder!
Of course, the metaphor of the Newton’s Cradle had its obvious limitations. The parent and child spheres shouldn’t be of equal size I guessed, and there was no accounting of how anyone learned how to put on socks. Still, I thought as I watched the spheres click back and forth, there is a lesson here.
I left the room for a couple minutes . When I came back, my son was upset.
The Newton’s cradle now looked like this.
My son was not happy. He definitely could have used the massage chair at this point. We spent the next few minutes and then hours trying to untangle the toy. But at in the end, it still looked like this:
As it turned out this toy illustrated yet another fundamental law of physics: the level of excitement generated at the initial unwrapping of a present is inversely proportional to the time the present will actually work, and directly proportional to the amount of stress the present will cause the parent.
At least this one came enveloped in bubble wrap. Another illustration of the therom above, the bubble wrap did provide hours of entertainment.
Systems tend toward entropy, I hear, especially around the holidays.