A serious materials scientist hunched over a kitchen table, flicking a dreidel across the wood grain and timing its spin with a stopwatch, has an almost comical quality. However, according to multiple accounts, that is essentially what happened when a Stanford researcher who studies the mechanics of spinning and rotating bodies began closely examining the small four-sided top that appears in Hanukkah gift bags and synagogue gift shops every December. It turns out that what she discovered is a tiny object that contains an excessive amount of physics.
A dreidel appears to be fairly straightforward. There are four sides, four Hebrew letters, and a wooden or plastic handle that you can twist by pinching it between your fingers. Kids use it to play with chocolate coins. Few people take the time to think about why a slightly worn one behaves differently from a brand-new one purchased at a pharmacy, or why it wobbles the way it does. This scientist appears to be interested in that particular aspect. Unlike a coin or die, the dreidel must balance a spinning motion on a single narrow point while its center of gravity is pulled in different directions by four flat, uneven faces. It shouldn’t remain upright for nearly as long as it does.
Gyroscopes are found in airplanes and submarines for the same reason that a dreidel can wobble significantly while still correcting itself in midair. Abrupt changes in orientation are resisted by angular momentum. For a brief moment, a rapidly spinning object acts as though it has a mind of its own, struggling to maintain its vertical position despite the forces of friction and gravity. A pocket-sized example of that idea is the dreidel, which is more forgiving than most classroom gyroscopes because it is inexpensive, lightweight, and almost impossible to break.
It’s difficult to ignore how frequently the best physics lessons can be found inside items that were not created with physics in mind. The Dreidel was not created in a laboratory. Tradition, religious symbolism, and perhaps a good deal of trial and error by toy manufacturers attempting to create something that spins consistently and doesn’t roll off a table all contributed to its development over centuries. It’s a folk object that just so happens to behave like a textbook example without anyone trying to make it one, which is perhaps why materials scientists find it fascinating.
More than most people realize, the friction at the tip is important. The dreidel’s spin duration, wobble pattern, and predictability are all altered by the slight difference between a polished plastic point and a dull metal point’s grip on a tabletop. A “good” dreidel can be distinguished from a bad one almost immediately by anyone who has played the game, even if they are unable to articulate why. Instinct may be performing actual physics, albeit informally.
It would be a stretch to say that the dreidel is underappreciated in any urgent sense, and none of this makes it revolutionary. Dreidel research is not essential to anyone’s career. However, there is a subtle allure to the notion that a Hanukkah toy carries the same rotational principles that maintain satellites’ stability in orbit. It’s easy to understand why a scientist might find that little performance worth a second look after witnessing one spin on a table, slowing, wobbling, and managing to stay upright for a beat longer than anticipated.