How Math Can Help You Decide What to Order for Dinner

In a scene that could easily have featured in an episode of the American television sitcom The Big Bang Theorythe late American physicist Richard Feynman once turned a visit to a Thai restaurant where he often dined into a mathematical conundrum: How adventurous should we be in trying new dishes? Feynman quickly solved this problem on a sheet of paper.

Now, behavioral scientists have reexamined Feynman’s solution—some of which had been obscured by his impenetrable writing—and found that his strategy was indeed optimal.

Feynman’s dilemma is familiar to any restaurant fan. Do we continue to order the best dish we’ve eaten so far, or do we explore the menu in hopes of finding something better? A study published in the Proceedings of the National Academy of Sciences June 1 examines this question and includes experimental results that participants adopt meal choice strategies that closely approximate Feynman’s mathematical solution.

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Behavioral scientist Shoham Choshen-Hillel of the Hebrew University of Jerusalem says the authors have written a “super creative article.” “The restaurant example represents decisions in many contexts,” she adds. Real-world examples include choosing a home to buy, deciding who to partner with, and selecting a parking spot.

Have you chosen?

The story begins with a regular visit from Feynmana Nobel Prize-winning physicist at the California Institute of Technology in Pasadena, and his friend Ralph Leighton, at a Thai restaurant in nearby Glendale in the late 1970s. (Leighton helped Feynman write his popular 1985 memoir. You’re probably joking, Mr. Feynman! and was the son of the late physicist Robert Leighton, co-author of the influential 1964 The Feynman lectures on physics, with Feynman and Matthew Sands.) Leighton debated whether to order ginger chicken – his favorite dish – or explore the rest of the menu. Feynman began scribbling and immediately claimed to have found a mathematical solution: in his simplified model of the situation, he calculated a threshold – a number of visits beyond which Leighton’s rational decision would be to always settle for his favorite dish.

What Feynman had done was turn the restaurant dilemma into a question of decision theory – a field at the intersection of economics and psychology that analyzes strategies in individual games. In particular, it was an original contribution to a larger family of decision theory problems called stopping problems. These include real-life problems in which someone must decide whether the opportunity in front of them is sufficient or whether they should keep looking.

Leighton saved the notes, and years later he partially transcribed Feynman’s cursive writing to the best of his ability. Leighton described his interpretation in an article he posted online in the early 2000s. A decade later, in 2013, Tom Griffiths, a cognitive scientist at Princeton University in New Jersey, became interested in the question while researching a book with his collaborator Brian Christian, a computer scientist and cognitive scientist. Griffiths then transcribed Feynman’s notes in their entirety for the first time.

Christian, who now works at the University of California, Berkeley, says the question lay dormant for nearly a decade, until the two researchers decided to revisit it in 2021. “We understood the meaning of Feynman’s notes, but there was all this work to do,” he says. The researchers later confirmed that Feynman had indeed found the best solution and had also solved a generalized version of the problem.

Behavior matches math

Working with a third co-author, cognitive psychologist Evan Russek of the City University of New York, the team decided to test whether people’s choices would resemble anything close to the mathematical solution. They translated the restaurant question into an online game, recruiting 2,520 participants to answer it. Participants were asked to imagine visiting a new city for a period of between one and four weeks and having to choose which restaurant to eat at each evening. Players could earn points for the quality of the restaurant they chose (a number between 1 and 100) and had to try to maximize their total number of points. Participants became less willing to risk trying new restaurants as the end of their visit approached, which followed a similar logic to Feynman’s optimal formula.

Although the participants did not find the mathematical solution – which involves a formula with square roots – their behavior was a very good approximation.

“The fact that, even in this simplified setting, they still find that people behave quite consistently – and quite effectively – is quite impressive,” says Choshen-Hillel.

Although Feynman’s problem may have applications in economics and marketing, it doesn’t fully model people’s behavior in a restaurant, Choshen-Hillel says. In particular, this doesn’t take into account boredom, Christian explains, because the best option for players is to settle for one dish once and for all. In real life, someone might want to keep choosing the same dish every other time, for example, and continue exploring the menu on subsequent visits. But the problem “distills into its essential form this fundamental tension that is very familiar in everyday life: the decision between doing what you prefer and trying something new,” he says.

This article is reproduced with permission and has been published for the first time June 1, 2026.