Manhattan Project physicist Richard Feynman’s forgotten notes on ‘the restaurant problem’ deciphered after 50 years

It started with a plate of ginger chicken.

In the late 1970s, physicist Richard Feynman — best known for his earlier work on the Manhattan Project — sat down for lunch with his friend Ralph Leighton at a restaurant in Glendale, California. Leighton was agonizing over ordering his usual favorite, or risking something new.

For decades, Feynman’s notes on the “restaurant problem” were unreadable. But now, researchers reconstructed a decision-making problem from Richard Feynman’s previously undeciphered notes and proved him to be right. The findings were published on June 1 in the journal Proceedings of the National Academy of Sciences.

The problem with picking lunch

Brian Christian, a computer scientist and cognitive scientist at University of Oxford, began working on the problem about 13 years ago alongside his collaborator Tom Griffiths. They tracked down Feynman’s original notes through the Feynman Lectures website.

The team proved that Feynman’s solution was indeed optimal, then extended it to other versions of the problem: do people actually solve the problem this way?

They recruited 2,520 participants online and presented them with a digital version of the scenario: a grid of restaurants in a virtual city, each with a hidden quality score revealed only on the first visit. Participants aimed to maximize their total score over a fixed number of nights. Each person played just once.

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“We wanted to really capture people’s gut intuitions,” Christian told Live Science. “When you just get thrown into this situation, what do you do?”

The answer: People don’t follow Feynman’s optimal curve in reality. Instead of the precise mathematical threshold, participants used a much simpler rule. Their quality bar started high and dropped by the same fixed amount each night regardless of how long the trip was or what the restaurant landscape looked like.

The simple strategy captured about 90% of the value that the optimal approach would yield.

“People are not doing the optimal thing. They’re doing something radically simpler,” Christian said. “And still the simple strategy is being tailored in a way that feels very situationally appropriate.”

The slope of people’s declining threshold was identical across every condition — a week-long trip or a month-long one, restaurants distributed evenly in quality or skewed toward extremes. What did shift was where people set their starting bar, adjusting it appropriately based on the landscape they’d seen.

In other words, people used a universal rule for how fast to lower their standards, but calibrated how high to set them in the first place.

An order of redemption

Christian, B., Russek, E. M., & Griffiths, T. L. (2026). Resolving Feynman’s restaurant problem reveals optimal solutions and human strategies. Proceedings of the National Academy of Sciences, 123(23), e2509612123. https://doi.org/10.1073/pnas.2509612123