Mathematician finally solves 60-year-old moving sofa problem popularised by Friends ‘pivot’ scene
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Long-standing Friends sofa problem cracked by Korean mathematician
- Korean mathematician Dr Baek Jin Eon has resolved the long-standing "moving sofa problem", a geometry puzzle that has challenged researchers for nearly 60 years.
- Dr Baek, a research fellow at the Korea Institute for Advanced Study, proved that no shape larger than Joseph Gerver's previously proposed design, known as Gerver's sofa, can move through a right-angled corridor of fixed width.
- His 119-page proof, published in late 2024, was achieved entirely through logical reasoning, without the use of computer simulations, a departure from many earlier attempts.
- The 31-year-old's work has been recognised by Scientific American as one of its "Top 10 Math Discoveries of 2025" and is currently undergoing peer review at the prestigious Annals of Mathematics.
- The "moving sofa problem" asks for the largest possible two-dimensional shape that can be carried through an L-shaped corridor of width one, a concept famously referenced in the US sitcom Friends.