Fermi, Pasta and Ulam: studies of nonlinear problems

What changed

Used numerical experiments on a nonlinear oscillator chain to test energy sharing among modes and observed unexpected recurrence rather than the anticipated rapid approach to equipartition.

Scientific scope

The record is Los Alamos report LA-1940 of May 1955. Later FPUT analyses, soliton theory, chaos thresholds and broad claims about the first computer simulation remain separate.

Evidence

The linked sources identify this contribution and its scope. WRS has not independently reconstructed the scientific claims. The record is Los Alamos report LA-1940 of May 1955. Later FPUT analyses, soliton theory, chaos thresholds and broad claims about the first computer simulation remain separate.

Contributors

• Enrico Fermi · SCIENCE: Named source author of the scoped work; individual effort shares are not measured.
• John R. Pasta · SCIENCE: Named source author of the scoped work; individual effort shares are not measured.
• Stanislaw M. Ulam · SCIENCE: Named source author of the scoped work; individual effort shares are not measured.

• UNT archive record for Studies of Nonlinear Problems
• CERN record for Los Alamos report LA-1940

Provisional WRS assessment, edition 2026-10-16.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.

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