The three-body problem was attacked head-on by Andrei Kolmogorov, who outlined the guidelines for its treatment. His program was completed by Vladimir Arnold and Jurgen Moser in 1962 in the so-called KAM theorem. Henri Poincaré had already tackled the problem at the end of the 19th century, with a topological study of nonlinear differential equations and the apparently chaotic behavior of their solutions depending on small changes in the initial conditions, intuiting that the problem was linked to number theory, and in particular to small divisors with large coefficients.
