  We prove the conjecture of Baik, Deift, and Johansson which says that with
respect to the Plancherel measure on the set of partitions of $n$, the 1st,
2nd, and so on, rows behave, suitably scaled, like the 1st, 2nd, and so on,
eigenvalues of a Gaussian random Hermitian matrix as $n$ goes to infinity. Our
proof is based on an interplay between maps on surfaces and ramified coverings
of the sphere. We also establish a connection of this problem with intersection
theory on the moduli spaces of curves.
