title: The Fermi-Pasta-Ulam problem as a challenge for the foundations of physics.
abstract: The Fermi-Pasta-Ulam (FPU) problem is discussed in connection with its physical relevance, and it is shown how apparently there exist only two possibilities: either the FPU problem is just a curiosity, or it has a fundamental role for the foundations of physics, casting a new light on the relations between classical and quantum mechanics. To this end, a short review is given of the main conceptual proposals that have been advanced. Particular emphasis is given to the perspective of a metaequilibrium scenario, which appears to be the only possible one for the FPU paradox to survive in the physically relevant case of infinitely many particles.
authors.affiliation: Università di Milano, Dipartimento di Matematica, Via Saldini 50, 20133 Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Carati
authors.forename: L
authors.initials: L
authors.lastname: Galgani
authors.forename: A
authors.initials: A
authors.lastname: Giorgilli