Applications of Hofer's geometry to Hamiltonian dynamics

  • Felix Schlenk

    Universität Leipzig, Germany


We prove that for every subset of a tame symplectic manifold meeting a semi-positivity condition, the -sensitive Hofer–Zehnder capacity of is not greater than four times the stable displacement energy of ,

This estimate yields almost existence of periodic orbits near stably displaceable energy levels of time-independent Hamiltonian systems. Our main applications are:

  • The Weinstein conjecture holds true for every stably displaceable hypersurface of contact type in .
  • The flow describing the motion of a charge on a closed Riemannian manifold subject to a non-vanishing magnetic field and a conservative force field has contractible periodic orbits at almost all sufficiently small energies.

The proof of the above energy-capacity inequality combines a curve shortening procedure in Hofer geometry with the following detection mechanism for periodic orbits: If the ray , , of Hamiltonian diffeomorphisms generated by a compactly supported time-independent Hamiltonian stops to be a minimal geodesic in its homotopy class, then a non-constant contractible periodic orbit must appear.

Cite this article

Felix Schlenk, Applications of Hofer's geometry to Hamiltonian dynamics. Comment. Math. Helv. 81 (2006), no. 1, pp. 105–121

DOI 10.4171/CMH/45