Gromov’s famous non-squeezing theorem (1985) states that the standard symplectic
ball cannot be symplectically squeezed into any cylinder of smaller radius. Does there
exist an analogue of this result in contact geometry? Our main finding is that the
answer depends on the sizes of the domains in question: We establish contact
non-squeezing on large scales, and show that it disappears on small scales. The
algebraic counterpart of the (non)-squeezing problem for contact domains is the
question of existence of a natural partial order on the universal cover of the
contactomorphisms group of a contact manifold. In contrast to our earlier beliefs, we
show that the answer to this question is very sensitive to the topology of
the manifold. For instance, we prove that the standard contact sphere is
non-orderable while the real projective space is known to be orderable. Our
methods include a new embedding technique in contact geometry as well as a
generalized Floer homology theory which contains both cylindrical contact
homology and Hamiltonian Floer homology. We discuss links to a number of
miscellaneous topics such as topology of free loops spaces, quantum mechanics and
semigroups.
Dedicated to Dusa McDuff on the
occasion of her 60th birthday
Keywords
contact manifolds, contact squeezing and orderability,
Floer homology, holomorphic curves