  We develop the Lifshitz theory of van der Waals forces in a wedge of a
dielectric material. The non-planar geometry of the problem requires
determining point-wise distribution of stresses. The findings are relevant to a
wide range of phenomena from crack propagation to contact line motion. First,
the stresses prove to be anisotropic as opposed to the classical fluid
mechanics treatment of the contact line problem. Second, the wedge
configuration is always unstable with its angle tending either to collapse or
unfold. The presented theory unequivocally demonstrates quantum nature of the
forces dictating the wedge behavior, which cannot be accounted for with the
classical methods.
