Application of nonlinear symmetry realisation technique to gravity is
studied. We identify the simplest extensions of the Poincare group suitable for
nonlinear realisation. Among them only one model is suitable for description of
massless spin-2 states. This model, unlike general relativity, describes states
with well-defined mass that lack a linear interaction with the matter states.
We argue that this phenomenon points on a necessity to draw a distinction
between gravitational states with well defined masses and states that
participate in interaction with matter.Comment: Minor correction
