  The Einstein equations for static gravitational field depend on energy
density and pressure. So one may expect that solutions should depend on two
parameters: mass and its analogue originated from pressure. Yet the
Schwarzschild solution have only mass parameter. So does its linear
approximation. On the other hand the solutions of linearized Einstein
equations, obtained using graviton propagator, contain mass and its pressure
analogue. This suggests that a phenomenological approach to gravity, using
propagators and many graviton vertices, should lead to a theory different from
general relativity.
