The existence of negative pressure of vacuum follows from the cosmological models, based on the results of observations. The gravitational defect of mass is interpreted as the transfer of energy to the vacuum, which becomes apparent from its deformation.The gravitational impact of matter on the vacuum and opposite in the sign pressure of it can be determined in case of weakly gravitating static centrally symmetric distribution of matter. A possibility to extend the obtained results to arbitrary gravitational systems is evaluated. The equation of state (p_v =-(1/3)[q_L+q_m+q_rel]) gives the deceleration parameter of the universe consistent with its accelerating expansion.
Remi,
According to the strong equivalence principle the gravitation laws are the same in large and small distances and there is no observational evidence to the contrary.
The gravitational mass of bodies placed in confined volume, is less than the sum of the gravitational masses of these bodies, dispersed over infinite distance. The matter, located more compactly, distorts the space in the local domain in a greater degree, however, creating smaller gravitational mass in comparison with the same amount of matter, distributed over a greater volume. This phenomenon is explained by transfer of energy into the gravitational field, which results in the deformation of vacuum. Accumulation of energy during deformation demonstrates its elasticity.
If the vacuum pressure around any gravitating mass was absent, then the space around it would be turned into some analog of the environment of the Black Hole.
According to GTR , the space is curved around a mass and is considered the source of the local gravitational field .The shift from the Euclidean (flat) to Riemannian (positively curved) geometry in a local gravitational field, creates stress/tension to the fabric of the vacuum.As a consequence to stress/tension ,pressure of the vacuum can be detected around the gravitating object. The object doesn't attract vacuum or another mass but is constantly under pressure of the vacuum due to its curved fabric
In fact, one way to understand the observed accelerated expansion of the universe is to invoke the negative pressure of vacuum. According to general relativity, the gravitational acceleration is proportional to - (energy density + 3 times pressure) times volume. Since, for the vacuum, pressure = - energy density, the gravitational acceleration becomes +ve, implying gravitational repulsion. So, pressure of the vacuum leads to repulsive gravity.
Formula pressure =-energy density for vacuum largely based on an interpretation of the lambda term (L) in the Friedman's equations for the flat space, in the first (da / dt) ^ 2 / a ^ 2-L / 3 = q / 3 as its density and in the second 2(d^2 a / dt^2) + (da / dt) ^ 2 / a ^ 2-L = -p as the pressure. If in the second equation to consider L also as in the first as density of energy of the vacuum, at critical density of energy q_c=q+L and pressure of the vacuum p=-(1/3) q_c the gravitational acceleration is found to be equivalent to L/2. This brings the deceleration parameter close to -1. Thus, provided that the equation of state, following from the properties of the local gravitational system, is also consistent with repulsive gravity.
If the vacuum pressure really depends on the density of the matter contained in it, the collapse of the star, leading to the formation of the Black Hole by Oppenheimer and Snyder, needs be revised.
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