When there is a lot of free space between the galaxies, the new fundamental force is borned - the anti-gravity. Made of virtual-particle atoms, which form in a split of a second and then they are destroyed. How to do it here, near galaxies?.. no way.
If no force is applied to an object in inertial system it remains at rest or moves with constant linear velocity. The inertial system is connected to the object. From another point of view. If we say that a body is accelerating, we must state in which way. The force of inertia is then applied to the body in other direction from motion. Do we need to define what are we accelerating from? I think we do as it is defined from position which has to have a base no? If there was nothing in the universe only 2 particles, the acto of accelerating would be only defined towards the other particle. Can we speculate whether the force of inertia would be applied?
Is the inertia a direct consequence of the matter or other parts of the universe?
Is it measurable? If the universe is not equi-dense in different direction, would the inertial force applied to accelerating bodies be different?