FORCE OF GRAVITY

"Gravity, a non-contact force between two objects. The force exerted
on each body by the other through weight is proportional to the mass
of the first body times the mass of the second body divided by the
square of the distance between them. The direction of the force is
from the body acted on towards the body applying the force. A
human body's weight is a non-contact force exerted by the Earth
on their mass."
http://en.wikipedia.org/wiki/Non-contact_force

In the AV model, at the outer limit of Space during an expansion
period, Space converts to inward flowing radial lines of Gravity.
At a mass center, i.e., the center of a Shell, opposing lines of
Gravity convert to expanding spheres of Space. Unopposed lines
of Gravity convert to Linear motion. This Linear motion moves
the mass center inward and usually in the direction of another
mass center. Here, there is just a conversion of one field to
another field. Force is a human concept.