If so, how is it possible for a galaxy to organize with a diameter of several million light years?
I do not know that's a more than two bodies complex problem. Its beyond me. It appears to that inertial mass is the universe's reaction to the local induced gravitational field. The induced field act like a reservoir of momentum and energy allowing for the propagation of the original field to remote regions. The induced field acting on the mass of the universe appears to account for the inertial mass of matter. The analysis is at page 4 of this chapter.
http://www.angelfire.com/scifi2/zpt/chapter9.html
Frank Znidarsic
