I've been philosophing about Newtons shell theorem, which tell us that inside a symmetrical sphere, gravity is zero if the sphere is hollow, and linearly declining while moving closer to the center if the sphere is massive and of constant density. Now, if the sphere was hollow it would naturally collapse unless it was excedingly hard, since the sphere itself is affected by the gravity of every other particle that makes up the hollow sphere. So expanding the shell theorem, we should see inverted gravity inside the sphere if the sphere is collapsing. Every particle inside the shell will experience negative gravity toward the center of the sphere. Vice versa; if the sphere is growing, every particle inside it will experience gravity toward the center. Do anybody here agree with me? If not, please assume anyway, that I am correct in the following reasoning: Would you agree that if a galaxy were surrounded by a collapsing sphere - the outer stars orbiting the galaxy would rotate slower? They would have "help" in keeping their distance from the central black hole. If two galaxies were inside the collapsing sphere, would they not be pulled apart from eachother? Could not any less dense area of space, surrounded by a semi-uniform highly dense collapsing area experience similar effects? I've been thinking about this for years, and I've not got the mathematical skills to prove this - but I'm certain somebody could help me with some of the math involved. However, I believe that a configuration of this "sphere" surrounding the observed universe could be found and make Newtonian physics agree more with General Relativity on large distances. If the surrounding sphere is collapsing, it would mean that at one point we will reach somewhat of a singularity, before the momentum of the collapse fly by and create another expansion period in which all mass left behind will be compressed into the center (because of the expanding shell). All of this is because we need to incorporate the propagation delay of gravity into the shell theorem. Now, I am aware that by writing down so many implications of this idea, a lot of people will be very sceptical to it. Best regards, Frode Børli, Norway.