We propose that the QCD vacuum pion tetrahedron condensate density should vary in space and should drop in the Kennan, Barger and Cowie (KBC) void for example in analogy to earth’s atmospheric density drop with elevation from earth. Based on Modified Newtonian Dynamics (MOND) theory, we propose to calculate the non-uniform pion tetrahedron condensate density in space and propose a formula for the gravitation acceleration based on the non-uniform pion tetrahedron condensate. A microscopic mechanism for the MOND acceleration crossover at the galaxies’ edges is proposed in terms of the non-uniform pion tetrahedron condensate. The major difference between classical and quantum physics may be the antimatter and the non-empty vacuum discovered by Dirac. The central roles of antimatter and the non-empty QCD vacuum in physics were not anticipated by both general relativity (GR) and quantum mechanics (QM). Their central roles are not fully understood still and the KBC voids and the non-uniform pion tetrahedron condensate are two examples that need further study.