There is a revised version of this topic. See Spaces and Spheres (Redux).
The isotropic vector matrix can be modeled as spheres, vectors, tensegrities, space-filling polyhedra, or as the concave polyhedra occupying the spaces and interstices between radially close-packed spheres. The space between radially close-packed spheres is a continuous web of concave octahedra and concave vector equilibria (VEs).
Six spheres close-packed as octahedra surround a nuclear space (“Space”) in the shape of a concave VE, whose volume is slightly less than 1/3 that of the sphere, and slightly more than 1/3 that of the octahedron. The following volumes are all measured in unit tetrahedra. See Areas and Volumes in Triangles and Tetrahedra.
The tetrahedral volume of the concave VE space at the center of six close-packed unit-diameter spheres is the volume of the unit octahedron (4) minus the the volumes of six 1/10 spheres.
Volume of concave VE “space” = 4 – 3π√2/5 ≈ 1.334270237
≈ 33.356755928% the volume of the unit octahedron
≈ 33.298224115% the volume of the unit-diameter sphere

Four spheres close-packed as tetrahedra surround an interstitial space (“Interstice”) in the shape of a concave octahedron, whose volume is a little more than 11% that of the tetrahedron, and a little more than 2.5% that of the sphere.
The tetrahedral volume of the concave octahedron interstice at the center of four close-packed unit-diameter spheres is the volume of the unit tetrahedron (1) minus the the volumes of four 1/20 spheres.
Volume of concave octahedron “interstice” = 1 – π√2/5 ≈ 0.111423412
≈ 11.1423412% the volume of the tetrahedron
≈ 2.5079079% the volume of the sphere

The space-to-sphere ratio of the VE is about 44.5/55.5
(6 × volume of concave VE) + (8 × volume of concave octahedron) ≈ 8.00562+ 0.89139 ≈ 8.89701
≈ 44.485043608% the volume of the VE (20)
≈ 25.031631616% the the volume of the VE’s circumsphere (volume about 35.543)

The space-to-sphere ratio of the cube is about 31.5%
(5 × volume of concave VE) + (8 × volume of concave octahedron) ≈ 6.67135 + 0.89139 ≈ 7.56274
≈ 31.51142% the volume of the cube (volume 24)

In the jitterbug transformation, the spheres and spaces exchange places. The concave VEs become convex VEs (and vice versa) in a transformation that can be described as turning themselves inside-out.

When modeled in quanta modules, the exchange takes place between the two distinct constructions of rhombic dodecahedra, the one found at the center of the VE (the sphere, or convex VE), and the other at the center of the octahedron or cube (the space, or concave VE).

The jitterbug transformation can also be described by the polarity reversal of the tetrahedra. This is manifested in the vector model by the two tetrahedra, one positive, and one negative, that the rotating triangle in the jitterbug alternately describes.

The polarity reversal of the tetrahedron may be modeled as a 90° rotation. Each tetrahedron is rotated ninety degrees in the transition between the VE and octahedron phases, turning their respective concave octahedron into orientations that describe either a sphere or a concave VE space at their common center.

Again, this correlates beautifully with the quanta-module model. Eight quanta-module cubes (each containing a tetrahedron) are rotated 90° to alternately reveal one of the two quanta-module constructions of the rhombic dodecahedron at their common center—one representing the sphere, and one representing the space.

Because the concave octahedron interstices remain constant when the spheres and concave VE spaces exchange places in the jitterbug transformation, their volumes cancel out, and the sphere-to-space ratio of the isotropic vector matrix as a whole is identical with the ratio of volumes of the sphere and concave VE space. That is, the ratio of space to sphere is approximately 2:3.