What If the Vacuum Gravitates? A Reinterpretation of ΛCDM That Might Resolve Its Paradoxes

We propose a framework in which Einstein's cosmological constant Λ and the quantum vacuum energy density ρ_vac are treated as physically distinct quantities—reversing the identification assumed without proof by Zel'dovich in 1967. The cosmological constant remains a geometric property of spacetime driving uniform expansion. Vacuum energy is placed in the stress-energy tensor as a local form of matter-energy that gravitates, dilutes with cosmic expansion as (1+z)³ (a scaling selected by self-consistency, not assumed as a free parameter), and is suppressed by the local matter density through the ansatz ρ_vac(ρ_m) = ρ_vac,0 − α ρ_m, where α ∼ 0.01–0.05 is constrained by Big Bang nucleosynthesis, matter density evolution, and running vacuum model data.

Inside gravitationally bound structures, where cosmic expansion is suppressed, vacuum energy gravitates without compensation—producing an invisible, collisionless, uniformly distributed gravitating component whose qualitative properties match those attributed to dark matter. The halo boundary is identified as a phase transition between bound and expanding vacuum. Vacuum energy does not enter the Friedmann equation (it is sequestered from cosmological dynamics), ensuring compatibility with CMB observations while remaining gravitationally active at galactic scales.

The total gravitational mass of a galaxy consists of three components: visible baryonic matter, invisible compact remnants (whose population remains observationally unconstrained in significant mass ranges), and gravitationally bound vacuum energy. In the early universe, when the vacuum was ∼2000× denser, the enhanced gravitational environment facilitated rapid structure formation, offering a natural mechanism for the supermassive black holes observed by JWST at z > 7. The cosmic web is reinterpreted as a dynamic fixed-point structure of the cycle ρ_m → ρ_vac → g_μν → ρ_m.

The model reinterprets the physical content of ΛCDM—not its mathematics—and reframes four outstanding paradoxes (the cosmological constant problem, the non-detection of dark matter particles, the cosmic web morphology, and the early supermassive black hole puzzle) as consequences of a single unproven assumption. The framework is falsifiable: it fails if Λ = ρ_vac can be demonstrated, if CMB analysis excludes a sequestered vacuum component, or if no consistent α fits the observational constraints simultaneously.

The manuscript has undergone four rounds of peer review documented in the appendix.

Keywords: vacuum energy; cosmological constant; dark matter; cosmic web; cosmic voids; galactic rotation curves; supermassive black holes; ΛCDM reinterpretation; gravitational structure; Casimir effect; running vacuum models

License: Creative Commons Attribution 4.0 International

Related identifiers:

• Kriger, B. (2026). Matter-Dependent Vacuum Energy Density and Inhomogeneous Cosmic Expansion. doi:10.5281/zenodo.18896536
• Kriger, B. (2026). Known Properties of Vacuum Energy, Dark Matter and JWST Early Galaxy Formation. Information Physics Institute.
• Kriger, B. (2026). On Quantum Vacuum Energy, Cosmological Constant and Missing Mass. Information Physics Institute.