The dark energy density fraction derived from the STF scalar field potential. Consistent with observed value of ~0.68–0.71.
The observed dark energy density ΩDE ≈ 0.68–0.71 is one of the most precisely measured yet least understood quantities in physics. Quantum field theory predicts a vacuum energy 10120 times larger. This “cosmological constant problem” has resisted solution for decades.
In the STF framework, dark energy is not a cosmological constant but the potential energy of the scalar field in its cosmological tracking regime. The field equation's late-time attractor gives:
| Source | ΩDE |
|---|---|
| STF derived | 0.71 |
| Planck 2018 | 0.6847 ± 0.0073 |
| DESI 2024 | ~0.69 (preliminary) |
Unlike a bare cosmological constant, the STF predicts a slowly evolving equation of state w(z) that differs from w = −1 at the sub-percent level. Euclid and DESI are expected to reach the sensitivity needed to test this within the next decade.
Falsified if precision measurements establish ΩDE outside the range 0.50–0.80. In tension if ΩDE is measured at 0.55–0.60. The ~10% uncertainty reflects O(1) UV factors in the 10D compactification chain (Appendix O).