Sometimes a beautiful failure teaches more than a successful fit.

Inverse Relativity – A Bold Test of Gravity from Dwarfs to Clusters

1. The Theory & Equations

What if mass isn’t the source of gravity, but a consequence of spacetime’s “holes”?

Inverse Relativity (IR) flips General Relativity (GR):

· GR: Mass → Curvature → Gravity · IR: Hole (H) → Flow → Spin → Mass

Key equations (weak-field, covariant form):

∇²Φ = 4πG ρ_bar + ξ ∇²φ

∇²φ – m_φ²(φ–φ₀) = –2ξ ∇²Φ

Where φ is the “Hole field,” ξ the coupling constant, and m_φ the field mass.

2. Test Results – Pass & Fail

Using a single universal parameter set (ξ ≈ 17.86, m_φ ≈ 7.33 kpc⁻¹) :

✅ Pass: Dwarf spheroidals (dSph) & Ultra-diffuse galaxies (UDGs) IR naturally explains their high mass-to-light ratios without dark matter.

❌ Fail: Large disk galaxies (SPARC data) IR predicts B ∝ M_bar^0 (constant excess), but data shows B ∝ M_bar^0.72.

❌ Fail: NGC 1052-DF2 (the smoking gun) This UDG shows Newtonian rotation (no extra gravity). A universal IR should predict strong extra gravity here – but it doesn’t.

❌ Fail: Solar System (Cassini limit) IR requires a chameleon screening mechanism, which then breaks universal predictability.

❌ Fail: Energy conditions The minimal coupling violates NEC & DEC in the Einstein frame, implying ghost instabilities.

3. Lessons & The Way Forward

🚫 Single-field, universal coupling is dead.

No single (ξ, m_φ) can simultaneously satisfy:

· Solar system (no 5th force) · Large disks (M_bar^0.72 scaling) · dSph/UDGs (strong extra force) · DF2 (Newtonian)

✅ Required architecture upgrade:

We need multi-field theories with environment-dependent coupling:

L = ½(∂φ)² + ½(∂χ)² + V(φ,χ) + ξ(χ) φ R + β(χ) φ T_matter

Where ξ(χ) vanishes in high-density or high-tidal environments (like DF2’s location), but activates in isolated, low-density dwarfs.

Conclusion: Inverse Relativity fails as a universal theory – but its core idea (mass from spacetime holes) survives. The path forward requires a scalar sector that “knows” about its local environment.