The Einstein-Hilbert Term
The effective 13D gravitational action (from the 26D two-time framework) that reduces to Einstein gravity in 4D upon compactification.
The gravitational sector of the effective 13D bulk action (26D → 13D via Sp(2,R) gauge fixing)
26D Origin
In the full 26D theory with signature (24,2), the gravitational action includes contributions from both time dimensions. The Sp(2,R) gauge symmetry reduces the two-time structure to an effective 13D shadow:
The F(R,T,τ) Function
The gravitational sector is governed by a modified gravity function that depends on the Ricci scalar R, the stress-energy trace T, and the torsion scalar τ:
Here α, β, γ, δ are coupling constants determined by the underlying 26D geometry. The torsion terms (γτ + δτ²) arise naturally from the Pneuma spinor condensates.
After imposing the Sp(2,R) constraints (X² = 0, X·P = 0, P² + M² = 0), the orthogonal time dimension is gauge-fixed, leaving an effective 13D description. The Z₂ mirror structure creates two copies of this 13D shadow, related by time-reversal symmetry.
Component Breakdown
The effective Einstein-Hilbert term is the standard gravitational action in the gauge-fixed 13D shadow. It couples the fundamental mass scale to the curvature of the effective bulk spacetime.
Fundamental Mass Scale
The single fundamental mass scale of the theory in 13D. All other scales (Planck mass, GUT scale, etc.) emerge from M* through dimensional reduction.
Correct Dimensions
The power 11 ensures correct mass dimension: in 13D, [R] = mass2, and the action must be dimensionless, so we need mass11 to compensate for d13x.
Ricci Scalar
The effective 13D Ricci scalar R = GMNRMN, encoding the curvature of the gauge-fixed spacetime including both 4D and internal directions.
Ricci Tensor
The contraction of the Riemann tensor: RMN = RPMPN. Contains second derivatives of the 13D metric GMN.
Effective 13D Gravitational Action
After Sp(2,R) gauge fixing, the complete effective 13D gravitational action is:
Components of the Metric
For Kaluza-Klein reduction, the 13D metric GMN decomposes as:
Where gμν is the 4D metric, hab is the metric on KPneuma, and we have omitted off-diagonal terms (gauge fields) for clarity.
4D Effective Gravity
Upon compactification over the 8-dimensional internal manifold KPneuma, the 13D action reduces to 4D Einstein gravity:
The Planck Mass Relation
The 4D Planck mass emerges from the fundamental scale and internal volume:
Where V8 = ∫KPneuma d8y √|h| is the volume of the internal manifold. This explains why MPl ~ 1018 GeV can emerge from a more fundamental scale M* that could be much lower.
Key Relation
With M* ~ 1016 GeV (GUT scale) and V8 ~ (M*-1)8, one can recover MPl ~ 1018 GeV. The internal manifold size is thus naturally tied to the GUT scale.
F(R,T,τ) Modifications
The framework naturally includes modifications to Einstein gravity through the F(R,T,τ) formalism, where T is the trace of the stress-energy tensor and τ is the torsion scalar:
Modified Einstein Equations
Varying the action with respect to the metric yields the modified Einstein field equations:
Here Θμν contains matter-geometry coupling terms, and Sμν(τ) encodes torsion contributions from the Pneuma spinor condensates.
Effective Cosmological Constant
The torsion terms generate an effective cosmological constant:
This provides a dynamical origin for dark energy: the effective cosmological constant arises from torsion contributions rather than being a fixed parameter. As the universe evolves, τ varies, yielding a dynamical dark energy component.
These modifications arise from:
- Higher-order curvature terms from the 26D → 13D reduction
- Moduli stabilization effects from KPneuma
- The Mashiach field dynamics driving dark energy
- Z⊂2 mirror sector contributions from the orthogonal time direction
- Torsion coupling from Pneuma spinor condensates
This provides a natural framework for cosmic acceleration without a bare cosmological constant, with the equation of state w → -1 as a late-time attractor.
Connection to the Pneuma Field
While the Einstein-Hilbert term appears as a separate contribution to the action, it is fundamentally sourced by the Pneuma field. The metric GMN itself is determined by Pneuma condensates:
This is the deep meaning of the fermionic geometry hypothesis: even the gravitational degrees of freedom ultimately trace back to the fundamental Pneuma field.