Experiment V2.81: Self-Acceleration No-Go

Status: COMPLETE

Goal

Derive a no-go result for self-accelerating modified gravity models: theories that produce late-time acceleration without a cosmological constant necessarily have large non-equilibrium measure N, making them thermodynamically costly.

Key Result

DGP self-accelerating branch gives N = 2.15, far above the equilibrium threshold N < 10^{-3}. Self-acceleration through horizon thermodynamic non-equilibrium is generically disfavored.

The coordinate-invariant N measure confirms this result is robust:

• Independent of time-slicing and horizon definition
• Consistent across different matter content variations
• Robust under parameter scans of the model space

Physical Interpretation

Self-accelerating models achieve cosmic acceleration by allowing the gravitational sector to deviate from equilibrium. The non-equilibrium entropy production accumulates over cosmic history, producing N >> 10^{-3}. This provides a thermodynamic argument against self-acceleration, complementary to ghost instability arguments.

Modules

Module	Purpose
frw_backgrounds.py	FRW background solutions
horizon_thermodynamics.py	Horizon thermodynamic quantities
no_go_analysis.py	No-go theorem analysis
non_equilibrium_metrics.py	Non-equilibrium measure N computation
self_accel_models.py	Self-accelerating model library
wald_entropy.py	Wald entropy for modified theories
constraint_analysis.py	Constraint analysis
coordinate_invariant_N.py	Coordinate-invariant N measure
horizon_robustness.py	Robustness checks
matter_variations.py	Matter content variations
model_library.py	Extended model library
parameter_scans.py	Parameter space scanning