Observable detail · SOLAR

γ_PPN − 1

post-Newtonian γ

Prediction−1.998 × 10⁻⁵
MeasuredAwaiting BepiColombo MORE 2027–2028
Residualopen (Cassini consistent)
Statusopen
Source paperDCT-PPN-01

Mechanism

γ − 1 = −1/(ω_0 + 2). Master identity 2ω_0 + 3 = c_BD·P_0² = 100,077 fixes ω_0 = 50,037, giving γ − 1 = −1.998 × 10⁻⁵. Cassini bound (2.1 ± 2.3) × 10⁻⁵ is consistent at 13% margin; BepiColombo MORE 2027–2028 will distinguish DCT from GR at 6.7σ.

Derivation

γ − 1 = −1/(ω_0 + 2). Master identity 2ω_0 + 3 = c_BD·P_0² = 100,077 fixes ω_0 = 50,037, giving γ − 1 = −1.998 × 10⁻⁵. Cassini bound (2.1 ± 2.3) × 10⁻⁵ is consistent at 13% margin; BepiColombo MORE 2027–2028 will distinguish DCT from GR at 6.7σ.

The closed-form prediction is

$$ \text{predicted} = −1.998 × 10⁻⁵ $$

against the measurement Awaiting BepiColombo MORE 2027–2028, giving residual open (Cassini consistent).

Python verification

The verification script for this observable is gravity_tests.py. Run it with python3 gravity_tests.py to reproduce the canonical DCT result against the public-archive measurement source listed above (Bertotti, Iess, Tortora 2003 (Cassini); Iess 2021 (BepiColombo MORE projection).).

References

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