BAO Coherence Modulation (TEST-04)
Derivation PendingStatus: TEST-04 is listed as Tier-1 and is potentially discriminating against ΛCDM. However, the derivation of the predicted 10−4 shift and the specific estimator required to test it do not yet exist on this site. This page is a derivation stub. The physics argument is given below; the quantitative derivation is open.
The Prediction
Synchronism predicts that BAO (Baryon Acoustic Oscillation) peak positions shift by approximately 10−4 between high-density and low-density large-scale environments. Standard ΛCDM predicts no such density-dependent shift — the BAO scale is set at recombination and propagates identically through all environments.
Kill criterion: if the BAO peak is identical to 10−5 precision across density environments, the prediction is falsified.
Measurement caveat (Pass 4 review, 2026-04-29): DESI Y3 precision on isotropic BAO α is ~0.5–1%, not 10−5. A 10−4 density-split modulation requires a dedicated cross-correlation estimator — split the sample by environmental density (e.g., Voronoi tessellation), compute BAO peaks per bin, look for a fractional shift. The kill criterion as stated (10−5 precision) is not achievable with any current dataset. The achievable precision on a density-split estimator from DESI Y3 is likely ~10−3. This page needs to be updated when the estimator is specified.
Why This Prediction Follows from the Framework
In Synchronism, the coherence function C(ρ) is density-dependent. High-density environments have higher C(ρ), meaning correlations persist to longer scales. The BAO feature is imprinted at a scale set by the sound horizon at recombination, but the apparent peak position in a survey depends on how coherence modulates the two-point correlation function in the clustering regime.
Qualitatively: in denser environments (galaxy clusters, filaments), C(ρ) is higher, meaning the coherence length extends further, which should slightly shift the BAO peak outward. In voids, C(ρ) is lower, the coherence length is shorter, and the apparent peak position should shift inward.
What Is Missing (the open derivation)
The qualitative argument above does not produce the number 10−4. To get there, we need:
- A quantitative model of how C(ρ) modifies the two-point correlation function ξ(r). This requires either a perturbation theory calculation or an effective description of how coherence modifies the matter power spectrum.
- A mapping from C(ρ) density-dependence to BAO peak displacement Δr/r_BAO. The 10−4 number is the prediction — but it currently has no derivation. If it is an order-of-magnitude estimate (e.g., from the magnitude of C(ρ) variation between void and filament), that reasoning should be shown explicitly.
- A specification of the observational estimator: which density proxy, what bin boundaries, what cross-correlation statistic, what the expected signal-to-noise is in DESI Y3.
Until the number 10−4 is derived (not assumed), this prediction is an exploratory hypothesis, not a sharp falsifier. The prediction badged above reflects that status honestly.
Why It Matters
TEST-04 is one of a small number of predictions that could genuinely discriminate Synchronism from standard ΛCDM+MOND. Environment-dependent BAO is not a prediction of any standard cosmological model. If the effect exists at the predicted scale, it would be a clear signal. If it does not, it would falsify this aspect of the framework.
The data required already exists (DESI public releases). This is a 4–8 week computational task for someone with access to a BOSS/DESI galaxy catalog and a density estimator. The framework should not wait to learn the answer.