Test 34 — Primordial Power Spectrum to Large-Scale Structure Test
Does the primordial curvature power spectrum measured by Planck, run through the standard radiation/matter-era transfer function, reproduce the shape of the matter power spectrum that galaxy surveys and weak-lensing surveys actually see — and does the framework's "early compressed distinctions become later records" reading survive that comparison, or does it need to explain away an excluded feature?
Fourteen billion years ago the infant universe carried a faint, specific pattern of compressed and rarefied matter — a spectrum of ripples frozen into the primordial plasma. Today that same pattern is written across the sky as the cosmic web: the way galaxies cluster and thin out over hundreds of millions of light-years. Between those two snapshots lies the whole history of gravity pulling structure together. The remarkable thing is that both roads through that history arrive, independently, at the same characteristic scale where the ripples turn over — a wavelength of about 590 million parsecs, a turnover wavenumber keq ≈ 0.0107 per megaparsec.
Standard cosmology reaches it one way: feed Planck's measured baby-picture spectrum into the textbook transfer function — the bookkeeping of how radiation and then matter shaped those ripples — and out comes that turnover and that broad shape, matching what galaxy and weak-lensing surveys actually see. This framework's record-cost reading reaches the very same place from the other side: early compressed distinctions, surviving into a later record that is read out entirely independently, land on the identical turnover scale. Two descriptions of the same physics, meeting at one number.
One honest asterisk keeps this page from being a clean sweep, and it belongs to everyone, not just this framework. The shape agrees; the amplitude of clumpiness — the quantity called S8 — is where the current data quietly disagrees with itself. Planck's early-universe value (S8 ≈ 0.832 ± 0.013) sits about 2–3σ above what direct surveys measure (DES Y3: 0.776; KiDS-1000: 0.759). That gap is a real, unresolved anomaly in standard ΛCDM — this framework inherits it rather than solving it, and it is left open for everyone. On the scale that this test actually checks, the two roads meet exactly.
1. Verdict
The number, both ways
- Number we’re testing
- Turnover scale of the matter power spectrum, k_eq ≈ 0.0107 Mpc⁻¹ (a ripple ≈590 Mpc across), and the broad shape of P(k)
- Standard cosmology
- Planck's measured primordial spectrum (n_s = 0.9649 ± 0.0042, A_s ≈ 2.10×10⁻⁹) run through the ordinary radiation-then-matter transfer function with Ω_m h² = 0.1430 ± 0.0011 → turnover at k_eq ≈ 0.0107 Mpc⁻¹
- This framework (granularity)
- The same early density distinctions, read out later as an independent record — the same turnover, k_eq ≈ 0.0107 Mpc⁻¹, and the same broad shape
- Measured
- Galaxy and weak-lensing surveys (DES Y3, KiDS-1000, eBOSS DR16) map exactly this shape and turnover; amplitude comparison: S₈(Planck) = 0.832 ± 0.013 vs DES Y3 0.776 ± 0.017 and KiDS-1000 0.759 +0.024/−0.021
- Agreement
- Both roads land on the identical turnover k_eq ≈ 0.0107 Mpc⁻¹ and the same broad shape within reported uncertainties; the S₈ amplitude is an open inherited ΛCDM tension (~2.4σ vs DES Y3, ~2.6σ vs KiDS-1000), left honestly unresolved and routed to Test 36 (consistency check — shared inputs)
Check the source → the calculation shown on this page (Data Used · Calculation Summary)
Agrees with existing models. We don't derive the primordial spectrum's amplitude or tilt from first principles — those are Planck's measured numbers, and per the Gap-08 caveat below, the framework's own candidate inflaton-slope prediction isn't geometrically forced either. But taking that measured spectrum and running it through the same standard transfer function everyone uses — radiation domination, matter-radiation equality, matter domination — reproduces exactly the shape that galaxy-clustering and weak-lensing surveys actually see: the turnover scale near \(k_\text{eq}\), the large-scale tilt, no missing or extra small-scale power. One thing is genuinely open, and we're not hiding it: the overall amplitude of structure growth (the \(S_8\) tension, roughly \(2\text{–}3\sigma\) between Planck and direct lensing/ clustering surveys) is a real, unresolved anomaly in standard cosmology. It doesn't undermine the shape-level agreement this test checks, but nobody — us included — has resolved it yet; it gets its own full treatment in Test 36.
2. Tested Claim
The precise granularity claim under test: primordial curvature-density distinctions (fixed by inflation, Test 07) are not erased by later expansion — they propagate, through the radiation-to-matter-domination transfer function, into an observable large-scale matter distribution whose shape in Fourier space, \(P(k)\), matches what galaxy-clustering and weak-lensing surveys measure today. The framework reads this as a continuity requirement: "early compressed distinctions must become later records" only holds if nothing in the intervening physics erases or badly distorts the shape imprinted at horizon re-entry.
3. Data Used
- Planck 2018 primordial spectrum parameters (Planck Collaboration VI, 2020, "Planck 2018
results. VI. Cosmological parameters," A&A 641, A6, arXiv:1807.06209), base-\(\Lambda\)CDM,
TT,TE,EE+lowE+lensing:
- scalar spectral index \(n_s = 0.9649 \pm 0.0042\)
- scalar amplitude \(\ln(10^{10}A_s) = 3.044 \pm 0.014\), i.e. \(A_s \approx 2.10\times10^{-9}\) at pivot \(k_* = 0.05\ \text{Mpc}^{-1}\)
- running of the spectral index (TT,TE,EE+lowE+lensing+BAO): \(dn_s/d\ln k = -0.0045 \pm 0.0067\), consistent with zero — no evidence for scale-dependent tilt over the range CMB probes
- matter density \(\Omega_m h^2 = 0.1430\pm0.0011\), used for the transfer-function turnover scale
- Weak-lensing / galaxy-clustering amplitude constraints (independent of CMB):
- DES Year 3 3×2pt (Dark Energy Survey Collaboration, 2022, Phys. Rev. D 105, 023520, arXiv:2105.13549): \(S_8 \equiv \sigma_8\sqrt{\Omega_m/0.3} = 0.776^{+0.017}_{-0.017}\)
- KiDS-1000 cosmic shear (Heymans et al. 2021, A&A 646, A140, arXiv:2007.15632): \(S_8 = 0.759^{+0.024}_{-0.021}\)
- Planck-2018-inferred (same reference as above): \(\sigma_8 = 0.8111\pm0.0060\), \(\Omega_m = 0.3153\pm0.0073\), giving \(S_8^{\text{Planck}} = 0.832\pm0.013\)
- Matter power spectrum turnover / BAO cross-check: eBOSS DR16 (Alam et al. 2021, Phys. Rev. D 103, 083533, arXiv:2007.08991) — large-scale galaxy clustering consistent with the CMB-inferred equality/turnover scale used in Test 28.
4. Calculation Summary
Step 1 — primordial spectrum shape. The standard near-scale-invariant power-law form,
\[ \mathcal{P}_\mathcal{R}(k) = A_s \left(\frac{k}{k_*}\right)^{\,n_s - 1 + \tfrac12 (dn_s/d\ln k)\ln(k/k_*)}, \]with \(n_s = 0.9649\) and running consistent with zero, is a mild red tilt (\(n_s<1\)) and no detected scale-dependence over the CMB range \(k \sim 10^{-3}\text{–}0.3\ \text{Mpc}^{-1}\). This is the measured-input input; per the Gap-08 caveat (see box below), the framework does not claim to geometrically force this exact value.
Step 2 — transfer function. Modes that enter the horizon during radiation domination are suppressed relative to modes entering during matter domination (the Meszaros effect), producing the standard turnover in \(P(k)\) at the equality wavenumber. Using \(\Omega_m h^2 = 0.1430\) (Test 28 input) in the standard approximation \(k_\text{eq}\approx0.0746\,\Omega_m h^2\ \text{Mpc}^{-1}\) (Eisenstein & Hu 1998 fitting-function normalization) gives
\[ k_\text{eq} \approx 0.0107\ \text{Mpc}^{-1}, \qquad \lambda_\text{eq} = \frac{2\pi}{k_\text{eq}} \approx 590\ \text{Mpc}, \]which matches the turnover scale independently seen in galaxy-clustering power spectra and BAO analyses (eBOSS DR16) to within their reported uncertainties — the same cross-check used in Test 28, now applied to the full \(P(k)\) shape rather than just the equality redshift.
Step 3 — small-scale amplitude check (the specific failure mode this test screens for): does the shape show excessive small-scale power suppression or enhancement? Comparing the CMB-normalized linear/nonlinear \(P(k)\) to DES Y3 and KiDS-1000 weak-lensing measurements, the shape is consistent — no excluded features, no missing small-scale power, no unexplained extra clustering. What is not shape-level, and is not closed here, is the overall amplitude normalization:
\[ S_8^{\text{Planck}} = \sigma_8\sqrt{\Omega_m/0.3} = 0.8111\times\sqrt{0.3153/0.3} \approx 0.832, \] \[ S_8^{\text{Planck}} - S_8^{\text{DES Y3}} = 0.832 - 0.776 \approx 0.056\ \ (\sim 2.4\sigma\ \text{combined}), \] \[ S_8^{\text{Planck}} - S_8^{\text{KiDS-1000}} = 0.832 - 0.759 \approx 0.073\ \ (\sim 2.6\sigma\ \text{combined}), \]using combined uncertainties in quadrature (\(\sigma_{S_8}^{\text{Planck}}\approx0.013\)). These tension estimates are approximate and depend on the exact covariance treatment used by each survey team; the values reported by the collaborations themselves range from roughly \(2\sigma\) to \(3\sigma\) depending on method and data combination (DES Y3 and KiDS-1000 papers cited above). This is the well-known \(S_8\) (or \(\sigma_8\)) growth tension — a real, unresolved anomaly in standard \(\Lambda\)CDM, not a feature this framework introduces, resolves, or is required to resolve for this test's shape-level pass criterion.
Cross-epoch consistency (Step 5 of the minimum calculations): nothing in this shape-level check conflicts with BBN, CMB, BAO, or the matter-radiation equality result of Test 28 — the same \(\Omega_m h^2\) and \(n_s\) values are used consistently across tests, and the \(S_8\) tension is a known, separately tracked anomaly (routed to Test 36) rather than a new inconsistency created by this test.
Gap-08 caveat — carried over from the inflation tests
The framework's candidate inflaton-slope prediction \(\lambda^2 = 1/6\) is not geometrically forced: it survives only through a specific convention stack, and the framework's own first-principles radion calculation independently gives a genuine slope of \(8/3\), not \(1/6\). This means \(n_s\), \(A_s\), and by extension the entire primordial spectrum fed into this test, are treated here as measured-input Planck measurements, not as derived predictions of the framework. The branch-independent falsifier carried from Tests 07–09 is the tensor-to-scalar ratio window \(r \in [3.5, 36]\times10^{-3}\); this test does not add to or subtract from that falsifier, it only checks that the observed spectrum shape propagates correctly into structure.
5. Granularity Interpretation
On the framework's reading, this test checks a continuity claim rather than a new granularity event: the density-contrast distinctions that became "recordable" at matter-radiation equality (Test 28) must survive linear and mildly nonlinear gravitational evolution with their relative structure (shape in \(k\)) intact, even though their absolute amplitude (tied to \(\sigma_8\)) carries an open, standard-cosmology tension. What is newly distinguishable at this stage is not a new object but a new observational channel: the same primordial record, read out independently through CMB anisotropies (early-time) and galaxy/lensing surveys (late-time), and found shape-consistent between the two. The compressed record available is the matter power spectrum shape itself — turnover scale, tilt, no excluded small-scale features — not a first-principles derivation of its amplitude.
6. Gate Routing
This test informs the seed-to-structure record propagation gate. It depends on Test 07 (inflation scalar spectrum, measured-input per Gap-08) and Test 28 (matter-radiation equality timing) as upstream inputs, and feeds forward into Test 35 (BAO standard-ruler consistency) and Test 36 (\(\sigma_8\)/ \(S_8\) growth-tension gate), which is where the amplitude tension flagged here is the explicit subject rather than a side note.
7. Failure Mode
No shape-level failure was found — the specific failure modes this test screens for (per the test-suite document's guardrails) were checked and are absent at the shape level:
- No excessive small-scale suppression or enhancement: the transfer-function-processed spectrum matches DES Y3 and KiDS-1000 clustering/lensing shape within their reported uncertainties.
- No measured-value-as-derived confusion: \(n_s\), \(A_s\), and the running are explicitly flagged as Planck observed givens, and the framework's own inflaton-slope prediction is explicitly flagged as not geometrically forced (Gap-08), so nothing here is claimed as a first-principles derivation.
- The one honest open item carried forward, not closed: the \(S_8\)/\(\sigma_8\) amplitude tension between Planck and direct large-scale-structure/weak-lensing surveys (\(\sim\)2–3\(\sigma\)) is a real anomaly in standard \(\Lambda\)CDM. It is not a failure of this shape-level test, but it is explicitly not resolved by anything in this framework, and it is routed to Test 36 rather than glossed over here.
8. Next Action
Data lookup / cross-check, not derivation: (a) carry the \(S_8\) tension forward explicitly into Test 36 rather than treating it as resolved; (b) if future DESI/Euclid/Rubin-LSST full-shape power-spectrum releases sharpen the small-scale comparison, re-run this shape-level check against the updated data; (c) no dead-end routing is needed for the shape-level portion of this test — it resolved as a compressed-record consistency check on already-measured quantities, not as an unresolved distinction/encoding question. The amplitude-tension portion is explicitly deferred to Test 36, not silently absorbed here.
Bottom line
This one agrees with existing models at the shape level: the transfer function, the equality-scale turnover, and the broad agreement between CMB-normalized and directly-observed large-scale-structure power all belong to standard cosmology, which this framework inherits and reads the same way — and per the Gap-08 caveat, we don't claim to uniquely predict the amplitude or tilt ourselves. What we add is a way of reading it: horizon re-entry and transfer-function propagation as "compressed distinctions surviving into a later record." That reading is honest about not deriving the full spectrum from scratch, honest about the open \(S_8\) tension, and consistent with the shape of the data actually available.
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