Photon–baryon acoustic structure in the CMB
Before recombination, scattering tightly coupled photons and baryons.
Key knowledge
Before recombination, scattering tightly coupled photons and baryons. Gravitational perturbations drove small-amplitude acoustic oscillations, with photon pressure providing restoring force and baryons contributing inertia. Density/temperature and velocity contributions had different phases. Their projection at last scattering produces peak structure in the CMB angular spectrum; imperfect coupling, photon diffusion and finite last-scattering width suppress small-scale anisotropy.
Conditions and scope
- This is a mechanism within a perturbed expanding-background model, not an exact single oscillator for the whole sky. Sound propagation, background geometry, initial perturbations and scattering history jointly affect the spectrum.
- No current cosmological best-fit value, universal peak position, complete Boltzmann solution or unique parameter inference is asserted.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual coupled-fluid, baryon inertia, out-of-phase velocity, projection and diffusion/finite-width paragraphs. Excluded dated code-precision and likelihood-fit claims; qualitative core mechanism is distinguished from parameter estimation.
2026-10-10 · Independent AI editorial review: All44 exact root-authored compact records, equations/variable units/conditions and140 origin edges accepted after independently reading final6/18 with bounded primary bodies and matching prior38/122 scientific fingerprints unchanged. Exact claim/edge review is distinct from combined inventory scope and separate CLE26 approval; no entire cited books or old-corpus experimental revalidation is asserted. Receipt: cosmos-completion-independent-content-and-inventory-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-cosmos-cmb-acoustic-mechanism
- Revision
- core.1
- Structured reference record
- University core expansion