C_ℓ multipoles: acoustic peaks from baryon-photon fluid; first peak ℓ≈220 → flat universe; Silk damping at high ℓ; integrated Sachs–Wolfe at low ℓ.
C_ℓ multipoles: acoustic peaks from baryon-photon fluid; first peak ℓ≈220 → flat universe; Silk damping at high ℓ; integrated Sachs–Wolfe at low ℓ.