{"section":"cosmology","label":"Cosmology","count":12,"generatedAt":"2026-03-20","items":[{"slug":"big-bang-cosmology-and-lambda-cdm","path":"/cosmology/big-bang-cosmology-and-lambda-cdm/","title":"Big Bang Cosmology & The ΛCDM Model","description":"How the six-parameter spatially flat Lambda-Cold Dark Matter (ΛCDM) concordance model explains cosmic expansion, the CMB, and large-scale structure.","questionOrTopic":"What is the standard ΛCDM Big Bang model and what are its six foundational parameters?","epistemicStatus":"standard-model-consensus","formula":"H²(z) = H₀² [ Ω_r (1 + z)⁴ + Ω_m (1 + z)³ + Ω_Λ ]","keyMetricsCount":4,"sources":["src:planck-2018","src:shoes-2022"]},{"slug":"cosmic-microwave-background","path":"/cosmology/cosmic-microwave-background/","title":"The Cosmic Microwave Background (CMB)","description":"How the 2.7255 K thermal blackbody afterglow of recombination and its 10⁻⁵ acoustic anisotropies encode the geometry and composition of the universe.","questionOrTopic":"What is the Cosmic Microwave Background and what do its acoustic peaks measure?","epistemicStatus":"strong-observational-evidence","formula":"T_CMB(z) = T₀ (1 + z)  ;  θ_* = r_s(z_*) / D_M(z_*) = 0.010411 rad (0.596°)","keyMetricsCount":4,"sources":["src:planck-2018"]},{"slug":"hubble-parameter-and-expansion-history","path":"/cosmology/hubble-parameter-and-expansion-history/","title":"Hubble Parameter H(z) & Expansion History","description":"How the Hubble parameter H(z) evolves across cosmic epochs from radiation and matter deceleration to dark-energy-driven acceleration.","questionOrTopic":"How does the Hubble parameter H(z) change over cosmic time?","epistemicStatus":"strong-observational-evidence","formula":"E(z) ≡ H(z) / H₀ = √[ Ω_m (1 + z)³ + Ω_Λ ]  ;  q(z) = Ω_m(z)/2 − Ω_Λ(z)","keyMetricsCount":4,"sources":["src:planck-2018","src:shoes-2022"]},{"slug":"hubble-tension","path":"/cosmology/hubble-tension/","title":"The Hubble Tension in Modern Cosmology","description":"Why early-universe CMB measurements (67.4 km/s/Mpc) and local distance-ladder measurements (73.0 km/s/Mpc) disagree at the 5-sigma level.","questionOrTopic":"What is the Hubble tension and why do early- and late-universe measurements of H₀ disagree?","epistemicStatus":"competing-interpretations","formula":"T_σ = |H₀,local − H₀,CMB| / √(σ_local² + σ_CMB²) ≈ |73.04 − 67.36| / √(1.04² + 0.54²) ≈ 4.9σ","keyMetricsCount":4,"sources":["src:planck-2018","src:shoes-2022","src:jwst-archive","src:gaia-dr3"]},{"slug":"dark-matter-evidence-and-candidates","path":"/cosmology/dark-matter-evidence-and-candidates/","title":"Dark Matter: Evidence & Particle Candidates","description":"How galaxy rotation curves, cluster gravitational lensing, the Bullet Cluster, and CMB acoustic peaks prove non-baryonic cold dark matter.","questionOrTopic":"What is the astrophysical evidence for dark matter and what are the leading particle candidates?","epistemicStatus":"standard-model-consensus","formula":"M(<r) = r v_circ² / G  ;  ρ_NFW(r) = ρ_0 / [ (r/r_s)(1 + r/r_s)² ]","keyMetricsCount":4,"sources":["src:planck-2018","src:gaia-dr3"]},{"slug":"dark-energy-and-cosmic-acceleration","path":"/cosmology/dark-energy-and-cosmic-acceleration/","title":"Dark Energy & Cosmic Acceleration","description":"How Type Ia supernovae, BAO, and the CMB reveal that 68.5% of the universe consists of negative-pressure dark energy driving accelerated expansion.","questionOrTopic":"What is dark energy and why does it cause the expansion of the universe to accelerate?","epistemicStatus":"active-research-frontier","formula":"(d²a / dt²) / a = −(4πG / 3) · ρ_total (1 + 3w)  ;  ρ_DE(z) = ρ_DE,0 (1 + z)^(3(1 + w))","keyMetricsCount":4,"sources":["src:planck-2018","src:shoes-2022"]},{"slug":"cosmic-inflation-and-horizon-problem","path":"/cosmology/cosmic-inflation-and-horizon-problem/","title":"Cosmic Inflation & The Horizon Problem","description":"How an early epoch of exponential expansion solves the horizon and flatness puzzles and stretches quantum vacuum fluctuations into cosmic structure seeds.","questionOrTopic":"What is cosmic inflation and how does it explain the horizon problem and primordial fluctuations?","epistemicStatus":"standard-model-consensus","formula":"N_e = ln(a_end / a_init) = ∫ H dt ≥ 60  ;  P_ℛ(k) = A_s (k / k_* )^(n_s − 1)","keyMetricsCount":4,"sources":["src:planck-2018"]},{"slug":"recombination-and-surface-of-last-scattering","path":"/cosmology/recombination-and-surface-of-last-scattering/","title":"Recombination & Surface of Last Scattering","description":"How the primordial plasma cooled below 3,000 K at z ≈ 1,090 (380,000 years), forming neutral hydrogen and releasing the Cosmic Microwave Background.","questionOrTopic":"How did recombination turn the opaque early universe transparent at 380,000 years?","epistemicStatus":"strong-observational-evidence","formula":"[x_e² / (1 − x_e)] = (1 / n_H) (m_e k_B T / 2πℏ²)^(3/2) e^(−E_I / k_B T)  ;  dτ = n_e σ_T c dt","keyMetricsCount":4,"sources":["src:planck-2018"]},{"slug":"big-bang-nucleosynthesis","path":"/cosmology/big-bang-nucleosynthesis/","title":"Big Bang Nucleosynthesis (BBN)","description":"How the first three minutes of the universe fused protons and neutrons into ~75% hydrogen, ~25% helium-4, trace deuterium, and lithium-7.","questionOrTopic":"How did Big Bang Nucleosynthesis forge the lightest elements in the first three minutes?","epistemicStatus":"strong-observational-evidence","formula":"Y_p = 2(n / p)_fusion / [ 1 + (n / p)_fusion ] ≈ 0.247","keyMetricsCount":4,"sources":["src:planck-2018"]},{"slug":"baryon-acoustic-oscillations","path":"/cosmology/baryon-acoustic-oscillations/","title":"Baryon Acoustic Oscillations (BAO)","description":"How frozen primordial sound waves with a 147-megaparsec comoving radius serve as a precision cosmic standard ruler across galaxy redshift surveys.","questionOrTopic":"What are Baryon Acoustic Oscillations and how do they act as a cosmic standard ruler?","epistemicStatus":"strong-observational-evidence","formula":"r_d = ∫_(z_d)^∞ [ c_s(z) / H(z) ] dz ≈ 147.09 ± 0.26 Mpc  ;  Δθ_BAO = r_d / D_M(z)","keyMetricsCount":4,"sources":["src:planck-2018"]},{"slug":"matter-antimatter-asymmetry","path":"/cosmology/matter-antimatter-asymmetry/","title":"Baryogenesis & Matter-Antimatter Asymmetry","description":"Why the universe contains galaxies of matter rather than equal antimatter, governed by Sakharov's conditions and the 6 × 10⁻¹⁰ baryon-to-photon ratio.","questionOrTopic":"Why is the observable universe made of matter instead of equal amounts of matter and antimatter?","epistemicStatus":"active-research-frontier","formula":"η = (n_B − n_B̄) / n_γ = 2.74 × 10⁻⁸ Ω_b h² = (6.12 ± 0.04) × 10⁻¹⁰","keyMetricsCount":4,"sources":["src:planck-2018"]},{"slug":"ultimate-fate-of-the-universe","path":"/cosmology/ultimate-fate-of-the-universe/","title":"The Ultimate Fate of the Universe","description":"How the dark energy equation of state determines whether the universe ends in an asymptotic de Sitter Heat Death (Big Freeze), Big Rip, or Big Crunch.","questionOrTopic":"How will the universe end according to modern cosmological observations?","epistemicStatus":"active-research-frontier","formula":"a(t) ∝ exp(H₀ √Ω_Λ · t)  [for w = −1]  ;  t_rip − t₀ ≈ (2 / 3|1 + w|) · H₀⁻¹ / √Ω_DE  [for w < −1]","keyMetricsCount":4,"sources":["src:planck-2018","src:shoes-2022"]}]}