Experiment #150 · Scientific experiment

WMAP and Planck CMB Anisotropy Maps

Cosmological parameters to percent-level precision

WMAP team (NASA); Planck Collaboration (ESA) · 2003 / 2013–2018 · Cosmology

First published: C. L. Bennett et al. (WMAP), "First-Year WMAP Observations", *ApJS* 148 (2003): 1; Planck Collaboration, "Planck 2018 results", *A&A* 641 (2020).

Tiny temperature variations in the CMB (one part in 100,000) encode the geometry, content, and age of the universe to percent precision.

The temperature anisotropies of the cosmic microwave background — variations of ~10⁻⁵ on the 2.725 K mean — encode the entire content of the early universe. COBE (1992) detected the anisotropies; WMAP (2003) and Planck (2013, 2015, 2018) mapped them at increasing angular resolution. Fitting the angular power spectrum against ΛCDM yields cosmological parameters: H₀ ≈ 67.4 km/s/Mpc, Ω_m ≈ 0.315, Ω_Λ ≈ 0.685, age 13.8 Gyr, all to percent precision. The maps also constrain inflation, primordial non-Gaussianity, and the optical depth to reionisation. The CMB anisotropies are the single most consequential dataset in modern cosmology.

Formulation

All-sky maps of CMB temperature (and polarisation) at multi-frequency. Decompose into spherical harmonics; compute angular power spectrum C_ℓ. Fit ΛCDM-derived prediction to data: extract 6 cosmological parameters (H₀, Ω_b, Ω_c, n_s, A_s, τ) plus derived (Ω_Λ, age, etc.). Statistical errors at percent or sub-percent level.

Compare this experiment

Dimensions Engaged

⧖

Time

Pins universe age to ±20 Myr.

◉

Matter

Determines baryon and cold-dark-matter densities to percent precision.

✦

Space

Confirms spatial flatness to ~0.5%.

⚡

Energy

Establishes dark-energy density and equation of state.

Responses — How Schools Engage

Affirms / takes the bait 4

Naturalism

A foundational triumph of empirical cosmology: a precise quantitative model of the early universe fitted to extraordinary precision.

Realism

The cosmological parameters are real features of the universe, measured to percent precision; the early universe is empirically reconstructed.

Eternalism

The block universe accommodates a precisely-dated early-universe state; CMB maps are slices through cosmic history.

Logical Positivism

Operationally exemplary: a 6-parameter quantitative model is fitted to high-precision data, yielding empirically constrained values for fundamental cosmological quantities.

Reframes the question 2

Multiverse Theory

Inflationary cosmology (which CMB confirms) generically predicts eternal inflation and a multiverse; the CMB is the strongest indirect evidence for that framework.

Catholic/Thomistic

A finite-age universe with quantitatively-characterised origin is congenial to creation cosmology; theological commitments accommodate but do not depend on specific values.