Summary
Tiny temperature fluctuations in the CMB encode the primordial density variations that later grew into galaxies and large-scale cosmic structure.
Observation / Fact
High-resolution measurements (WMAP, Planck) reveal anisotropies at the level of ~10⁻⁵ in the CMB temperature map. These fluctuations follow a precise angular power spectrum.
Why This Is Non-Trivial
The statistical properties of the anisotropies match predictions for a universe that began in a hot, dense state with well-defined initial conditions. Random or steady-state processes do not reproduce the observed spectrum.
What It Implies
Large-scale structure traces back to minute, early-universe conditions. This links present-day cosmic order directly to finely specified initial states rather than ad hoc later processes.
Related
- Isotropy of the CMB
- Blackbody Spectrum Precision