From universe origin to 300,000 years later, from any space point most other space points had space expansion rate faster than light speed. Because universe radius was larger than cosmic horizon, light from most early-universe space points did not reach most other space points, and space did not reach thermal equilibrium {thermalization}. Space was non-homogeneous, and space regions had different temperatures, mass-energy densities, and space curvatures. However, cosmic microwave background radiation has same temperature to 1 part in 10,000, showing that universe is almost homogeneous. How did space regions beyond each other's cosmic horizons become almost homogeneous {horizon problem}? Perhaps, beyond current cosmic horizon, universe is not really homogeneous. Perhaps, random quantum-mechanical processes kept variations to 1 part in 10000. Perhaps, in-phase sound waves caused compressions and rarefactions of 1 part in 10000. Perhaps, early-universe space inflation greatly decreased space curvature, mass-energy density, and temperature, so variations greatly decreased.
Physical Sciences>Astronomy>Universe>Cosmology
5-Astronomy-Universe-Cosmology
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Date Modified: 2022.0224