AST-663intermediate

The Big Bang Model: Physical Mechanisms

The Big Bang model describes an early universe that was hotter, denser, and more uniform than today and has expanded and cooled over cosmic time. The Big Bang framework connects particle physics, nucleosynthesis, recombination, structure formation, cosmic age, and the thermal history of the universe.

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The Big Bang Model: Physical Mechanisms

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AST-662The Big Bang Model: Structures & Vocabulary→

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AST-664The Big Bang Model: Observation, Measurement & Evidence→

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The Big Bang model describes an early universe that was hotter, denser, and more uniform than today and has expanded and cooled over cosmic time.

supported

Running cosmic expansion backward implies increasing density and temperature.

supported

The CMB has an almost perfect thermal spectrum, observed helium and deuterium abundances agree with early-universe nuclear calculations, and galaxy redshifts demonstrate expansion.