PhysicsChapter 9: Cosmology
Evidence For the Big Bang
Evidence for the Big Bang
Definition
Evidence for the Big Bang consists of observations that support the model of an expanding universe that evolved from a hot, dense early state.
1. Expansion of the Universe
Three major lines of evidence are: Distant galaxies show cosmological redshift. Hubble's relation: **v=H₀d** supports large-scale expansion.
2. Cosmic Microwave Background
The universe contains nearly uniform microwave radiation coming from all directions. It has an almost perfect thermal spectrum corresponding to a temperature of about: **2.7 K** This is interpreted as relic radiation from the hot early universe.
3. Primordial Light Elements
Hot Big Bang calculations predict characteristic early production of light nuclei, especially: hydrogen; helium; * small amounts of certain other light nuclei. Observed primordial abundances broadly agree with this framework.
Formula / Key Relation
**v=H₀d TCMB≈2.7K**
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Review the key facts, formulas and checks before you move on.Evidence For the Big Bang
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BIG BANG EVIDENCE
- 1. Expansion
- 2. CMB ≈ 2.7 K
- 3. Light elements
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- Several independent observations support hot Big Bang cosmology.
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