Big-Bang model

Definition

The model that the universe developed from an extremely hot, dense early state and has expanded and cooled over time.

Used by OCR

Specification P8.3b · Paper 2 (Foundation), Paper 4 (Higher)

The Big-Bang model describes an expanding universe. About 13.8 billion years ago, the universe was in an extremely hot, dense state. As it expanded, it cooled.
Revise: Big-Bang evidence

Paper 1, Paper 2

The scientific model that the Universe began in a very hot, dense state about 14 billion years ago and has since expanded.

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The subsequent expansion is described by the Big Bang model, which places this early stage about 14 billion years ago.