Cosmology
4 marks · EasyScientists use both red-shift and the cosmic microwave background (CMB) radiation to support their model of the universe.
State what is meant by cosmic microwave background (CMB) radiation.
Explain how observations of both red-shift and the CMB together provide evidence for the Big Bang.
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(a) CMB is microwave radiation detected in all directions, the afterglow of the Big Bang.
(b) Red-shift shows galaxies are moving away from each other (the universe is expanding). The CMB is leftover energy from an early, hot and dense state. Together, they show the universe started in a hot, dense explosion – the Big Bang.
Common mistakes: Confusing CMB with radiation from stars; Not linking both pieces of evidence to an origin event
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Marking points
B1 (a) · 1 mark · States CMB is microwave radiation detected in all directions
B2 (a) · 1 mark · Mentions CMB is the afterglow from the early universe or Big Bang
B3 (b) · 1 mark · States red-shift as evidence for expansion
B4 (b) · 1 mark · Explains both red-shift and CMB show the universe began in a hot, dense event (Big Bang)
Worked solution
(a) CMB is microwave radiation detected from all directions in space, considered the afterglow of the Big Bang.
(b) Red-shift means the universe is expanding; CMB is energy left over from when the universe was very hot and dense. Together, these show there was an initial explosion – the Big Bang.