GCSE Physics · AQA 8463 · Topic 4.8.2
Red-shift
Key points
- Red-shift is the increase in observed wavelength of light from galaxies moving away from us.
- More distant galaxies show greater red-shift, so they are moving away faster. This shows the universe is expanding.
- This evidence supports the Big Bang theory: the universe began from a very small, extremely hot and dense region.
- Since 1998, observations of supernovae suggest that distant galaxies are moving away faster and faster.
- Scientists still do not fully understand dark mass and dark energy, which may explain this; our models change as new evidence appears.
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When astronomers spread out the light from distant galaxies, the patterns of colours are shifted towards the red end of the spectrum. That simple observation is the main evidence that the universe is expanding and that it began with a Big…
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