# The Big Bang theory is the currently accepted model for the origin of the universe. Describe how the observed red shift of light from distant galaxies supports the idea that the universe began from a single point.

> Eduqas GCSE Physics — 10.2 Red shift and the Big Bang · Describe · 4 marks

> Astronomers studying light from galaxies across the universe have found that the wavelength of light received from almost all galaxies is longer than expected.

## Mark scheme (4 marks)

1. Red shift means the wavelength of light from galaxies is increased / stretched (compared to the same light source on Earth)
2. Red shift shows that galaxies are moving away from us / the universe is expanding
3. More distant galaxies show a greater red shift, meaning they are moving away faster
4. If galaxies are moving apart in all directions, tracing this back in time suggests everything was once at a single point / the universe started from a single point (Big Bang)

## Key terms

- [red shift](https://www.gradenine.co.uk/glossary/red-shift)
- [Big Bang](https://www.gradenine.co.uk/glossary/big-bang)
- [universe](https://www.gradenine.co.uk/glossary/universe)

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/the-big-bang-theory-is-the-297c6bd6) · Published by Druglandscape Ltd.