# Scientists use observations of distant stars and galaxies to investigate the large-scale structure of the universe. One important observation is that more distant galaxies are moving away from us faster than closer ones. Explain what this tells us about the origin and history of the universe.

> WJEC GCSE Physics (Wales) — 2.6 Particle physics and using physics to investigate the universe · Explain · 4 marks

## Mark scheme (4 marks)

1. The universe is expanding / galaxies are moving apart / everything is moving away from everything else
2. If the universe is currently expanding, in the past all matter must have been closer together / compressed into one point
3. This is evidence that the universe began with a Big Bang / a massive explosion / a sudden rapid expansion from a single point
4. The greater speed of more distant galaxies shows the universe has been expanding since the beginning / the further away a galaxy is, the longer it has been moving, so it is further away — consistent with a single starting event

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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