Edexcel IGCSE Physics 8.18P Expansion of the universe
Practise explaining how galaxy red-shift and Hubble-style graphs support an expanding universe and the Big Bang model.
- Syllabus
- First assessment 2019
- Course
- Physics 4PH1
Practise explaining how galaxy red-shift and Hubble-style graphs support an expanding universe and the Big Bang model.
Between 1929 and 1931, physicists Hubble and Humason investigated the red-shift of light from galaxies at different distances from the Earth.
The distance unit they used is the megaparsec (Mpc).
The graph shows some of the results of their investigation.

Explain why the graph from Hubble's investigation provides evidence for the expansion of the universe.
any two from:
MP1. change in wavelength increases with distance (from Earth or Milky Way);
MP2. idea that (recession) velocity increases with distance (from Earth or Milky Way);
MP3. galaxies are all moving away from each other;
allow red-shift for
change in wavelength