A computer model follows the same large region of space at two stages as the Universe expands.
| Stage | Volume of the region |
|---|---|
| 1 | 2.0 × 1070 m3 |
| 2 | 1.6 × 1071 m3 |
Astronomers also make these observations.
| Observation | Result |
|---|---|
| Absorption lines in light from galaxies | The lines from almost every distant galaxy are at longer wavelengths than laboratory values. The increase in wavelength is generally larger for more distant galaxies. |
| Radiation from apparently empty parts of the sky | Faint microwave radiation of almost the same intensity arrives from every direction. |
Compare what the Big Bang theory and the Steady State theory predict about the amount of matter and the average density in the region at stage 2.
Your answer should also compare how well the observations support the two theories.
94 exam-style questions on Edexcel GCSE Physics 7.2 The Universe and red-shift, covering 7.2.1 Big Bang and Steady State theories, 7.2.2 Evidence for the Big Bang, 7.2.3 The Doppler effect and red-shift, 7.2.4 Red-shift as evidence for an expanding Universe, and 7.2.5 The CMB and the accepted model. Each one has a worked solution and a mark scheme showing where the marks go.