The table summarises two proposed models.
| Property | Model P | Model Q |
|---|---|---|
| Distances between distant galaxies | Increase | Increase |
| Average density over time | Decreases | Stays constant |
| Beginning in time | Yes | No |
Which correctly identifies the models and an observation both can explain?
P is Big Bang; Q is Steady State; galactic red-shift.
P is Steady State; Q is Big Bang; galactic red-shift.
P is Big Bang; Q is Steady State; the cosmic microwave background.
P is Steady State; Q is Big Bang; the cosmic microwave background.
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.