| Contrast the stated motivations of Bondi and Gold on the one hand, and Hoyle on the other, for developing the "Steady State" cosmological model. | [2] |
| What are the testable predictions of the Steady State model? Explain how developments in observational cosmology through the 1960s effectively disproved the Steady State model. | [4] |
| Discuss the observational evidence for and against the "classical" (i.e. not inflationary) Big Bang model as it stood around 1980. Hence, briefly explain what motivated Alan Guth to propose the idea of inflation in 1981. | [4] |