A research team records two observations while comparing the Big Bang theory with the Steady State theory.
| Measurement | Result |
|---|---|
| Wavelength of an absorption line from a distant galaxy | 512 nm512\ \mathrm{nm}512 nm |
| Wavelength of the same absorption line in a laboratory | 500 nm500\ \mathrm{nm}500 nm |
| Microwave signal detected from the sky | Faint radiation of almost the same intensity from every direction |
State what the wavelength comparison shows about the motion of the galaxy relative to the Earth.
Explain why the wavelength measurements cannot be used to choose between the Big Bang theory and the Steady State theory.
Explain why the microwave result favours the Big Bang theory rather than the Steady State theory.
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.