A space observatory collects two sets of measurements.
The observatory measures the same absorption line in a laboratory and in light from 40 distant galaxies distributed across the sky.
| source | wavelength of absorption line |
|---|---|
| laboratory | 486 nm |
| distant galaxies | between 499 nm and 515 nm |
The observatory also measures a microwave signal in different directions.
| direction | temperature corresponding to the microwave signal |
|---|---|
| north | 2.73 K |
| south | 2.72 K |
| east | 2.74 K |
| west | 2.73 K |
Explain what the visible-light measurements suggest about the Universe.
Explain why the microwave measurements provide stronger support for the Big Bang theory than for 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.