An astronomer analyzing the absorption spectra of hydrogen from a series of distant galaxies observes that the spectral lines are shifted towards the red end of the spectrum compared to a laboratory reference.
Explain how this cosmological red-shift provides evidence that supports the Big Bang theory.
53 exam-style questions on Edexcel GCSE Physics 7.2 The Universe and red-shift. Each one has a worked solution and a mark scheme showing where the marks go.