The Big Bang theory is the scientific model used to explain the origin and development of the universe. Describe the evidence that supports the Big Bang theory and explain how this evidence links to the theory.

1. The light from distant galaxies is red‑shifted, i.e. its wavelength is shifted towards the red end of the spectrum.
2. This red‑shift shows that the galaxies are moving away from us, indicating that the universe is expanding.
3. Galaxies that are further away show a greater red‑shift, meaning they are receding faster – a relationship described by Hubble’s law.
4. The cosmic microwave background (CMB) radiation is detected uniformly from all directions in space.
5. The CMB is the remnant energy, or afterglow, from the hot, dense state of the early universe, providing evidence that the universe began from a single point.