Evidence for the Big Bang
Physics: Edexcel IGCSE, topic 8.3.2
Red-shift
Light from distant objects in space becomes shifted towards the red end of the spectrum. This effect is called red-shift.
Red-shift
- As an object moves away from us, the wavelength of light that the object emits (sends out) gets longer.
- The light gets redder because red has the longest wavelength of the visible colours.
- This effect is called red-shift.
- The faster the object is moving away from us, the longer its wavelength gets and the redder it appears.
Evidence for an expanding universe
- Light from distant galaxies in space is red-shifted.
- The further a galaxy is from Earth, the greater the red-shift.
- This means that the further away a galaxy is, the faster it is moving away from us.
- This is evidence that the universe is expanding.
Explained by the Big Bang
- Red-shift provides evidence for the Big Bang theory as it shows that all objects in the universe are moving away from one another.
- This suggests that the objects began from a single point, the point at which the Big Bang occurred.
Test yourself on Evidence for the Big Bang
Which colour has the longest wavelength?