Topic 8 - The Universe

• Describe what an absorption spectrum looks like

  Absorption spectra are created when light shines through a cloud or atmosphere, it is absorbed and re-emitted but with gaps in the spectra (dark lines)
• What does an absorption spectra tell us about the composition of stars?

  It tells us the elements contained in the star/cloud/atmosphere, we can identify these by looking at the wavelengths of the dark lines
• What is cosmological redshift and what does it tell us about galaxies?

  Redshift is if we compare lab results for spectra with a distant galaxy then the galaxy dark lines have been moved to the red side of the spectra. It tells us their speed and distance, the more they are redshifted the further they are from us and the faster they are travelling
• How would the absorption spectra of distant galaxies be different to closer galaxies?

  Same amount of lines but the distant galaxy would have the lines redshifted further
• What is the Big Bang Theory?


  The theory that the universe expanded from a single point
• How does Redshift give evidence for the Big Bang Theory?

  Because the universe should be expanding, that objects should be moving away from us so their light should be redshifted and it is
• What is Cosmic Microwave Background Radiation?

  Energy remaining that was produced by the Big Bang, it has been stretched from gamma into microwaves - it is found everywhere in the Universe, as the universe expands it carries CMBR with it
• How does CMBR give evidence for the Big Bang Theory?

  It has been stretched from gamma into microwaves – it is found everywhere in the Universe, as the universe expands it carries CMBR with it