The universe

• Absorption spectra


  Pattern of black lines on the spectrum representing wavelengths of light that have been absorbed by elements in the gases in the star's atmosphere
• Absorption spectra


  • Every element has a unique pattern of lines
  • The example above is a hydrogen spectrum, only hydrogen will absorb light in that specific pattern of lines
• Cosmological red shift


  The pattern of lines in the spectrum of light from distant galaxies has been shifted towards the red side of the spectrum, with the longer wavelength
• Light is stretched as it travels through expanding space


  Light from galaxies that are further away is stretched more as the light travels through space for longer
• Using the cosmological red shift information, it can be theorised that all galaxies started at the same point and the universe has expanded from that point
• The Big Bang Theory


  The universe started from one point where all the energy and matter was released
• CMBR (Cosmic microwave background radiation)


  High energy Gamma radiation released at the Big Bang has travelled through the universe since then, and the wavelength of these waves has been stretched to become microwave radiation
• As microwave radiation can be measured throughout the universe it is evidence that the universe started from a hot Big Bang which released a lot of energy