Red shift and the Big Bang: Space physics: Physics: GCSE (9:1)

• Electromagnetic spectrum

  A continuous spectrum containing all different types of electromagnetic radiation

  
• Emission spectrum

  A spectrum containing dark lines when the elements in a star absorb certain frequencies of light

  
• What an emission spectrum tells us

  Different elements absorb different frequencies of light to produce a unique pattern of dark lines on the spectrum

  
• Galaxy


  A cluster of billions of stars that is held together by gravity.

  
• Emission spectra from different galaxies

  The dark lines in the spectra from distant galaxies are further along the spectrum and show an increase in wavelength
• Red shift


  When the lines on an emission spectrum are moved or shifted towards the red end of the spectrum

  
• What red shift tells us

  The space between the Earth and distant galaxies is expanding

  
• Relationship between amount of red shift and speed of galaxies

  The more the light from a distant galaxy is red-shifted, the faster the galaxy is moving away from Earth
• How red shift lead to the development of the Big Bang theory

  Generally, the further away a galaxy is, the more its light is red-shifted which suggests that the Universe is, and has been, expanding since it was created
• Big Bang Theory


  The scientific theory that is used to describe the early stages of the Universe

  
• When the Big Bang occurred

  13.8 billion years ago
• What happened during the Big Bang

  There was a huge explosion which started the formation and expansion of the Universe from an extremely small, hot and dense region of matter

  
• CMBR (Cosmic Microwave Background Radiation)


  The remains of the heat energy released from the Big Bang which is now spread thinly across the whole Universe

  
• How CMBR provides evidence for the Big Bang theory

  Astronomers have discovered microwave radiation from all directions in space which is at a temperature of about –270 ºC
• Dark energy


  An unknown form of energy that could explain why the expansion of the Universe is accelerating

  
• Dark matter


  An unseen form of matter that could explain why galaxies rotate faster than their visible mass should allow