red shift

• What is red-shift?


  The apparent increase in the wavelength of light from most distant galaxies because of their motion relative to the observer
• What is the observed red-shift evidence for?

  That space itself (the universe) is expanding and supports the Big Bang theory.
• What is the Big Bang Theory?


  It suggests that the universe started from a very small, hot and dense region in space
• What did scientists observe to provide evidence that the universe is expanding at an ever faster rate?

  supernovae
• What do observations of supernovae suggest?

  Distant galaxies are receding even faster
• What 2 ideas could explain the universe's increasing rate of expansion?

  Dark matter and dark energy
• What is dark matter?


  An unknown substance which holds galaxies together, but doesn't emit any electromagnetic radiation
• What is dark energy?


  A hypothesised form of energy causing the expansion of the universe to accelerate
• What are the limitations of dark matter and dark energy?


  These ideas are still being developed by scientists and are not yet fully understood
• Give one reason why peer review is an important process.

  detects false claims
• Describe how the wavelength and frequency of the light from Andromeda seem to have changed when viewed from the Earth.

  wavelength seems to have decreased and frequency seems to have increased