Red-Shift

• What happens to wavefronts when an object emits waves symmetrically?


  The wavefronts spread out symmetrically.
• What occurs to the waves if the wave source moves?


  The waves can become squashed together or stretched out.
• How does a moving object affect the wavelength and frequency of waves?


  A moving object changes the wavelength and frequency of the waves.
• What happens to the wavelength of waves in front of a moving source?


  The wavelength decreases (λ – Δλ).
• What happens to the frequency of waves in front of a moving source?


  The frequency increases.
• What happens to the wavelength of waves behind a moving source?


  The wavelength increases (λ + Δλ).
• What happens to the frequency of waves behind a moving source?


  The frequency decreases.
• What is the Doppler effect?


  The Doppler effect is the change in wavelength and frequency due to the motion of the wave source.
• What is blueshift?


  Blueshift occurs when an object moves towards an observer, decreasing the wavelength of light.
• What is redshift?


  Redshift occurs when an object moves away from an observer, increasing the wavelength of light.
• What does light from a star moving towards an observer indicate?


  It indicates that the light is blueshifted.
• What does light from a star moving away from an observer indicate?


  It indicates that the light is redshifted.
• What does the observer in front of a moving object observe?


  The observer in front observes a blue shift.
• What does the observer behind a moving object observe?


  The observer behind observes a red shift.
• Which color of light has the longest wavelength?


  Red light
• How does the sound of a motorbike change as it travels away from you?


  The pitch of the sound becomes lower, indicating a decrease in frequency.
• What does the observation of redshift from distant galaxies indicate?


  • Galaxies are moving away from us
  • The universe is expanding
  • Supports the Big Bang theory
• What does the light spectrum from distant galaxies show?


  The light spectrum shows that the lines are shifted towards the red end.
• What is the relationship between the distance to a galaxy and its redshift?


  The greater the distance to the galaxy, the greater the redshift.
• What does the Big Bang theory propose about the universe's origin?


  The universe began from a very small region that was extremely hot and dense.
• How long ago did the Big Bang occur?


  Around 14 billion years ago.
• What happens to the universe as a result of the Big Bang?


  The universe expands and cools.
• What is observed from galaxies as a result of the universe's expansion?


  Galaxies are moving away from each other.
• What evidence supports the idea that the universe is expanding?


  Galaxies moving away from each other at increasing speeds.
• What is the evidence for the Big Bang?


  • Light spectrums from supernovae show redshift
  • Distant galaxies are receding faster
  • Indicates the universe is expanding
• What happens to matter during an explosion like the Big Bang?


  It moves out in all directions, getting further from the source.
• How does the speed of matter vary after an explosion?


  Lighter matter travels faster and moves further from the source.
• What happens to galaxies if we travel back in time?


  They would become closer together until the universe was a single point.
• What would be observed if galaxies were originally grouped together at a single point?


  We would see a similar effect to an explosion.
• How does the distance galaxies move relate to their speed?


  The distance they move is proportional to their speed.
• What are dark energy and dark matter?


  • Dark matter: Unseen matter in the universe, nature unknown
  • Dark energy: Causes accelerated expansion of the universe
• What evidence suggests there is more matter in the universe than we can account for?


  Evidence from the rotation and motion of galaxies.
• What do measurements of the universe's expansion suggest?


  That the universe is expanding at a faster rate.
• What is a possible explanation for the accelerated expansion of the universe?


  Dark energy pushing everything apart.
• How does dark energy relate to gravity in the universe?


  Dark energy may counteract gravity and expand the universe.
• wavefronts produced from a stationary object and a moving object

  
• Light from a star that is moving towards an observer will be blueshifted and light from a star moving away from an observer will be redshifted

  
• The observer in front observes a blue shift, the observer behind observes a red shift