Red-shift

• What is red shift?

  It is the stretching of light waves.
• What does the observation of red shift indicate about the universe?

  The universe is expanding.
• What is the main evidence for the universe's expansion?

  The red shifting of light from galaxies.
• What do we need to understand before red shift?

  Absorption spectra.
• What does the absorption spectra for visible light show?

  Patterns of dark lines in the spectrum.
• Why are certain wavelengths missing in the absorption spectra?

  Certain chemicals absorb specific wavelengths.
• What happens to light from distant galaxies as it reaches Earth?

  It appears shifted towards the red end.
• What does red shift indicate about the movement of galaxies?

  Galaxies are moving away from us.
• How does the expansion of the universe differ from galaxies moving through space?

  Space itself is expanding between galaxies.
• How can we visualize the expansion of the universe?

  Using a balloon with markers.
• What happens to galaxies as the universe expands?

  They get further apart from each other.
• What is a limitation of the balloon model for the universe?

  Balloons can burst, unlike the universe.
• What does the big bang theory propose about the universe's origin?

  The universe started from a tiny, dense space.
• What occurred after the initial explosion in the big bang theory?

  Space itself began to expand.
• What is the current state of the universe according to the big bang theory?

  The universe is still expanding.
• What are the key concepts of red shift and the big bang theory?

  • Red shift indicates galaxies moving away.
  • Universe is expanding.
  • Absorption spectra show missing wavelengths.
  • Space between galaxies is expanding, not galaxies moving.
  • Big bang theory explains universe's origin from a tiny, dense state.
• What are the limitations of models used to explain the universe's expansion?

  • Models may oversimplify complex phenomena.
  • Balloons can burst, unlike the universe.
  • Models may not represent all galaxies accurately.