Red - shift

• What is the central idea discussed in the video?

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

  The red shifting of light from galaxies.
• What does redshift indicate about distant galaxies?

  They are moving away from us.
• What is absorption spectra?

  Light wavelengths absorbed by chemicals.
• What do the dark lines in the absorption spectra represent?

  Missing wavelengths of light.
• How does the absorption spectra of distant galaxies differ from that of the sun?

  It is shifted towards the red end.
• What causes the redshift in light from distant galaxies?

  The stretching of light waves as they travel.
• Why are galaxies not moving through space but rather the space itself is expanding?

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

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

  They get further apart.
• What is a limitation of the balloon model used to explain the universe's expansion?

  Balloons can burst when stretched too far.
• What does the big bang theory propose about the universe's origin?

  It started from a tiny, dense space.
• What is the state of the universe after the big bang?

  It began to expand rapidly.
• What is the current status of the universe's expansion?

  It is still continuing today.
• What are the key concepts of redshift and the big bang theory?

  • Redshift indicates galaxies moving away.
  • Absorption spectra show missing wavelengths.
  • The universe is expanding, not galaxies moving.
  • The big bang theory explains the universe's origin.
• What are the limitations of using models to explain complex concepts like the universe's expansion?

  • Models are simplifications of reality.
  • Balloons can burst, unlike the universe.
  • Models may not include all elements (e.g., galaxies inside).