8.3.1 Evidence for the Expanding Universe

• The expansion of the universe is driven by dark energy.


  True
• What is red-shift caused by in the context of the expanding universe?

  Doppler effect
• Match the type of red-shift with its cause:

  Cosmological Red-shift ↔️ Expansion of the universe

  Gravitational Red-shift ↔️ Gravity of massive objects

  Doppler Red-shift ↔️ Motion of an object away
• Gravitational red-shift is caused by the motion of galaxies away from the observer.

  False
• Arrange the following events in order to describe the Doppler effect:

  1️⃣ Object moves away from the observer

  2️⃣ Light wavelength increases

  3️⃣ Red-shift is observed
• What does the Doppler effect help astronomers determine?

  Relative motion of bodies
• Galaxies farther away have lower red-shift values.

  False
• Hubble's Law states that the velocity of a galaxy's recession is proportional to its distance.
• What evidence supports the idea of an expanding universe?

  Hubble's law and red-shift
• Hubble's law states that the velocity of a galaxy's recession is proportional to its distance
• Red-shift is caused by the Doppler effect due to the expansion of the universe.
• Gravitational red-shift occurs when light escapes a strong gravitational field.


  True
• Which type of red-shift is the primary evidence for the expanding universe model?

  Cosmological red-shift
• What happens to the wavelength of light from an object moving away from the observer?

  It increases
• What do astronomers use the Doppler effect to determine about celestial bodies?

  Relative motion
• What is the formula for Hubble's law?

  $v =$$H_{0} d$
• The Hubble constant in Hubble's law is denoted by the symbol H0
• The Cosmic Microwave Background (CMB) is the residual heat from the Big Bang.

  True
• The Cosmic Microwave Background was discovered by Arno Penzias and Robert Wilson
• The large-scale structures of the universe are moving apart due to its ongoing expansion.


  True
• The Cosmic Microwave Background provides evidence for the Big Bang and the expanding universe
• What is meant by the term "expanding universe"?

  Increasing separation of galaxies
• The increasing separation between galaxies over time is evidence for the expanding universe
• Red-shift occurs when light shifts to longer wavelengths.


  True
• The cosmological red-shift is key evidence for the expanding universe
• What powers the expansion of the universe?

  Dark energy
• Blue-shift occurs when an object moves towards the observer.

  True
• The relationship between red-shift and distance is described by Hubble's Law.
• What is dark energy believed to be responsible for in the universe?

  Accelerated expansion
• The expansion of the universe is driven by a mysterious force called dark energy
• Dark energy causes the universe to expand at an accelerating rate.


  True
• What does red-shift indicate about the movement of distant galaxies?

  They are moving away
• What type of red-shift is caused by the expansion of the universe?

  Cosmological red-shift
• Doppler red-shift is caused by the motion of an object away from the observer
• The Doppler effect manifests as red-shift when an object moves away
• Blue-shift occurs when an object moves towards the observer.


  True
• The red-shift of distant galaxies is directly proportional to their distance
• What does the variable 'v' represent in Hubble's law?

  Velocity of recession
• Match the galaxy with its red-shift value:

  Andromeda ↔️ -0.001

  Triangulum ↔️ -0.0006

  Messier 82 ↔️ 0.0007

  Whirlpool ↔️ 0.0025
• When was the light from the Cosmic Microwave Background emitted?

  380,000 years after Big Bang