Question 1

The Hubble Space Telescope can be used to study galaxies at a redshift equal to 2. How much has the universe expanded since that the light was emitted from these galaxies?

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Question 2

Does the expansion of the Universe make the Sun bigger? What about the Milky Way? Why or why not?

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Question 3

The COBE and WMAP satellites detected fluctuations in the CMB. On average, how big were these fluctuations, and what does that tell us about the universe at a redshift of z = 1,000?

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Question 4

The cosmic microwave background (CMB) has a temperature of approximately 2.7 K and a Planck blackbody spectrum. Calculate the wavelength where the CMB spectrum peaks.

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Question 5

Name two predictions of the standard Big Bang theory that have been verified by observations.

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Question 6

What does the value of R_U, the scale factor of the universe, tell us?

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Question 7

What important event in the universe's history marked the creation of the cosmic background radiation?

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Question 8

You observe a distant quasar in which the Lyman alpha line of hydrogen (rest wavelength = 121.6 nm) is found at a wavelength of 547.2 nm. When the light from this quasar was emitted, how large was the universe compared to its current size?

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Question 9

Does Hubble's law imply that our galaxy is sitting at the center of the universe? Explain.

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Question 10

If the density of normal matter, such as protons and electrons, were higher in the early universe, would there have been more or less ⁴He made in the Big Bang?

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Quiz 19: The Expanding Universe