ASTR 101-3, FALL 2010 1

LECTURE 24, NOVEMBER 30, 2010

ASTR 101, SECTION 3INSTRUCTOR, JACK BRANDT

jcbrandt@unm.edu

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a) is explained by general relativity.b) results from the presence of dark matter.c) is a statement of Olbers’ paradox.d) is the cosmological principle.e) occurs if the universe is static and unchanging.

Question 6

The darkness of the sky in an infinite universe

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a) is explained by general relativity.b) results from the presence of dark matter.c) is a statement of Olbers’ paradox.d) is the cosmological principle.e) occurs if the universe is static and unchanging.

Question 6

The darkness of the sky in an infinite universe

If the universe is homogeneous in composition, and appears the same in

all directions, then for the sky to be dark, it must be either finite in age, or

evolving in time, or both.

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a) the size of the universe.b) the age of the universe.c) the shape of the universe.d) the temperature of the universe.e) the distance the universe has expanded.

Question 2

Hubble’s constant, H0, can be related to

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a) the size of the universe.b) the age of the universe.c) the shape of the universe.d) the temperature of the universe.e) the distance the universe has expanded.

Question 2

Hubble’s constant, H0, can be related to

H0 is currently estimated to be about 70 km/sec/Mpc.

This translates to an age for the universe of about 14

billion years.

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a) is infinitely old and getting larger.b) began expanding long ago, and has a finite age.c) will slow down because of dark matter.d) has repeatedly expanded and contracted.e) will eventually stop and recollapse.

Question 4

Hubble’s law implies that the universe

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a) is infinitely old and getting larger.b) began expanding long ago, and has a finite age.c) will slow down because of dark matter.d) has repeatedly expanded and contracted.e) will eventually stop and recollapse.

Question 4

Hubble’s law implies that the universe

Using the Hubble constant H0,

astronomers can estimate that the universe was born

about 14 billion years ago.

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a) the Milky Way must be located at the edge of the universe.

b) the Milky Way is at the center of the universe.

c) the universe is expanding.d) the sky is dark at night.e) the universe has not changed significantly.

Question 1

Because distant galaxies in every direction are moving away from us,

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a) the Milky Way must be located at the edge of the universe.

b) the Milky Way is at the center of the universe.

c) the universe is expanding.d) the sky is dark at night.e) the universe has not changed significantly.

Question 1

Because distant galaxies in every direction are moving away from us,

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a) a Doppler shift of the random motions of galaxies.

b) an aging of light as the universe ages.c) space itself expanding with time, stretching

light.d) the result of the Milky Way’s position at the

center.e) due to the temperature differences in the early

and late universe.

Question 3

The redshift of galaxies is explained best as

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a) a Doppler shift of the random motions of galaxies.

b) an aging of light as the universe ages.c) space itself expanding with time, stretching

light.d) the result of the Milky Way’s position at the

center.e) due to the temperature differences in the early

and late universe.

Question 3

The redshift of galaxies is explained best as

As the universe expands, photons of

radiation are stretched in

wavelength as they move through

space.

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