ASTR 123 Modules 7&8
Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is
about 13.8 billion years
Which of the following is not a candidate for the identity of dark matter:
anti-matter
Which of the following statements about dark matter is FALSE:
astronomers have a pretty good idea what the dark matter is made of
If the universe consisted only of matter and its density were equal to critical, the universe would
continue expanding, eventually slowing down to zero
When the age of the universe was about 10 seconds, it had cooled sufficiently for neutrons and protons to bind together and form the key nuclear species which allows production of helium to proceed. This key nucleus is called
deuterium
Where in space did the expansion of the universe begin?
everywhere at once
Measurements of the cosmic microwave background provide strong evidence that the overall geometry of space is
flat, or zero curvature
According to the Cosmological Principle, the universe
is isotropic and homogeneous over large distances
Which of the following does NOT happen when two galaxies collide?
many of the stars in one galaxy collide with the stars in the other
Protons and neutrons are composed of other more elementary particles known as
quarks
Galaxies that we see as they were 11 billion years ago or more, as compared to galaxies today, are generally:
redder and smaller
Which of the following did NOT happen during the first few minutes after the Big Bang?
some very massive early stars formed
How do astronomers currently think the amount of detectable (observable) matter in the universe compares to the amount of dark matter?
the amount of detectable matter is about 1/5th the amount of dark matter
The three observational pillars of cosmology are the expanding universe, big bang nucleosyntheses, and
the cosmic microwave background
An astronomer is observing a distant galaxy at lookback time of 11 BY which looks blue. Which of the following can she conclude from this observation?
the galaxy must have a lot of star formation going on at the time we are seeing it
With enormous effort, a team of astronomers manages to collect enough light from a galaxy far, far away [*] to produce a spectrum. That spectrum has lines from the elements carbon, silicon, and sulfur. This tells the team that
the galaxy must have had an entire generation of stars that was born, lived, and died
Which of the following does not represent evidence for dark matter?
the rate of cosmic ray showers
In the observation of galaxies, astronomers refer to look-back time, which means
the time it took for the observed light from a galaxy to reach us
What happened when the age of the universe was 380,000 years which allows us to observe the cosmic microwave background?
the universe cooled sufficiently to allow neutral hydrogen to form
The reason nucleosynthesis stopped when the age of the universe was about 3 minutes was
the universe was cooling too fast to produce elements beyond helium
The observed cosmic microwave background (CMB) is extremely uniform. What is the significance of the small deviations from uniformity which show up as red or blue regions in the CMB images?
they seed the large scale structure we observe today
