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This is a preview of the published version of the quiz
Reading Quiz 10 - Chapters 16 & 17 of Understanding Our Universe
Chapter 16
Question 1
1 pts
We have learned that, in general, expanding gases cool and gases that are
compressed heat up. The physics works on Earth and it also works in the Universe.
What do these statements have to do with the early universe?
- If the Universe has been continuously expanding, it must have been smaller in the
past.
- Since observations show that the Universe is expanding, it must also be cooling.
- The Universe must at one time be extremely hot and dense.
- All of these answers pertain to the Universe and how it has changed over time.
Question 2
1 pts
Our knowledge of the value of the Hubble constant Ho has changed over time as more
accurate and precise observations were made. All current measurements indicate that
Ho = 70 km/s per Mpc, corresponding to an age of approximately 14 billion years. Not
that many years ago, Ho was assumed to be close to 100 km/s per Mpc. This larger
value made the age of the Universe
- older; approximately 18 billion years old.
- smaller; more like 10 billion years old.
- to be14 billion years old as the age of the Universe doesn't depend on the Hubble
constant.
Question 3
2 pts
Match the type of shift in electromagnetic radiation (all forms of light) to the event
described.
[ Choose ]
Doppler redshift
cosmological redshift
gravitational redshift
no shift in light
Doppler blueshift
A nearby star in the Milky Way is coming towards the Sun. The wavelengths of light being emitted from near a stellar black hole are stretched. The rest wavelength of hydrogen line at 656.3 nm is measured at 700 nm for a distant
galaxy.
Expelled gases from a planetary nebula are moving away from us at 300 km/s Question 4
1 pts
Figure 16.8 of UOU
The spectrum of the cosmic microwave background radiation is nearly a perfect
blackbody spectrum. This spectrum tells us that the early universe was -
similar to the white dwarfs present in today's universe: hot, dense, and degenerate.
filled with hydrogen and helium and the very first massive stars.
hot, ionized, opaque; similar to the interior of a star.
about 15 million degrees Kelvin, similar in temperature to the Sun's core.
Question 5
1 pts
As applied to the Universe, critical density basically refers to the Universe in a perfect
balance - expansion slowing but never stops. What are the options for the actual
density of the Universe, referred to as
Match the value of
(Omega_mass) with the fate of the universe.
[ Choose ]
Universe is balanced on the borderline and expanding ever so slowly.
Gravity is too weak to stop the expansion; the universe expands forever.
Anti-gravity cancels out gravity and acceleration occurs.
Gravity is strong enough to stop the expansion and cause the universe to collapse.
Omega_mass < 1
Omega_mass = 1 Omega_mass > 1
Question 6
1 pts
The group of astronomers who first discovered that the expansion of the universe is
not slowing down but is rather speeding up, or accelerating in its expansion, used a
standard candle that you should be familiar with by now. What did they use?
-
Hubble's Law using a sample of 1000 distant elliptical galaxies.
RR Lyrae variables in the globular clusters of distant galaxies.
Type Ia supernovae in very distant galaxies.
A large sample of Cepheid variable stars.
We bring in Figure 16.15 to help you with the next question.
Question 7
2 pts
Match the era or period with its characteristics, events, or description.
[ Choose from ]
Fusion of hydrogen into helium.
What came before the theory of everything for which we have no physics.
Nuclei grabbed electrons; atoms form.
The strong force and the electroweak force separate.
Particles and antiparticles annihilate.
Filled with galaxies containing stars, interstellar material, and dark matter.
Planck Era
GUT breaks Electron-particle pair annihilation Big Bang nucleosynthesis Era of recombination Today Question 8
1 pts
Astronomers (led by Alan Guth in the 1980's) hypothesized a very early period of rapid
expansion of the Universe known as inflation in order to explain why the universe was
much too flat and the cosmic microwave background much to smooth: (or incredibly close to it). Each of the following represent predictions of the period of
inflation, except one. Which one should not be included?
- Any curvature of the universe would not be apparent from any location.
- Space expanded so rapidly that distances between points in space increased faster
than the speed of light.
- Around the age of
factor of
seconds, the scale factor of the universe increased by a
or more.
- The large fluctuations caused by quantum uncertainty are much too large today to be
measureable.
- The sudden inflationary period would have created parallel universes that were too
far apart to be detectable.
Chapter 17
Question 9
1 pts
Each of the following terrestrial objects - except one - may resemble the large scale
structure of the Universe only on an infinitesimally smaller scale. Which one does not
belong?
Soap bubbles
Porous chunk of pumice
Porous sponge
Large flock of about 10,000 starlings
Question 10
1 pts
Which one of the following characteristics is thought NOT to be associated with the
very first stars in the Universe?
- The first stars formed inside dark matter mini-halos that had about 1 million solar
masses.
- The first stars exploded as supernovae, possibly forming black holes and gammaray bursts.
- The first stars contained only hydrogen, helium, and a tiny amount of lithium.
- The first stars were much more massive than today's average star.
- The first stars were formed in large clusters called "super-stellar" clusters of a million
stars or more.
Question 11
1 pts
Galaxies in the very young universe were
-
almost all classified as elliptical galaxies.
smaller, clumpier, and more irregular than they are today.
much larger than they are today, splitting into smaller ones as they evolved.
very similar to the ones located within a billion light years of the Milky Way.
Question 12
2 pts
This last question combines a number of topics from this part of the course. Each
choice is used just once.
http://www.spacetelescope.org/static/archives/images/screen/heic1219a.jpg
(Links to an external site.)
[ Choose from]
The most distant object identified.
Fully formed spiral galaxy.
Quasar or active galactic nucleus.
Merging galaxies.
Star in the Milky Way
An elliptical galaxy.
A ______
B _____
C _____ D _____
E _____