6 Quiz
Answer the following questions in order to test your understanding of the key ideas that you have been learning about.
Question 1
a.
0.23 Mpc
b.
5.0 Mpc
c.
21 Mpc
d.
34 Mpc
e.
50 Mpc
f.
68 Mpc
The correct answer is e.
Answer
The Hubble constant implies that the apparent recession speed of galaxies increases by 67.7 km s-1 for every increase in distance by 1 Mpc. Using Equation (1), , so D = 50 Mpc.
Question 2
a.
The expansion rate of the Universe has been constant since soon after the big bang.
b.
The expansion rate of the Universe has constantly decelerated since soon after the big bang.
c.
The expansion rate of the Universe has constantly accelerated since soon after the big bang.
d.
The expansion rate of the Universe initially decelerated soon after the big bang but has accelerated more recently.
e.
The expansion rate of the Universe initially accelerated soon after the big bang but has decelerated more recently.
f.
The expansion rate of the Universe cannot be measured.
The correct answer is d.
Answer
Soon after the big bang, the expansion rate of the Universe decelerated because of the dominance of matter. About 6 billion years ago, dark energy came to dominate the Universe causing the expansion rate to accelerate.
Question 3
a.
The CMB radiation currently has a spectrum that is characteristic of a temperature of about 3000 K.
b.
The CMB radiation is perfectly uniform in temperature and intensity across the entire sky.
c.
The CMB radiation is today detected mainly in the infrared part of the electromagnetic spectrum.
d.
The fluctuations in the CMB radiation across the sky imply that the geometry of the Universe has positive curvature.
e.
The fluctuations in the CMB radiation across the sky imply that the geometry of the Universe has negative curvature.
f.
The CMB radiation is a relic of the decoupling of photons from atoms that happened 380,000 years after the big bang.
The correct answer is f.
f.
True
Answer
Only the last statement is true.
Question 4
a.
Baryonic matter makes up about 5% of the matter-energy density of the Universe.
b.
Non-baryonic matter makes up about 25% of the matter-energy density of the Universe.
c.
Baryonic matter comprises the familiar protons, neutrons and electrons.
d.
Non-baryonic matter may be composed of WIMPS and/or axions.
e.
Baryonic and non-baryonic matter together cannot account for all of the critical density of the Universe.
f.
Baryonic and non-baryonic matter exceed the critical density of the Universe.
The correct answers are a, b, c, d and e.
a.
True
b.
True
c.
True
d.
True
e.
True
Answer
All statements are true except the last one.
Question 5
a.
baryonic matter, dark energy, dark matter
b.
dark matter, dark energy, baryonic matter
c.
baryonic matter, dark matter, dark energy
d.
dark matter, baryonic matter, dark energy
e.
dark energy, baryonic matter, dark matter
f.
dark energy, dark matter, baryonic matter
The correct answer is c.
Answer
The correct order is baryonic matter (5%), dark matter (25%), dark energy (70%).
Question 6
Which values of the equation of state parameter are associated with each of the following types of fluid?
Using the following two lists, match each numbered item with the correct letter.
Match each of the previous list items with an item from the following list:
a.radiation
b.cosmological constant
c.quintessence
d.baryonic matter
- 1 = d,
- 2 = a,
- 3 = b,
- 4 = c
Answer
The equation of state parameter is zero for matter, minus one for a cosmological constant, +1/3 for radiation, and a function of the scale parameter for quintessence.
Question 7
a.
The monopole problem
b.
The flatness problem
c.
The horizon problem
d.
The problem of the accelerating expansion of the Universe
e.
The problem of dark energy
f.
The problem of dark matter
The correct answers are d, e and f.
Question 8
What type of curvature does the universe have for each of the following combinations of matter density (Ωm) and dark energy density (ΩΛ)? (Assume that only matter and dark energy are present in these hypothetical universes.)
Using the following two lists, match each numbered item with the correct letter.
-
flat
-
negative
-
positive
Match each of the previous list items with an item from the following list:
a.Ωm = 0.25, ΩΛ = 0.75
b.Ωm = 0.05, ΩΛ = 0.50
c.Ωm = 0.65, ΩΛ = 0.65
- 1 = a,
- 2 = b,
- 3 = c
Answer
If Ωm + ΩΛ > 1, the universe has positive curvature; if Ωm + ΩΛ < 1, the universe has negative curvature; and if Ωm + ΩΛ = 1, the universe is flat.