CHAPTER 14 ORIGINS
Name:
QUESTIONS
14.1 Cosmology — the evolution of the universe
1.
Write a short description of how our planet fits into the universe. How can you be sure
this is correct? Try to mentally place yourself back two thousand years. The best minds
are telling you that the Earth is at the centre of the universe and everything revolves
around us. Would you believe that? Explain why or why not.
2.
The first few decades of the twentieth century brought huge changes to our model of the
universe. Construct a small table listing the names of the most important researchers
involved (you should be able to include at least five) and a brief summary of their
contribution.
3.
This question may involve a small amount of research on your part. It has taken some
time to discover all of the quarks shown in table 14.2, because they do not all have the
same mass. In fact, some have much more mass than others, and these were the difficult
ones to discover. Find out which was the last to be discovered and why.
4.
Construct a timeline of the big bang process.
5.
The COBE and WMAP satellite images were important because they showed some
lumpiness but were nevertheless quite uniform. Explain why these two apparently
opposite features were an important discovery.
14.2 The evolution of stars
6.
What are some alternative variables that can be placed on the vertical and horizontal axes
of an H–R diagram?
7.
How does the mapping of a single star on an H–R diagram differ from the mapping of a
whole star cluster? Which mapping is more valuable, and why?
8.
Describe how our knowledge of nuclear reactions has helped us to piece together a model
for the life of a star.
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9.
This question may involve a little research. Where does our Sun appear on an H–R
diagram? At what stage does that place the Sun in its evolution?
Review questions
Understanding
1.
List the twentieth-century discoveries that have furthered our model of the universe.
2.
What is a quark?
3.
Make a table of information about the quarks required to make:
(a)
a proton
(b)
a neutron.
The table should have three columns: type of quark, symbol, and charge. Total the charge
column to show that the charges work out correctly.
4.
(a)
Describe Hubble’s Law in qualitative terms.
(b)
Write down the equation for Hubble’s Law.
(c)
Why is Hubble’s constant of significance to cosmologists?
5.
How does Hubble’s discovery of the expansion of the universe lead to the idea of the big
bang?
6.
(a)
Why was the discovery of microwave background radiation by Penzias and Wilson
viewed by cosmologists as experimental evidence for the big bang?
(b)
This interpretation of the microwave background radiation relied upon the work of
which two scientists?
7.
8.
Immediately after the big bang there was only energy present, but the stars are formed of
matter.
(a)
Where did this matter come from?
(b)
What equation describes this process?
(a)
What two variables of a star are plotted on a Hertzsprung–Russell diagram?
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(b)
9.
Which variable is plotted onto which axis?
List each of the major star groups and pro-vide a description of the stars found in each.
10. What generalisation can be made about the masses of the stars in the main sequence?
11. Copy the following table, then complete it by writing a short description of the nuclear
reaction occurring at each location indicated.
12. Draw an H–R diagram and indicate on it the main star groups. On this diagram, draw the
path followed by a star of 1 solar mass during the course of its life.
13. How do the H–R diagrams of open and globular star clusters provide evidence for the life
path you drew in the previous question?
14. What evidence exists that:
(a)
the Sun is a second generation star?
(b)
our solar system consists, at least partially, of supernova remnant?
15. List the essential features of the current structure of our solar system.
16. Outline the currently accepted model for the development of our solar system.
Challenge
17. For each of the geocentric and heliocentric models:
(a)
describe the model in more detail
(b)
list the advantages of this model, from the perspective of someone living at that
time
(c)
comment on how the technology of the time influenced or limited the development
of this model.
18. Write a one-paragraph description of the current model of the universe. The scale of your
description should range from planet to universe.
19. Edwin Hubble’s discovery of the expansion of the universe relied upon the earlier work
of two scientists and verified the work of a third. Who were the other scientists and what
was the contribution of each?
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20. Read the narrative describing the process of the big bang on pages 334–5, then tabulate
that information. Your table should include two columns: time and a very brief
description.
21. (a)
(b)
What is the significance of the time of recombination?
Why was it not possible for stars or galaxies to form before this time?
22. The processed image from the COBE satellite answered many questions, but
cosmologists were not satisfied. Explain the purpose of the higher resolution WMAP
mission.
23. Outline the formation of galaxies through the process of accretion.
24. How is the formation of stars (and their possible planetary systems) similar to the
formation of galaxies?
Notes:
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