13 of 13 people found the following review helpful:
5.0 out of 5 stars
A Superb Introduction to Galactic Astronomy and Cosmology, May 10, 2007
This review is from: An Introduction to Galaxies and Cosmology (Paperback)
This book deserves six stars. It is the companion book to "An Introduction to the Sun and Stars", (actually there are four books in the series but these two are the most closely related). I bought both books to follow-up the introductory astronomy text "Voyages to the Stars and Galaxies" by Fraknoi, Morrison, and Wolff. I was so impressed with "Voyages", it has been the standard by which I have measured other astronomy texts. "Sun and Stars", was an excellent book, but it didn't quite measure up to the clarity of "Voyages". In contrast, "Galaxies and Cosmology" is every bit as good as "Voyages". The scope is more limited than "Voyages", but the depth of the material covered is deeper. It is a perfect book to follow an introductory text such as "Voyages". Where "Voyages" gave a broad introduction to astronomy with essentially no math, "Galaxies and Cosmology" follows up with a more in depth treatment of galactic astronomy and cosmology that includes a fair amount of math, but nothing beyond basic algebra. Only algebra? Absolutely! This text walks an incredible line between a purely conceptual book, and a university level math heavy text for an astronomy major.
As with "An Intro to the Sun and Stars", "An Intro to Galaxies and Cosmology" has an excellent set of questions and problems which do a very good job of illuminating and clarifying key concepts. The problems are not difficult, requiring nothing more than a decent high school math background including algebra and trigonometry, but their strength is in illuminating the concepts beyond just a descriptive narrative. The problems are not as in depth or rigorous as you might find in a degree oriented program in astronomy, but they are certainly rewarding for the interested amateur, and will take you a step beyond purely descriptive introductions.
CONTENT
The book covers the following material, (if you don't want to read about every chapter, just skip to the summary).
Chapter 1 - The Milky Way Galaxy
A very good description of how we have come to know what we do about our Galaxy, the Milky Way, including how we determine size, mass, shape, etc.
Chapter 2 - Normal Galaxies
Describes the standard Hubble classification of galaxies including how we are able to determine such things as their size, mass, and composition. Provides a clear indroduction to theories of the formation and evolution of galaxies, and includes a an excellent description of the methods used to determine galactic distances.
Chapter 3 - Active Galaxies
Very good introduction to quasars, radio galaxies, Seyferts, and other galaxies with an active galactic nucleus, and the theories of what produces the incredible amounts of power emanating from the center of these galaxies. Also has an excellent detailed description of galactic spectra.
Chapter 4 - The Spatial Distribution of Galaxies
Nice introduction to large scale structure within the universe, including galaxy clusters, superclusters, and larger scale structure. Talks about recent and on-going surveys to map out these large scale structures. Also includes a nice description of how the distribution of intergalactic gas clouds can be investigated via a spectral feature known as the Lyman alpha forest. Also provides a pretty good explanation of the reionization epoch.
Chapter 5 - Introducing Cosmology - The Science of the Universe
This was one of my favorite chapters. It briefly introduces General Relativity's Field Equations and then introduces the main cosmological models that have been derived from them. At this level, the introduction is essentially conceptual, but amazingly the authors have been able to use only algebra to give greater insight into the concepts and to give a feel for some of the quantitative issues. If you have ever wanted to really know about Einstein's cosmological constant, or exactly what the FRW models are and where Einstein's initial model of the universe fits in relation to these, this is the book to get. Other topics touched on include how Hubble's constant is tied to cosmology, what vacuum energy density is, what cosmological models say about the age of the universe, and a whole host of other interesting topics.
Chapter 6 - Big Bang Cosmology - The Evolving Universe
Following chapter 5's introduction to the various models of the universe consistent with General Relativity, chapter 6 goes into more detail about the early universe in those models which begin with a "big bang". This chapter walks you through the first fractions of a second, minutes, and years following the "big bang". It goes into more detail about energy density, the interaction of fundamental particles and forces, recombination, and the cosmic microwave background radiation, among other things. This was the only chapter however that did seem a little dry in parts... primarily the sections on nucleosyntheis. The material was well covered though, so it is probably just a reflection of what interests me and what does not rather than a reflection on the book.
Chapter 7 - Observational Cosmology - Measuring the Universe
Chapter 7 picks up again with a thoroughly fascinating discussion of astronomers' efforts to measure the primary parameters associated with the FRW models that would determine what kind of universe we actually live in. The parameters include the Hubble constant, the deceleration parameter, and several density parameters. The last part of the chapter provides an excellent introduction on how the angular power spectrum of the CMB is being used as one method to determine the cosmological parameters to great precision, (basically curve fitting). Overall, this is one of the most interesting chapters in the book.
Chapter 8 - Questioning Cosmology - Outstanding Problems About the Universe
This closing chapter highlights some of the questions yet to be answered. Perhaps of necessity details are rather slim in this chapter, but it still provides a nice end of book perspective on how much we still don't know. The questions discussed include,
1. What is dark matter? -- A discussion of MACHOS and WIMPS
2. What is dark energy? -- Einstein's cosmological constant? Quantum vacuum energy? Quintessence?
3. Why is the universe so uniform?
4. Why does the universe have a flat geometry?
5. Where did the structure come from?
Inflation theory could solve these three, but inflation is still a theory with many unanswered questions. Some of these are discussed.
6. Why is there more matter than antimatter? -- lack of baryon number conservation at extremely high energies?
7. What happened at t=0? -- a few paragraphs mentioning chaotic inflation, quantum cosmology, and m-theory.
8. Why is the Universe the way it is? - Why do the fundamental constants of nature have the values they do? A discussion of the anthropic principle.
SUMMARY
Bottom line is this is an excellent introduction to galactic astronomy and cosmology. It is recommended that you have some understanding of stellar astronomy including basic stellar evolution such as you would find in an introductory book such as "Voyages to the Stars and Galaxies" by Fraknoi, Morrison, and Wolff or "An Introduction to the Sun and Stars" by Green and Jones, and that your be comfortable with basic algebra and trig, but beyond that the book is very self contained and rewarding to read. It is a perfect balance between armchair reading and textbook. I only wish more popular science books were written at this level.
As a side note, if anyone knows of other astronomy texts written at a similar level, leave a comment. I would love to find other texts at the level and quality of this one.
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3 of 3 people found the following review helpful:
5.0 out of 5 stars
Great job with both topics, April 26, 2009
I think this is a great intermediate level book on galaxies and cosmology. The writing style is clear and easy to follow. There are many useful diagrams and a fair number of beautiful images.
The first part of the book focuses on galaxies. The Milky Way is the subject of the first chapter. In addition to providing a nice description of the galaxy we live in, a lot of concepts are introduced that are needed for the remainder of the book. This includes things like globular clusters, open clusters, density waves, stellar halos, HR diagrams, rotation curves and dark matter.
This is followed by a chapter on normal galaxies. The Hubble classification of galaxies is covered here. The treatment goes beyond morphology, it also describes the properties these classifications have (for example mass to gas ratio) and how they are measured. A very high level view of structure formation is given. This topic is treated in more detail in the cosmology part. The extremely important topic of the cosmological distance ladder is covered.
The following chapter on active galaxies is excellent. In addition to describing the types of active galaxies, it explains the current models of how they are powered. It also provides reasons for thinking that they are fundamentally the same kind of thing, just being viewed in different ways by us. This is followed by a chapter on the large scale distribution of galaxies which provides a nice transition to the study of cosmology.
The cosmology part is equal in quality to the galaxies part. It opens with a qualitative discussion of general relativity. Obviously it isn't very detailed, the most complicated part presented is the Robertson-Walker line element. However it's enough to motivate important things like the cosmological redshift, the cosmological constant and the critical density. This basic material is built upon to discus dark matter (both baryonic and non-baryonic), structure formation, anisotropies in the microwave background (the detail here was more than I expected form an introductory book, it actually went a bit into multipole expansions), problems with the standard cosmology (standard here meaning pre-inflation, today it would probably be safe to say that inflation is now the standard) and inflation (no details to speak of, just qualitative).
In summary I think this is a great book, suitable for students without any previous knowledge of the topics. Most of the concepts from astronomy needed are described, but not covered in detail. This includes things like population I/II/III starts, variable stars and what astronomers mean when they say "metal". This is a lot of information for someone without any background in astronomy. Such people would probably have a fairly tough time following the presentation, but could probably still do it with sufficient motivation. I would expect the best audience would be undergraduate astronomy students. More advanced students would probably be familiar with most of the material, but may still enjoy it because the presentation is so good.
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