AST 301 Scalo Review for Exam #7 Exam 7 covers chapters 26 and 27. As on previous exams, emphasis is on understanding the basic ideas and their implications and connections, not on memorization of details or on numerical values. To simplify things, let’s agree that I will not test you on any of the Discovery or More Precisely boxes, but strongly encourage you to read them just because they are interesting (e.g. you will learn how strange “string theory” is). There will be a number of questions related to deuterium and helium as produced in the era of nucleosynthesis and how those provide tests of cosmological models. However you do not have to memorize any of the nuclear reactions involved. A few of the exam questions will be versions of some of the questions found at the textbook web site multiple choice self-tests, or at the end of the chapters, or on this review sheet. Suggested questions are listed below. I strongly suggest that you do not try these questions until you have thoroughly studied—it is a waste of time otherwise, other than indicating whether you need to study more. Another suggestion that bears repeating: Test yourself by seeing if you could explain most of the material, or the answers to the questions at the end of the chapter (Review and Discussion), to someone who hasn’t taken the course, without consulting the book at all. Not being able to do this (and it should be pretty clear when you can’t) is a sure sign that you don’t understand the material enough and need further study. The “Learning Goals” at the beginning of the chapters, in case you haven’t noticed them, and the “Review and Discussion” questions at the end of the chapters, are often perfect for this kind of review, although not all of them. I’ll suggest some below. The TA, Julie Hollek-Kruger, will have office hours Thursday 2-4 (as far as I know at the time of this writing). For people who can’t make Julie’s hours, I am reserving some hours before and after for my office hours, but only if you tell me that you need to see me and when. Otherwise, the best bet is to have a telephone review session: 478-2748, any time between 3pm and 9pm on Wednesday, and 9am to 9pm Thursday. If I’m not there, leave a message and state your name and phone number clearly, or just call back later—I sometimes don’t check my phone messages frequently. Do NOT ask about the material by email—it is too time-consuming and easily misunderstood—feel free to call. Chapter 26 (Cosmology). Because this material has been discussed at length in lecture, I won’t enumerate the sections--all of them are important. Don’t be too worried if you feel like you don’t understand the material on the curvature of space: very few people really understand that. But do remember the 2-dimensional analogies so that you’ll know what we’re talking about if you encounter the terms “closed” and “open” universe. Similarly, I don’t expect you to understand Fig. 26.11, although the evidence presented there is something that you should try to explain in words. Same with Fig. 26.34—I’m not going to be specific about those curves, but you should be able to make sense of them if you understand 26.8 and 26.9. We didn’t talk about the reason there is a Fig. 26.18, so the point it is illustrating won’t be on the exam. I found that the “Learning Goals” at the beginning of the chapter provide a clean way to find if you have been keeping up well enough that you can verbalize the answers to the points listed there. All of them should be within your reach, except number 7 which you can skip. Remember that the first sections of ch.26 are presented in a strange order, telling you about the largest structures in the universe as if it was just because “biggest” is interesting, a curiosity, but actually that observational material is the test for the cosmological principle, which is presented after those observations. The order is corrected in the slides. End of chapter: Review and discussion: All except 10, 18, 19, 20. Especially important are 4, 7, 9, 11, 12, 15. TF/MC: 11, 12, 14, 15, 19, 20. (Most of these are fairly easy). Online ebook: MC1: 4, 6-13, 15; MC2: 1, 2, 6, 7, 10-13.Chapter 27 (The Early Universe). This is a challenging but extremely interesting chapter because of all the strange phenomena and physical conditions discussed. I am mostly concerned that you get the basic ideas. In particular, you don’t have to memorize the numerical or other details of Table 27-1 (and I won’t ask you about much terminology, like what is a hadron or a lepton, etc.). But we did go over a simpler version of this “time line” in detail in class, so I do expect you to know what went on and when (i.e. roughly how old the universe was when this or that occurred) during the following key phases: 1. Nucleosynthesis; 2. Inflation; 3. Creation of virtual particles and antiparticles; 4. Decoupling of matter and radiation (and why that implies that there must be a cosmic background radiation); and 5. The formation of galaxies from fluctuations. Note: these are not in the correct order, just so you will at least have to learn that much about these events. The horizon and flatness problems are difficult to understand intuitively for most people, but you should be able to say what they are, and why inflation solves them. We only talked about that briefly in class on Wednesday, but the textbook has an excellent presentation. You should also be able to explain the evidence that supports the big bang theory in general, and inflationary cosmological theory in particular, and which evidence indicates the presence of a large component of “dark energy.” These are all related, so see if you can explain that relation. Finally, you should be able to explain what the cosmic background radiation is, and what properties of it are important as a test of the big bang theory, or as a diagnostic of dark matter and energy (for example its temperature, its spectrum, and especially the analysis of its “blotchiness”). Try “Learning Goals” 4-8 at the beginning of the chapter. End of chapter: Review and discussion: All except 1, 8, 17. Also, 10 requires a long narrative answer. Especially important are 4, 6, 7, 11, 12; 13-16 are all about inflation, so think about these as a group; 19, 20 are about COBE and WMAP. TF/MC: 13, 16, 17, 18, 19.
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