PHY229: Extrasolar Planets and Astrobiology Rationale The goals of this course are for you to learn: How to assimilate and organise and large body of different information, ideas, and theories in different areas. How to present a coherent, logical overview or argument in good written English. How to research and summarise an unfamiliar topic at an appropriate level. We will do this in the context of astrobiology in which we need to cover large amounts of information and ideas from astronomy, biology (genetics, biochemistry, molecular etc. etc.), physics, chemistry, geophysics, planetary science, atmospheric and climate science, geology, palaeontology, and also the social sciences and philosophy. This is a vast array of ideas, concepts, terminology, arguments and theories and there is no answer (yet). Given the large amount of information we need to cover I will discuss much of it only lightly in lectures. I suggest reading around the topics we cover to gain more understanding and insight. The rapid delivery of large amounts of material often without a detailed discussion or explanation is quite deliberate. It is one of your goals to learn how to assimilate and organise this information and support that with extra reading and research if needed. Assessment is in two parts. Article (20%). You will pick a topic at random from a bag and have to research and learn about that topic and write an article explaining it to somebody else on the course who knows very little about it. The topics are deliberately chosen to be from outside of physics and your usual comfort zone (non-physicists will have their topics checked by me to make sure they are outside your usual degree). Exam (80%). The exam is two essays in two hours from a choice of five titles from the list included here. All of these titles are very broad and require you to synthesise information from many different parts of the course to answer the sort of questions that a person on the street might ask you if you said you had done a course on astrobiology. 1
Suggested Reading There are many sources of information on the topics we cover. A-level or first year text books from different subjects are often a good source of information on technical topics you are unfamiliar with. Below are some books on astrobiology which I have found useful in no particular order. Astrobiology: An Introduction by Longstaff. Good book that covers many areas, usefully divided into many short sections and subsections. Rare Earth by Ward & Brownlee. Even if you don t buy the Rare Earth argument this is still interesting and has lots of useful and interesting information. The Reason Why by Gribbin. Lots of interesting ideas and speculation arguing advanced life is very rare. I don t buy all the ideas, but a good read (and dedicated to me which was really nice of John). Understanding Earth by Press, Siever, Grotzinger & Jordan. A really nice introduction to geology, I m sure there are other textbooks covering the same ground, but I found this in a remainder shop and have found it very useful. Astrobiology: an Evolutionary Approach eds. Kolb. A recent book which I have only just requested copies of for the library. Some good, but technical discussions concentrating mainly on chemistry/biology. Chapter 15 is an excellent overview of arguments on what is life. Astrobiology: A Multidisciplinary Approach by Lunine. A technical textbook, with lots of very detailed coverage. The thermodynamics of life chapter is particularly good from a physics perspective. Cassell s Atlas of Evolution by Dixon, Jenkins, Moody & Zhuravlev. A nice introductory textbook on evolution concentrating mostly on post-cambrian explosion life. Life on Other Worlds by Dick. An interesting historical overview of the debates about extraterrestrial life. Interesting coverage of SciFi, SETI and UFOs in their historical context. An introduction to Astrobiology by Rothery, Gilmour & Sephton. Concentrates mostly on planets and planet finding, but does this well and a pretty low-level. 2
Life in the Universe by Bennett & Shostak. Low-level introduction, but useful as a starting point. What does a Martian look like by Cohen & Stewart. Interesting popular book discussing what aliens might be like, nice descriptions of some of the biology. Young Sun, Early Earth and the Origins of Life by Gargaud, Martin, López- García, Montmerle & Pascal. Really good books about the formation and early evolution of the Earth and a really good coverage of the possible origins of life. Extrasolar Planets and Astrobiology by Scharf. Nice general book tending to concentrate on the astro side. Life on a Young Planet by Knoll. Really readable book about the all pre-cambrian life, lots of interesting information. 3
PHY229: Extrasolar Planets and Astrobiology EXAM QUESTIONS The exam for PHY229 will be to answer any TWO essay questions from a selection of five from the following list. The exam is two hours, so each essay should take around an hour to plan and write. Each question is worth 40 marks. By the end of this course you should be able to provide a considered answer to all of these questions supported by relevant information. You should be able to distinguish between facts, well-supported theories, and speculation of varying degrees, and explain the difference between them. When discussing a statement you can agree with it, disagree with it, or take a maybe/maybe not approach as long as your argument is clearly made and supported by relevant information. A good essay must show all of these facets, but the balance may differ. E.g. an extremely well-written and argued essay with a lack of supporting information will get a similar-ish mark to a badly written, poorly-structured essay with lots of supporting information. There is no such thing as a model answer to any of these questions. Each question can be addressed in many different ways with many different spins. Some questions clearly have a baseline of information required in an essay, but the depth and/or breadth of an answer is flexible: you may want to cover many things quite generally, or a few things in depth. The questions are deliberately broad and offer you the chance to provide your own take on the question. Whatever you do address the question you have been asked. A discussion is not a list of facts, but rather a coherent argument or overview of a topic. Be careful with what you write. I cannot assume what you mean, I can only read what you have written. If what you write makes no sense or is wrong because of a bad sentence structure it cannot get any credit, and it can lose credit. It is your job in writing the essay to demonstrate to me your understanding of the question and the topic. I strongly suggest you spend some time planning your essay before starting to write it. The length of an essay will depend on the size of your handwriting and how succinctly you write. I expect you to spend an hour planning and writing each essay, so typically I would expect an answer to be 3-5 pages in the answer book but this is a very rough guideline and I will mark the content not the length. A long, rambling essay is much worse than a short, punchy essay which contains the same basic content. When writing an essay parse what you write for its information content. I sometimes see long essays which, when looked at closely, contain very little content, and have the same information constantly repeated in slightly different ways. You can only typically only gain credit for a part of your argument/discussion of a piece of information once, repeating it in slightly different words is a waste of your time. 4
Similarly, irrelevant information/arguments can gain no credit (no matter how interesting/correct/clever). Everything you write in your essay must be focused towards answering the question you have been asked. I will use the full marks range. A well-written and argued essay supported by relevant information that answers the question will get a very high mark (I am known to give 100%). A garbled and incoherent essay that uses incorrect and/or irrelevant information and does not address the question may well fail badly. Since I have provided you with a list of all the questions that I can ask you I expect you to have put time and effort into preparing to answer them. Therefore my marking will be more strict than for an unseen question. 5
Possible exam questions 1. Critically discuss the Drake Equation. 2. Critically discuss the use of the terms Earth-like planet and life as we know it in astrobiology. 3. In the context of astrobiology broadly describe the evolution of life on Earth and its interaction with the planet. 4. Critically discuss the statement Alien life would be very similar to us. 5. Describe how our current knowledge of the properties of extrasolar planets informs the search for alien life. 6. The Galaxy contains many intelligent civilisations. Discuss. 7. Discuss the fundamental properties of life on Earth and how these inform our search for alien life. 8. Critically discuss the definition of life in the context of the search for alien life. 9. Discuss the importance (or not) of the distinction between simple life, advanced life, and technological civilisations in astrobiology. 10. Describe in detail what we know about extrasolar planets, how we know it, and how this informs our search for extrasolar life. 11. Critically discuss the Rare Earth hypothesis. 12. Describe what the Cambrian Explosion was and discuss its importance (or not) to astrobiology. 13. Life is most likely to be found on an Earth-like planet around a Sun-like star. Discuss. 14. Discuss the origin and evolution of life on Earth from an astrobiological perspective. 15. Critically discuss the Fermi Paradox. 16. There are so many stars in the Galaxy that life must be common. Discuss. 17. We are the first technological civilisation in the Galaxy. Discuss. 18. Discuss what is meant by technology and civilisation in astrobiology. 19. Explain and critically discuss some methods proposed to search for extra-terrestrial life. 20. A technological civilisation is a natural consequence of evolution. Discuss. 21. There is almost certainly life on a planet within 100 pc. Discuss. 22. What we already know about extrasolar planets tells us life is common in the Galaxy. Discuss. 23. The Earth is probably the only living planet in the Galaxy. Discuss. 24. Is absence of evidence for alien life evidence of its absence in our Galaxy? 25. SETI is a waste of time. Discuss. 26. Human civilisation is the result of so many highly improbable events that technological civilisations must be extremely rare. Discuss. 27. Earth-like planets with advanced life are extremely rare. Discuss. 28. Life is common, but technological civilisations are rare. Discuss. 29. Life is common, but advanced life is rare. Discuss. 6
30. Life is so varied that we could well not realise if we encountered it. Discuss. 31. Only an Earth-like planet could have life as we know it. Discuss. 32. We will almost certainly discover alien life in the next 30 years. Discuss. 33. The eukaryotic cell is a pre-requisite for intelligence. Discuss. 34. All life will be based on cells. Discuss. 35. Discuss how life on Earth works and has evolved, and the implications to astrobiology. 36. Intelligent life will be common, but technological intelligences will be very rare. Discuss. 37. Technological intelligences are unlikely to be biological. Discuss. 38. CHON is almost certainly the basis for all life in the Universe. Discuss. 39. Our understanding of life is too parochical to usefully inform a search for aliens. Discuss. 40. Any number produced by the Drake Equation is worse than useless. Discuss. 7