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Chapter 1

Life in the universe - Chapter 1 notes.docx

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Natural Science
NATS 1880
Paul Delaney

Chapter 1-Auniverse of life? - stars are like planets - each star has planets - with so many possibilities, it’s hard to imagine life only on Earth - we do not know whether it exists somewhere else or not - learning if the universe is full of life holds great significance for how we view our planet - if there is no other life we will view our planet with added wonder - if there is other life we will now that earth is not as special as we thought - if there are common life forms we will be forced to accept that we ourselves are just one of many intelligent species throughout the universe - books purpose is to give you background needed to understand new and exciting developments in the human quest to find life beyond earth 1.1 The possibility of Life beyond Earth - scientists searching for life elsewhere - looking for evidence of life on other worlds in our solar systems - trying to learn whether we should expect to find life on planets orbiting other stars - searching for signal broadcast by other civilizations - discovery of life of any kind beyond earth will change our perspective on how we fit into the universe and teach use more about life here on earth as well What are we searching for? - when we search for extraterrestrial life or life beyond earth, we are looking for any sign of life - simple, complex, or intelligent - doesn’t matter if it is the same as life on earth or different - cant really answer this question until we know what life is - defining life is hard so scientific search for extraterrestrial life in the universe generally presumes a search for life that is at least somewhat Earth-like and that we could therefore recognize from what we know from studying earth - limited but have to start somewhere, with what we know Is it reasonable to imagine life beyond earth? - scientific search for life in the universe is a recent development in human history, but the idea of extra- terrestrial life is not - any ancient cultures told stories about beings living among the starts - idea remained speculative – no way to study the question of extraterrestrial life scientifically - possible to imagine extraterrestrial life, no scientific reason to think that it would really exist - the relatively small amount of data shedding light on question of life beyond earth was misinterpreted 1. Scientists guessed that Venus may harbor tropical paradise – based on fact that venus is covered by clouds and closer to the sun than the earth 2. Mars was subject to more intense debate - scientists thought they saw long, straights canals on the surface, were cited as evidence of martian civilization - canals did not really exist - today, enough telescopic and space craft photos of the planets & large moons our solar system to be quite confident that no civilization has ever existed there - large animals seem as unlikely -Scientific interest in life beyond earth has exploded in the past few decades. Why? 1. Large, multi-cellular life in our solar system seems unlikely anywhere but earth - new discoveries in both planetary science and biology have given us some reason to think that simpler life perhaps tiny microbes – might exist on other planets or moons that orbit our sun 2. Stars are full of planets, thus, far more places where we can search for life 3.Advance in both scientific understanding and in technology now makes it possible to study the question of life on the universe through established techniques of science, something not possible few decades ago 1.2 The Scientific Context of the Search - math helps us do many computations that help us understand all other areas of science - computers to stimulate everything from formation of stars and planets to ways in which molecules interact with one another - 3 particular disciplines play an important role in framing the context of the scientific search for life 1.Astronomy 2. Planetary science (geology and atmospheric science) 3. Biology Astronomy helping us understand possibilities for extraterrestrial life? - Before earth was assumed to be the center of the universe, planets were lights on the sky - stars other lights _ no one thought we might search for life here - stars were distinguished form planets because THEYWERE FIXED IN PATTERNS - when we found out the earth orbited the sum, there were nor reason to think that planets didn’t orbit the stars - astronomy provided context to the search for life in many other ways as well - by stu
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