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PHYS125 lt5 ET

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Information about PHYS125 lt5 ET
Education

Published on January 24, 2008

Author: Veronica1

Source: authorstream.com

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PHYS 125:  PHYS 125 The Big Issues Lecture 5 Extraterrestrial Life Dr Chris Bowdery The Big Issues:  The Big Issues Extraterrestrial Life First, what about any extraterrestrial life? Later, intelligent life? Any Life Outside Earth:  Any Life Outside Earth There is no evidence of life outside the Earth (although we have unintentionally sent some of our life to the Moon and elsewhere) Any Life Outside Earth:  Any Life Outside Earth This statement could quickly change. There are indications of life on Mars. Life on Mars?:  Life on Mars? FossilLife? Life on Mars?:  Life on Mars? FossilLife? Life on Mars?:  Life on Mars? If this is life it is very small in size. Too small? Some scientists are convinced it is life. Most are still unsure. Life on Mars?:  Life on Mars? It has been proven there is water ice on Mars. Probably below the surface today but a large ocean in the past. Water  life but is it extinct, dormant or alive? Life on Mars?:  Life on Mars? Methane gas detected on Mars. Only lasts about 100 years (UV light destroys it) Must be recently made! Life (micro-organisms) or volcanoes? Life on Mars?:  Life on Mars? Direct search by space probes 1976 Viking probes - inconclusive 2003 Beagle II – crashed on landing Life on Europa?:  Life on Europa? Ice covered moon of Jupiter Life on Comets?:  Life on Comets? Balls of ice and dust orbiting the Sun Left-overs from formation of the solar system If not life, then maybe precursors of life? Extremophiles on Earth:  Extremophiles on Earth Life used to be thought of as fussy about its environment. In recent years, life found in extreme places: Very cold ice Very hot acidic springs Deep ocean floor (dark) Extremophiles in space?:  Extremophiles in space? Maybe life is hardier than we think and thus present in many environments in the solar system. Life on Mars?:  Life on Mars? If life exists on Mars Same as on Earth? Different from Earth life? Could life have evolved on Mars and been carried to Earth on meteorites? Possibly yes Major step forward in biology research Eating with ET:  Eating with ET If different extraterrestrial life exists, it will probably have a genetic store like our DNA However it is unlikely that it will use the same amino acids we use (to make proteins) We won’t be able to eat ET’s food! Intelligent ET Life?:  Intelligent ET Life? The time problem Life on Earth began within 1 billion years of formation of Earth (earlier?) :3.5 billion years ago; 500 million years of multi-cellular life; a million year or so years of hominid life (150,000 years of homo sapiens, 20,000 years of farming, 5,000 years of urban life/'civilisation'). Intelligent ET Life?:  Intelligent ET Life? The time problem But the Universe is 13.7 billion years old and 2nd generation stars may have first formed 10 billion years ago. The implication is that life could have reached our stage, somewhere, as long as 5 billion years ago. Unlikely to meet with life at a similar stage to ours. Intelligent ET Life?:  Intelligent ET Life? The Fermi Paradox If ET civilizations exist, some should be very old and have had plenty of time to travel the galaxy. Thus they should be here. Since they are not here, they do not exist. Enrico Fermi, also Frank Tipler Intelligent ET Life?:  Intelligent ET Life? The Alternatives Are they in fact here? Been and gone? Watching? Unrecognised? Stay-at-homes? Intelligent ET Life?:  Intelligent ET Life? Maybe advanced civilisations prefer to stay at home or cannot travel for some reason. Attempts have been made to listen for their radio transmissions. SETI Search for Extraterrestrial Intelligence Intelligent ET Life?:  Intelligent ET Life? The Drake Equation actually a formula to estimate the number of communicating civilisations in our galaxy Drake Equation:  Drake Equation Answers vary depending on the input values (see the calculator on websites) Typically 10,000 communicating civilisations out there ‘today’ But no signal detected yet. Intelligent ET Life?:  Intelligent ET Life? Not finding a signal could mean: They are not there / only a very few exist We haven’t listened for long enough We have pointed our dishes at the wrong stars. They are not communicating by radio waves Perhaps they use laser light, gravity waves, neutrinos,……. Science Fiction Ideas:  Science Fiction Ideas © 1968 Turner Entertainment Co., a Time Warner Company 2001: A Space Odyssey Arthur C Clarke & Stanley Kubrick Science Fiction:  Science Fiction 2001: A Space Odyssey Arthur C Clarke & Stanley Kubrick Extraterrestrial travellers journeyed through our galaxy millions of years ago searching for intelligent life. They found struggling apes on Earth. They saw potential and helped them to survive by promoting thinking. Science Fiction:  Science Fiction 2001: A Space Odyssey Arthur C Clarke & Stanley Kubrick Extraterrestrial travellers left a machine on the Moon for when humanity had evolved. This machine was activated when sunlight fell on it after being uncovered. Science Fiction:  Science Fiction © 1968 Turner Entertainment Co., a Time Warner Company 2001: A Space Odyssey Science Fiction:  Science Fiction 2001: A Space Odyssey Arthur C Clarke & Stanley Kubrick Also a ‘gateway to the stars’ was left near Jupiter to allow astronauts to travel to meet ET. This encounter led to the death and re-birth of the astronaut who made the journey. Science Fiction:  Science Fiction Contact Carl Sagan Science Fiction:  Science Fiction Contact Carl Sagan Extraterrestrials billions of years ago set up a star travel system to allow advanced civilisations to meet. More recently the current users, not the builders, listen out for emerging civilisations using radio. Science Fiction:  Science Fiction Contact Carl Sagan Earth’s first TV broadcast is detected about 50 light years from Earth. A reply is automatically sent back with instructions to build a capsule to use the space travel system. Science Fiction:  Science Fiction Contact Carl Sagan A scientist goes and meets the extraterrestrial but it is just a first meeting. Science Fiction:  Science Fiction In both these books/films, the extraterrestrials are not shown directly. Conclusion:  Conclusion Life has not been found yet off the Earth This might change quickly Search for intelligent life has not found any This could change quickly too

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