Life Characteristics As part of our search for life beyond the Earth, we try to understand how life began on the Earth, i.e. the origins of life on Earth, so that we can figure out how life might arise on another planet or moon. There is also the question of what will be the future of life on the Earth and the universe. However, whether you are looking for now existing life or for how life began or at how the environment will affect life in the far future, you need to know what life is. Unfortunately, we don't have an universally, agreed-upon definition of life. A couple of approaches that complement each other try to answer what is alive vs. not alive in the origins of life research: the " top-down " and " bottom-up " approaches. The top-down approach looks at all sorts of living and fossil life forms to figure out the most primitive forms that are or were alive. Unfortunately, all the life forms we know of are already very sophisticated. There is a big gap between the life forms we know of (either current or fossilized) and the never living material and reactions. The
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.