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Question
How can we detect life on other planets? Are there certain machines that can do so? If possible, can you also include diagrams?
Scientists have not invented a universal life detection machine, primarily because we do not have a universal definition of life. On Earth, we have many systems for detecting even minute amounts of life, but they depend on the specific chemistry of terrestrial life (for example the presence of DNA or RNA). We have no reason to assume that these techniques would detect alien life. One general approach is to look for evidence of chemical disequilibrium as a signature of life, since life on Earth is able to change the chemistry of its surroundings and of the atmosphere itself in ways that are not possible without organic activity. Many astrobiologists are working on this challenge, but we are probably still long way from developing a real life detection machine.
David Morrison
NAI Senior Scientist
June 2, 2003
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