ASTR 104 Lecture Notes - Lecture 38: Messier 13, Interstellar Travel
Document Summary
How does seti work: seti experiments look for deliberate signals from extraterrestrial life, earth to globular cluster m13. We"ve even sent signals: hoping we"ll hear back in about 50,000 years. Fermi"s paradox time : so why haven"t we detected them, 100,000 civilizations, possible solutions, 1. We are alone: plausible arguments suggest that civilizations should be common, for example, even if only 1 in 1 million stars gets a civilization at some. Interstellar travel is more difficult than we think: life/civilizations much rarer than we might have guessed, our own planet/civilization looks all the more precious, 2. Civilizations are common, but interstellar travel is not, perhaps: the desire to explore is rare, civilizations destroy themselves before achieving interstellar because , 3. There is a galactic civilization and someday we"ll meet them: these are all possibilities, but they are not very appealing travel.
