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" "Had your spacecraft flown by the Earth a hundred million years ago, in the age of the dinosaurs when there were no humans and no technology, you would still have seen oxygen and ozone, the chlorophyll pigment, and far too much methane. At present, though, your instruments are finding signs not just of life, but of high technology — something that couldn’t possibly have been detected even a hundred years ago: You are detecting a particular kind of radio wave emanating from Earth. Radio waves don’t necessarily signify life and intelligence. Many natural processes generate them. You’ve already found radio emissions from other, apparently uninhabited worlds — generated by electrons trapped in the strong magnetic fields of planets, by chaotic motions at the shock front that separates these magnetic fields from the interplanetary magnetic field, and by lightning.
Carl Edward Sagan (9 November 1934 – 20 December 1996) was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space, the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued the hypothesis, accepted since, that the high surface temperatures of Venus can be attributed to, and calculated using, the greenhouse effect. He testified to the US Congress in 1985 that the greenhouse effect will change the earth's climate system.
Biography information from Wikiquote
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XIX. yüzyılda buharlı gemi yapımına girişilince, denizlere hiç de hayırlı olmayan bir çevre kirliliği işareti ulaştı: gürültü. Ticari ve askeri gemilerin daha da çoğalmasıyla okyanuslara yayılan gürültü (özellikle yirmi Hertz frekansında) kulak ardı edilemez duruma geldi. Okyanuslararası haberleşme girişimini yürüten balinalar için anlaşmak giderek zorlaştı. Haberleşme giderek kısa mesafelere indi. İki yüzyıl önce Finback denen balina türünün anlaşması 10.000 km uzaktan mümkün olurken, şimdi bu mesafe birkaç yüz kilometreye inmiş olabilir. Balinalar birbirlerini isimleriyle mi çağırırlar? Yalnızca ses yoluyla birbirlerini tanıyabilirler mi? Balinaların haberleşme olanaklarını kestik. Milyonlarca yıl haberleşebilen yaratıkları şimdi susturduk.
n those cultures lacking unfamiliar challenges, external or internal, where fundamental change is unneeded, novel ideas need not be encouraged. Indeed, heresies can be declared dangerous; thinking can be rigidified; and sanctions against impermissible ideas can be enforced — all without much harm. But under varied and changing environmental or biological or political circumstances, simply copying the old ways no longer works. Then, a premium awaits those who, instead of blandly following tradition, or trying to foist their preferences on to the physical or social Universe, are open to what the Universe teaches.
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