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Astrobiology: Odds that Intelligent Life Evolved on Earth ONLY & Nowhere Else in the Universe
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HenryDavidT
Apr 29, 2016, 1:02:07 AM4/29/16
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http://astrobiology.com/2016/04/are-we-alone-setting-some-limits-to-our-uniqueness.html
http://www.cbsnews.com/news/across-cosmic-history-intelligent-life-common/
What are the odds that intelligent life evolved on Earth and nowhere else among the 20 billion trillion stars in the observable universe across 13.8 billion years of cosmic history?
About one in 10 billion trillion, according to researchers writing in the journal Astrobiology -- meaning it's very, very unlikely humanity is unique across the sweep of cosmic space and time.
Put another way, even if life evolves on only one planet in a billion orbiting in the habitable zone of its star -- the region where water can exist as a liquid and life as it's known on Earth could, in theory, evolve -- "that still means it's happened on the order of 10 trillion times," said Adam Frank, an astronomer at the University of Rochester.
Armed with data from NASA's Kepler space telescope showing planets are commonplace, Frank and Woodruff Sullivan, an astronomer at the University of Washington, decided to take a fresh look at the Drake equation, developed in 1961 by astrophysicist Frank Drake as a way of making a rough estimate of how common technological civilizations might be across the Milky Way galaxy.
The Drake equation combines three terms from astronomy -- the frequency of star formation, the fraction of those stars that host planets, and the number of planets with environments suitable for life -- with three "biological" terms -- the fraction of such planets with life of any sort, the fraction that might have developed intelligent life, and the number of civilizations capable of making their presence known across interstellar distances.
http://www.cbsnews.com/news/across-cosmic-history-intelligent-life-common/
What are the odds that intelligent life evolved on Earth and nowhere else among the 20 billion trillion stars in the observable universe across 13.8 billion years of cosmic history?
About one in 10 billion trillion, according to researchers writing in the journal Astrobiology -- meaning it's very, very unlikely humanity is unique across the sweep of cosmic space and time.
Put another way, even if life evolves on only one planet in a billion orbiting in the habitable zone of its star -- the region where water can exist as a liquid and life as it's known on Earth could, in theory, evolve -- "that still means it's happened on the order of 10 trillion times," said Adam Frank, an astronomer at the University of Rochester.
Armed with data from NASA's Kepler space telescope showing planets are commonplace, Frank and Woodruff Sullivan, an astronomer at the University of Washington, decided to take a fresh look at the Drake equation, developed in 1961 by astrophysicist Frank Drake as a way of making a rough estimate of how common technological civilizations might be across the Milky Way galaxy.
The Drake equation combines three terms from astronomy -- the frequency of star formation, the fraction of those stars that host planets, and the number of planets with environments suitable for life -- with three "biological" terms -- the fraction of such planets with life of any sort, the fraction that might have developed intelligent life, and the number of civilizations capable of making their presence known across interstellar distances.
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