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Chapter 12

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Natural Science
NATS 1880
Paul Delaney

Drake Equation: simple equation that is used to summarize the factors that would determine the number of communicating civilizations in our galaxy. -Introduced at a conference in 1961 NHp = number of habitiable planets in our galaxy F life= fraction of habitable planets that have LIFE 1/ 1,000,000 Fciv= fraction of the life-bearing planets with civilization capable of interstellar communication 1/1000 N HpX f lifef civ Number of civilizations capable of interstellar communication. Fnow is the fraction of civilization bearing planets that happen to have civilization now NHp= number of habitable planets on which life can evolve Flife =fraction of habitable planets in our galaxy that have life (close to 1) Fciv=Fraction of life bearing planets on which a civilization capable of interstellar communication has arisen at some time. Fnow= fraction of these civ that happened to exist now. The discussion is limited to the Milky way (our own galaxy) since there are 100 billion galaxies. Original Drake Equation: N = R x f planet x Ne x Flife x Fintell X Fciv X L R=# of stars formed in galaxy each year fplanet= refers to the fraction of stars having planets ne= refers to the # of planets per system capable of supporting life F =refers to fraction of life-bearing planets which develop intelligent life. intell Fciv=refers to the fraction of planets in which intelligent life capable of inter-stellar communication L= the lifetime over which such civilizations exist. -We have been able to communicate interstellar since 1950. -Intelligent civilization= one that is capable of radio communication Conservative: (Technological) intelligence Optimistic: Evolutionary mechanism like our own is rare encourage an increase in intelligence Some intelligent species would evolved on Earth (optimistic) Convergent evolution : the tendency of organisms of different evolutionary backgrounds to resemble one another due to similar environment and common ecological niches. Examples Dolphin and shark body features are streamlined for faster speed Eyesight within the mammals have evolved 18 different times. -Intelligence is also subject to natural selection. If it enhances survival value, then convergent evolution will occur. Measuring Intelligence - can be tested by measure the brain power of a variety of animal species over time. -Heavier animals have heavier brains -- In the graph, animals whose brain falls on this line are said to have encephalization quotient (EQ) of 1. -This means they have enough brain size for basic set of instructions. EQ of 1 serves as the indicator of general intelligence Human EQ is 7 which means our brain is 7 times more massive than average mammal. Higher than any species known or alive. -having a bigger brain is metabolically expensive (1/4 of our metabolism is for our brain) -competition between species also increases intelligence since when one animal catches another; it allows other victim of species to be more aware. -Intelligence is not merely required to make technology (I) Physiological: hands are needed (II) Sociological: societies that emerged from the ancient Greece have concept of science. 12.3 Searching for Intelligence BEST WAY TO SEARCH FOR INTELLGENCE IS TO look/listen for EXISTENCE Two Radio Pioneers (Marconi & Tesla) -Guglielmo Marconi (made radio practical) & Nikola Tesla (made the first fluorescent lamp, used AC to distribute power)said WRONGLY they head aliens on the airwaves. -The alien sounds they heard were infact whistler’s ( electrical noise created by distant lightening charges) Origins of modern SETI Modern SETI began with a paper from Cocconi and Morrison in 1959 -Said that interstellar communication was p
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