Notebook per
Are We Alone in the Universe?
Citation (APA): Impey, C. (2016). Are We Alone in the Universe? [Kindle Android version]. Retrieved from Amazon.com
Parte introduttiva
Evidenzia (giallo) - Posizione 2
Are We Alone in the Universe? By Chris Impey
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Suppose we woke up one morning to learn that scientists had made contact with an extraterrestrial
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IPOTESI
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What would that change?
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c
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we would know that we were not necessarily the pinnacle of creation,
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c
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Astronomers are sanguine that life beyond Earth will be detected.
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CERTEZZA
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within the next decade.
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x
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The universe is highly habitable. The major biogenic elements— carbon, nitrogen, oxygen, sulfur, and phosphorus— are routinely created within stars and then ejected into interstellar space, where they become part of the next generation of stars and planets.
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ABITABILE
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Models suggest that biochemistry could have begun within a billion years of the Big Bang. This means natural selection, or something like it, could have been operating for three times longer than the age of the Earth.
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PIÙ TEMPO
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A second reason scientists are bullish about the prospects of life elsewhere is the fact that simple cells formed from primitive molecular ingredients in the first 10 percent of the history of this planet.
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INOZIO
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We anticipate roughly a hundred million habitable worlds in the galaxy,
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NUMERI
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This assumes a conservative definition of habitability based on availability of liquid water.
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c
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The principal of mediocrity implies that the full census of habitable worlds among 100 billion galaxies in the observable universe is ten billion billion.
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c
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Mars was habitable
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Taking the next step— proving biology not just habitability— will be difficult.
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x ABITABILITÁ E BIOLOGIA
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The archetypal biomarker is oxygen since it was created on Earth by microbes and in the absence of life it would disappear in less than ten million years.
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OSSOGENO
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The discovery would generate front page headlines and reverberate around the scientific community for some time.
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c
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We have no idea how often life starts given a habitable environment, no idea how often biology develops something we would recognize as intelligence, no idea how often advanced organisms harness technology, and no idea of the longevity of creatures with these advanced capabilities.
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PUNTO MORTO
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The tools used to communicate with putative aliens— radio telescopes and powerful lasers— are likely to be fleeting technologies, and they can’t be wielded by the intelligent creatures who share our planet but who lack opposable thumbs, like orcas and cephalopods.
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STRUMENTI
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Undaunted, SETI researchers
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x
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after six decades of the “Great Silence.”
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x
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If the silence persists, they contend, it really will mean we’re operationally alone,
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ALONE
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There are many reasons why advanced civilizations might exist without us being aware of them. To communicate requires motivation and means.
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MOTIVAZIONE E MEZZI
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we can’t talk to animals that share 99% of our DNA.
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x
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Aliens might be to us as we are to bacteria.
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x
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we should move beyond strategies based on communication and “contact” and look for aliens by their artifacts.
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OLTRE IL CONTATTO
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Freeman Dyson
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x
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They might become post-biological, suggesting that we should look for astro-engineering on an interstellar or even a galactic scale.
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POSTBIOLOGICAL
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SETI might be doomed to fail because it’s unduly timid.
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x
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there is a “timing argument” made that since we have only just gained the capacity to travel and communicate in space, any civilization we discover or encounter will likely be substantially more advanced.
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CIVILTÀ AVANZATE
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Another thread of the discussion alluded not to life elsewhere, but to life on Earth, and some skepticism was expressed that the remarkable complexity of a biological organism could emerge naturally from primitive chemical components. This perspective leads into arguments based on design and teleology.
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DISEGNO
