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Aliens Don’t ExistEarthlike conditions are unique – no aliens – consensus is on our sideObserver 2k (Robin McKie, Science Editor, “When it comes to intelligent life, we’re as good as it gets”, July 16, L/N) WE ARE alone. Mankind may be the sole intelligent occupier of the entire galaxy, according to a growing number of scientists involved in the Search for Extraterrestrial Intelligence (Seti). After decades of employing radio telescopes in vain bids to hear E.T. phoning home, and after studying patterns of evolution on Earth, they believe that complex, brainy extraterrestrials must be rare, if not non-existent. Life may be ubiquitous, they admit, but only on our planet did it evolve into beings capable of rational thought, sophisticated behaviour and powerful civilisations. On other worlds, it has remained rooted at the level of amoebas, microbes, and primitive pond life. All aliens are scum, in other words an observation with crucial implications. As UK astronomer Ian Crawford points out in the latest issue of Scientific American, we may be 'the most advanced life-forms in the galaxy'. 'We used to think that once life emerged on a planet, intelligent beings would inevitably appear,' added Dr Ian Morison, director of Seti research at Britain's Jodrell Bank radio telescope. 'Now, it seems we only evolved thanks to an extraordinary series of fortuitous events.' The first and most important of these lucky breaks concerns location, as astronomers Peter Ward and Donald Brownlee recently revealed in Rare Earth: Why Complex Life is Uncommon in the Universe (Copernicus). Earth far from being an average world in an unimportant part of the cosmos turns out to be prime galactic real estate. First, our sun is a highly stable star and is unaffected by wild fluctuations in output of its radiation. Such afflictions emanate from many other stars and would destroy evolving advanced life-forms, allowing only bacteria-like entities to flourish. In addition, ours is a safe suburban part of the galaxy, the astronomical equivalent of Cheltenham. By contrast, in more crowded, 'down-town' galactic neighbourhoods, in stellar Sauchiehall Streets of the universe, jostling stars are likely to have continually dislodged the swathes of comets believed to hover at the edges of most solar systems. These comets would then have crashed into each star's family of planets with devastating consequences for their evolving life-forms. In addition, Earth has a planetary big brother, Jupiter, which sweeps up those few dangerous comets that do make it through to the solar system's inner regions, while our world is further blessed in having a relatively large moon which helped stabilise Earth's rotation, preventing wild swings in our seasons and climate. All these improbable conditions, in combination, provided the stability that allowed four-billion-year-old primitive slime to evolve about 250,000 years ago into the only intelligent creatures known to science, ourselves. Humanity may therefore be viewed as the outcome of the biggest accumulator bet in the universe. As Professor Brownlee, of Washington University, Seattle, puts it: 'Earth is a charmed place. We know of no other body that is even remotely like it.' Earthlike conditions are rare – even if they are common – unique circumstances make intelligent life possible that are unlikely to exist elsewhereCrawford 2k (Ian, Professor of Astronomy and Physics at University College in London, Scientific American, “Where Are They? Maybe We Are Alone In the Galaxy After All”, July, Volume 283, Issue 1, p. 38-43) To my mind, the history of life on Earth suggests a more convincing explanation. Living things have existed here almost from the beginning, but multicellular animal life did not appear until about 700 million years ago. For more than three billion years, Earth was inhabited solely by single-celled microorganisms. This time lag seems to imply that the evolution of anything more complicated than a single cell is unlikely. Thus, the transition to multicelled animals might occur on only a tiny fraction of the millions of planets that are inhabited by single-celled organisms. It could be argued that the long solitude of the bacteria was simply a necessary precursor to the eventual appearance of animal life on Earth. Perhaps it took this long—and will take a comparable length of time on other inhabited planets—for bacterial photosynthesis to produce the quantities of atmospheric oxygen required by more complex forms of life. But even if multicelled life-forms do eventually arise on all life bearing planets, it still does not follow that these will inevitably lead to intelligent creatures, still less to technological civilizations. As pointed out by Stephen Jay Gould in his book Wonderful Life, the evolution of intelligent life depends on a host of essentially random environmental influences. This contingency is illustrated most clearly by the fate of the dinosaurs. They dominated this planet for 140 million years yet never developed a technological civilization. Without their extinction, the result of a chance event, evolutionary history would have been very different. The evolution of intelligent life on Earth has rested on a large number of chance events, at least some of which had a very low probability. In 1983 physicist Brandon Carter concluded that “civilizations comparable with our own are likely to be exceedingly rare, even if locations as favorable as our own are of common occurrence in the galaxy.” Directory: files files -> Answer True False 2 points Question 2 files -> Integer programming and game theory files -> 4 Integer Programming files -> Bpa vehicle Window Repair Scenario #1 task: Procure vehicle window relacement. Objective files -> Pop Warner History files -> North Carolina Inclusion Initiative Mapping Where Children with ieps are Being Served Purpose files -> Fall 2013 Spring 2014 Program Data: Standard 1 Exhibit 4d files -> Hanban – asia society confucius classrooms network 2010 request for proposal files -> Northern England’s set-jetting locations Download 243.79 Kb. Share with your friends:
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