外星生命中英presentation解读.pptx

Extraterrestrial civilizations (地外文明） Extraterrestrial life Contents Extraterrestrial life is life that does not originate from Earth. It is also called alien life, or, if it is a sentient and relatively complex individual, an “extraterrestrial“ or “alien“. 外星生命指存在于地球以外的生命体这个概念囊括了简单的细菌到具有高度智慧的外星 人研究和测试关于外星生命猜想的学科被称作地外生物学或天体生物学 Possible basis(存在与否） Scientific search Background Cultural impact CONTENTS 1952年美国新泽西州所拍摄的UFO 人类普遍对外星人的刻板印象 Back ground Possible basis Alien life, such as microorganisms（微生物）, has been hypothesized to exist in the Solar System and throughout the universe. This hypothesis relies on the vast size（广博的面积）and consistent physical laws（一致的物理定律 ）of the observable universe. According to this argument, made by scientists such as Carl Sagan (卡尔·萨根:太空科学家) and Stephen Hawking (史 蒂芬·霍金), it would be improbable for life not to exist somewhere other than Earth. This argument is embodied in the Copernican principle, which states that Earth does not occupy a unique position in the Universe, and the mediocrity principle, which suggests that there is nothing special about life on Earth. Possible basisPossible basis Possible basis All life on Earth is based upon 26 chemical elements. However, about 95% of this life is built upon only six of these elements: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur, abbreviated CHNOPS（碳、氢、氧、磷及硫）. These six elements form the basic building blocks of virtually all life on Earth, whereas most of the remaining elements are found only in trace amounts（ 微量）. Possible basisPossible basis 认为地球之外存在生命有着很简单的事实的支持：仅仅在银河系中就有2000亿至4000亿颗恒星， 而银河系只是宇宙中超过1000亿星系中的一员。

据估计至少有十分之一的类似太阳的恒星具有行星 系统 Possible basis 科学家在搜索外星生命时，多以液态水和有机物的存在作为外星生命存在之前提条件水为地球生命体内 各种化学反应提供了场所 有人批评这样以地球生物为蓝本的先入为主的观点阻碍了外星生命的探索卡尔·萨根在1973年提出碳沙 文主义，认为这些以人类为中心的思想限制了我们对于地外生命可能性的想像例如在宜居带之外，有 可能通过地热等方式维持地底的生物圈；也有生物能够在高砷低磷的环境下存活，这说明生物组成“必备 ”的六大基本元素：碳、氢、氧、氮、磷、硫，可能不是必需的 Life on Earth requires water as its solvent in which biochemical reactions take place. Sufficient quantities of carbon and the other elements along with water, may enable the formation of living organisms on other planets with a chemical make-up and temperature range similar to that of Earth. Possible basisPossible basis Scientific searchScientific searchScientific search Scientific search Direct search 直接探索 Indirect search 间接探索 Extra solar planets 可能存在的外星生命 Scientists are directly searching for biosignatures within the Solar System, carrying out studies on the surface of Mars and examining meteors that have fallen to Earth. At the moment, no concrete plan exists for exploration of Europa for life. In 2008, a joint mission by NASA and the European Space Agency was announced that would have included studies of Europa. However, in 2011 NASA was forced to deprioritize the mission due to a lack of funding, and it is possible that the ESA will take on the mission by itself. Direct search 2003年6月10日和7月7日，美国国家航空航天局分别发射了勇气号和机遇号火星探测器，其目标是 探测火星上水存在的可能性、分析火星岩石和土壤的成分、评估火星是否适合生命生存等。

这两个 双胞胎探测器均在2004年1月在火星成功着陆在2011年11月26日发射的好奇号火星探测器也在 2012年8月6日成功登陆火星，用于评估火星上是否存在过适合微生物生存的环境 Terrestrial Planet FinderThe NASA Kepler for the search for extrasolar planets. Indirect search Scientists have proposed radiated heat from a planet as a way to find advanced civilizations. Large-scale power generation releases large amounts of heat, which can be detected using an advanced telescope, such as the proposed Colossus interferometric telescope. The fact that the heat signatures would be coming from power generation, especially in urban areas, where heat islands are created, would also confirm that the observed civilization is advanced. Larger power consumption correlates with more-advanced societies. Detecting thermal signatures allows the ability to detect advanced civilizations indirectly, as opposed to trying to make direct contact through messages like those created by Active SETI. SETI 对外星智能的探索 (search for extraterrestrial intelligence). 科学家认为生命可能曾经存在过或者依然存在的地方包括金星、火星、木星的卫星、土星的卫星。

除 了太阳系的行星和卫星之外，科学家在太阳系外也找到了数十颗位于宜居带太阳系以外的行星科学 家保守估计每两颗恒星中就有一颗拥有行星，每200颗恒星中就有一颗位于宜居地带 Extra solar planets Astronomers search for extrasolar planets that may be conducive to life, narrowing the search to terrestrial planets within the habitable zone. Current radiodetection methods have been inadequate for such a search, because the resolution afforded by recent technology is inadequate for a detailed study of extrasolar planetary objects. Culture impact The failure so far of the SETI program to detect an intelligent radio signal after decades of effort, has at least partially dimmed the prevailing optimism of the beginning of the space age. Notwithstanding, belief in extraterrestrial beings continues to be voiced in pseudoscience, conspiracy theories, and in popular folklore, notably “Area 51“ and legends. It has become a pop culture trope given less-than-serious treatment in popular entertainment with e.g. the ALF TV series (1986–1990), The X-Files (1993–2002), etc. 内华达375号州道旁的路牌，由于靠近51区而被称 命。