慶應SFC 1999年 環境情報学部 英語 大問1 全文

 In the early 1960s, the concept of self-organizing systems began to take hold. About that time, atmospheric chemist James Lovelock had an [1] ( 1 .erroneous 2. illuminating 3. alternative) insight into the organization of living systems that led him to formulate a model that is perhaps the most surprising and most beautiful expression of self-organization —the idea that the planet Earth as a whole is a living, self-organizing system.

 The origins of Lovelock’s daring [2] (1. hypothesis 2. method 3. attempt) lie in the early days of the NASA space program. While the idea of the Earth being alive is very ancient and speculative theories about the planet as a living system had been formulated several times, the space flights during the early 1960s [3] (1. enabled 2. urged 3. required) human beings for the first time to actually look at our planet from outer space and perceive it as an integrated whole. This perception of the Earth in all its beauty — a blue-and-white globe floating in the deep darkness of space — moved the astronauts deeply and, as several have [4]( 1. since 2. hence 3. thereby) declared, was a profound spiritual experience that forever changed their relationship to the Earth. The magnificent photographs of the whole Earth that they brought back provided the most powerful symbol for the global ecology movement.

 While the astronauts looked at the planet and beheld its beauty, the environment of the Earth was also examined from outer space by scientific instruments, and so were the environments of the moon and the nearby planets. During the 1960s the Soviet and American space programs launched over fifty space probes, most of them to explore the moon but some traveling beyond to Venus and Mars.

 At that time NASA invited James Lovelock to the Jet Propulsion Laboratories in Pasadena, California, to help them design instruments for the [5]( 1. proof 2. anticipation 3. detection) of life on Mars. NASA’s plan was to send a spacecraft to Mars that would search for life at the landing site by perform­ing a series of experiments with the Martian soil. While Lovelock worked on technical problems of instrument design, he also asked himself a more general question: How can we be sure that the Martian way of life, if any, will reveal itself to tests based on Earth’s lifestyle? Over the following months and years this question led him to think deeply about the nature of life and how it could be recognized.

 In contemplating this problem, Lovelock found that the fact that all living organisms take in energy and matter and discard waste products was the most general characteristic of life he could [6]( 1. identify 2. modify 3. codify). He first thought that one should be able to express this key characteristic mathematically in terms of entropy, but then his reasoning went in a different direction. Lovelock assumed that life on any planet would use the atmosphere and oceans as fluid media for raw　materials and waste products. Therefore, he speculated, one might be able, somehow, to detect the existence of life by analyz­ing the chemical composition of a planet’s atmosphere. Thus if there was life on Mars, the Martian atmosphere should [7] (1. remove 2. repel 3. reveal) some special combination of gases, some characteristic “signature” that could be detected even from Earth.

 These speculations were [8]( 1. rejected 2 .confirmed 3.discovered) dramatically when Lovelock and a colleague, Dian Hitchcock, began a systematic analysis of the Martian atmosphere, using observations made from Earth, and compared it with a similar analysis of the Earth’s atmosphere. They dis­covered that the chemical compositions of the two atmospheres are [9] (1. strikingly 2. slightly 3. arguably) different. While there is very little oxygen, a lot of carbon dioxide (C02) and no methane in the Martian atmosphere, the Earth’s atmos­phere contains massive amounts of oxygen, almost no C02, and a lot of methane.

 Lovelock realized that the [10] (1. assumption 2. tendency 3.reason) for that particular atmospheric profile on Mars is that on a planet with no life, all possible chemical reactions among the gases in the atmosphere were completed a long time ago. Today no more chemical reactions are possible on Mars; there is complete chemical equilibrium in the Martian atmosphere.

 The situation on Earth is exactly the opposite. The terrestrial atmosphere contains gases like oxygen and methane, which are very likely to react with each other but coexist in high propor­tions, resulting in a mixture of gases far from chemical equilib­rium. Lovelock realized that this special state must be due to the presence of life on Earth. Plants produce oxygen constantly and other organisms produce other gases, so that the atmospheric gases are being replenished continually while they [11] (1. subdue 2. undergo 3. resist) chemical reactions. In other words, Lovelock recognized the Earth’s atmosphere as [12] (1. a closed 2. a finite 3. an open) system, far from equilibrium, characterized by a constant flow of energy and matter. His chemical analysis identified the very hallmark of life.

 This insight was so [13] (1. progressive 2. painful 3. momentous) for Lovelock that he still remembers the exact moment when it occurred: For me, the personal revelation of Gaia came quite suddenly like a flash of enlightenment. I was in a small room on the top floor of a building at the Jet Propulsion Laboratory in Pasadena, California. It was the autumn of 1965… and I was talking with a colleague, Dian Hitchcock, about a paper we were preparing…. It was at that moment that I glimpsed Gaia. An awesome thought came to me. The Earth’s atmosphere was an extraordinary and unstable mixture of gases, yet I knew that it was constant in composition over quite long periods of time. Could it be that life on Earth not only made the atmosphere, but also [14] (1. froze 2. regulated 3. generated) it — keeping it at a constant composition, and at a level favorable for organisms?

 The process of self-regulation is the key to Lovelock’s idea. He knew from astrophysics that the heat of the sun has increased by 25 percent since life began on Earth and that, in spite of this increase, the Earth’s surface temperature has remained constant, at a level [15] ( 1 .ready 2 . profitable 3. comfortable) for life, during those four billion years. What if the Earth were able to regulate its temperature, he asked, as well as other planetary conditions — the composition of its atmosphere, the salinity of its oceans, and so on — just as living organisms are able to self-regulate and keep their body temperature and other variables constant? Lovelock realized that this hypothesis amounted to a radical break with conventional science: Consider Gaia theory as an alternative to the conventional wisdom that sees the Earth as a dead planet made of inanimate rocks, ocean, and atmosphere, and merely inhabited by life. Consider it as a real system, comprising all of life and all of its environment tightly [16] (1. wound 2. coupled 3. as­sociated) so as to form a self-regulating entity.

 The space scientists at NASA, by the way, did not like Lovelock’s discovery at all. They had developed an impressive array of life-detection experiments for their Viking mission to Mars, and now Lovelock was telling them that there was really no need to send a spacecraft to the red planet in search of life. All they needed was a spectral analysis of the Martian atmosphere, which could easily be done through a telescope on Earth. Not surprisingly, NASA [17] (1. disregarded 2. followed 3. solicited) Lovelock’s advice and continued to develop the Viking program. Their spacecraft landed on Mars several years later, and as Lovelock had [18] (1. predicted 2. wanted 3. wondered), it found no trace of life.

 In 1969, at a scientific meeting in Princeton, Lovelock for the first time presented his hypothesis of the Earth as a self-regulating system. Shortly after that a novelist friend, recognizing that Lovelock’s idea represents the renaissance of a powerful ancient myth, suggested the name “Gaia hypothesis” in honor of the Greek goddess of the Earth. Lovelock gladly accepted the sugges­tion and in 1972 published the first extensive version of his idea in a paper titled “Gaia as Seen through the Atmosphere.”

 At that time Lovelock had no idea how the Earth might regulate its temperature and the composition of its atmosphere, [19] (1. provided 2. except 3. granted) that he knew that the self-regulating processes had to involve organisms in the bio­sphere. Nor did he know which organisms produced which gases. At the same time, however, the American microbiologist Lynn Margulies was studying the very processes Lovelock needed to understand — the production and removal of gases by various organisms, including especially the myriad bacteria in the Earth’s soil. Margulies remembers that she kept asking, “Why does everybody agree that atmospheric oxygen … comes from life, but no one speaks about the other atmospheric gases coming from life? Soon several of her colleagues recommended that she speak to James Lovelock, which led to a long and fruitful [20] (1. corre­lation 2. combination 3. collaboration) that resulted in the full scientific Gaia Hypothesis.