全新版大学英语综合教程3课文原文及翻译

导读:伊萨克·阿西莫夫除了地球,在太阳系或许没有类似我们这样的生命的存在。可是,环绕其他恒星运行的星球上有生命吗?2Beforewecanreallytrytoanswerthat,wehavetoaskifthereareplanetscirclingotherstars.Overfivehundredyearsago,NicholasofCusatookitf

全新版大学英语综合教程3课文原文及翻译

伊萨克·阿西莫夫

除了地球,在太阳系或许没有类似我们这样的生命的存在。可是,环绕其他恒星运行的星球上有生命吗?

2 Before we can really try to answer that, we have to ask if there are planets circling other stars. Over five hundred years ago, Nicholas of Cusa took it for granted that there were. Modern astronomers think he is likely to have been right, for if our solar system was formed from a cloud of dust and gas that automatically formed planets, that should be true of many other stars as well, and even, perhaps, of nearly all stars.

在试图回答这个问题之前,我们得问一下是否有行星环绕其他恒星运行。五百多年前,库萨的尼古拉斯想当然地认为是有的。现代天文学家认为他很可能是对的,因为如果我们的太阳系在由尘埃和气体组成的云团生成的同时也自动生成了若干行星的话,那么其它许多恒星,甚至可能几乎所有恒星,也应该如此。

3 But that is risky reasoning. It would be much better if one star, aside from our own sun, were actually found to have a planetary system. Unfortunately, even with our present-day instruments, we can't see any planets circling other stars. Such a planet would be 4.4 light-years away, even if it were circling the very nearest star, and it would be shining only by the reflected light of that star, so that it would not deliver enough light to be seen at that distance. There is an answer, however. Sirius B was discovered by Bessel because its gravitational pull was forcing Sirius A to move in a wavy line, not because it was seen through a telescope. Might a planet, or group of planets, do the same for the stars they circle?

但这只是大胆的推理。如果能在太阳系以外真的发现一颗有行星系统的恒星,那这一推理就有根据多了。很遗憾,即使借助于当今的先进仪器,我们还是没法看到任何行星环绕其他恒星运行。哪怕环绕着距离我们最近的恒星运行,这种行星也将会远在4.4光年以外,而且由于行星仅仅依靠恒星的反射而发光,因此它发出的光在如此之远处是不可能被看见的。不过,答案还是有的。贝塞尔发现天狼B星不是通过望远镜看见的,而是由于其引力作用使得天狼A星呈波浪形运行。会不会有一颗行星,或一组行星,对它们所环行的恒星产生同样的作用呢?

4 In theory, yes, though the effect would be extremely small. (1) The best chance for detecting a planet outside our solar system is to choose a star that is very close to us so that we can measure any deviation from its path most accurately. It should also be small, so that a planet could affect its motion sufficiently, and the planet itself would have to be very large to produce a sizable effect. 这在理论上是成立的,尽管其作用将是极其微小的。探测太阳系外行星最有可能的机会是选择一颗离我们相当近的恒星,这样我们就能非常精确地测量其运行轨道的任何偏离。这颗恒星要小,这样行星就能明显地影响其运行,而那颗行星一定要相当之大,足以对其产生相当的影响。

5 The Dutch-American astronomer Peter Van de Kamp investigated nearby small stars for just that purpose. He felt that he had detected tiny irregularities in the motion of nearby stars such as 61 Cygni, Lalande 21185, and, in particular, Barnard's Star. In addition to being very near us, Barnard's Star is quite small and Van de Kamp thought that from its motion he had detected a Jupiter-sized planet circling it. He found similar large planets in connection with the other stars he

studied. But his work was at the very edge of what his instruments could detect, and later astronomers since have decided that his results were not reliable. 荷兰裔美国天文学家彼得·范德肯普为此观测了附近的小恒星。他认为自己观测到了附近恒星运行的细微的异常之处,如天鹅座61,拉兰德21185,尤其是巴纳德恒星。巴纳德恒星不仅与地球距离相当接近,而且比较小。彼得·范德肯普认为,他在该恒星的运行过程中发现有一颗与木星一样大小的行星环绕其运行。他发现同样大小的行星与他所研究的其他恒星也有这种联系。但他的研究超出了他的器材所能观测的范围,后来的天文学家认定,他的研究结果并不可靠。

6 On the other hand, in the last couple of years some bright stars have been found to be surrounded by bands of dust. It is hard to avoid thinking these might be asteroid belts, and where asteroids exist, larger planets ought to exist, too. Nevertheless, we still have not actually observed any planets circling other stars, and must be satisfied with reasoning they are very likely to exist just the same.

在另一方面,近年来发现有一些光线强烈的恒星为尘埃团所环绕。人们不禁要猜测,这些尘埃团可能是小行星带,而小行星带存在之处,也应该有较大的行星存在。然而,我们尚未能真正观测到任何环绕其他恒星运行的行星,只能推测它们是有可能存在的。

7 If, however, there are planets circling most stars, what does that tell us about the possibility of life on those planets?

然而,即使大多数恒星都有行星环绕运行,这与行星上是否可能存在生命又有什么联系呢?

8 Life certainly can't exist on any world that is part of another planetary system, just as it cannot exist on any world in our own planetary system. The planet has to be suitable for life. 生命当然不会在别的行星系的任何一个星球上存在,正如生命并不存在于我们的行星系中的任何一颗星球上一样。有生命存在的行星必须拥有适合生命存在的条件。

9 For one thing, a planet would have to have a reasonably stable orbit. (2) If it had an erratic orbit, there might be times when its temperature would rise above the boiling point of water or, at other times, drop below Antarctic temperatures, and there would not be much chance of finding life as we know it. What's more, a planet would have to be massive enough to hold on to an atmosphere and an ocean, but not so massive that it collected hydrogen and helium.

首先,这样的行星要有相对固定的运行轨道。如果运行轨道不定,很可能行星的温度时而会高于水的沸点,时而又会低于南极气温,那样就不太有可能找到我们所熟悉的生命。还有,这样的行星必须具有相当规模,足以保持住大气层以及大片水面,但又不能过于巨大,不然会积聚氢气和氦气。

10 (3) But even assuming that a planet is the right size and has the proper chemical composition and a stable orbit neither too far from its star nor too close, so that its temperature is at all times in the range of liquid water (as is true of Earth except for the polar regions), a great deal would still depend on the kind of star it was revolving about. Stars that are much more massive than the sun, for instance, would not be very apt to have such planets; their lives on the

main sequence are too short. After all, here on Earth, organisms as advanced as primitive shellfish did not appear until life had existed on the planet for 3 billion years. If that is the normal rate of evolution, then a planet circling a star such as Sirius could never have life advanced beyond the simplest form of bacterial life, for after a mere half-billion years, Sirius would become a red giant and destroy the planet.

但是即使假定有一颗行星,它的大小正好,化学成分适宜,运行轨道稳定,与恒星的距离既不太远也不太近,气温始终保持在液态水温的范围之内(正如地球上极地以外地区的温度一样),那儿是否存在生命,在很大程度上仍得取决于它所围绕运转的是什么样的恒星。例如,远比太阳巨大的恒星不太可能拥有这类行星;在主星序中它们的生命过于短暂。在我们的地球上,即便像原始壳类动物这样的生物也直到生命在地球上出现了30 亿年后才刚刚进化而成。如果这是正常的进化速度,那么一颗环绕着像天狼星这样的恒星运行的行星顶多只能进化到像细菌这样的最简单的生命体,因为只需5亿年时间,天狼星就会成为一颗红巨星将该行星毁灭。

11 Furthermore, if a star is very small and dim, a planet must be very close to it to get enough light and heat to support life as we know it. But at that close distance, tidal effects would cause the planet to face only one side to the sun, so that half the planet would be too hot and half too cold. 再者,如果一颗恒星又小又暗,行星要获得足够的光和热以维持我们所熟悉的生命,就必须与该恒星靠得相当近。但距离过近,潮汐作用就会导致其一面朝向恒星,这样该行星的一半球体会过于炎热,另一半则太冷。

12 In other words, we need stars about the size of our sun.

换言之,我们需要大小接近于我们的太阳的恒星。

13 Then again, such stars cannot be part of close binaries or in other regions where there would be too much energetic radiation from surrounding stars. Suppose we decide that only one out of three hundred stars has a chance of possessing a planet that would be hospitable to our kind of life, and only one out of three hundred of such stars has a planet of the right size, chemical composition, and temperature to actually support life. That might still mean the existence of millions of life-bearing planets scattered among the stars.

可是,这类恒星还不能是相邻的双星中的一颗,也不能处于周围恒星能量辐射活动过于强烈的区域。我们不妨假定,300颗恒星中只有一颗有可能拥有适宜于类似地球生命的行星,300颗这类恒星中只有一颗星大小合适,有着适宜的化学构成与温度以真正维持生命。那仍可能意味着星际间散布着数百万颗蕴含生命的行星。

14 However, what are the chances that on one of these planets intelligent life has developed, capable of developing a technology like ours?

可是,在这些行星当中,出现具有智慧的生命,能够发展类似于地球的科技文明的可能性又有多大?

15 There are no optimistic answers to that question. After all, Earth had to exist for 4.6 billion

years before a life form appeared that was capable of developing technology.

对这一问题没有乐观的回答。应该记住,地球在形成了46亿年之后方出现了能发展科技的生命体。

16 Even if the chances of its happening are small, it might still be that thousands of technologies have developed among the stars, but then there's a still more difficult question: How long would such technologies endure?

即使这一情形发生的可能性很小,星际间仍可能已经出现了成千上万种科技文明,但这就引发了一个更难以回答的问题:这些科技文明会持续多久?

17 Intelligent beings, as they learn to dispose of great sources of energy, might use them for self-destructive purposes. Certainly, now that mankind has developed advanced technologies, we have begun to use them in ruinous wars and are in the process of destroying our environment with them. If this is typical, then the universe might be full of life-bearing planets that have not yet achieved a technology, and equally full of others that have already achieved an advanced technology and have destroyed themselves. There would be only a very, very few besides ourselves who had achieved the technology and had not yet had time to destroy themselves.

具有智慧的生命在学会大量运用能源之后,或许会把能源用于自毁目的。的确,人类在发展了先进的科技之后,已经开始将其用于毁灭性的战争,我们也正在运用这些技术破坏自己的生存环境。如果这一情形具有典型性,那么宇宙之中既可能充满了无数尚未发展科技文明的有生命的行星,同样也可能有着许多业已拥有先进科技、并已自我毁灭的其他行星。除了地球之外,有为数极少的行星可能也已经发展了科技,但还没来得及将自身摧毁。

18 In about 1950, the Italian-American physicist Enrico Fermi asked the question: Where are they? What he meant was, if the stars are rich in technologies, why hasn't some alien life form reached us? (4) (We can't count wild tales of flying saucers and ancient astronauts, because the evidence in their favor is extremely weak.)

大约在1950年,意大利裔美国物理学家安里克·费米问道:它们在何方?他的意思是,如果星际间充满了科技文明,何以没有外星人前来造访?(我们不能把那些有关飞碟和古代太空人的荒诞传说当真,因为能对此加以证实的证据微乎其微。)

19 Perhaps aliens have not appeared because the distances between the stars is too great to cross, or they have reached us and decided to let us develop in peace, or have failed to appear for any number of other reasons. We can't be sure that simply because no alien is here, there are no aliens somewhere out there.

也许外星人尚未现身是由于星际间距离太遥远,或是他们曾经造访并决定任由人类自行发展,或是由于种种其他原因未能前来。我们不能仅仅因为外星人没有在我们这里出现,便断言他处并无外星人。

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