conveniently if not effortlessly. over millions of years such societies should have established colonies, which might themselves launch interstellar expeditions. why are they not here? the temptation is to deduce that there are at most a few advanced extraterrestrial civilizations -- either because statistically we are one of the first technical civilizations to have emerged or because it is the fate of all such civilizations to destroy themselves before they are much further along than we.

it seems to me that such despair is quite premature. all such arguments depend on our correctly surmising the intentions of beings far more advanced than ourselves, and when examined more closely i think these arguments reveal a range of interesting human conceits. why do we expect that it will be easy to recognize the manifestations of very advanced civilizations? is our situation not closer to that of members of an isolated society in the amazon basin, say, who lack the tools to detect the powerful international radio and television traffic that is all around them? also, there is a wide range of incompletely understood phenomena in astronomy. might the modulation of pulsars or the energy source of quasars, for example, have a technological origin? or perhaps there is a galactic ethic of noninterference with backward or emerging civilizations. perhaps there is a waiting time before contact is considered appropriate, so as to give us a fair opportunity to destroy ourselves first, if we are so inclined. perhaps all societies significantly more advanced than our own have achieved an effective personal immortality and lose the motivation for interstellar gallivanting, which may, for all we know, be a typical urge only of adolescent civilizations. perhaps mature civilizations do not wish to pollute the cosmos. there is a very long list of such "perhapses," few of which we are in a position to evaluate with any degree of assurance.

the question of extraterrestrial civilizations seems to me entirely open. personally, i think it far more difficult to understand a universe in which we are the only technological civilization, or one of a very few, than to conceive of a cosmos brining over with intelligent life. many aspects of the problem are, fortunately, amenable to experimental verification. we can search for planets of other stars, seek simple forms of life on such nearby planets as mars, and perform more extensive laboratory studies on the chemistry of the origin of life. we can investigate more deeply the evolution of organisms and societies. the problem cries out for a long-term, open-minded, systematic search, with nature as the only arbitor of what is or is not likely

new words

quest

n. search

extraterrestrial

a. (coming from) outside the earth

ponder

v. think about slowly and carefully

muse

v. think deeply, forgetting about the world around one

contemplate

v. look at or think about intently; have in mind as a possibility or plan

exotic

a. not native; fascinating because strange or different 外国的；异国情调的

biology

n. the scientific study of living things; animal and plant life, as of a given area 生物学；一个地区的生物

cosmic

a. of the universe, esp. the heavens as distinguished from the earth 宇宙的

exquisite

a. extremely beautiful or pleasant, esp. in a delicate or refined way

acceptable

a. good enough; satisfactory

extraordinary

a. very remarkable; exceptional

unimaginably

a. in an unimaginable manner; inconceivably

astronomy

n. the scientific study of the stars, planets, and other natural objects in space 天文学

array

n. collection; an impressive display of numerous persons or objects 列阵

detector

n. an instrument for discovering the presence of sth.

dedicated

vt. devoted

dedicate

vt. set apart for a special use or purpose

operationally

ad. in respect to operation

operational

a.

galaxy

n. any of the large groups of stars which make up the universe 星系

the milky way galaxy

银河系

assign

vt. fix; decide on

quantity

n. an amount or number

abundance

n. a great quantity; plenty

planetary

a. of a planet; having sth. to do with planets

likelihood

n. the degree to which sth. can reasonably be expected to happen; probability

probability

n. the condition of being likely to happen

characteristically

ad. in a characteristic manner

characteristic

n. a special feature or quality that makes sb. or sth. different from others

a. showing a special feature or identity

breathtakingly

ad. astonishingly

exhilarating

a. very exciting; causing happiness

diversity

n. difference; variety

diverse

a.

lifestyle

n. a way of living

commerce

n. the buying and selling of goods; trade 商业

candidate

n. a person or thing that is regarde