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Lesson 43
Are there strangers in space?
宇宙中有外星人吗?
What does the 'uniquely rational way' for us to communicate with other
intelligent beings in space depend on?
We must conclude from the work of those who have studied the origin of
life, that given a planet only approximately like our own, life is almost
certain to start. Of all the planets in our own solar system, we ware now pretty
certain the Earth is the only one on which life can survive. Mars is too dry and
poor in oxygen, Venus far too hot, and so is Mercury, and the outer planets have
temperatures near absolute zero and hydrogen-dominated atmospheres. But other
suns, stars as the astronomers call them, are bound to have planets like our
own, and as is the number of stars in the universe is so vast, this possibility
becomes virtual certainty. There are 100,000 million stars in our own Milky Way
alone, and then there are 3,000 million other Milky Ways, or galaxies, in the
universe. So the number of stars that we know exist is now estimated at about
300 million million million.
Although perhaps only 1% of the life that has started somewhere will
develop into highly complex and intelligent patterns, so vast is the number of
planets, that intelligent life is bound to be a natural part of the
universe.
If then we are so certain that other intelligent life exists in the
universe, why have we had no visitors from outer space yet? First of all, they
may have come to this planet of ours thousands or millions of years ago, and
found our then prevailing primitive state completely uninteresting to their own
advanced knowledge. Professor Ronald Bracewell, a leading American radio
astronomer, argued in Nature that such a superior civilization, on a visit to
our own solar system, may have left an automatic messenger behind to await the
possible awakening of an advanced civilization. Such a messenger, receiving our
radio and television signals, might well re-transmit them back to its
home-planet, although what impression any other civilization would thus get from
us is best left unsaid.
But here we come up against the most difficult of all obstacles to contact
with people on other planets -- the astronomical distances which separate us. As
a reasonable guess, they might, on an average, be 100 light years away. (A light
year is the distance which light travels at 186,000 miles per second in one
year, namely 6 million million miles.) Radio waves also travel at the speed of
light, and assuming such an automatic messenger picked up our first broadcasts
of the 1920's, the message to its home planet is barely halfway there.
Similarly, our own present primitive chemical rockets, though good enough to
orbit men, have no chance of transporting us to the nearest other star, four
light years away, let alone distances of tens or hundreds of light years.
Fortunately, there is a 'uniquely rational way' for us to communicate with
other intelligent beings, as Walter Sullivan has put it in his excellent book,
We Are not Alone. This depends on the precise radio frequency of the 21-cm
wavelength, or 1420 megacycles per second. It is the natural frequency of
emission of the hydrogen atoms in space and was discovered by us in 1951; it
must be known to any kind of radio astronomer in the universe.
Once the existence of this wave-length had been discovered, it was not long
before its use as the uniquely recognizable broadcasting frequency for
interstellar communication was suggested. Without something of this kind,
searching for intelligences on other planets would be like trying to meet a
friend in London without a pre-arranged rendezvous and absurdly wandering the
streets in the hope of a chance encounter.
ANTHONY MICHAELIS Are There Strangers in Space? from The Weekend
Telegraph
New words and expressions 生词与短语
Mercury
n. 水星
hydrogen
n. 氢气
prevailing
adj. 普遍的
radio astronomer
射电天方学家
uniquely
adv. 唯一地
rational
adj. 合理的
radio frequency
无线电频率
cm
n. 厘米
megacycle
n. 兆周
emission
n. 散发
intersteller
adj.星际的
rendezvous
n. 约会地点
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发表于 2016-7-11 22:47:59