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.) (1)_______________________. 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 recent book, We are not alone. This depends on the precise radio-frequency of the 21-cm wavelength, or 1420 megacycles per second. (2)_______________________. 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.
1 radio waves also travel as speed of the light and a .. such in ordianry messager take the our first broadcast of the 1920s . the message to its home planet is .. nearly heavy way there
2 it is the naturally frequency of mission of high ... space and it was discovered by us in 1951 . It must be known to any kind radio ... universe
发表于 2012-2-9 12:03
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发表于 2012-7-27 16:31
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