In 1961, scientists set up gigantic, sensitive apparatus to collect radio waves from the f
What reason is there to think that we may actually detect intelligent life in outer space? To begin with, modern theories of the development of stars suggest that almost every star has some sort of family of planets. So any star like our own sun (and there are billions of such stars in the universe) is likely to have a planet situated at such a distance that it would receive about the same amount of radiation as the earth.
Furthermore, such a planet would probably have the same general composition as our own; so, allowing a billion years or two--or three--there would be a very good chances for life to develop, if current theories of the origin of life are correct.
But intelligent life7 Life that has reached the stage of being able to send radio waves out into space in a conscious pattern7 Our own planet may have been in existence for five billion years and may have had life on it for two billion, but it is only in the last fifty years that we are capable of sending radio waves into space. From this it might seem that even if there were no technical problems involved, the chance of receiving signals from another planet would be extremely small.
This does not mean that intelligent life at our level does not exist somewhere. There are such an unimaginable number of stars that, even at such miserable odds, it seems certain that there are millions of intelligent life forms scattered through space. The only trouble is, none may be within our reach. Perhaps none never will be; perhaps the distances that separate us from our fellow inhabitants of this universe will forever remain too great to be conquered. And yet it is conceivable that someday we may come across one of them or one of them may come across us. What would they be like, these extraterrestrial(地球以外的) creatures?
If the radio waves had reached our planet one hundred years before, we would have______.
A.sent an immediate answer
B.sent an alarm against extraterrestrial attack
C.sent a short reply
D.sent no answer