Paragraf Tamamlama 66. Soru

66.

For a number of years, radio telescopes have been trying to pick up signals from outer space, so far without success. There are, however, millions of possible radio frequencies, and there is no reason why a completely alien civilisation should not use a different type of communication, such as X-rays, or even a type of wave we have not yet discovered. ………… . For example, if we made contact with beings 300-light years away - relatively close as space distances go - by the time we had sent an answer and received their response, the earth would be 600 years older.