“I am not interested in interstellar travel,” he said quietly, “if that’s what you meant to ask me. The idea is absurd and my opinion is based on fundamental properties such as time, acceleration, power, mass and energy. However, I would like to make it clear that I do not assume our civilization to be the one intelligent civilization in the universe.” That fleeting smile passed over his face, a jewel of forced and insincere patience, and he leaned forward a little in his chair. “I feel that life and intelligence will have developed at about the same speed as on earth wherever the proper surroundings and the needed time have been provided. Present data—and these are extremely limited—suggest that life may have developed on the planets of about six percent of all stars. I feel myself that the spectrum of light reflected from the dark areas of Mars shows characteristics that prove the presence of plant life. As I’ve said, I think the possibilities of interstellar travel absurd; but interstellar communication is something else again.
“The number of civilizations with whom we might possibly communicate depends upon six factors. One: The rate at which stars like our sun are being formed. Two: The fraction of such stars that have planets. Three: The fraction of such planets that can sustain life. Four: The fraction of livable planets upon which life has arisen. Five: The fraction of the latter that have produced beings with a technology adequate for interstellar communication. Six: The longevity of this high technology. About one in three million stars has the probability of a civilization in orbit. However, this could still mean millions of such civilizations within our galaxy alone and, as you gentlemen all know, there are billions of galaxies.” The hypocritical smile again passed over his face. Gas? Coverly wondered. “It seems unlikely to me,” he went on, “that technologies would develop on a planet covered with water. Some of my colleagues are enthusiastic about the intelligence of the dolphin but it seems to me that the dolphin is not likely to develop an interest in interstellar space.” He waited for the hesitant and scattered laughter to abate. “The twenty-one-centimeter band—that is, one thousand four hundred and twenty megacycles—emitted by the colliding atoms of hydrogen throughout space has produced some interesting signals, especially from Tau Ceti, but I am very skeptical about their coherence. I do believe that scientists in every advanced civilization will have discovered that the energy value of each unit or quantum of radiation, whether in the form of light or radio waves, equals its frequency times a value known to us, and perhaps to some of you, as Planck’s Constant.
“Optical masers appear to be our most promising means of interstellar communication.” Now he was deep in his classroom manner and nothing would stop him until he had inflicted on them all the tedium, excitement and pain of a lecture period. “The optical version of these masers can produce a beam of light so intense and narrow that, if transmitted from the earth, it would illuminate a small portion of the moon.” Again there was the fleeting, the sugary smile. “Extraneous wavelengths are eliminated so that unlike most light beams this one is pure enough to be modulated for voice transmission. A maser system could be detected with our present technology if it were transmitting from a solar system ten light years away. We must study the spectra of light from nearby stars for emission lines of peculiar sharpness and strength. This would be unmistakable evidence of maser transmissions from a planet orbiting that star. The light signals would be elaborately coded. In the case of a system one thousand light years away it would take two thousand years to ask a question and receive an answer. A superior civilization would load its signal beam with vast amounts of information. A highly advanced civilization, having triumphed over hunger, disease and war, would naturally turn its energies into the search for other worlds. However, a highly advanced civilization might take another direction.” Here his voice so grated with censoriousness and reproach that it woke two senators who were dozing. “A highly advanced civilization might well destroy itself with luxury, alcoholism, sexual license, sloth, greed and corruption. I feel that our own civilization is seriously threatened by biological and mental degeneration.
