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274 A civilization very far in our future is unlikely to be interested in us, argued Sagan; civilizations a million years in our future will be of much greater interest. Such a civilization will be engaged in a busy commu- nications traffic with its peers, but not with us, and not via technologies accessible to us. The civilizations vastly more advanced than we will be, for a long time, remote both in distance and accessibility. To us, suggested Sagan, the most advanced may be no more than insubstantial legends. Many believers assume that if the aliens are far more advanced than we are, they will adjust their communications to our level. “More advanced societies will be able to guess how backward we are and will, if they wish to communicate with us, make allowances,” claimed Sagan (emphasis added). Von Hoerner thought that if they have an interest in talking to us, they would know how to do it. However, they may have a lower limit, a standard below which they are not interested.*’ Our use of radio as our primary means of interstellar communication may place us among the Galaxy’s primitives. Even if more advanced aliens were interested, how would they know which technological means to use? Their potential recipients might range from those that have just acquired radio capabilities to those who aban- doned them long before. We may be limited to contact with civilizations that are not very far in advance of our own. James Funaro, an anthropologist who organizes con- ferences that simulate contact, speculated that the medium of communica- tion is going to select those societies that are something like us. Mind-Stretcher. Each technological civilization may have a lowest thresh- old of interest at each stage of its history. That threshold may rise with each civilization’s scientific and technological progress, excluding efforts to contact intelligences that lie below it. The factor L in the Drake equation is not the lifetime of the civilization itself but that of whatever beacon it can create. DAL. OM. .4 190769 The popular view of SETI is that the search is designed to pick up messages. In fact, Shostak clarified, the experiments are configured to find steady or slowly pulsing narrow-band signals. The earthly counterpart is the carrier wave. Carriers, with the highest signal-to-noise ratio of any part of a transmission, would be thousands or millions of times easier to detect than the modulation, or message. Before Contact There Will Be Lighthouses in the Cosmic Night —Robin Corbet, 1997”