The broadcast came in; a new transmission. The picture-pattern on Betsy's screen was obviously not the same as other broadcasts from nowhere. The chirps and peepings and the rumbling deep sounds were not repetitions of earlier noise-sequences. It should have taken many days of finicky work by technicians at the Pentagon before the originally broadcast picture could be seen and the sound interpreted. But a play-back recorder named Al, and a picture-unscrambler named Gus were in closed-circuit relationship with Betsy. She received the broadcast and they unscrambled the sound and vision parts of it immediately.
The translated broadcast, as Gus and Al presented it, was calculated to put the high brass of the defense forces into a frenzied tizzy. The anguished consternation of previous occasions would seem like very calm contemplation by comparison. The high brass of the armed forces should grow dizzy. Top-echelon civilian officials should tend to talk incoherently to themselves, and scientific consultants—biologists in particular—ought to feel their heads spinning like tops.
The point was that the broadcast had to be taken seriously because it came from nowhere. There was no faintest indication of any signal outside of Betsy's sedately gray-painted case. But Betsy was not making it up. She couldn't. There was a technology involved which required the most earnest consideration of the message carried by it.
And this broadcast explained the danger from which the alleged future wished to rescue its alleged past. A brisk, completely deracialized broadcaster appeared on Gus's screen.
In clipped, oddly stressed, but completely intelligible phrases, he explained that he recognized the paradox his communication represented. Even before 1972, he observed, there had been argument about what would happen if a man could travel in time and happened to go back to an earlier age and kill his grandfather. This communication was an inversion of that paradox. The world of 2180 wished to communicate back in time and save the lives of its great-great-great-grandparents so that it—the world of 2180—would be born.
Without this warning and the information to be given, at least half the human race of 1972 was doomed.
In late 1971 there had been a mutation of a minor strain of staphylococcus somewhere in the Andes. The new mutation thrived and flourished. With the swift transportation of the period, it had spread practically all over the world unnoticed, because it produced no symptoms of disease.
Half the members of the human race were carriers of the harmless mutated staphylococcus now, but it was about to mutate again in accordance with Gordon's Law (the reference had no meaning in 1972) and the new mutation would be lethal. In effect, one human being in two carried in his body a semi-virus organization which he continually spread, and which very shortly would become deadly. Half the human race was bound to die unless it was instructed as to how to cope with it. Unless—
Unless the world of 2180 told its ancestors what to do about it. That was the proposal. Two-way communication was necessary for the purpose, because there would be questions to be answered, obscure points to be clarified, numerical values to be checked to the highest possible degree of accuracy.