Contact - Carl Sagan [18]
Ellie had to take care that the tedium did not engulf her. Her co-workers were pleasant enough, but-even apart from the impropriety of a close personal relationship with a nominal subordinate-she did not find herself tempted into any real intimacies. There had been a few brief, torrid but fundamentally casual relationships with local men unconnected with the Argus project. In this area of her life, too, a kind of ennui, a lassitude, had settled over her.
She sat down before one of the consoles and plugged in the earphones. It was futile, she knew, a conceit, to think that she, listening on one or two channels, would detect a pattern when the vast computer system monitoring a billion channels had not. But it gave her a modest illusion of utility. She leaned back, eyes half closed, an almost dreamy expression enveloping the contours of her face. She's really quite lovely, the technician permitted himself to think.
She heard, as always, a kind of static, a continuous echoing random noise. Once, when listening to a part of the sky that included the star AC + 79 3888 in Cassiopeia, she felt she heard a kind of singing, fading tantalizingly in and out, lying just beyond her ability to convince herself that there was something really there. This was the star toward which the Voyager 1 spacecraft, now in the vicinity of the obit of Neptune, would ultimately travel. The spacecraft carried a golden phonograph record on which were impressed greetings, pictures, and songs from Earth. Could they be sending us their music at the speed of light, while we are sending ours to them only one ten-thousandth as fast? At other times, like now, when the static was clearly patternless, she would remind herself of Shannon's famous dictum in information theory, that the most efficiently coded message was indistinguishable from noise, unless you had the key to the encoding beforehand. Rapidly she pressed a few keys on the console before her and played two of the narrow-band frequencies against each other, on in each earphone. Nothing. She listened to the two planes of polarization of the radio waves, and then to the contrast between linear and circular polarization. There were a billion channels to choose from. You could spend your life trying to outguess the computer, listening with pathetically limited human ears and brains, seeking a pattern.
Humans are good, she knew, at discerning subtle patterns that are really there, but equally so at imagining them when they are altogether absent. There would be some sequence of pulses, some configuration of the static, that would for an instant give a syncopated beat or a brief melody. She switched to a pair of radio telescopes that were listening to a known galactic radio source. She heard a glissando down the radio frequencies, a "whistler" due to the scattering of radio waves by electrons in the tenuous interstellar gas between the radio source and the Earth. The more pronounced the glissando, the more electrons were in the way, and the further the source was from the Earth. She had done this so often that she was able, just from hearing a radio whistler for the first time, to make an accurate judgment of its distance. This one, she estimated, was about a thousand light-years away-far beyond the local neighborhood of stars, but still well within the great Milky Way Galaxy.
Ellie returned to the sky-survey mode of Project Argus.