Aub’s face split into a grin. From behind the professor, Clifford and Morelli stepped forward to complete the semicircle around the display.
“Well, since you’re an astronomer, we thought we’d better lay on something that would have the right kind of appeal,” Clifford replied. “As we said earlier, Aub’s been spending quite a lot of time modifying the detector to give an improved response to cosmic hi-radiation. Okay?” Zimmermann nodded. Clifford continued, “The most intense sources of naturally occurring hi-waves are the concentrated annihilations produced in large masses. Now, what’s the biggest mass you can think of very near where we’re all standing?”
Zimmermann frowned to himself for a moment.
“Near here . . . ? I suppose it would have to be the foundation and base supporting the reactor sphere out there . . .” He caught the look on Clifford’s face. “No . . . ?”
“Much bigger ‘n that. Try again.”
“Bigger by lots of orders of magnitude,” Morelli hinted, joining in the game.
“You don’t mean . . .” Zimmermann pointed down at the floor while the others nodded encouragingly. “Not Earth?” He looked from one to another, astonished.
“That’s what you’re looking at, all right,” Clifford confirmed. “That image is produced from data processed out of hi-radiation being generated right through this whole planet.”
Zimmermann stared again at the screen while his mind raced to comprehend fully the thing he was seeing. He knew that the hi-waves received by the detector did not arrive through normal space and could not be associated with any property of direction. He also knew that the everyday notion of distance had no direct counterpart in hi-space and that the information arriving at the detector was a summation of hi-waves originating from every part of the cosmos. How, then, could a representation of Earth be extracted from all that, and just what viewpoint did the image on the screen signify?
As if he could read the questions forming in the professor’s mind, Clifford picked up his explanation. “Distance does play a part in the k-equations, but not in the sense of determining any propagation time. It comes in as an amplitude-modulating coefficient.”
“How do you mean, Dr. Clifford?” Zimmermann asked.
“The total signal that’s picked up by the detector is made up of components that originate all over the universe,” Clifford replied. “The distance of a given source from the detector does not affect the time at which the hi-waves generated by it are received. In other words, all the components that are being picked up now are being generated now; whether the source is the GRASER or a star at the other end of the galaxy makes no difference.”
“Extraordinary,” Zimmermann mused. “So if somebody made a GRASER a thousand light-years from here and switched it on, information from that event would be buried in the signal that you detect here—at the same instant.”
“Yes, indeed,” Clifford confirmed. “But you’d have to be very clever to see it. You see, although components in the signal do exist from sources all over the universe, their strength falls off rapidly with distance. It’s the nearer and larger sources—big masses—that dominate in the equations. So it’s not impossible to single out the components that originate in Earth’s mass and use them as starting data to construct an image. The strength of the signals from other places falls off rapidly as they get farther away, and you can soon ignore them for all practical purposes. In theory, in the signal that produced the image on the screen there were components that originated, say, in the Andromeda Galaxy, but in practice they existed only as mathematical terms with values approximating to zero. There’s the cosmic background that we talked about, which is the sum of all the things like that, but we get rid of it by tuning in above the background-noise threshold.”
“Fascinating,” Zimmermann said, staring at the image again. “So presumably, from the information that you select out of the composite signal, you’ve developed some method of projecting directional representations.” He pointed at the screen. “I mean, that image presumably represents some aspect or other of this planet, seen from some particular direction or other.” His brow creased into an apologetic smile. “I must confess that what it is and where I’m looking at it from are questions that I find myself still unable to answer.”