Free Nightfall by Isaac Asimov, Robert Silverberg

certainly tell you what it
is
—more or less.”
    “So you believe that garbage too,” Beenay said, with a harshlaugh. “About the Theory of Gravitation being so complicated that only twelve people can understand its math.”
    “That’s what I’ve always heard.”
    “What you’ve always heard is ignorant folk wisdom,” said Beenay. “I could give you all the essential math in a sentence, and you’d probably understand what I was saying, too.”
    “You could? I would?”
    “No question of it. Look, Theremon: the Law of Universal Gravitation—the Theory of Universal Gravitation, I mean—states that there exists a cohesive force among all bodies of the universe, such that the amount of this force between any two given bodies is proportional to the product of their masses divided by the square of the distance between them. It’s that simple.”
    “That’s all there is to it?”
    “That’s enough! It took four hundred years to develop it.”
    “Why that long? It seems simple enough, the way you put it.”
    “Because great laws aren’t divined by flashes of inspiration, no matter what you newspaper people like to believe. It usually takes the combined work of a worldful of scientists over a period of centuries. Ever since Genovi 41 discovered that Kalgash rotates around Onos, rather than vice versa—and that was about four centuries ago—astronomers have been working on the problem of why all six of the suns appear and disappear in the sky as they do. The complex motions of the six were recorded and analyzed and unwoven. Theory after theory was advanced and checked and counterchecked and modified and abandoned and revived and converted to something else. It was a deuce of a job.”
    Theremon nodded thoughtfully and finished off his drink. He signaled the waiter for two more. Beenay seemed calm enough so long as he was talking about science, he thought.
    “It was some thirty years ago,” the astronomer continued, “that Athor 77 put the touch of perfection on the whole thing by demonstrating that the Theory of Universal Gravitation accounts exactly for the orbital motions of the six suns. It was an amazing achievement. It was one of the greatest feats of sheer logic anyone has ever accomplished.”
    “I know how you revere that man,” Theremon said. “But what does all this have to do with—”
    “I’m getting to the point.” Beenay rose and walked to the edge of the terrace, carrying his second drink with him. He stood there in silence for a time, looking out at distant Trey and Patru. It seemed to Theremon that Beenay was growing agitated again. But the newspaperman said nothing. After a time Beenay took a long gulp of his drink. Standing with his back still turned, he said finally, “The problem is this. A few months ago I began working on a recalculation of the motions of Kalgash around Onos, using the big new university computer. I provided the computer with the last six weeks’ actual observations of Kalgash’s orbit and told it to predict the orbital movements for the rest of the year. I didn’t expect any surprises. Mainly I just wanted an excuse to fool around with the computer, I guess. Naturally, I used the gravitational laws in setting up my calculations.” He swung around suddenly. His face had a bleak, haunted look. “Theremon,
it didn’t come out right.
”
    “I don’t understand.”
    “The orbit the computer produced didn’t match up with the hypothetical orbit I was expecting to get. I don’t mean that I was simply working on the basis of a pure Kalgash-Onos system, you realize. I took into account all perturbations that the other suns would cause. And what I got—what the computer was claiming to be the true orbit of Kalgash—was something very different from the orbit that is indicated by Athor’s Theory of Gravitation.”
    “But you said you used Athor’s gravitational laws in setting things up,” said Theremon, puzzled.
    “I did.”
    “Then how—”