Deniador said, "The Skeptic's view is, of course, that Earth's radioactivity and its large satellite are both simply legends. If we look for them, we look for sparrow-milk and rabbit-feathers."
"Perhaps, but that shouldn't stop Comporellon from at least taking on the search. If they find a radioactive world of the proper size for habitability, with a large satellite, what an appearance of credibility it would lend to Comporellian legendry in general."
Deniador laughed. "It may be that Comporellon doesn't search for that very reason. If we fail, or if we find an Earth obviously different from the legends, the reverse would take place. Comporellian legendry in general would be blasted and made into a laughingstock. Comporellon wouldn't risk that."
Trevize paused, then went on, very earnestly, "Besides, even if we discount those two uniquities-if there is such a word in Galactic-of radioactivity and a large satellite, there is a third that, by definition, must exist, without any reference to legends. Earth must have upon it either a flourishing life of incredible diversity, or the remnants of one, or, at the very least, the fossil record of such a one."
Deniador said, "Councilman, while Comporellon has sent out no organized search party for Earth, we do have occasion to travel through space, and we occasionally have reports from ships that have strayed from their intended routes for one reason or another. Jumps are not always perfect, as perhaps you know. Nevertheless, there have been no reports of any planets with properties resembling those of the legendary Earth, or any planet that is bursting with life. Nor is any ship likely to land on what seems an uninhabited planet in order that the crew might go fossil-hunting. If, then, in thousands of years nothing of the sort has been reported, I am perfectly willing to believe that locating Earth is impossible, because Earth is not there to be located."
Trevize said, in frustration, "But Earth must be somewhere. Somewhere there is a planet on which humanity and all the familiar forms of life associated with humanity evolved. If Earth is not in this section of the Galaxy, it must be elsewhere."
"Perhaps," said Deniador cold-bloodedly, "but in all this time, it hasn't turned up anywhere."
"People haven't really looked for it."
"Well, apparently you are. I wish you luck, but I would never bet on your success."
Trevize said, "Have there been attempts to determine the possible position of Earth by indirect means, by some means other than a direct search?"
"Yes," said two voices at once. Deniador, who was the owner of one of the voices, said to Pelorat, "Are you thinking of Yariffs project?"
"I am," said Pelorat.
"Then would you explain it to the Councilman? I think he would more readily believe you than me."
Pelorat said, "You see, Golan, in the last days of the Empire, there was a time when the Search for Origins, as they called it, was a popular pastime, perhaps to get away from the unpleasantness of the surrounding reality. The Empire was in a process of disintegration at that time, you know.
"It occurred to a Livian historian, Humbal Yariff, that whatever the planet of origin, it would have settled worlds near itself sooner than it would settle planets farther away. In general, the farther a world from the point of origin the later it would have been settled.
"Suppose, then, one recorded the date of settlement of all habitable planets in the Galaxy, and made networks of all that were a given number of Millennia old. There could be a network drawn through all planets ten thousand years old; another through those twelve thousand years old, still another through those fifteen thousand years old. Each network would, in theory, be roughly spherical and they should be roughly concentric. The older networks would form spheres smaller in radius than the younger ones, and if one worked out all the centers they should fall within a comparatively small volume of space that would include the planet of origin-Earth."
Pelorat's face was very earnest as he kept drawing spherical surfaces with his cupped hands. "Do you see my point, Golan?"
Trevize nodded. "Yes. But I take it that it didn't work."
"Theoretically, it should have, old fellow. One trouble was that times of origin were totally inaccurate. Every world exaggerated its own age to one degree or another and there was no easy way of determining age independently of legend."
Bliss said, "Carbon-14 decay in ancient timber."
"Certainly, dear," said Pelorat, "but you would have had to get co-operation from the worlds in question, and that was never given. No world wanted its own exaggerated claim of age to be destroyed and the Empire was then in no position to override local objections in a matter so unimportant. It had other things on its mind.
"All that Yariff could do was to make use of worlds that were only two thousand years old at most, and whose founding had been meticulously recorded under reliable circumstances. There were few of those, and while they were distributed in roughly spherical symmetry, the center was relatively close to Trantor, the Imperial capital, because that was where the colonizing expeditions had originated for those relatively few worlds.
"That, of course, was another problem. Earth was not the only point of origin of settlement for other worlds. As time went on, the older worlds sent out settlement expeditions of their own, and at the time of the height of Empire, Trantor was a rather copious source of those. Yariff was, rather unfairly, laughed at and ridiculed and his professional reputation was destroyed."
Trevize said, "I get the story, Janov. Dr. Deniador, is there then nothing at all you could give me that represents the faintest possibility of hope? Is there any other world where it is conceivable there may be some information concerning Earth?"