And those purposes could not be found out from their creators. Like the planet, the artifact was uninhabited.

Tamara and Damon Savalle found themselves cruising in their pinnace along one of the filaments, a metal-and-polymer tube three kilometers wide and fifty thousand long. Maintenance machines crept along the inner surface, moving so slowly that their motion was hardly perceptible. The machines ignored the little pinnace completely.

Tamara was at the communications panel, in contact with the main ship. “They confirm our analyses of meteorite pitting,” she said. “At least ten million years old, uninhabited for more than three. And I don’t see anything to grin at.”

“Sorry.” Damon did not look it. “I was thinking of the old paradox from before Expansion. If there are aliens, where are they? Twenty days ago we thought we had the answer: no aliens. Now we’re asking it all over again. Where are they, Tammy? Who built all this stuff? And where are the builders?”

She shrugged. Damon’s question would remain unanswered for more than three thousand years.

But while they stared and marveled, a weak incoming signal was reaching the main ship from a small and struggling colony on Eta Cassiopeiae A. It told of an intriguing new physical theory involving Bose-Einstein statistics, along with a suggestion for a subtle and complex deep-space experiment far beyond the limited resources of the little colony.

With everyone at Lacoste focused on the Builders, the new message received no attention at all.

But the Builders were long gone; and superluminal travel was on the way.

ARTIFACT: COCOON