Livia said, "Conceptually, that argument is veryappealing. But there could still be deviations from the rules — far toosmall to have been detected so far — that would change the outcome ofyour experiment completely."

"So it’s a sensitive test," Cass agreed. "But that’s notwhy I’ve proposed it." They were talking in circles. "If the ruleshold, the graph I’ve designed should be stable for almostsix-trillionths of a second. That’s long enough to give us a wealth ofobservations of a space-time utterly different from our own. If itdoesn’t last that long, I’ll be disappointed. I’m not doing this in thehope of proving Sarumpaet wrong!"

Cass turned to Darsono, seeking some hint that he mightshare her exasperation, but before she could gauge his mood, Liviaspoke again.

"What if it lasts much longer?"

Finally, Cass understood. "This is about safety?I’ve addressed the potential risks, very thoroughly — "

"On the basis that the Sarumpaet rules are correct."

"Yes. What other basis should I have used?" Phoenicianastrology? Californian lithomancy? Cass resisted the urge tolapse into sarcasm; there was too much at stake. "I’ve admitted thatthere’s no certainty that the rules hold in every last untestedcircumstance. But I have nothing better to put in their place."

"Nor do I," Livia said gently. "My point is, we mustn’tover-interpret the success of the Sarumpaet rules. General relativityand quantum field theory confessed from the start that they were justapproximations: pushed to extremes, they both yielded obvious nonsense.But the fact that QGT doesn’t — the fact that there is no fundamentalreason why it can’t be universally applicable — is no guarantee that itreally does stretch that far."

Cass gritted her teeth. "I concede that. But where doesit leave us? Refusing to perform any experiment that hasn’t been triedbefore?"