Convergent Series by Charles Sheffield

got near thecomet shower. He'd seen fossil evidence for changes, right? It's a classic case—the man on the spot knew more than anyone light-years away could know. He overrode instructionsfrom his own headquarters, and he was a hero for doing it."
    "Not quite. He got chewed out for doing it." The car had touched down and was taxiing toward the edge of the port, and Rebka was ready to let the subject drop. It was not the right time to tell Max Perry the identity of the man involved. And although he had been reprimanded in public, he had been congratulated in private for his presumption in countermanding a Sector Coordinator's written instructions. The fact that his immediate supervisors had deliberately left him ignorant of those written instructions was never mentioned. It seemed to be part of the Phemus Circle's government philosophy: Troubleshooters work better when they do not know too much. More and more, he was convinced that he had not been given all the facts before he was sent to Dobelle.
    "All I'm saying is that you could face a similar situation on Opal," he went on. "When a system is disturbed by a periodic force, increasing the force may not simply lead to a bigger disturbance of the same kind. You may hit a bifurcation and change to a totally different final state. Suppose the tides on Opal become big enough to interact chaotically? You'll have turbulence everywhere—whirlpools and waterspouts. Monstrous solitons, maybe, isolated waves a mileor two high.
    "Boats wouldn't live through that, nor would the Slings.Could you evacuate everyone if you had to, during Summertide? I don't mean to sea—I mean right off-planet?"
    "I doubt it." Perry was switching off the engine and shaking his head. "I can be more definite than that. No, we couldn't. Anyway, where would we take them to ? Gargantua has four satellites nearly as big as Opal, and a couple of them have their ownatmospheres. But they're methane and nitrogen, not oxygen—and they're far too cold. The only other place is Quake." He stared at Rebka. "I assume we've given up on the idea that anyone should go there ? "  
    The torrential rain that had plagued their approach to Starside had eased, and the car had come to a halt close to the building that Perry had assigned to Darya Lang as living quarters.
    Hans Rebka stood up stiffly from his seat and rubbed at his knees. Darya Lang was supposed to be waiting to meet them, and she must surely have heard the aircar's approach. But there was no sign of her at the building. Instead, a tall skeletal man with a bald and bulging head was standing half-clear of the overhanging eaves, staring at the arriving car. He was holding a garish umbrella above his head. The shimmering white of his suit, with its gold epaulets and light-blue trim, could have come only from the spun fiber cocoon of a Ditron.
    From a distance he appeared elegant and commanding, even though his face and scalp had been burned purple-red by hard radiation. Close up, Rebka could see that his lips and eyebrows jerked and twitched uncontrollably.
    "Did you know he'd be here?" Rebka jerked a thumb below the window level of the car, so that the newcomer could not see it.
    He did not need to mention the stranger's identity. Members of the Alliance councils were seldom seen, but the uniform was familiar to every clade on every world in the spiral arm.
    "No. But I'm not surprised." Max Perry held the car door so that Rebka could step down. "We've been gone for six days, and his schedule fitted that time slot."
    The man did not move as Perry and Rebka stepped out of the car and hurried to shelter under the broad eaves. He folded his umbrella and stood for half a minute, ignoring the raindrops that spattered his bald head. Finally he turned to meet them.
    "Good day. But not good weather. And I gather that it is getting worse." The voice matched the man, big and hollow, with an edge of roughness overlaid on the sophisticated accent of a native of Miranda. He held