Vornan and the Danish girl took places facing one another and caught the rhythm of the dance. There was nothing difficult about it: blatant pelvic thrusts combined with a pattern of stomping and clutching, just like all the other dances of the past forty years. The girl stood with feet flat, knees flexed, legs far apart, head tipped back; the giant cones of her breasts rose toward the faceted mirrors of the ceiling. Vornan, clearly enjoying himself, adopted the knees-in, elbows-out posture of the boys about him and started to move. He picked up the knack of it easily, after only a brief preliminary moment of uncertainty, and off he went, whirled through the hall by the mechanism beneath the floor, facing now this girl, now that, and performing the explicit erotic movements expected of him.

Nearly all the girls knew who he was, it appeared. Their gasps and expressions of awe made that apparent. The fact that a global celebrity was moving in the throng created a certain amount of confusion, throwing the girls off their pace; one simply stopped moving and stared in rapture at Vornan for the whole period of ninety seconds or so that he was her partner. But there was no serious trouble for the first seven or eight turns. Then Vornan was dancing with a plumply pretty dark-haired girl of about sixteen who became totally catatonic with terror. She froze and twisted jerkily and managed to step backward beyond the electronic guard signal at the rear of her moving strip. A buzzer sounded to warn her, but she was beyond any such guidance, and a moment later she had one foot on each of two strips heading in opposite directions. She went down, her short skirt flipping upward to reveal pudgy pink thighs, and in her fright she grabbed at the legs of the boy nearest her.

He toppled too, and in another moment I had a graphic demonstration of the domino effect, because dancers were losing their balance all over the room. Nearly everyone was on more than one strip at once and was clutching at someone else for support. A wave of collapse rippled across the great hall. And there was Vornan-19, still upright, watching the catastrophe in high good humor. His Junoesque paramour was also on her feet, 180 degrees away from him; but then a groping hand caught her ankle, and she went down like a felled oak, careening into two or three other dancers as she dropped. The scene was straight from the pit: writhing figures everywhere, arms and legs in the air, no one able to rise. The machinery of the dance pavilion finally crunched to a halt. The untangling took long minutes. Many girls were crying. Some had skinned knees or abraded rumps; one had somehow contrived to lose her skirt in the melee and was crouched in a fetal huddle. Where was Vornan? Vornan was already at the rim of the hall, safely extricating himself the instant the floor stopped moving. The blonde goddess was beside him.

“He’s got an immense talent for disruption,” said Kettridge.

Kralick, laughing, said, “This isn’t as bad as the business yesterday at the smorgasbord place in Stockholm, when he punched the wrong button and got the whole table revolving.”

The screen darkened. An unsmiling Kettridge turned to me. “This man will be the guest of the United States three days from now, Dr. Garfield. We don’t know how long he’s staying. We intend to monitor his movements closely and try to head off some of the confusion that he’s been known to cause. What we have in mind. Professor, is appointing a committee of five or six leading scholars as — well, guides for the visitor. Actually they’ll also be overseers, watchdogs, and… spies.”

“Does the United States officially believe that he’s a visitor from 2999?”

“Officially, yes,” said Kettridge. “That is, we’re going to treat him as if he’s kosher,”

“But—” I spluttered.

Kralick put in, “Privately, Dr. Garfield, we think he’s a hoaxer. At least I do, and I believe Mr. Kettridge does. He’s an extremely sharp-witted and enterprising phony. However, for purposes of public opinion, we choose to accept Vornan-19 at face value until there’s some reason to think otherwise.”

“For God’s sake, why?”

“You know of the Apocalyptist movement, Dr. Garfield?” asked Kralick.

“Well, yes. I can’t say I’m an expert, but—”

“So far, Vornan-19 hasn’t done anything much more harmful than mesmerizing a roomful of Danish schoolgirls into falling on their butts. The Apocalyptists do real damage. They riot, they loot, they destroy. They’re the force of chaos in our society. We’re attempting to contain them before they rip everything apart.”

“And by embracing this self-appointed ambassador from the future,” I said, “you explode the chief selling point of the Apocalyptists, which is that the world is supposed to come to an end next January 1.”

“Exactly.”

“Very good,” I said. “I had already suspected it. Now you confirm it as official policy. But is it proper to meet mass insanity with deliberate dishonesty?”

Kettridge said ponderously, “Dr. Garfield, the job of government is to maintain the stability of the governed society. When possible, we like to adhere to the Ten Commandments in so doing. But we reserve the right to meet a threat to the social structure in any feasible way, up to and including the mass annihilation of hostile forces, which I think you will regard as a more serious action than a little fibbing, and which this government has resorted to on more than one occasion. In short, if we can ward off the Apocalyptist lunacy by giving Vornan-19 a seal of approval, it’s worth a bit of moral compromise.

“Besides,” said Kralick, “we don’t actually know he’s a fraud. If he isn’t, we’re not committing any act of bad faith.”

“The possibility must be very soothing to your souls.” I said.

I regretted my flippancy at once. Kralick looked hurt, and I didn’t blame him. He hadn’t set this policy. One by one, the frightened governments of the world had decided to short-circuit the Apocalyptists by proclaiming Vornan to be a real thing, and the United States was merely falling in line. The decision had been taken on high; Kralick and Kettridge were merely implementing it, and I had no call to impugn their morality. As Kralick had said, it might just turn out that hailing Vornan this way would be not only useful but even correct.

Kettridge fussed with the spines of his ornate costume and did not look at me as he said, “We can understand, Dr. Garfield, that in the academic world people tend to view moral issues in the abstract, but nevertheless—”

“All right,” I said wearily, “I suppose I was wrong. I had to put myself on record, that’s all. Let’s go past that point. Vornan-19 is coming to the United States, and we’re going to roll out the red carpet for him. Fine. Now what do you want from me?”

“Two things,” said Kralick. “First: you’re widely regarded, sir, as the world’s ranking authority on time-reversal physics. We’d like you to provide us with your opinion as to whether it’s theoretically possible for a man to travel backward in time as Vornan-19 claims to have done, and how, in your appraisal, it might have been accomplished.”

“Well,” I said, “I have to be skeptical, because so far we’ve succeeded only in sending individual electrons backward in time. This converts them into positrons — the antiparticle of the electron, identical in mass but opposite in charge — and the effect is one of virtually instant annihilation. I see no practical way to sidestep the conversion of matter into antimatter during time-reversal, which means that to account for the purported time trip of Vornan-19, we must first explain how so much mass can be converted, and then why it is that although presumably composed of antimatter he does not touch off the annihilation effect when—”

Kralick politely cleared his throat. I stopped talking. Kralick said, “I’m sorry that I didn’t make myself quite clear. We don’t want an immediate reply from you. We’d like a position paper, Dr. Garfield, which you can file in the next forty-eight hours or thereabouts. We’ll provide any necessary secretarial assistance. The President is quite anxious to read what you have to say.”