S. S. Krupp observed that card catalogs, a recent invention, had not existed at the Library of Alexandria, and though he would have preferred, ceteris paribus, to have the catalog, we didn't have one now, that was too bad, and we were going to have to make do. There was dissent and profound shock over his position, and righteous editorials in the Monitor, but after a week or two most people decided that, though Krupp was an asshole, there wasn't any point in arguing.

"Welcome and thanks for coming to the mass driver demonstration." Casimir Radon swallowed some water and straightened his glacier glasses. "The physics majors' organization Neutrino has put a lot of time and work into this device, much of it over the Christmas holiday, and we think it is a good example of what can be done with activities money used constructively. God damn it!"

He was cursing at the loudness of his Plex neighbor, Dex Fresser, whose stereo was an electronic signal processor of industrial power. For once Casimir did not restrain himself; he was so nervous over the upcoming demonstration that he failed to consider the dire embarrassment, social rejection and personal danger involved in going next door to ask this jerk-off to turn down his music. He was pounding on Dex Fresser's door before his mind knew what his body was doing, and for a moment he hoped his knocks had been drowned out by the bass beats exploding from Fresser's eighteen-inch woofers. But the door opened, and there was Dex Fresser, looking completely disoriented, "Could you turn that down?" asked Casimir. Fresser, becoming aware of his presence, looked Casimir over from head to foot. "It kind of disturbs me," Casimir added apologetically.

Fresser thought it over. "But you're not even there that much, so how can it disturb you?" He then peered oddly into Casimir's face, as though the goggle-eyed Radon were the captain of a ship from a mirror Earth on the other side of the sun, which was pretty much what he was thinking. Chagrined, Casimir ground his teeth very loudly, generating so much heat that they became white hot and glowed pinkly through his cheeks. He then receded off into infinity like a starship making the jump into hyperspace, then came around behind Fresser again in such a way as to make it appear (due to the mirror effect) that he was actually coming from the same direction in which he'd gone. Just as he arrived back in the doorway two years later, the space warp snapped shut behind him; but at the last moment Dex Fresser glanced through it, and saw lovely purple fields filled with flowers, chanting Brazilians, leaky green ballpoint pens and thousands of empty tea boxes. He wanted very much to visit that place.

"Well, it does disturb me when I do happen to be in my room. See how that works?" The man who was running this tape, a lanky green tennis shoe with bad acne and an elephant's trunk tied in a double Windsor knot around his waist, stopped the tape and ran it back to Fresser's previous reply.

"But you're not even there that much, so how can it disturb you?" As Fresser finished this, Casimir did exactly what he had done last time, except this time the purple fields were being clusterbombed by flying garages. The space warp closed off just in time to let a piece of shrapnel through. It zoomed over Casimir's shoulder and embedded itself in the wall, and Fresser recognized it as a Pershing 2 missile.

"Right," said Casimir, now. speaking through a sousaphone around his shoulder, which bombarded Dex Fresser with white laser rays. "I know. But you see when I am in my room I prefer not to be disturbed. That's the whole point."

Fresser suddenly realized that the Pershing 2 was actually the left front quarter-panel of a '57 Buick that he had seen abandoned on a street in Evanston on July 28, 1984, and that Casimir was actually John D. Rockefeller. "How can you be so goddamn selfish, man? Don't you know how many people you've killed?" And he slammed the door shut, knowing that the shock would cause the piece of the Buick to fall on Rockefeller's head; since it was antimatter, nothing would be left afterward.

The confrontation had worked out as badly as Casimir had feared. He went back to his room, heart pounding irrationally, so upset that he did not practice his speech at all.

The lack of rehearsal did not matter, as the only audience in Sharon's lab was the Neutrino membership, Virgil, Sarah, a photographer from the Mortoplex Monitor and I. Toward the end of the speech, though, S. S. Krupp walked in with an official photographer and a small, meek-looking older man, causing Casimir to whip off his glasses in agitation and destroying any trace of calmness in his manner. Finally he mumbled something to the effect that it was too bad Krupp had come in so late, seeing as how the best part of this introduction was over, and concluded that we should stop jabbering and have a look at this thing.

The mass driver was four meters long, built atop a pair of sturdy tables bolted together. It was nothing more than a pair of long straight parallel guides, each horseshoe-shaped in cross-section, the prongs of the horseshoes pointed toward each other with a narrow gap in between. The bucket, which would carry the payload, was lozenge-shaped in cross-section and almost filled the oval tunnel created by the two guides. Most of the bucket was empty payload space, but its outer jacket was of a special alloy supercooled by liquid helium so that it became a perfect superconducting electromagnet. This feature, combined with a force field generated in the two rails, suspended the bucket on a frictionless magnetic cushion. Electromagnets in the rails, artfully wound by Virgil, provided the acceleration, "kicking" the bucket and its contents from one end of the mass driver to the other.

Casimir relaxed visibly as he began pointing out the technical details. With long metal tongs he reached into a giant thermos flask and pulled out the supercold bucket, which was about the size of two beer cans side by side. He slid it into the breech of the mass driver. As it began to soak up warmth from the room, a cascade of frigid white helium poured from a vent on its back and spilled to the floor.

Krupp stood close by and asked questions. "What's the weight of the slug?"

"This," said Casimir, picking up a solid brass cylinder from the table, "is a one-kilogram mass. That's pretty small, but– " "No, it isn't." Krupp looked over at his friend, who raised his eyebrows and nodded. "Nothing small about it."

Casimir smiled weakly and nodded in thanks. Krupp continued, "What's the muzzle velocity?"

Here Casimir looked sheepish and shifted nervously, looking at his Neutrino friends.

"Oh," said Krupp, sounding let down, "not so fast, eh?"

"Oh, no no no. Don't get me wrong. The final velocity isn't bad." At this the Neutrino members clapped their hands over their mouths and stifled shrieks and laughs. "I was just going to let you see that for yourselves instead of throwing a lot of numbers at you."

"Well, that's fine!" said Krupp, sounding more sanguine. "Don't let us laymen interfere with your schedule. I'm sorry. Just go right ahead." He stepped back and crossed his arms as though planning to shut up for hours.

Casimir gave the empty bucket a tap and there were oohs and aahs as it floated smoothly and quietly down the rails, bounced off a stop at the end and floated back with no change in speed. He reinserted the one-kilogram brass cylinder. "Now let's try it. As you can see we have a momentum absorber set up at the other end of the lab."

The "momentum absorber" was ten squares of 3/8-inch plywood held parallel in a frame, spaced two inches apart to form a sandwich a couple of feet long. This was securely braced against the wall of the lab at the same level as the mass driver. had assumed that the intended target was a wastebasket floor beneath the "muzzle" of the machine, but now realized that Casimir was expecting the weight to fly about twenty feet without losing any altitude. "I suggest you all stand back in case something goes wrong," said Casimir, and feeling somewhat alarmed I stood way back and suggested that Sarah do likewise. Casimir made a last check of the circuitry, then hit a big red button.