Mammoth

"Since coming to work for you," said Jim, the metallurgist, "I've run into stuff that sent me ru

That's exactly what Matt was coming to feel, too, that the device was not so much a practical, working thing as a one-time assemblage put together just to frustrate him. Something for him to look at, three paper cups for him to study while the real action with the hidden pea was happening somewhere just out of his sight.

Prestidigitation. Misdirection.

Nevertheless, he couldn't proceed on that assumption until he'd ruled out as many other possibilities as possible. What was important here?

"IN a problem like this," he told Susan, "the first thing you do is try to limit the variables. Too many variables, you never get anywhere."

"Like your twenty-four hundred marbles."

"Twenty-four-oh-one."

"Who's counting?"

"Two thousand, four hundred and one is seven to the fourth power."

"Really? Is that important?" "I wish to hell I knew."

About once a minute the baby mammoth squealed what Matt supposed was the mammoth word for "Mommy!" All three pachyderms waved their trunks helplessly.

They were on the grounds of the La Brea Tar Pits, and the mammoths were robots. Within walking distance was a working excavation. A stone's throw in the other direction, six lanes of traffic whizzed by on Wilshire Boulevard.

There were a thousand very good restaurants within an easy drive of the mammoth warehouse, and he took her to two before she admitted she didn't really enjoy eating in restaurants that much. It turned out that what she liked was picnics.

"I can do picnics," Matt had said, and headed for the mall. He'd been intending to buy something from Sears, but halfway there he remembered he was rich, turned around, and found a shop in Beverly Hills that sold him a beautiful basket complete with Waterford glasses and fine china and linen napery and a chill compartment for white wine for a price that only made him a little light-headed.

Any of the fine restaurants in Santa Monica or Westwood were happy to oblige when Matt dropped the basket off in the evening and told them, "We will be two for lunch. Surprise us."

They ate together two or three times a week while Matt gathered the courage to ask her out on a real date. They tried to visit a different park each time. Today they were on the grounds of the George C. Page Museum, overlooking the tar pit, and Matt was trying to explain the dimensions of his problem.

"Allotropes are different ways the same element can arrange itself, different crystal structures," he said.

"Right, graphite and coal and diamond. All pure carbon, different arrangements."

"Yes. Some of the metals have several allotropes. In the marbles, the zirconium and... sorry, Howard wants me to call them temporal spheres."

"Sounds like Howard," Susan laughed.

"Okay, call 'em marbles. Listen, I could explain this easier if I showed you, back at the lab."

"Suits me. I have to get back anyway." A big table had been set up in one part of the warehouse away from the glove box containing the actual gadget. On it was a very long rack of wooden cubbyholes, set at a forty-five-degree angle for easy access. They had bought the box from a Chinese language typesetter, who often had over five thousand characters to keep sorted. This one was thirty cubbies deep and one hundred wide, and all but the top few rows were full of the marbles they had assembled, marked 0001 to 2401. Each cubby held twenty identical marbles. Matt was going to make ten identical time machines and hope that one of them worked. If not, he'd try a few more things and use the ten spares of each type.

It was a problem with no easy solution. Say you have a sphere of zirconium, one-half inch in diameter. How can you be sure it's zirconium clear through? You know the surface is pure zirconium, but that might be a shell covering a layer of iron or copper.

They had probed each marble with X rays, sonic imaging equipment, and magnetic resonance and had found no obvious anomalies. The pure zirconium sphere seemed to be pure right to the center.

"There's no way we could exactly duplicate some of them," he said. "You ever look through a bag of marbles?"

"Sure. Girls can play marbles, too."

"Then you know there are no two cat's-eyes perfectly alike. We've sorted through thousands and found some that are amazingly close... but who knows? And the glass of most of them is marked up, scratched, tiny little chips. One of them, number 451, has a fairly large chunk out of it."

"You know them all by number?"

"No, but it feels like I do. And if I never saw another marble in my life I would be a happy man."

THE next evening Matt completed the first assembly and called Howard's office to see if he wanted to take a look at it. Howard did, and showed up that night in another of his vintage automobiles, an olive-green 1939 Talbot-Lago hardtop racer that had barely room for one person in its streamlined cockpit.

Matt led him inside and showed him the opened assembly. Beside it were a few numbered glass dishes containing metal marbles, or temporal spheres, of varying hues. "We wanted to reproduce the gadget exactly," Matt said. "Because we don't know just what it does, much less how it does it, assuming it does anything at all... we don't know what's important. But if we have to duplicate it at the subsubatomic level, we're screwed. No way we can analyze the neutrons and protons within the spheres for up-quarks and down-quarks, spin, strangeness, charm, all those too-cute words they use to describe properties nobody can really visualize.

"So then there's the nuclear level. Some of the spheres are ninety-nine point nine nine percent pure. But each element has isotopes—you know, different numbers of neutrons with the same number of protons—"

"Sorry, Howard, I keep forgetting..."

That I'm smarter than you are, except in the really rarefied realms of math, Howard thought. It grated on him, but he kept quiet about it because he needed Matt. Matt was a professor, after all, used to lecturing. And he'd probably been doing a lot of it lately, on his daily dates with Susan Morgan. Was there love in the air?

"Okay. Different isotopes have different weights, per atom. The ratio of isotopes found naturally is fairly standard; a lot of them decay into something else. Almost all the single-element spheres are what you'd expect, not some exotic variation. You follow?"

Howard nodded.

"But a few were a little odd. Take osmium. Atomic number, 76. Atomic weight, 190 and change. Seven stable isotopes, six radioactive ones, but with half-lives so short there'd be almost none in a normal sample. Commonest isotope, Os-192. Seventy-six protons and one hundred sixteen neutrons. A bit over forty percent of osmium ought to be Os-192. But our little ball only has thirty-five percent. To compensate, there's more Os-188 than there should be."

"Is it a radioactive decay thing?" Howard asked. "One form of osmium emits an alpha particle—"

"No, no. Osmium decays into rhenium and iridium, a little tungsten later on. Those are all there, in trace amounts, what we'd expect. No, somebody, the builder, made sure the osmium ball had a different isotopic ratio from normal. So we have to duplicate that ratio, because it's so weird it just has to be something important." He stopped, and looked at Howard for a moment. "Don't you think?"

Howard laughed. "That's what I'm paying you the big bucks for. If you think it's important, I will, too."