When she sniffed with disdain, Max said quickly, “But negative energy density exists. You know the Casimir effect?”
“No.” More theoretical hand-waving? She should have thoroughly checked out this guy first.
“It shows that if you have a small metal box, the space inside can have a net negative energy density.”
“That’s crazy.”
“Not so,” he said, cheerily oblivious to her expression. “The metal keeps out electromagnetic waves, right? Make the box small enough, the effect gets large. The missing waves depress the effective energy density inside the box. Do it enough, you get a negative energy.”
“How small a box?”
She had to admire how casually he tossed off, “Oh, maybe as big as a proton.”
“A proton!”
“Sure, but that’s just an in-principle argument, proof of principle. Point is, there’s nothing crazy about making a bridge that can hold itself together and sit there in your lab.”
“That’s another question. You’re talking about holes in space-time, but this thing is a solid.”
“Stuff made of negative energy density might feel solid, too.” He jabbed a finger at her. “You can’t say it’s made of ordinary atoms, can you?”
“No, but—”
“No atomic line emission, no lattice like a crystal?”
“No, but—”
“Then that question’s open. Nobody, but nobody, has any idea what such stuff looks like, feels like.”
“Look, I appreciate your coming down here and having a try, but—”
“I know, I know.” He held both hands up, palms out. “But I can make a prediction. Try a stress meter test and you’ll measure that tidal force.”
She blinked. “How so?”
“It should drop off fast, as the inverse cube of the distance from the sphere.”
“That’s…” She stopped to ponder how the experiment might work.
“Crazy?” He gave her the grin again, which was starting to get irritating. “Maybe just crazy enough to do the job.”
“Just crazy enough to waste a lot of my time.”
“You have another appointment?”
Yeah, she thought, with Brookhaven’s lawyers. “You know, when I brought you down here, I thought you’d look over the data, think of some exotic material it could be made of—”
“I did,” he said brightly. “Just more exotic than you planned on.”
After he left, she sat in the lab and thought over his remarks. It was early evening and her stomach rumbled, but things had moved so fast she felt a need to sit still and work the ideas around in her mind.
She was more convinced than ever that Max was a waste, his ideas fanciful. But if there was a definitive experiment, she would do it. Data always overruled theory. She might learn something new, anyway.
It took nearly a week to set up the stress analysis and then a full week to get it to work. Brad and Zak pitched in. Zak delayed for a few days the vacation to Mexico he had planned with his parents. To her surprise, they had dutifully agreed and visited the lab, seeming awed at how far their son had come from their tailor shop.
The undergraduates kept plugging away at restoring the Core Element, and she had to shepherd that, as well as keep up with her 3-B lectures, the homework, office hours, the usual. The department chairman, Onell, was after her again to show up for the excruciating Minority Mentorship committee meetings. She didn’t answer her e-mail and managed to dodge him in the corridors. Hiding out in her lab helped. She came in early and stayed late and ignored Jill’s calls. Their last outing had been a farce and she was not willing to brave the social gauntlet quite yet.
Particle experimenters learned skills in the three big areas: designing experiments, building detectors, and sifting data. Specialize, sure, but know all three—that she had learned early. Versatile physicists rose; “desk types” or “floor physicists” stayed where they were. Most of them, she suspected, wanted it that way.
Adaptability came in handy now. She had never thought about how to measure a gravitational stress before and learned a lot by talking to Riley Newman, a senior professor who had made a high-accuracy measurement of the gravitational constant, G. His method used delicate, tiny torsional pendulums. Their periods fell the farther they were from a mass, an effect she would only have to measure to one part in a thousand to check Max’s assertion. Newman’s gear was portable and could do the job.
The task looked easy and proved otherwise. Alicia kept Max informed, asking just how precise a measurement he thought would be decisive. She was busy with Physics 3B and would have handed the project off to Zak Nguyen, but he had delayed his family’s long-planned vacation as long as their tickets would allow, so he took off for two weeks. This was just as well; he and Brad had rubbed each other the wrong way several times in the last week. Quick, assertive, Brad kept intruding on Zak’s patient methods. Worse, Brad shortcut to get a quick feel for results, whereas Zak carefully framed every move, so there were few surprises. Brad wanted to spend more time on the sphere, less on the Core Element. When he left, Alicia could tell Zak was glad to get a break both from the lab and from Brad. Still, she found it odd not to have his steady presence.
His absence sent Brad into high gear. She used him as a general gofer while setting up Newman’s rig. As usual, there were plenty of vexing details to go wrong. The magnetic field complicated matters, but late one afternoon she and Brad pieced together the data and plotted it on the blackboard. The gravitational tidal force around the sphere dropped off cleanly, inversely as the distance cubed.
“What the hell can it mean?” Brad asked.
“That we’ve found a very odd object indeed. It’s spherical, but gives us a tidal force that means it has a lopsided mass distributed inside somehow.” She was tired but strangely happy. She had not seen Max since his visit, though they had talked by telephone and exchanged terse e-mail queries. This would be fun to tell him.
“That theory guy, he predicted this?” Brad asked skeptically.
“He did indeed” came a voice from the distant shadows of the lab.
Max. She was startled as he walked into the lab spotlights illuminating the U-magnet. “I came in half an hour ago, but I wanted to see you at work,” he said. “I just sat in the back.”
“How did you know—”
“You said you were nearly done. I’m due to give a seminar at UCSD tomorrow, thought I’d drop by.”
For all the rivalry between theorists and experimenters, she derived an unclouded pleasure in stepping him through the experiment, showing the sharp, clear data. In a world beset by people and their endlessly warring opinions, their heartfelt passions, a firm foundation in fact, scrupulous fact, was welcome.
She could see the lines of concern deepen in his face as she led up to the final result. A theorist awaiting a test of his prediction was vaguely like a prisoner on trial with the jury out. The prisoner knew whether she was guilty, so she hoped the jury will get it wrong if guilty and get it right if she was innocent. In science the jury of Nature was always right, though one had to be careful to ask it exactly the right question. The predicter had to await a verdict, not knowing whether she was innocent or guilty, so there was genuine suspense as the foreman of the jury rose to speak—
“By damn!” Max grinned. “A lopsided mass inside, all right—internal structure we can’t see.” They all beamed and Max asked a few questions about details, breaking off to say, “No chance this is just some coincidence?”
She laughed. “This is much too clear an effect. Anyway, coincidence is God’s way of remaining anonymous.”
“Great.” Max’s unalloyed joy was a pleasure in itself.
“A prediction fulfilled—rather a rarity,” Alicia said.
“I don’t get it,” Brad said, arms folded, leaning skeptically forward to peer at the data. “We’ve spent days checking this out, fine. It’s a pretty peculiar thing we got here. But a wormhole?”
“Exotic objects
require exotic explanations,” Max said.
“It’s spitting UV! What’s at the other end?”
“A star, I’d say,” Max answered blithely.
Alicia smiled. This was a classic theorist’s casual lure, tossing off a snap judgment. Extra points if it was, like this one, particularly outrageous.
“An ultraviolet star?” Brad said dubiously.
“Not ultraviolet seen from outside. This wormhole could be inside a star, where it’s hotter.”
“Why?”
“Most of the galaxy’s mass is tied up in stars. If this wormhole opened up near one, it could fall in.”
“Seems unlikely,” Brad said. Alicia wondered if he was trying to make his mark by being hard to convince. His chance to shine, since Zak was off on vacation. Indeed, he had been working quite hard recently, too.
“It is, you’re right. Or maybe somehow a wormhole wants to open up where there’s a local depression in the gravitational potential. Stars fit the bill.”
“Sounds like a lot of guessing to me,” Brad sniffed.
Max gave Brad a thin, tolerant smile that quickly sank from view. “Granted, but to figure this out, we need to make leaps.”
Alicia had to respect Brad’s indifference to Max’s position; a good sign in a student, though often a quick route to a momentary humiliation. “We’re all guessing here anyway,” she said.
Max sketched some numbers on the blackboard. “Say it’s a star like ours, pretty typical as stars go. Then it’s got lots of light rattling around in it…”
He jotted down symbols Alicia vaguely recalled from her few courses in astronomy. She knew that light took decades to make its way from the sun’s core out to the surface, bouncing around among the compressed atoms. Max rearranged his equation, then turned to Brad. “How many photons are you guys getting out of that sphere, per second?”
Brad had to look up the number and while he did Max went through his steps on the blackboard, ending up with an expression for how many photons of UV would have to come through the other end of the wormhole. It was a simple idea, really. If the wormhole opened in the blue-hot interior of a star, then light would shine through. “But we can’t even see the light,” Alicia said.
“Yeah, that bothered me,” Max said. “But suppose the other end’s not the same size as this. Nothing says it has to be.”
Brad came back with the number, a bit less than a million photons per second. Max put this number in his equation and wrote ~ 10-4 CM. on the blackboard. “Tiny,” he reflected. “No bigger than a dust mote.”
Alicia shook her head. “So it’s a speck on the other side, but a bowling ball here?”
“Ummm, I guess so,” Max said.
“Calculations like this don’t prove much,” Brad said, echoing Alicia’s thoughts.
“Particularly because,” she said slowly, “you’ve skipped the obvious. If this is a wormhole, how come we can’t go through it? Or the star’s hot interior—why isn’t it spewing out here?”
Max nodded, tossing his chalk into the tray. “Must be the stuff it’s made of. All we know is that if a wormhole can exist, pretty exotic material has to hold it open. That’s what’s giving us this tidal force. Could be, such stuff doesn’t let ordinary matter pass through it, but does let light through.”
“Ummm,” Alicia said, trying to be polite. “Still sounds like we’re just making this up as we go along.”
“We are.” Max grinned. “Invent, then check. It’s really the only way to make progress.”
Brad scowled. “Doesn’t explain much.”
“I’m wondering if that’s also a gravitational shift,” Max said, still seeming unbothered by Brad’s acerbic tone. “You mentioned early on that you had thought maybe you were seeing a red shift, rather than something cooling off.”
“We abandoned that idea. I think it’s cooling,” Alicia said cautiously. Ideas were winging around a bit too fast.
She vaguely recalled that light, climbing up from the Earth to the moon, got redder. The effect had been measured using lasers. She thought of it as light getting sort of tired out and knew that was wrong, but that was a handy way to remember it. If the other end of the wormhole were buried deep in a star, then in getting here it would climb a steep gravitational hill and look weaker to their instruments. She tried to get a picture of this in her mind and failed.
“Could be, could be… though I’ll admit”—Max crisply jotted more symbols on the board—“that doesn’t work too well, either. It turns out, see, that to get that big a gravitational shift, you’d have to be near a black hole. Something that’s really compressed, at the bottom of a steep gravitational well. Ordinary stars won’t do.”
“Why in the world should we have any faith in this idea, then?” Alicia asked.
Max shrugged. “Theory doesn’t have to be right. It just has to be interesting.”
Alicia had always hated this it’s-just-artistic-taste way of looking at science, but she could see why he was making light of his troubles. “Give us the number, then,” she said. “What’s it take to make a gravitational red shift of—what was Zak’s number?”
“Two percent of the speed of light,” Brad said. “One hell of a shift.”
“That requires… ummmm… about ten thousand times the mass of the sun,” Max said, writing out the relation and underlining the result.
“Isn’t there supposed to be a black hole at the center of our galaxy?” Alicia asked.
“It’s supposed to be maybe a few million times a sun’s mass,” Max said. “So our wormhole pops out there?”
“Sounds pretty shaky,” Brad said.
“Yeah.” Max tossed the chalk into the tray again, snapping it in two. “Big problems we’ve got.”
Alicia pointed to a sign she had nearly forgotten sticking to a spot on the wall above a chugging vacuum pump. It was copied from the Cavendish Laboratories of Cambridge. In archaic type, it said:
1. Do not choose the topics for scientific investigation simply because they are fashionable.
2. Never fear the scorn of theorists.
3. To see what has not been seen before, look where no one has looked before.
“Nearly a century old, but these rules still work.” She looked at Brad. “In reverse, too—never scorn theorists just because they can’t explain everything.”
“Ummm, thanks.” Max glanced at the sphere. “It seems stable…”
“But?”
“The exotic matter needed to build a traversable wormhole of that size is pretty big, about a Jupiter mass.”
“Good grief!”
“But the total mass of the wormhole can be close to zero.” He addressed this to Brad, taking pains to be cordial. “Y’see, the negative energy density walls offset the mass of the rest of the wormhole. The sum leaves just a little residue mass.”
“Of 100 kilograms? That fine a balance, it sounds unstable.”
“Not particularly. Not like a pencil balanced on end, anyway. No reason an equilibrium can’t be robust and rugged. You’ve moved it from New York to here without it blowing apart.”
“Ummm.” Still, if this idea were remotely right, she felt foolish for taking risks. “And all this is because you want it to be a wormhole,” Alicia smiled skeptically. “Suppose it isn’t?”
“Then we couldn’t explain the big tidal effect,” Max said. “That’s key.”
Massive objects produced stresses in nearby objects, just as Earth’s moon pulled water around in the oceans. For an apparently spherical bowling ball to do it meant that it had some asymmetric masses inside.
She shook her head. “You think it’s key,” Alicia said sardonically. She had a headache. Was it just from thinking?
11
Her headache started going away when Max asked her out to dinner. They went to a place near UCI, a long chilly hangar affair with enough bare concrete and ribbed ducts and stark lighting to be a Franz Kafka theme bar.
They settled into a booth a
nd Max started chuckling. She was distracted. On the ride over she had started mentally replaying her telephone scrap with Dave Rucker. She looked at Max, puzzled, and he said, “I love it. Listen to this: ‘A mellow, tempting blend of our hand-rolled angel hair pasta, smothered in a saffron-laced sauce of aged fromage, served on blue-white china with complete, authentic silverware.’ Priceless; even worse than L.A.”
“Law of the universe,” she said. “The longer the menu description, the worse the food.”
“I usually skip singles’ watering holes like this.” He gazed around speculatively. She noticed that the bar commanded most of the restaurant and was half-filled with various sleek animals in their hunting garb: molded jackets, tight skirts, big hair, even some show-off, in-your-face hats.
“Me, too,” she said a little guiltily, thinking of Jill.
“I like Orange County, though. It’s like L.A. without caffeine.”
“Actually, I was surprised when you immediately jumped in your car and came down here to look at the sphere,” she said.
“I’m curious. Also…” He gave her a veiled glance, eyelids hooding an assessing gaze. “I had a girlfriend down here, thought I might surprise her.”
She felt a mild surprise herself. “And…?”
“She was having a little dinner party for two.”
“You ‘had’ a girlfriend?”
“Right, past tense.”
Reassuring, somehow, to find that someone else was striking out in the social world. They ordered drinks and then she said lightly, “The search eternal,” casting a sliver of bait.
“Tough for us, I suspect. Physicists, scientists generally, are a difficult lot to get along with.”
“The way I look at it,” she said, deciding to trot out one of her set pieces, “in your emotional life empathy is important, what I call the Ah! response. In humor you’re going for the Ha-ha! In science we seek the Aha! moment.”
She had found this a useful litmus test, whether a stranger would fall into the oblique angle of view she offered. Max’s half-smile grew, one corner turning down in a quizzical curve. “The eureka experience? A sudden flashing insight into territories never seen before? The surge that had sent Archimedes running naked from his bath and through the streets, ecstatically driven and taking ancient dress codes to their limit?”
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