The Best of Gregory Benford

by David G. Hartwell

  “So now it goes to Asia,” Mary said slowly. “The future.”

  Somehow I smiled. “At least we have one.”

  Gravity’s Whispers

  (2010)

  The best is the enemy of the good,” Sam said over my shoulder.

  I whirled around, coming out of my work trance, knowing the voice, smiling. “What—?”

  He sauntered in, grinning in his lopsided way, eyes dancing. “At 11 pm you’re still working. Know your limits! The data can’t get better when you’re tired, y’know.”

  I threw down my pencil. “Right. Pursue the good. Let’s get a beer.”

  At the Very Large Array, this meant a long drive back to Socorro. Our offices were there, but I liked spending time out among the big radio dishes, too. On the way back I rolled down the window to catch the tangy spring sagebrush. Plus wondering if Sam the Slow had finally decided to make a date with me, in his odd way. I’d been waiting half a year.

  Then he said, slow and sly, “I was just passing by, thought I’d follow up on that puzzle I sent last week.”

  I recalled he had sent a noise-dominated file. I had run one of my custom programs, gotten interested, and wasted a day pulling out a pattern. “You know me too well. I cracked it, yeah.” I gave him a smile he didn’t notice. “Not a very interesting solution.”

  “You’d be surprised,” Sam said, watching the desert slide by.

  “It’s you guys who surprised the world—the first gravity waves, wow.”

  “Yeah, decades of work on LIGO paid off.”

  Sam was also modest, a trait that gave him gal problems in the fanatic tech crowd more than once; I had checked. Getting a gravitational wave to tweak a cavity, and detect that with interfering waves, a huge problem, had burned twenty years of his life. Years that might’ve been better if he’d spent less of it frowning at screens. Like me.

  He shrugged, lifted an eyebrow. “We thought it was a signal from a rotating neutron star with a deformed crust. Say, you have that solution handy?”

  I flipped open my laptop. Always with the quick answers… “Sure. It’s a string of numbers, turns out to be the zeroes of the Riemann zeta function.”

  A frown, quick glance away from the road. “Uh-huh. Which is—?”

  “A famous function of complex argument—that is, has real and imaginary parts.” Like your life, I thought. And mine. “See, it analytically continues the sum of an infinite series.”

  A shrug. “Sounds boring.”

  “Not so.” This fetched from him a side-flick, eyes puzzled. At least he was looking at me now. “It’s a big deal in analytic number theory. Plenty of applications in physics, probability theory, Bose–Einstein condensates, spin waves—”

  “Useful, good.” Sam was usually sharp, focused, but now he gazed pensively, above the highway, at the stars. “But…”

  “So how’d you get the detection?” It would help if I got him started about his work—that is, his life. “You guys got rid of the noise from that road traffic and logging at the Louisiana site?”

  “Yeah, took years. Finally nailed it. The signal we wrung out, it had plenty of chirps and bursts in it, a bitch to clean up.”

  I grinned. Sam had worked decades on LIGO, the big, long-term gravity wave detector, and the milestone was here. “Okay, so now that you’ve got LIGO sensitive enough, there’ll be plenty of signals. Supernovas in other galaxies, maybe rattling cosmic strings—”

  A vexed glance, troubled. “I want to understand this one. It’s not a neutron star crust vibration, I think.”

  “Huh?” I was already tasting the beer in my mind.

  “That decoding you did? That was our signal.”

  I blinked. “Can’t be. No natural system—”

  “Exactly.” Sam hooked an eyebrow at me.

  “What? A gravitational wave with a signal? That’s im—”

  “—possible, I know. Unless you can sling around neutron stars and make them sing in code.”

  “To send a signal, that means the transmitter is tunable…” I noticed my mouth was gaping open.

  Maybe, just maybe, this could be more important than at last getting Sam to date me. Maybe. I took a deep breath of dry New Mexico air. “Then…you should know that the signal, it’s not just a list of numbers. After twenty of the Riemann zeros, there’s something like a proof of the Riemann hypothesis. I think. Can’t follow it really well, actually.”

  He frowned. “Uh, so?”

  “The Riemann hypothesis, it’s one of the greatest unsolved problems in mathematics. It says that any non-trivial zero has its real part exactly equal to 1/2.”

  He shook his head. “A theorem? After some numbers? And that’s the attention-catching opener to a—a what?”

  I finally got it. “To a SETI signal?”

  “Look, I sent you that because we couldn’t understand it. Now you’re gonna tell me—”

  He still didn’t get it. Maybe I didn’t either. “Look, it can’t be. A SETI signal? We’ve thought about that a lot already. Opening up your message with pi, or e, prime numbers, some astro data—that makes sense.”

  “Sense to the likes of us.”

  “So I must’ve made some mistake.”

  “No you didn’t.” Sam looked at me with a warm smile. “You’re the only one I could run to with this analysis—the rest of ’em would laugh. You’re good, really good.”

  I leaned over and kissed him. “Congratulations on the Nobel.”

  He kissed back, his eyes flickered, a sudden dart of tongue, he jerked back, grinned—but he didn’t look happy. He grasped the steering wheel and peered ahead into the starlit darkness. In the high desert you can see stars glimmering in their reds and blues, far above the headlights. I knew him enough to see that he was thinking about something that could whisper across the galaxies with gravitation, not using obvious means like radio or lasers.

  “To make a gravitational wave signal—look,” he said adamantly, “we figured there would be natural events—catastrophes, really, like stars falling into black holes, or neutron stars smacking together—big enough to give a signal we could detect with this huge, expensive LIGO experiment…which has run for decades now, getting better, slowly. And now we have a signal, clear and solid…”

  “Some aliens know a better way to make waves, is all.” I wanted to move his attention away from the physics and toward, well, me.

  “Look, I think this is cause for celebration,” I said helpfully.

  “But… if it’s not just a simple signal—like a wave breaking on a beach, I mean, only in gravitational pulses—then… My God.” He stared up at the darkness above our headlights.

  “Yeah.” I looked at those burning stars, too. Mysteries, all of them.

  “Think of it. To make a signal, you don’t just slam stuff together. You have to make them oscillate. How?”

  “Ah, I…”

  “Say they take two black holes, make them orbit close together. Put some electrical charges on them. Then you can make them swerve by each other, radiate grav waves, but stay stable.” A snort. “Easy—just make black holes, the rest is simple.” A dry laugh. “You tap-tap-tap to make a signal…”

  He was getting overwhelmed, and so was I. The desert flittered past in our headlights.

  “Unimaginable,” I said.

  “Right. I can’t even think what you would do to make such masses move…”

  We were alone out here on a solitary road, in a desert far from anyone…just like humanity, I thought.

  Sam said, “Any mind that thinks the Riemann numbers are a calling card—and can throw around stars…”

  I got it. “Yeah. Know your limits. Maybe it’s good, really good, that we can’t possibly answer them.”

  He laughed, bless him. But I didn’t.

  Mercies

  (2011)

  All scientific work is, of course, based on some conscious or subconscious philosophical attitude.

  —Werner Heisenberg


  He rang the doorbell and heard its buzz echo in the old wooden house. Footsteps. The worn, scarred door eased open half an inch and a narrowed brown eye peered at him.

  “Mr. Hanson?” Warren asked in a bland bureaucratic tone, the accent a carefully rehearsed approximation of the flat Midwestern that would arouse no suspicions here.

  “Yeah, so?” The mouth jittered, then straightened.

  “I need to speak to you about your neighbor. We’re doing a security background check.”

  The eye swept up and down Warren’s three-piece suit, dark tie, polished shoes—traditional styles, or as the advertisements of this era said, “timeless.” Warren was even sporting a gray fedora with a snap band.

  “Which neighbor?”

  This he hadn’t planned on. Alarm clutched at his throat. Instead of speaking he nodded at the house to his right. Daniel Hanson’s eye slid that way, then back, and narrowed some more. “Lemme see ID.”

  This Warren had expected. He showed an FBI ID in a plastic case, up-to-date and accurate. The single eye studied it and Warren wondered what to do if the door slammed shut. Maybe slide around to the window, try to—

  The door jerked open. Hanson was a wiry man with shaggy hair—a bony framework, all joints and hinges. His angular face jittered with concern and Warren asked, “You are the Hanson who works at Allied Mechanical?”

  The hooded eyes jerked again as Warren stepped into the room.

  “Uh, yeah, but hey—whassit matter if you’re askin’ ’bout the neighbor?”

  Warren moved to his left to get Hanson away from the windows. “I just need the context in security matters of this sort.”

  “You’re wastin’ your time, see, I don’t know ’bout—”

  Warren opened his briefcase casually and in one fluid move brought the short automatic pistol out. Hanson froze. He fired straight into Hanson’s chest. The popping sound was no louder than a dropped glass would make as the silencer soaked up the noise.

  Hanson staggered back, his mouth gaping, sucking in air. Warren stepped forward, just as he had practiced, and carefully aimed again. The second shot hit Hanson squarely in the forehead and the man went down backward, thumping on the thin rug.

  Warren listened. No sound from outside.

  It was done. His first, and just about as he had envisioned it. In the sudden silence he heard his heart hammering.

  He had read from the old texts that professional hit men of this era used the 0.22 automatic pistol despite its low caliber, and now he saw why. Little noise, especially with the suppressor, and the gun rode easily in his hand. The silencer would have snagged if he had carried it in a coat pocket. In all, his plans had worked. The pistol was light, strong, and—befitting its mission—a brilliant white.

  The dark red pool spreading from Hanson’s skull was a clear sign that this man, who would have tortured, hunted, and killed many women, would never get his chance now.

  Further, the light 0.22 slug had stayed inside the skull, ricocheting so that it could never be identified as associated with this pistol. This point was also in the old texts, just as had been the detailed blueprints. Making the pistol and ammunition had been simple, using his home replicator machine.

  He moved through the old house, floors creaking, and systematically searched Hanson’s belongings. Here again the old texts were useful, leading him to the automatic pistol taped under a dresser drawer. No sign yet of the rifle Hanson had used in the open woods, either.

  It was amazing, what twenty-first century journals carried, in their sensual fascination with the romantic aura of crime. He found no signs of victim clothing, of photos or mementos—all mementos Hanson had collected in Warren’s timeline. Daniel Hanson took his victims into the woods near here, where he would let them loose and then hunt and kill them. His first known killing lay three months ahead of this day. The timestream was quite close, in quantum coordinates, so Warren could be sure that this Hanson was very nearly identical to the Hanson of Warren’s timeline. They were adjacent in a sense he did not pretend to understand, beyond the cartoons in popular science books.

  Excellent. Warren had averted a dozen deaths. He brimmed with pride.

  He needed to get away quickly, back to the transflux cage. With each tick of time the transflux cage’s location became more uncertain.

  On the street outside he saw faces looking at him through a passing car window, the glass runny with reflected light. But the car just drove on. He made it into the stand of trees and then a kilometer walk took him to the cage. This was as accurate as the quantum flux process made possible during a jogg back through decades. He paused at the entrance hatch, listening. No police sirens. Wind sighed in the boughs. He sucked in the moist air and flashed a supremely happy grin.

  He set the coordinates and readied himself. The complex calculations spread on a screen before him and a high tone sounded screeeee in his ears. A sickening gyre began. The whirl of space-time made gravity spread outward from him, pulling at his legs and arms as the satin blur of color swirled past the transparent walls. Screeeee…

  For Warren the past was a vast sheet of darkness, mired in crimes immemorial, each horror like a shining, vibrant, blood-red bonfire in the gloom, calling to him.

  He began to see that at school. History instruction then was a multi-show of images, sounds, scents and touches. The past came to the schoolboys as a sensory immersion. Social adjustment policy in those times was clear: only by deep sensing of what the past world was truly like could moral understanding occur. The technologies gave a reasonable immersion in eras, conveying why people thought or did things back then. So he saw the dirty wars, the horrifying ideas, the tragedies and comedies of those eras…and longed for them.

  They seemed somehow more real. The smart world everyone knew had embedded intelligences throughout, which made it dull, predictable. Warren was always the brightest in his classes, and he got bored.

  He was fifteen when he learned of serial killers.

  The teacher—Miss Sheila Weiss, lounged back on her desk with legs crossed, her slanted red mouth and lifted black eyebrows conveying her humor—said that quite precisely, “serials” were those who murdered three or more people over a period of more than thirty days, with a “cooling off” period between each murder. The pattern was quite old, not a mere manifestation of their times, Miss Weiss said. Some sources suggested that legends such as werewolves and vampires were inspired by medieval serial killers. Through all that history, their motivation for killing was the lure of “psychological gratification”—whatever that meant, Warren thought.

  Miss Weiss went on: Some transfixed by the power of life and death were attracted to medical professions. These “angels of death”—or as they self-described, angels of mercy—were the worst, for they killed so many. One Harold Shipman, an English family doctor, made it seem as though his victims had died of natural causes. Between 1975 and 1998, he murdered at least two hundred and fifteen patients. Miss Weiss added that he might have murdered two hundred and fifty or more.

  The girl in the next seat giggled nervously at all this, and Warren frowned at her. Gratification resonated in him, and he struggled with his own strange excitement. Somehow, he realized as the discussion went on around him, the horror of death coupled with his own desire. This came surging up in him as an inevitable, vibrant truth.

  Hesitantly he asked Miss Weiss, “Do we have them…serial killers…now?”

  She beamed, as she always did when he saw which way her lecture was going. “No, and that is the point. Good for you! Because we have neuro methods, you see. All such symptoms are detected early—the misaligned patterns of mind, the urges outside the norm envelope—and extinguished. They use electro and pharma, too.” She paused, eyelids fluttering in a way he found enchanting.

  Warren could not take his eyes off her legs as he said, “Does that…harm?”

  Miss Weiss eyed him oddly and said, “The procedure—that is, a normalization of character before the fact of
any, ah, bad acts—occurs without damage or limitation of freedom of the, um, patient, you understand.”

  “So we don’t have serial killers anymore?”

  Miss Weiss’s broad mouth twisted a bit. “No methods are perfect. But our homicide rates from these people are far lower now.”

  Boyd Carlos said from the back of the class, “Why not just kill ’em?” and got a big laugh.

  Warren reddened. Miss Weiss’s beautiful, warm eyes flared with anger, eyebrows arched. “That is the sort of crime our society seeks to avoid,” she said primly. “We gave up capital punishment ages ago. It’s uncivilized.”

  Boyd made a clown face at this, and got another laugh. Even the girls joined in this time, the chorus of their high giggles echoing in Warren’s ears.

  Sweat broke out all over Warren’s forehead and he hoped no one would notice. But the girl in the seat across the aisle did, the pretty blonde one named Nancy, whom he had been planning for weeks to approach. She rolled her eyes, gestured to friends. Which made him sweat more.

  His chest tightened and he thought furiously, eyes averted from the blonde. Warren ventured, “How about the victims who might die? Killing killers saves lives.”

  Miss Weiss frowned. “You mean that executing them prevents murders later?”

  Warren spread his hands. “If you imprison them, can’t they murder other prisoners?”

  Miss Weiss blinked. “That’s a very good argument, Warren, but can you back it up?”

  “Uh, I don’t—”

  “You could research this idea. Look up the death rate in prisons due to murderers serving life sentences. Discover for yourself what fraction of prison murders they cause.”

  “I’ll…see.” Warren kept his eyes on hers.

  Averting her eyes, blinking, Miss Weiss seemed pleased, bit her lip and moved on to the next study subject.

  That ended the argument, but Warren thought about it all through the rest of class. Boyd even came over to him later and said, with the usual shrugs and muttering, “Thanks for backin’ me up, man.”