The Best of Gregory Benford

by David G. Hartwell

  The two blue jets lanced out, cutting through the spiral arms and breaking free into the blackness beyond. One plate, taken in that spectral spike where ionized hydrogen clouds emit, giving H II radiation, showed a string of beads buried in the curling spiral lanes. These were vast cooling clouds. Where the jets crossed the H II regions, the spiral arms were pushed outward, or else vanished altogether.

  Opposite each blue jet, far across the galaxy, a red jet glowed. They, too, snuffed out the H II beads.

  From these gaps in the spiral arms I estimated how far the barred spiral galaxy had turned, while the jets ate away at them: about fifteen degrees. From the velocity measurements in the disk, using the Doppler shifts of known spectral lines, I deduced the rotation rate of the NGC 1097 disk: approximately a hundred million years. Not surprising; our own sun takes about the same vast time to circle around our galactic center. The photons telling me all these specifics had begun their steady voyage sixty million years ago, before there was a New General Catalog of Nebulae and Clusters of Stars to label them as they buried themselves in my welcoming emulsion. Thus do I know thee, NGC 1097.

  These jets were unique. The brightest blue one dog-legs in a right angle turn and ends in silvery blobs of dry light. Its counter-jet, offset a perverse eleven degrees from exact oppositeness, continues on a warmly rose-colored path over an immense distance, a span far larger than the parent galaxy itself. I frowned, puckered my lips in concentration, calibrated and calculated and refined. Plainly these ramrod, laconic patterns of light were trying to tell me something.

  But answers come when they will, one piece at a time.

  I tried to tell my son this when, that evening, I helped him with his reading. Using what his mother now knowingly termed “word attack skills,” he had mastered most such tactics. The larger strategic issues of the sentence eluded him, still. Take it in phrases, I urged him, ruffling his light brown hair, distracted, because I liked the nutmeg smell. (I have often thought that I could find my children in the dark, in a crowd, by my nose alone. Our genetic code colors the air.) He thumbed the book, dirtying a corner. Read the words between the commas, I instructed, my classroom sense of order returning. Stop at the commas, and then pause before going on, and think about what all those words mean. I sniffed at his wheatlike hair again.

  I am a traditional astronomer, amid all the digital buzz sweeping through the field. I am accustomed to the bitter cold of the cage at Palomar, the Byzantine marriage of optics at Kitt Peak, the muggy air of Lick. Through that long morning yesterday I studied the NGC 1097 jets, attempting to see with the quick eye of the theorist—“dancing on the data” as Roger Blandford down the hall had once called it. I tried to erect some rickety hypothesis that my own uncertain mathematical abilities could brace up. An idea came. I caught at it. But holding it close, turning it over, pushing terms about in an overloaded equation, I saw it was merely an old idea tarted up, already disproved.

  Perhaps computer enhancement of the images would clear away some of my enveloping fog, I mused. I took my notes to the neighboring building, listening to my footsteps echo in the long arcade. The buildings at Caltech are mostly done in a pseudo-Spanish style, tan stucco with occasional flourishes of Moorish windows and tiles. The newer library rears up beside the crouching offices and classrooms, a modern extrusion. I entered the Albert Sloan Laboratory of Physics and Mathematics, wondering for the nth time what a mathematical laboratory would be like, imaging Lewis Carroll in charge with talking rabbits, and went into the new computer terminal rooms. The indices which called up my plates soon stuttered across the screen. I used a medium numerical filter, to suppress variations in the background. There were standard routines to subtract particular parts of the spectrum. I called them up, averaging away noise from dust and gas and the image-saturating spikes that were foreground stars in our own galaxy. Still, nothing dramatic emerged. Illumination would not come.

  I sipped my coffee. I had brought a box of crackers from my office; and I broke one, eating each wafer with a heavy crunch. I swirled the cup and the coffee swayed like a dark disk at the bottom, a scum of cream at the vortex curling out into gray galactic arms. I drank it. And thumbed another image into being.

  This was not NGC 1097. I checked the number. Then the log. No, these were slots deliberately set aside for later filing. They were not supposed to be filled; they represented my allotted computer space. They should be blank.

  Yet I recognized this one. It was a view of Sagittarius A, the intense radio source that hides behind a thick lane of dust in the Milky Way. Behind that dark obscuring swath that is an arm of our Galaxy, lies the center. I squinted. Yes: this was a picture formed from observations sensitive to the 21-centimeter wavelength line, the emission of nonionized hydrogen. I had seen it before, on exposures that looked radially inward at the Galactic core. Here was the red band of hydrogen along our line of sight. Slightly below was the well-known arm of hot, expanding gas, nine thousand light years across. Above, tinted green, was a smaller arm, a ridge of gas moving outward at 135 kilometers per second. I had seen this in seminars years ago. In the very center was the knot no more than a light year or two across, the source of the 1040 ergs per second of virulent energy that drove the cooker that caused all this.

  Still, the energy flux from our Galaxy was ten million times less than that of a quasar. Whatever the compact energy source there, it was comparatively quiet. NGC 1097 lies far to the south, entirely out of the Milky Way. Could the aim of the satellite camera have strayed so much?

  Curious, I thumbed forward. The next index number gave another scan of the Sagittarius region, this time seen by the spectral emissions from outward-moving clouds of ammonia. Random blobs. I thumbed again. A formaldehyde-emission view. But now the huge arm of expanding hydrogen was sprinkled with knots, denoting clouds which moved faster, Dopplered into blue.

  I frowned. No, the Sagittarius A exposures were no aiming error. These slots were to be left open for my incoming data. Yet they were filled.

  Someone had co-opted the space. Who? I called up the identifying codes, but there were none. As far as the master log was concerned, these spaces were still empty.

  I moved to erase them. My finger paused, hovered, went limp. This was high-quality information, already processed. Someone would want it. They had carelessly dumped it into my territory, but…

  My pause was in part that of sheer appreciation. Peering at the color-coded encrustrations of light, I recalled what all this had once been like: impossibly complicated, ornate in its terms, caked with the eccentric jargon of long-dead professors, choked with thickets of atomic physics and thermodynamics, a web of complexity that finally gave forth mental pictures of a whirling, furious past, of stars burned now into cinders, of whispering, turbulent hydrogen that filled the void between the suns. From such numbers came the starscape that we knew. Time and labor had simplified and shaped this welter into apparent beauty. From a sharp scratch on a strip of film we could catch the signature of an element, deduce velocity from the Doppler shift, and then measure the width of that scratch to give the random component of the velocity, the random jigglings due to thermal motion, and thus the temperature. All from a scratch. No, I could not erase it.

  When I was a boy of nine my mother brow-beat me into serving at the altar, during the unendurably long Episcopal services she felt we should attend. I wore the simple robe and was the first to appear in the service, lighting the candles with an awkward long stick with its sliding wick. The organ music softly murmured, not calling attention to itself, so the congregation could watch undistracted as I fumbled with the wick and tried to keep the precarious balance between feeding it too much (so that, engorged, it bristled into a ball of orange) and the even worse embarrassment of snuffing it into a final accusing puff of black.

  Through the service I had to alternately kneel and stand, murmuring the worn, rolling phrases as I thought of the softball I would play in the afternoon, feeling the prickly gathering heat u
nderneath my robes. On a bad day the sweat would accumulate and a drop would cling to my nose. I’d let it hang there in mute testimony. The minister never seemed to notice. I would often slip off into decidedly untheological daydreams, intoxicated by the pressing moist heat, and miss the telltale words of the litany, which signaled the beginning of communion. A whisper would come skating across the layered air and I would surface, to see the minister turned with clotted face toward me, holding the implements of his forgiving trade, waiting for me to bring the wine and wafers to be blessed. I would surge upward, swearing under my breath with the ardor only those who have just learned the words can truly muster, unafraid to be muttering these things as I snatched up the chalice and sniffed the too-sweet murky wine, fetching the plates of wafers, swearing that once the polished walnut altar rail was emptied of its upturned and strangely blank faces, once the simpering organ had ebbed into silence and I had shrugged off these robes swarming with the stench of mothballs, I would have no more of it, I would erase it.

  I asked Redman who the hell was logging their stuff into my inventory spaces. He checked.

  The answer was: nobody. There were no recorded intrusions into those sections of the memory system. Then look further, I said, and went back to work at the terminal.

  They were still there. What’s more, some index numbers that had been free before were now filled.

  NGC 1097 still vexed me, but I delayed working on the problem. I studied these new pictures. They were processed, Doppler-coded, and filtered for noise, all freshly done by the auto-software. I switched back to the earlier plates, to be sure. Yes, it was clear: these were different.

  Current theory held that the arm of expanding gas was on the outward phase of an oscillation. Several hundred million years ago, so the story went, a massive explosion at the galactic center had started the expansion: a billowing, spinning doughnut of gas swelled outward. Eventually its energy was matched by the gravitational attraction of the massive center. Then, as it slowed and finally fell back toward the center, it spun faster, storing energy in rotational motion, until centrifugal forces stopped its inward rush. Thus the hot cloud could oscillate in the potential well of gravity, cooling slowly.

  These computer-transformed plates said otherwise. The Doppler shifts formed a cone. At the center of the plate the velocities were far higher than any observed before, over a thousand kilometers per second. That exceeded escape velocity from the Galaxy itself. The values tapered off to the sides, coming smoothly down to the shifts that were on the earlier plates.

  I called the programming director. He looked over the displays, understanding nothing of what it meant but everything about how it could have gotten there; and his verdict was clean, certain: human error. But further checks turned up no such mistake. I went and stood over his messy desk.

  “Must be comin’ in on the transmission from orbit,” he mused. He seemed half-asleep as he punched in commands, traced the intruders. These data had come in from the new combination optical, IR, and UV ’scope in orbit, and the JPL programs had obligingly performed the routine miracles of enhancement and analysis. But the orbital staff were sure no such data had been transmitted. In fact, the ’scope had been down for inspection, plus an alignment check, for over two days. The programming director shrugged and promised to look into it, fingering the innumerable pens clipped to his shirt pocket.

  So these had come in somehow from…where? I stared at the Doppler cone, and thumbed to the next index number. The cone had grown, the shifts were larger. Another: still larger. And then I noticed something more. A cold sensation seeped into me, banishing the causal talk and mechanical-printout stutter of the terminal room.

  The point of view had shifted. All the earlier plates had shown a particular gas cloud at a certain angle of inclination. This latest plate was slightly cocked to the side, illuminating a clotted bunch of minor H II regions and obscuring a fraction of the hot, expanding arm. Some new features appeared. If the JPL program had done such a rotation and shift, it would have left the new spaces blank, for there was no way of filling them in. These were not empty. They brimmed with specific shifts, detailed spectral indices. The JPL program would not have produced the field of numbers unless the new data contained them. I stared at the screen for a long time.

  That evening I drove home the long way, through the wide boulevards of Pasadena, in the gathering dusk. I remembered giving blood the month before, in the eggshell light of the Caltech dispensary. They took the blood away in a curious plastic sack, leaving me with a small bandage in the crook of my elbow. The skin was translucent, showing the riverwork of tributary blue veins, recently tapped and nearly as pale as the skin. I had never looked at that part of me before and found it tender, vulnerable, an unexpected opening. I remembered my wife had liked being stroked there when we were dating, and that I had not touched her there for a long time. Now I had myself been pricked there, to pipe brimming life into a sack, and then to some other who could make use of it. Bloody charity.

  That evening I drove again, taking my son to his Open House. The school bristled with light and seemed to command the neighborhood with its luminosity, drawing families out of their homes. Standing on its slight hill, it was the center of the children’s galaxy, for now. My wife was taking my daughter to another school, so I was unshielded by her ability to recognize people we knew. I could never sort out their names in time to answer the casual hellos. In our neighborhood the PTA nights draw a disproportionate fraction of technical types, like me. Tonight I saw them shorn of my wife’s the quicksilver verbal fluency. They drove compact cars that seemed too small for their large families, wore shoes whose casualness offset the formal, just-come-from-work jackets and slacks, and carried creamy folders of their children’s accumulated work, to use in conferring with the teachers. The wives were sun-darkened, wearing crisp, print dresses that looked fresh for the occasion, and spoke with ironic turns about PTA politics, bond issues, and class sizes.

  In his classroom my son tugged me from board to board, where he had contributed nature paragraphs, mostly wildlife. The crowning exhibit was of Io, Jupiter’s pizza-mocking moon, which he had made from a tennis ball and thick, sulphurous paint. It hung in a box painted black and looked remarkably, ethereally real. My son had won first prize in his class for the mockup moon, and his teacher stressed this as she went over the less welcome news that he was not doing well at his reading. Apparently he arranged the plausible phrases—A, then B, then C—into illogical combinations, C coming before A, despite the instructing commas and semicolons that should have guided him. It was a minor problem, his teacher assured me, but should be looked after. Perhaps a little more reading at home, under my eye?

  I nodded, sure that the children of the other scientists and computer programmers and engineers did not have this difficulty, and already knew what the instructing phase of the next century would be, before the end of this one. My son took the news matter-of-factly, unafraid, and went off to help with the cake and Kool-Aid. I watched him mingle with girls whose awkwardness was lovely, like giraffes’. I remembered that his teacher (I had learned from gossip) had a mother dying of cancer, which might explain the furrow between her eyebrows that would not go away, contradicting her fixed, welcoming smile.

  My son came bearing cake. I ate with him, sitting with knees slanting upward in the small chair; and quite calmly and suddenly an idea came to me and would not go away. I turned it over and felt its shape, testing it in a preliminary fashion. Underneath I was both excited and fearful and yet sure that it would survive: it was right. Scraping up the last crumbs and icing, I looked down, and saw my son had drawn a crayon design, an enormous father playing ball with a son, running and catching, the scene carefully fitted into the small compass of the plastic, throwaway plate.

  The next morning I finished the data reduction on the slit-image exposures. By carefully covering over the galaxy and background, I had managed to take successive plates, which blocked out segments of the
space parallel to the brightest blue jet. Photometry of the resulting weak signal could give a cross section of the jet’s intensity. Pinpoint calibration then yielded the thickness of the central jet zone.

  The data was somewhat scattered, the error bars were larger than I liked, but still—I was sure I had it. The jet had a fuzzy halo and a bright core. The core was a hundred light years across, a thin filament of highly ionized hydrogen, cutting like a swath through the gauzy dust beyond the galaxy. The resolute, ruler-sharp path, its thinness, its profile of luminosity: all pointed toward a tempting picture. Some energetic object had carved each line, moving at high speeds. It swallowed some of the matter in its path; and in the act of engorgement the mass was heated to incandescent brilliance, spitting UV and X-rays into an immense surrounding volume. This radiation in turn ionized the galactic gas, leaving a scratch of light behind the object, like picnickers dumping luminous trash as they pass by.

  The obvious candidates for the fast-moving sources of the jets were black holes. And as I traced the slim profiles of the NGC 1097 jets back into the galaxy, they all intersected at the precise geometrical center of the barred spiral pattern.

  Last night, after returning from the Open House with a sleepy boy in tow, I talked with my wife as we undressed. I described my son’s homeroom, his artistic achievements, his teacher. My wife let slip offhandedly some jarring news.