Superclusters are the largest clearly identified structures in the universe. A supercluster is a megalopolis of galaxies containing dozens of rich clusters and uncounted thousands of galaxies, gathered into eddies or drifting alone. Galaxies that are not connected to any cluster are known as field galaxies, a term that somehow suggests the way in which wildflowers speckle a meadow. A typical supercluster has a peculiar shape: that of a ropy blob, like a yam; or maybe a curved sheet, like part of a bubble (astronomers are having a glorious time haggling over that). In any case, superclusters are cloudlike agglomerations of galaxies enclasping huge voids, or bubbles of apparently empty space.
The most densely populated region of our own Local Supercluster is a thick concentration of galaxies visible in the constellation Virgo. Those galaxies are maybe thirty, or maybe sixty, million light-years away from the Milky Way. Other nearby superclusters paint the sky: the Hydra-Centaurus Supercluster, the Perseus Supercluster. The Pavo-Indus Region is a supercluster containing hundreds of thousands of galaxies dusted across the southern sky. Then, as a telescope looks outward, the realm of the superclusters stretches into unmapped deserts of time. There may be about one million superclusters in the observable universe. These numbers are slippery. The universe may contain ten billion observable galaxies, or maybe one hundred billion—nobody really knows.
As a telescope looks backward into time (or out into space) the galaxies appear smaller and fainter. The atmosphere of the earth emits a slight natural glow at night, called the skyglow, which drowns the faintest galaxies. When a telescope probes about five billion light-years into lookback time, it can detect only the brightest galaxies—giant, elliptical galaxies—because spiral galaxies similar to the Milky Way are too dim to be seen at that distance, even with the best instruments. At extreme distances a telescope can only resolve the brightest beacons, the quasars. Quasars are the only class of luminous object that a telescope can see at cosmic distances, shining among and well beyond the most distant visible galaxies; and the most deeply redshifted quasars are probably the most remote objects that the Hale Telescope will ever detect.
During three nights in March, the scanning for quasars began. What these scans would reveal of the outer edge of the known universe remained unknown to Maarten Schmidt, who did not like to guess what surprises the universe might have in store for astronomers. The video screens were filled with galaxies, which were moving, giving the data room the appearance of the bridge of a starship. We must have been traveling at warp fifteen, except when 4-shooter bombed, when the screens would fill with jazzy stripes and we would drop to auxiliary impulse power, and Jim Gunn and Don Schneider would shout invective at 4-shooter and pound keys, while Maarten Schmidt whistled bits of Bach. When 4-shooter behaved, the astronomers liked to discuss what was passing on the screens.
Don Schneider touched the main screen. “Look at that, Maarten. A straight line of galaxies.”
“It looks like a string,” Maarten commented rather dryly.
“Goodness,” Don said. “Still more galaxies. This must be a supercluster. There’s lots of little junk going by.” What he considered to be “little junk” were galaxies the size of the Milky Way, but viewed from such a distance that they were only dapples on the screen, like shoals of leaves that had fallen onto a pond.
I wondered aloud if the galaxies we were looking at had ever been given names by people.
Jim Gunn said, “Absolutely not.”
“Have they ever been numbered or catalogued in some way?”
“No, actually not,” he said.
“Have they ever been seen by any astronomers before?”
“I don’t think so.” Jim pulled a handkerchief and blew his nose. “Maarten, would these galaxies ever have turned up on a photographic plate?”
Holding a Chips Ahoy! cookie, Maarten reflected on that idea. “I would say not—eh what, James?”
“We are going pretty deep.”
“Ja, except for the bright ones, most of these galaxies are too faint to show up on a survey plate.”
“It is somewhat mind-boggling, isn’t it?” Jim remarked. He turned to the night assistant. “This is an exciting night.”
“Oh, yes,” Juan said. “Everything is working,”
Jim laughed. “Don’t say that!”
The stereo in the data room was now playing Beethoven. While Maarten Schmidt found Beethoven not completely objectionable, he was mindful that J. S. Bach’s three hundredth birthday was coming up. Crossing to the stereo, he said, “I’ll interrupt this to see if there’s Bach on the radio.” He got a crash of cymbals and a soprano’s wail. “That’s not Bach.” He kept turning. Human voices soared. Schmidt cranked up the volume. He had found a Bach cantata—and a radio station that was playing nothing but Bach that night. Schmidt said, “It’s a good bet that you can find him on the radio on the night before his birthday.” A while later, the B Minor Mass came on: “Gloria, Gloria in excelsis Deo …”
Juan leaned over and called to Don, “What do you think of the seeing tonight?”
Don thought it was pretty good on the whole, despite some high haze.
So did the Principal Investigator. He conducted the B Minor Mass with a Chips Ahoy! cookie held between thumb and forefinger, and the voices sang: “Et in terra pax hominibus /Bonae voluntatis …”
“Quick—Jim! There’s a strange one!” Juan Carrasco called.
Jim Gunn rolled forward in his chair and stared at a large, bright galaxy. He said, “Is there a warp in that galaxy?”
Maarten Schmidt sat down and yanked off his glasses and squinted at the galaxy in question. It was bent like a crushed and twisted hat. Maarten groped around the table until he had found a plastic ruler. He put it against the drifting galaxy on the screen. He said, “Why, yes, yes—ah, James—this does look like a warp.”
“It’s certainly not symmetrical,” Jim remarked.
“Gad, that’s a neat galaxy!” said Maarten.
“Isn’t that beautiful,” Jim said. “Someone could spend a long time studying that thing. Strange things …” His voice trailed off, and he took a swig from a can of Von’s Lemon-Lime soda.
“Should I get a picture of it?” Juan asked.
“Yeah, go for it!” Jim said.
Juan grabbed a Polaroid camera from a shelf. He pointed it at his television screen and snapped a picture of the warped galaxy. He pulled the photograph and watched it develop. Slowly a contorted and apparently mangled galaxy appeared. This smear of light had met with an accident. Perhaps a heavy cloud of dark matter had fallen into it, or perhaps it had passed too close to another galaxy. Whatever the cause, a few tens of billions of stars had been sucked out of their normal orbits around the galactic center, thereby curling the galaxy like a bent bicycle wheel. Juan smiled. In all likelihood this galaxy had never been seen by human eyes before and might not be seen again for a long time. He said, “Beautiful, Professor James E. Gunn. You made my night.” He aimed the camera at another galaxy. Click. Zweee. “Portrait of an Anonymous Galaxy.” Zweee. “Still Life with a Galaxy”; “The Return of the Prodigal Galaxy”; “The Persistence of Galaxies”; “The Starry Night.” A pile of Polaroids accumulated at his control desk. “You can have these,” he said, pushing the pile at me. “I have too many already.”
The Principal Investigator was less easily satisfied. Maarten Schmidt often went up to the catwalk that encircled the dome. He claimed that he was worried about the weather, but I noticed that the better the weather became, the more often Maarten Schmidt vanished to the catwalk and the longer he stayed there. I asked Jim Gunn what was going on. “Maarten likes to get dark-adapted,” Gunn said, which I understood to be a polite way of saying that Schmidt had a peculiar habit of staring at the stars. When I asked Schmidt about this, his phrased answer was, “I find these trips to the catwalk not a tranquilizer, as it were, but a marvelous contrast to the pressures of the day.” Given the slightest excuse, he would put on his parka and slip out of the data roo
m. Walking underneath the Hale Telescope, he would cover his flashlight with his fingers, because the dome had to be kept pitch-black or the sensors in 4-shooter would go haywire. He would find a set of stairs, climb them, throw a lever, and open a steel door that led to the catwalk and the night sky. He would switch off his flashlight and stand in the darkness. Then he would walk slowly around the catwalk, traveling “anticlockwise” around the dome, as he described his preferred direction.
At fifty-five, Maarten Schmidt had reached the age at which prominent scientists can find themselves running their paperwork through a trash compactor in order to fit it in a briefcase. He served on a half dozen advisory boards and flew to conferences all over the world. He liked the catwalk at three in the morning, because, he said, “It is quite pleasant to be able to think about nothing in particular.” He struck many American astronomers as an attractive yet distant and somehow unknowable figure, perhaps like a quasar. He was a familiar figure at conferences, where he seemed to make a passage through a sea of colleagues. He towered above them, distinguished by curly gray hair, a white shirt, and a bow tie—the president of the American Astronomical Society. He was born and educated in the Netherlands. After living for twenty-six years in southern California, he still carried a so-called green card, identifying him as an alien. He retained his Dutch citizenship and voted in Dutch elections. Unlike most astronomers, he dressed up for observing runs. He wore a checked sport coat and a shirt as red as a fire engine, and when he went up to the catwalk, he put on a dapper yellow cashmere scarf. Schmidt had international contacts. “I talk a lot on the telephone—too much,” he said. “These days I find that I am doing all of my office work in the office and all of my science at home. Which is strange.” After he left Caltech in the evening he had a quiet dinner with his wife, Corrie, sitting in their backyard. They saw the dusk settling and watched for the first stars. Strangely enough, the majority of professional astronomers do not know their constellations very well—they find stars by the numbers. But Maarten Schmidt knew his way around the sky. After dinner he would work on his quasars far into the night, and then he would watch television; later he would sometimes dream of the Big Eye, although he could never remember what happened in these dreams.
When he and Corrie had first been married, they had lived a casual existence, staying up until three in the morning and getting up late. Then they had had three daughters. Their daughters, Maarten explained, “didn’t allow us to continue that way.” Now that their daughters had grown up, Maarten and Corrie liked to take off for a little resort in the Anza-Borrego Desert, where they could sit outdoors in lounge chairs under a palm tree and look at the stars. They would pass a pair of binoculars back and forth, in order to discuss the excellence of a particular constellation. They had found a kind of peace watching things happen at night in the desert—jackrabbits running past, bats flipping after moths, meteors razoring the sky. They talked a bit or were quiet. Maarten particularly enjoyed the desolate yips of coyotes, a sound he had never known growing up in Holland. They noted the comings and goings of planets, and the galaxy wheeling overhead, until dawn caught them by surprise.
Maarten Schmidt grew up during the Second World War in the city of Groningen, in the north of Holland, where his father was a civil servant in the city government. He did not do well at sports (except at the high jump); he was the sort of kid who would rather look at stars. Groningen was blacked out during most of the war, and Maarten was thirteen years old when he first began to notice unnaturally brilliant stars hanging over his lightless city. They attracted him. His grandfather give him a thick magnifying lens and an eyepiece. Maarten taped the lens to a cardboard toilet-paper tube and put the eyepiece into the other end of the tube. He took the invention to the third floor of his house and looked out the window. He found a double star in Lyra. He explored the sky. Then the sirens would start up. Waves of Allied bombers passed over Groningen almost every night on their way to Hamburg and Bremen, and a tremendous roar of their engines shook the city. Sometimes the German antiaircraft batteries that ringed the city started shooting like mad, trying to hit the bombers, searchlights stabbing everywhere. Allied fighters would strafe the German batteries, or the bombers would loose their bombs into Groningen. One night a bomb fell in the street near their house. They huddled under the stairs until two in the morning, when the “all-clear” sirens sounded, and then they tried to get a little sleep.
Maarten’s discovery in 1963, that quasars are brilliant and remote, had pushed him into fame, something he had not looked for and at times had resisted. Schmidt’s quasars burned like beacons across unimaginable reaches of night. People would ask him if he had invented the Schmidt telescope. (“No—that was old Bernhard Schmidt. No relation. He was drunk most of the time, so he must have been brilliant in between.”) His face appeared on the cover of Time magazine in 1967, when, after several years of photographing quasars alone in the prime focus cage of the Hale Telescope, he had smashed open the universe, had driven the limits of the Hale Telescope into territory beyond anything its builders had imagined, identifying quasars at greater and greater leaps, plunging into lookback time.
He lingered on the catwalk. So much about quasars remained unfathomable. In twenty-two years he had not found more than partial answers to his questions about their birth and death. In an interview with an historian of science named Spencer Weart, he once said that in his mind’s eye he imagined science as a cloth being knotted together by many hands, in the manner of the anonymous Flemish weavers of old, who had worked side by side on benches. Corrie was a weaver. She had hung the inside of their house with large tubes and wheels of knotted cloth in muted colors. He lived surrounded by his wife’s tapestries, which, he said, might have given him the feeling that science is a kind of tapestry extending back into the past. As he put it to the historian Weart, “I have strongly the feeling that as an astronomer on the earth, you are a link in history, because in science more than anything else, and certainly in astronomy, you build on what your predecessors did. You contribute a little here, you put in a couple of links there. It’s all being knitted together, and a few of the stitches are yours.” He sensed the presence of others working on the tapestry, sitting beside him; taking up threads, tying up small knots, while mysteriously, a design appeared. “And then,” he said, “the fabric goes on.” When your life as a scientist was over and others had taken up the weaving, you could always find your stitches in the cloth later, and you could say, “Well, they are there.”
He wanted to know what had happened back in the early history of the universe, when quasars began to burn. He hoped that 4-shooter might see the light of the first quasars at the dawn of time; that 4-shooter might see first light. If these scans with 4-shooter could dig into time and bring up something new, then for Maarten Schmidt that would amount to a few more threads in a long cloth—a modest reply to nature’s disregard for human reason. If the experiment worked, then 4-shooter would capture a few archaic photons of deeply redshifted quasar light. They would have left some remote quasar to travel through the void, without hitting anything, for almost as long as time itself had existed—a nice demonstration of how empty the universe is—until, some two or three times older than the earth, they ran into a mirror. The Milky Way lay in a mist along the eastern ridge of Palomar Mountain. Accustomed to the whine of the oil pumps, he noticed an eerie silence over Palomar; the oil bearings were shut off because the telescope was not moving tonight. Palomar Mountain was birdless and quiet. Even the toads had gone to sleep. One heard only a faint breeze fingering the cedars and humming along the catwalk rail. Coma Berenices and Bootes the Herdsman were climbing to the top of the sky, along with the beautiful golden K star Arcturus—the outriders of spring. He tightened his scarf and stuffed his hands in his pockets. His feet clanged on the catwalk. The fog had spread everywhere, drowning the lights of San Diego and Los Angeles, and had risen in a tide, lifting the domes of Palomar Mountain loose from their moorings on the world, to
drift for a while above the shoals of mortality, below a heaven not exactly empty, but a long way from earth.
PART 2
The
Shoemaker
Comets
On a mountainside near Flagstaff, Arizona, a low house made of concrete blocks sat in a forest of ponderosa pines. It resembled a bomb shelter. A second house rested on top of it—a soaring structure with walls made of volcanic boulders and glass. At the dining room table inside the house made of boulders and glass, the astronomer and geologist Eugene M. Shoemaker examined a newspaper. He read aloud: “ ‘Astronomers Locate Possible Distant Galaxy.’ ” He grinned and said, “What in the heck is this? What’s this mean?” He put on a pair of half-glasses. “Cheezus, there’s only about a hundred billion visible galaxies.”
“I wonder which one they found,” his wife, Carolyn Shoemaker, remarked dryly. She was clearing dinner dishes from the table. Night had fallen, and a steady rain poured down.
Gene dropped the newspaper on the table. He had a robust face tanned by years of prospecting for the remains of giant craters left by asteroids and comets that had struck the earth. He wore a thong tie with a clasp of Hopi silver in the shape of an eagle. He said to me, “Astronomers have essentially abandoned the solar system. In the nineteenth century the solar system was the object of central interest in astronomy. As their tools improved, astronomers focused their attention on what they called the larger questions. That’s what the Hale Telescope was built for—to put enough horsepower in the optics to go after the structure of the universe.” His wire-brush mustache conformed to his grin. He said, “So the geophysicists came along and adopted this orphan—the solar system.”
A drumroll of October rain hit the house and reverberated along ponderosa rafters. Gene and Carolyn had lived with their children in the lower house until it had started to feel cramped, whereupon the roof had seemed a natural place to begin another house, especially one made of volcanic boulders. Eventually the children had grown up and moved out, and now Gene’s mother lived in the lower house.