First Light: The Search for the Edge of the Universe (6 page)

The theorists babbled on at conferences about the nature of the early universe. Maarten Schmidt found something amusing in all this talk. “The theoreticians”—he smiled—“the theoreticians are so clever. Once we have found something, they can find four ways to explain it.” In the case of quasars, the theoreticians had already found at least four ways to explain the redshift cutoff
before
it had been mapped. “In all these discussions,” Maarten said, “you find that you need hard numbers. How many quasars of this redshift? How many of that redshift? How many quasars of a particular luminosity? It seemed that the bullet had to be bitten.”

Exploring the edge of the universe was a dirty job, but somebody had to do it. Somebody had to look. Somebody had to commit
quite a few years of a scientific career toward the goal of mapping the realm of the earliest quasars—a gamble that so far had not shown signs of a big payoff. Schmidt and his people had already fed plenty of nickels into the slot machine. Schmidt guessed that years of work lay ahead of him before he might see the structure of the redshift cutoff—if ever. Astronomers learned not to count on results. “This exercise,” he said, “is to gather in the facts. You cannot, of course, solve all the questions in the field. Sometimes you get answers to questions you didn’t ask.”

Edwin Hubble had showed that the redshift of a galaxy depended on its distance from earth: the more redshifted the galaxy, the farther away it was. Much to their regret, astronomers had not yet been able to link this redshift scale to an absolute measure of distance. Thus they could not tell precisely how far away from earth any galaxy or quasar was, except within a relative range. But even if he could not know exactly how far away the quasars were, Maarten Schmidt felt that if he could collect a sample of quasars of the highest redshifts and plot their redshifts on a graph, then he could learn things about the birth of quasars. He wanted to see the distribution of quasars through time in the vicinity of the redshift cutoff.

He had urged Gunn to try to jury-rig 4-shooter, so that the camera would scan long ribbons of sky. To gather a tapestry of stars and then to search the tapestry for quasars might be a good way to find a lot of quasars. The strips of sky would be recorded on magnetic tape. When enough tapes had piled up, from a variety of scans, then Don Schneider, the team’s image-processing expert, would analyze the tapes, searching for stabs of quasar light. They could sweep the Hale Telescope across the sky, of course, but it seemed easier to stop the motion of the telescope and let the turning of the earth move the sky past the mouth of the telescope. This was a technique known as a transit. To put a telescope in transit, you shut down the telescope’s drive motors, clamp the bearings, and let stars drift past the mouth of the telescope as the earth turns. Instead of scanning the telescope across the sky, Maarten thought that he would let the earth do the work.

The telephone rang in the data room.

Don Schneider picked up the receiver. “Big Eye,” he said, and then, after a pause, “It’s going to be just unbelievable. Amateur night at the Big Eye—”

“Don’t say that, Donz!” Gunn barked.

Don stretched the cord to get out of Gunn’s hearing. He lowered his voice and said, “We’ve been working for three days and we still haven’t been able to get the experiment to work. We were just lucky it snowed last night—we couldn’t have started, anyway.”

Maarten Schmidt, the Principal Investigator, crossed the room and looked over Jim Gunn’s shoulder while Jim clacked at the keyboard of the computer.

Jim muttered, “I don’t know what will happen tonight, Maarten.”

“That’s an exciting way to start,” Maarten said pleasantly.

“Juan, we need to slew,” Jim said. He wanted to move the telescope rapidly (slew it), to point it at a bright star in order to calibrate the sensors.

The night assistant hit a switch. Nothing happened.

Maarten said, “Is there a problem, Juan?”

“No,” Juan said, running out of the room.

Maarten laughed. “The telescope has rusted!”

Juan returned. Somebody had left the stairs under the telescope—the telescope always refused to move until the stairs were rolled away. Hitting toggle switches, Juan slewed the telescope across the sky and centered it on a bright star. Jim Gunn typed a command to 4-shooter on his computer keyboard:
EXPOSE
.

4-shooter responded on the computer screen:
OK
. But nothing happened.

Gunn peered into the main video screen, which displayed whatever the camera saw. “Black!” he said. “I don’t see any stars!” Everyone talked at once.

“4-shooter is real unhappy.”

“Something’s getting in the way.”

“Maybe we’re pointed at the ceiling.”

There was a pause, and then, “Naw, that’s not the problem!”

“Well, where is the dome pointed?”

“We’re looking east.”

“Is the mirror open?”

“The mirror is open.”

“Yeah, but I don’t see any stars!” Gunn groaned. “Where’s my calculator?” He tore through a pile of papers.

Maarten paced back and forth. He began to whistle “The March of the Wooden Soldiers,” from
The Nutcracker
—whistling in the dark, so to speak.

Juan said, “The mirror is open. The dome is open. The stars are out—”

“We’re getting no light!” complained Jim Gunn.

“No evidence of light?” Maarten asked.

“Absolutely none at all.”

By now they understood that 4-shooter had gone dead.

An hour later, the telephone rang in the data room. It was Jim Gunn’s wife, Jill Knapp, calling from New Jersey. She is a radio astronomer.

“Hello, love,” Jim said, and after a pause, “We’re getting light, anyway.”

Maarten Schmidt laughed, and to the others he said, “It’s like Galileo all over again. First you have to get light down the tube.”

Jim and Jill talked quietly. She asked him how he was feeling. He said he felt all right. She asked him if he was getting any sleep. Of course not, he said. Jill Knapp, who is Scottish, once described the frantic hours before an observing run this way: “There is a feeling amongst us astronomers that time on a telescope is extremely precious. One feels the privilege. What a peculiar idea it is for a species to be looking at those …” She paused, seeking a word. “At those
things
out there.”

The team settled into more tinkering. Jim Gunn kept sending Don Schneider on errands up to the telescope, to flip the switch on the kludge one way or the other. Meanwhile Barbara Zimmerman finished writing her jazz program and left for Pasadena—she had done all she could. Examining a few white blobs on the television screen—stars—Gunn said, “Let’s get this pig focused.” The night had grown slightly colder, shrinking the Hale Telescope by one-half a millimeter, throwing the stars out of focus. Hitting switches, Juan Carrasco said, “You have the focus.” Juan handed a box with
buttons on it—a control paddle—to Don. Don tweaked buttons on the paddle, which moved the secondary mirror at the top of the Big Eye by a few hundredths of an inch, and a motor pinged, echoing in the dome. They tested different focuses.

“Ten north,” Jim said to Juan.

“Ready,” answered the night assistant.

“Ten north again.”

“Ready here.”

“Twenty north.”

“You have it.”

The stars on the screen eventually grew sharp. “Delicious!” Juan said.

“Focus disabled?” Don asked Juan.

“Focus off,” Juan said.

Jim Gunn turned to Maarten Schmidt. He said, “The telescope is yours.”

“What are we going to do?” cried Maarten.

“We can try a transit.”

“Really!” Maarten turned to Juan. “Let’s shut down the pumps, lights, everything.”

Juan said, “Pumps off.” The oil pumps shut down, the dome became silent, and the telescope settled and locked onto its bearings. “Lights off,” Juan said. The dome went black inside.

“Tracking off?” asked Maarten.

“That is correct,” said Juan.

“Somebody has to hit the switch on Jim’s box,” Don reminded the others. Juan ran out of the data room, followed by Maarten. Juan rolled the stepstairs under the telescope, and Maarten loped up the ladder into the cage, his flashlight bobbing. Overhead stretched a hanging cloth of stars—the dome slit, open to the north. Maarten flipped the toggle switch on the kludge to “scan.” He climbed down; Juan rolled the stairs away. In the data room, Jim Gunn punched a computer key and the video screen went dark. A moment later it filled with galaxies. The galaxies were streaming upward across the screen.

“Whoo!” said Schmidt, breathing hard, slapping a pencil against his palm.

“What are we seeing there?” Don Schneider yelled.

“There’s a galaxy,” Juan said.

“Look at that star truck by,” Don said.

“James! By God!” Maarten said. “Wow! Look at that! Aw, fantastic! We are doing it!”

Gunn smiled. It was a small Gunn grin.

They watched the sky move past for a while, and then they decided to shut down the system. It had been a test. “You can stop the sky now,” Schmidt said.

Gunn hit a key and the galaxies stopped moving.

“I felt a little jerk,” Maarten said, and everyone laughed. He added, “You wouldn’t believe the environmental impact statements we had to file to get the sky to do that.”

The astronomers decided to try it again. Gunn hit a key, and galaxies began climbing upward across the video screen. A look of disbelief spread over Gunn’s face. He could not believe that the kludge was working.

The apparent motion of the night sky, caused by the earth’s rotation, rapidly drew objects up the screen, because Hale Telescope’s field of view covers only a tiny piece of sky. The video monitor displayed the sky’s motion as if the sky were moving from the bottom of the screen to the top: a cloud of galaxies would erupt at the bottom of the screen. In a short while the galaxies would reach the top and disappear one by one, like small bubbles floating up a glass of beer. A computer downstairs was receiving the view and writing it onto spinning tapes.

“How serious is this exercise?” Maarten wondered. Too bad he asked—the screen went blank. 4-shooter had bombed again. Gunn and Schneider pounded keys, while Schmidt paced the room and whistled. Half an hour later, 4-shooter came back to life, and galaxies again floated up the screen. The telescope was looking north, into rotating sky just below the bowl of the Big Dipper. Faint galaxies spattered the screen—usually twenty or thirty galaxies at once—puffs of lint, pinwheels, pearls, eggs, coins. Some galaxies were close and large, but most appeared tiny, resembling bits of confectioner’s sugar sprinkled on black velvet. Occasionally a foreground star inside the Milky Way would splash a brilliant, lingering track on the screen as it passed. The view gave a palpable sense of depth to the sky. A big telescope pointed in any direction except
into the plane of the Milky Way sees many more galaxies than foreground stars. If you took a hamburger bun and picked one of those little black seeds off it—a poppy seed—and you held the seed out at arm’s length, it would just cover the Hale Telescope’s field of view when using 4-shooter. In certain areas of the sky that small, 4-shooter had taken snapshots that held as many as two thousand galaxies. This suggests that the sky is largely unexplored. The universe is rather well explored (by human astronomers) out to a distance of about two hundred million light-years from the Milky Way. Farther out, things become vague, while the edge of the knowable universe has been charted with somewhat less conviction than that of the monk who drew the Americas as a little island west of Greenland.

A pair of wretched galaxies with twisted arms passed. They appeared to be puffed up and ensnared in each other, throwing away tendrils of stars.

“Gaw!” said Maarten. “Ejecting galaxies.”

A while later, a line crossed the screen.

“What was that?” asked Juan Carrasco.

“Somebody flew by,” said Don Schneider.

“It was a meteor,” said Jim Gunn.

The Principal Investigator pulled out a pocket calculator. He examined the width of the line and the angle at which the line had traversed the screen. He said that this was not a meteor. He punched some buttons on the calculator. He said that the thing appeared to be a fat, blurry object on a low orbit that passed near the poles of the earth, which would make it a military satellite, probably a spy satellite.

Don remarked that somebody must be watching. He dug up a bag of Chips Ahoy! cookies and passed them around. He settled into a chair with a fistful of cookies, for a night of television. “Man,” he said, munching a cookie, “this is pretty good stuff.” There were several viewing screens in the data room, including a main screen, which was a video box that sat on a table. All four of 4-shooter’s cameras were gathering strips of sky, but the screens showed an identical view, a scene from one of the four strips.

Maarten tapped the main video screen with a pencil. He said, “That’s a galaxy, that’s a galaxy, that’s a galaxy, that’s a star. These
objects are mostly galaxies.” Some of the fainter objects, he said, would be giant elliptical galaxies near the limits of the Hale Telescope’s ability to collect light. They were fossil images—their light had started toward the Milky Way more than five billion years ago, before the earth had condensed. The telephone rang. Maarten picked it up. “Big Eye,” he said. “O, hallo.” It was his wife, Corrie, calling. They chatted quietly in Dutch. He said, “Ja?… Dat het gaat regenen? O.” He turned to the other astronomers. “She says there’s a pressure area forming in the Pacific. We should be all right for another day or two, then we could get some rain.”