PROFESSOR RICHARD KRON-ASTRONOMY
THE MAP, IF YOU PLEASE, MR. SPOCK . . .
Every day at the stroke of noon, University of Chicago astronomers take a break from their studies of the cosmos and assemble for two minutes in a large, overheated passageway at Yerkes Observatory in Williams Bay, Wis. The purpose: To learn if anyone has discovered anything overnight-a new galaxy, a dying star, a meteor screaming toward Earth.
Richard Kron has not attended one of these ”Eureka!” meetings in months. He has been too busy. But when his current project, still in the early stages, comes to fruition a few years from now, he will be able to top everybody when he finally does drop by. For if all goes according to plan, by the time the project is finished in the year 2000, Kron will have discovered not one, not two, but the unfathomable total of nearly 200 million new galaxies and stars, all at one blow. And-hang on, now-he won`t even be trying. He will find all these heavenly objects in passing, as a byproduct of his real goal, which-hold on, again-is to produce a detailed, motor club-style map of the universe, astronautical mile by astronautical mile, as if it were Greater Los Angeles.
”Existing maps only have a couple of thousand objects in them,” says Kron, professor of astronomy and astrophysics at the U. of C. and director of Yerkes, which the school owns. The observatory is a patch of U. of C. territory in the middle of Wisconsin, just as a Vatican consulate is part of the Holy See. ”So this map will be about 100 times as detailed. It will be an incredible jump over the past.”
All right, you ask, why should anybody want a map of the universe? The first answer is pretty obvious. To find things. Things people didn`t even know they wanted to find. Most of the 200 million or so galaxies, stars and quasars on the map will be new to science-never before seen. It will be up to other astronomers to study and name these features.
”We can`t undertake that,” admits Kron, who, at 39, is a trim, informally dressed man, the son of two San Francisco-based astronomers, who divides his harried time running between Yerkes, Fermilab and the university. ”We would be overwhelmed by all that data. It`s 10 million megabytes, equivalent to the information contained in a telephone directory listing 250 billion people.”
Instead, project participants-who, besides the University of Chicago, consist of Princeton University, Fermilab and the privately run Institute for Advanced Study-will use the data to answer more profound questions, questions that threaten to upset moder According to the Big Bang hypothesis (the currently accepted view that the cosmos began with a cataclysmic explosion from a siy in all directions. Instead, matter nests. Stars are bunched into galaxies, and galaxies crowd into clusters and clusters of clusters. Moreover, some galaxies are spirals; others, such as our Milky Way, are disc-shaped; and still others take on every shape imaginable.
”So you have high-density regions occurring occasionally,” Kron says.
”In between, are gigantic voids, hundreds of millions of light years in diameter. This emptiness contains the so-called `dark matter,` the mysterious invisible mass. You can`t see it, but we know it`s there, because it exerts gravitational influence.
”So now there`s another way to view the universe. Formerly, we thought of it as matter with some empty space between. Instead, it turns out to be 180 degrees the other way. The universe is largely empty, with clusters of galaxies where the voids are not. These galaxies surround the voids in some structure-filaments, sheets or even, as some have suggested, in bubbles, like soap bubble surfaces.”
Determining the nature of these odd structures is one question to be answered. The structures, and the much larger structure they collectively form that makes up what we call the ”universe,” are of such large scale that until now, no one has been able to recognize a pattern in them. The map should take care of that.
Another question involves how the structures were formed in the first place. Some think the shape of the universe was dictated by the influence of subatomic particles whose identity is still unknown, particles that acted as
”seeds” or mini-diagrams of these gargantuan structures during the first fraction of a second of the Big Bang. Again, the map, or ”sky survey” as it is officially called, may shed some light on the issue, just as it might provide clues as to the purpose and origin of dark matter.
Kron`s own research passion is to determine ”whether and by how much the universe has evolved. A basic precept of the Big Bang is that objects are growing farther apart with time. That ought to be manifest in the properties of galaxies and quasars (very distant, starlike objects with the brightness of a hundred galaxies, condensed into the size of one small galaxy). If we could make some measurements, we could see if these properties are consistent with movement.”
The problem, as Kron points out, is that one cannot look at the same distant object at two different times without waiting many years. ”I can only look at two different objects,” he says, ”an ensemble of things at great distances, to see if they are perceptibly different from things nearby.”
The three-dimensional map, which will simultaneously show relatively nearby objects and objects at very great distances-as much as 15 billion light years away (the light we see now from these remote stars and quasars was actually emitted 15 billion years ago, shortly after the Big Bang)-will tell Kron and others whether the distant bodies are the direct ancestors of the bodies we see close up, as they would be if there were expansion and movement in the universe.
The way one tells the difference between a distant star and a close one is not so obvious. The skyscape looks flat, like a theater ceiling, all the stars shining with an intensity that does not betray their position in the firmament. A quasar billions of light years away can shine with the same glare as a star a ”nearby” few million light years away.
So over the years, astronomers have developed an instrument called a spectrograph, which detects the so-called ”red shift” present in the light from distant stars. Red shift refers to the tendency of distant light, which is receding from us, to become longer in wave length and thus pointed toward the red end of the color spectrum. The greater the shift to the red, the farther away the object is.
Kron hopes that by showing movement, he will establish that the momentum of celestial objects comes from the Big Bang. He also wants to have a large enough sample of objects to come up with some kind of typical number of objects per given patch of sky. Such a pan-universal average, which would permit one to make some assertions about what is going on in parts of the sky one cannot readily see, should be facilitated by the map.
The map is not really a map at all but a highly detailed digital photograph shot in a series of contiguous strips by a scanning telescope. And it won`t really show the entire universe, only a quadrant of it. Although the project`s 20 scientists have the capability of shooting the complete universe, cost limits them to a quarter of the sky-two triangular views pointing toward Virgo and away from the Milky Way (whose gases and dust absorb light and would interfere with the picture). As it is, the project will cost approximately $20 million.
The telescope, a 2.5-meter scope with a very wide-angle view (about 3 degrees-an area of sky 36 times the size of a full moon) is to be located at Apache Point in the Sacramento Mountains of New Mexico. It will take three years to construct (the mirror is being ground right now). Five more years will be needed to take the picture, giving the map a target completion date of the year 2000.
The telescope will feature a camera with 47 special light detectors, similar to those in consumer videocams but distinguished by extremely low
”noise.”
”This camera will push technology beyond where it`s been before,” says Kron, noting that the light detectors will record 120 million points of light at one time, making President Bush look like a piker. The camera image will be shot through four filters- ultraviolet, blue, red and infrared-permitting a full-color photo. Infrared is particularly important because far objects can only be detected by infrared light.
The telescope will also be fitted with a powerful spectrograph, which will be able to measure the light color of some 600 celestial bodies at once. To perform this task, the instrument is to be fed light images from each object via optical fibers. A computerized robot will drill small holes in a metal plate at the precise positions occupied by these images, requiring an accuracy of one one-thousandth of an inch. Another computer will insert one end of 600 optical fibers into these holes, and the other ends into the spectrograph in a perfectly corresponding pattern. The metal plate will then be mounted to the telescope and the light from distant galaxies directed through the fibers to the spectrograph, which can then measure the red shifts. The map will depict the sky to a scale of 0.4 light seconds, equivalent to mapping the Earth`s surface to a resolution of 40 feet between features.
The telescope will scan night after night, switching back and forth from camera to spectrograph, creating 15,000 contiguous ”tiles” or cells that will be spliced together by computer to make a single photograph. On that photograph will be captured the images of nearly 100,000 galaxies and 100,000 stars, almost all of them never witnessed by humankind.
”No one has ever built a camera like this before,” says Kron, who can be forgiven a boast. ”It should be a real showstopper.”
