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National Geographic : 1974 May
Contents
JAMESP. BLAIR(TOP); FRANKJ. LOWANDGEORGEH. RIEKE Taking space's temperature... Arming his tel escope with a sensor of supercooled germanium (in the gold-plated box above his hand), Professor Frank J. Low of the University of Arizona scans the heavens for slight temperature variations. Converting these infrared readings into a color coded map, he obtains a picture of the Milky Way's center (lower). Great clouds of interstellar dust hide the center of the galaxy from optical astronomers. Dust and gas may constitute a sig nificant part of the matter in the universe. in brightness faster than the time it takes light to cross it. Therefore if a quasar is seen to change substantially within a week, it can be only a few times larger than our solar system, which light can cross in just about half a day. By contrast, light requires 100,000 years to traverse our galaxy. So the quasars are remarkably small, ce lestially speaking. But if they are so small, and yet we can see them at such prodigious distances, they must be emitting energy at an unheard-of rate. In fact, some quasars pro duce more energy than a hundred large gal axies, totaling as many as ten thousand billion stars. In one second a typical quasar throws out enough energy to supply all earth's elec trical needs for billions of years. To account for such stupendous energies is difficult. Some scientists believe that even the nuclear processes in the atom are not suf ficient, and suggest such extreme sources as massive gravitational collapse or even the annihilation caused by collision of matter and its counterpart, antimatter. And that is one reason why a few scientists are loath to believe that the quasars are truly cosmological-that is, at the outer reaches of the universe. A small group of astronomers argue that the quasars are local, probably among nearby galaxies, and that the large red shifts are caused by gravitation or some other circumstance, not by swift recession at great distances. If this view is correct, then of course the quasars are not emitting phe nomenal amounts of energy at all. But the large majority of astrophysicists favor the cosmological theory. As the most eminent of Dutch astronomers, Professor Jan Oort of Leiden Observatory in the Nether lands, told me, "If the quasars are not cosmo logical, it would raise so many questions that I'm not willing to countenance them. I think the quasars are extremely important for cosmological research." Maarten Schmidt himself leans toward this view: "I think of the quasar as the brilliant central core of some much larger object, per haps the nucleus of a galaxy about to be born. But we know very little yet, and it is still very uncertain." With philosophical humor he adds: "When we look at a quasar over such enor mous distances, we are looking back in time almost to the beginning. Are we therefore seeing now almost all the available universe? Will we get cosmic claustrophobia?" National Geographic,May 1974 608
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