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How the stars were born
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Scientists take an incredible journey to the dawn of the universe Richard Ellis paces impatiently back and forth across a small room lined with computer terminals, trying to contain his mounting frustration. Tonight he intended to bag something most astronomers consider next to impossible: the most distant galaxy ever seen -- and not the farthest by just a little bit. The current record for distance, held by Japan's Subaru telescope, is for a galaxy whose light started its journey to Earth a billion years or so after the Big Bang. But Ellis suspects he has found not one but six galaxies from an astonishing half a billion years earlier still. A discovery like that would give astrophysicists their first real glimpse into a crucial and mysterious era in the evolution of the cosmos. Known as the Dark Ages of the universe, it's the 200 million-year period (more or less) after the last flash of light from the Big Bang faded and the first blush of sun-like stars began to appear. What happened during the Dark Ages set the stage for the cosmos we see today, with its billions of magnificent galaxies and everything that they contain -- the shimmering gas clouds, the fiery stars, the tiny planets, the mammoth black holes. When the Dark Ages began, the cosmos was a formless sea of particles; by the time it ended, just a couple hundred million years later, the universe was alight with young stars gathered into nascent galaxies. It was during the Dark Ages that the chemical elements we know so well -- carbon, oxygen, nitrogen and most of the rest -- were first forged out of primordial hydrogen and helium. And it was during this time that the great structures of the modern universe -- superclusters of thousands of galaxies stretching across millions of light-years -- began to assemble. So far, however, even the mightiest telescopes haven't been able to penetrate into that murky era. "We have a photo album of the universe," says Avi Loeb, a theoretical astrophysicist at Harvard University, "but it's missing pages -- as though you had pictures of a child as an infant and then as a teenager, with nothing in between." Ordinarily, you could never see galaxies a mere 500 million years after the Big Bang; they're just too faint for any telescope now in existence. But the universe itself has supplied a way of boosting a telescope's magnifying power. The theory of relativity says massive objects warp the space around them, diverting light rays from their original path. In the 1930s Albert Einstein realized that this meant a star, say, could act as a lens, distorting and amplifying the light from something behind it. In practice, he said, it probably happens so rarely that we will never see it. Einstein was wrong. So-called gravitational lenses have become a major factor in modern astronomy. They have revealed, among other things, the existence of tiny planets around stars thousands of light-years away. If you look at a massive cluster of galaxies, Ellis figured, you might see amplified images of more distant galaxies, too faint to be seen otherwise. So a year or two ago he started aiming Hawaii's Keck telescope at galactic clusters and identified six candidate objects. In order to be sure that these were truly far away, Ellis and his observing partner, graduate student Dan Stark, have come back to the Keck for a second, more intensive look. "We want to be absolutely sure we aren't fooling ourselves," says Ellis. "Before we claim we've really found them. For an hour or so, it looked as though he wouldn't get the chance. But the engineers this night have figured out the problem. When his assistant entered his user name in the online telescope log, he had made a typo. Every time the focusing routine came upon it, the program froze. The typo has now been corrected. The Keck can focus again, and to his delight, Ellis is able to confirm that at least three of their faint galaxies do seem to lie hundreds of millions of light-years farther away -- and hundreds of millions of years closer to the Big Bang -- than anything ever seen before. http://www.cnn.com/2006/TECH/space/08/27/coverstory.tm/index.html |
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