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  3. Two teams of astronomers using the Hubble Space Telescope have overturned several decades of conjecture and theory by ruling out

Two teams of astronomers using the Hubble Space Telescope have overturned several decades of conjecture and theory by ruling out

admin2016-01-30  68
问题     Two teams of astronomers using the Hubble Space Telescope have overturned several decades of conjecture and theory by ruling out the possibility that small, dim stars make up most of the mass in the universe.
    Until now, small stars known as faint red dwarfs were considered ideal candidates for the so-called "dark matter" that is believed to account for more than 90 percent of the mass of the universe.
    All visible celestial objects, such as planets, stars and galaxies, are believed to account for only 10 percent of the mass of the universe. The rest of the "missing mass" is presumably invisible because it does not emit or reflect light, or the light is too feeble to be detected. But dark matter can be indirectly detected due to its gravitational influence on other visible objects.
    According to Bacall, professor of natural science at the Institute of Advanced Study in Princeton, New Jersey and leader of one of the teams, the nature of dark matter, and its abundance, are among the most important questions in modern cosmology today.
    The ultimate fate of the universe will be determined by the amount of dark matter present. If there is not enough dark matter to bind the universe together gravitationally, it could continue expanding forever. If there is enough mass to hold the universe together gravitationally, the universe may slow down its expansion, come to a halt and begin to contract and eventually collapse.
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答案 两组天文学家通过哈勃太空望远镜的观测，推翻了几十年来的猜想和看法，排除了微小而暗淡的怛星是手宙的主要构成物质的可能性。 直到现在，微小的红矮星仍是最被看好的暗物质候选者，“暗物质”被认为代表了宇宙中90％以上的物质构成。 所有可见的天体，如行星、恒星和银河系仅仅占到了宇宙物质总量的10％。其他物质不是因为不能发光或反光,就是因为光太暗而无法直接观测得到。但是通过它自身的重力对其他可见物体的影响，科字家们可以间接地探测到它的存在。 巴考尔是新泽西州普林斯顿大学高级研究院自然科学的教授，同时也是其中一个研究小组的领头人，他说：“现如今宇宙学研究的首要问题就是‘暗物质’的性质和量。” “暗物质”的量关乎宇宙的最终命运。如果没有足够的“暗物质”用引力来限制宇宙的膨胀，那么它就会永远扩张下去。如果有足够的“暗物质”用引力来控制住宇宙，那么它的膨胀就会减慢，继而停止膨胀而逐渐开始收缩，最终被摧毁。
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