脉冲星:宇宙的物理学“礼物”-凯发k8官网

脉冲星:宇宙的物理学“礼物”
文章来源:未知 文章作者:enread 发布时间:2012-02-21 04:52 字体: [ ] 
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pulsars(脉冲星) , superdense 2 stars, are perhaps the most extraordinary physics laboratories in the universe. research on these extreme and exotic objects already has produced two nobel prizes. pulsar researchers now are 3 to learn otherwise-unavailable details of nuclear physics, to test general relativity in conditions of extremely strong gravity, and to directly detect gravitational waves with a "telescope" nearly the size of our 4. neutron stars are the remnants of massive stars that exploded as supernovae(超新星) . they pack more than the mass of the sun into a sphere(范围,球体) no larger than a medium-sized city, making them the 5 objects in the universe, except for black holes, for which the concept of 6 is theoretically 7. pulsars are neutron stars that emit beams of radio waves outward from the poles of their magnetic fields. when their 8 spins a beam across earth, radio telescopes detect that as a "pulse" of radio waves.

by 9 measuring the 10 of such pulses, 11 can use pulsars for unique "experiments" at the frontiers of modern physics. three scientists presented the results of such work, and the promise of future discoveries, at the american association for the 12 of science meeting in vancouver, british columbia.

pulsars are at the forefront of research on gravity. albert einstein published his theory of general relativity in 1916, and his description of the nature of gravity has, so far, withstood numerous experimental tests. however, there are competing theories.

"many of these alternate theories do just as good a job as general relativity of predicting behavior within our solar system. one area where they differ, though, is in the extremely 1 environment of a neutron star," said ingrid stairs, of the university of british columbia.

in some of the alternate theories, gravity's behavior should vary based on the internal structure of the neutron star.

"by carefully timing pulsar pulses, we can precisely measure the properties of the neutron stars. several sets of observations have shown that pulsars' motions are not dependent on their structure, so general relativity is safe so far," stairs explained.

recent research on pulsars in binary-star systems with other neutron stars, and, in one case, with another pulsar, offer the best tests yet of general relativity in very strong gravity. the precision of such measurements is expected to get even better in the future, stairs said.

another prediction of general relativity is that motions of masses in the universe should cause 13 of space-time in the form of gravitational waves. such waves have yet to be directly detected, but study of pulsars in binary-star systems have given indirect evidence for their existence. that work won a nobel prize in 1993.

now, astronomers are using pulsars throughout our 14 way galaxy as a giant scientific instrument to directly detect gravitational waves.

"pulsars are such extremely precise timepieces that we can use them to detect gravitational waves in a frequency range to which no other experiment will be sensitive," said benjamin stappers, of the university of manchester in the uk.



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1 aonzx     
a.密集的,稠密的,浓密的;密度大的
参考例句:
  • the general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
  • the path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。
2 neutron     
n.中子
参考例句:
  • neutron is neutral and slightly heavier than the proton.中子是中性的,比质子略重。
  • based on the neutron energy,the value of weighting factor was given.根据中子能量给出了相应的辐射权重因子的数值。
3 slhzbu     
a.摆好姿势不动的
参考例句:
  • the hawk poised in mid-air ready to swoop. 老鹰在半空中盘旋,准备俯冲。
  • tina was tense, her hand poised over the telephone. 蒂娜心情紧张,手悬在电话机上。
4 ohoxb     
n.星系;银河系;一群(杰出或著名的人物)
参考例句:
  • the earth is one of the planets in the galaxy.地球是银河系中的星球之一。
  • the company has a galaxy of talent.该公司拥有一批优秀的人才。
5 196f3886c6c5dffe98d26ccca5d0e045     
密集的( dense的最高级 ); 密度大的; 愚笨的; (信息量大得)难理解的
参考例句:
  • past botoi some of the densest jungle forests on anopopei grew virtually into the water. 过了坊远湾,岛上的莽莽丛林便几乎直长到水中。
  • earth is the densest of all of these remaining planets. 地球是所剩下行星中最致密的星球。
6 rodzz     
n.密集,密度,浓度
参考例句:
  • the population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • the region has a very high population density.该地区的人口密度很高。
7 zkgy6     
adj.不恰当的,无关系的,不相干的
参考例句:
  • that is completely irrelevant to the subject under discussion.这跟讨论的主题完全不相关。
  • a question about arithmetic is irrelevant in a music lesson.在音乐课上,一个数学的问题是风马牛不相及的。
8 lxmxe     
n.旋转;循环,轮流
参考例句:
  • crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
  • the workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。
9 zlwzub     
adv.恰好,正好,精确地,细致地
参考例句:
  • it's precisely that sort of slick sales-talk that i mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • the man adjusted very precisely.那个人调得很准。
10 rguzgc     
n.时间安排,时间选择
参考例句:
  • the timing of the meeting is not convenient.会议的时间安排不合适。
  • the timing of our statement is very opportune.我们发表声明选择的时机很恰当。
11 569155f16962e086bd7de77deceefcbd     
n.天文学者,天文学家( astronomer的名词复数 )
参考例句:
  • astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
  • astronomers used to ask why only saturn has rings. 天文学家们过去一直感到奇怪,为什么只有土星有光环。 来自《简明英汉词典》
12 tzgzil     
n.前进,促进,提升
参考例句:
  • his new contribution to the advancement of physiology was well appreciated.他对生理学发展的新贡献获得高度赞赏。
  • the aim of a university should be the advancement of learning.大学的目标应是促进学术。
13 a0726bd74d4516cd6fbe05e362bc74af     
n.骚乱( disturbance的名词复数 );打扰;困扰;障碍
参考例句:
  • the government has set up a commission of inquiry into the disturbances at the prison. 政府成立了一个委员会来调查监狱骚乱事件。
  • extra police were called in to quell the disturbances. 已调集了增援警力来平定骚乱。
14 jd0xg     
adj.牛奶的,多奶的;乳白色的
参考例句:
  • alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
  • i like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。
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