共查询到20条相似文献,搜索用时 875 毫秒
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1暗物质存在的发现1937年,天文学家弗·扎维奇(F.Zwick)发现,大型星系团中的星系的运动速度,远远超出星系团核心物质形成的结果,这表明除了人类已知的星系团核心物质对该星系的引力外,还存在其他物质的 相似文献
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评述了天体物理中暗物质的发现以及标准模型所面临的问题,综述了解决这些问题及标准模型之外可能出现的新物理与暗物质的联系。介绍了暗物质粒子选择条件和可能的暗物质粒子的候选者;对圆柱形暗物质表面密度与星系和星系团暗物质晕的晕核半径的关系进行了讨论,与其他模型进行了比较,得出暗物质晕的特征半径r*的暗物质表面密度分布不是一个普适量;并叙述了近几年暗物质研究中提出的新理论模型-Hidden dark matter,最后叙述了中国暗物质实验探测研究的进展,2016年底DAMPE的第一批数据有可能给出;中国锦屏地下实验室(CJPL)的CDEX和PandaX合作组的第一期实验没有发现暗物质粒子存在的信号,期待他们下期的实验。A review of the evidence of the dark matter found in universe and the problems faced by the standard model. To address these issues as well as the possible relationship between the new physics beyond the standard model and dark matter, and given the selection condition of dark matter and possible candidates of the weakly-interacting massive particles (WIMPs). The correlation between the column surface density and the halo core radius of the dark matter halos of galaxies and cluster of galaxies is discussed, and the other models are compared. We find that the surface density within the halo characteristic radius r* is not an universal quantity; The new model (hidden dark matter)proposed in the study of dark matter is described. At last, the research progress of dark matter experiment in China is commented. At the end of 2016, the first batch of DAMPE data may be given;No significant excess events of WIMPS were found in the first stage of both the CDEX and PandaX experiments located in the China Jinping Underground Laboratory(CJPL). Look forward to their the next stage of these experiments in CJPL. 相似文献
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远在30年代,天文学家惠兹克已注意到,在星系团中,星系的绕行速度是如此之快,按理,它们无法稳定地呆在星系团中.他推测存在某种看不到的物质,提供了引力“胶质”.70年代,又发现银河系边缘的恒星运动速度,要比理论家预言的快得多,这也暗示着有大量的暗物质弥漫于星际空间.以后,对旋涡星系旋转情况所作的射电和光学观测表明,它们被暗物质晕所包围.分析了很多星系对和星系群的运动之后,人们确信,星系所含物质的总量,要比其可见的大得多.故天文学家断言,宇宙并不仅仅含有组成我们身体、地球和星星的那类通常物质.所谓通常物质,是指由重子(质子、中子等)组成的物质.而其他粒子,诸如电子,它们数量虽多,但对宇宙质量的贡献是很小的. 相似文献
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笔者最近有机会听了一些老师的初中物理课,在一些老师的“内能”概念教学实践中,笔者发现他们总是在想方设法运用各种教学手段强调如下两个教学要点: 相似文献
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一类不连续不可逆保面积映象可以展示类似耗散的行为,因此可称其为“类耗散系统”.在一种类耗散系统中观察到了椭圆周期轨道及其周围的椭圆岛与映象不连续边界碰撞而消失的现象.周期轨道消失后,经过一系列过渡椭圆周期轨道之后,系统的行为由一个混沌类吸引子主导.在混沌类吸引子刚刚出现时,混沌时间序列呈现层流相与湍流相的无规交替.这一切都与不连续耗散系统中发生的Ⅴ型阵发的相应性质十分相似,因此可称为“类Ⅴ型阵发”.然而,当混沌类吸引子刚刚出现时,仅可以找到最后一个过渡椭圆岛的“遗迹”,并不存在它的“鬼魂”,因此类Ⅴ型阵发不遵从Ⅴ型阵发的特征标度规律.反之,混沌类吸引子的鬼魂却存在于最后一个过渡椭圆周期轨道的类瞬态过程中,因此在类Ⅴ型阵发导致混沌运动的临界点之前,由此“类瞬态混沌奇异集”中逃逸的规律就成为标志这一种临界现象的标度律.这与Ⅴ型阵发又根本不同.
关键词:
类耗散性
类混沌吸引子
类Ⅴ型阵发 相似文献
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Nasuno S 《Chaos (Woodbury, N.Y.)》2003,13(3):1010-1013
Highly localized, dynamic particle-like excitations are observed in a dc-driven, quasi-two-dimensional gas-discharge system. These localized excitations undergo a transition from isolated to aggregated state as the discharge current is increased. Although they provide us a macroscopic analogue of microscopic atoms and molecules, they are quite distinct from the latter in the point that they exhibit a rich variety of complex dynamics. The fact that these localized excitations can show synchronous dynamics even in distant places, together with recent theoretical studies, indicates that a global coupling plays an important role on the dynamics of such localized excitations. 相似文献
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A newly discovered group of alloys, called Gum Metals, approaches ideal strength in bulk form, exhibits significant plastic deformation prior to failure, and shows no indications of conventional-dislocation activity. Two conditions must be met for a material to exhibit this "ideal" behavior: (1) the stress required to trigger conventional-dislocation plasticity in the material must exceed its ideal strength, and (2) the material must be intrinsically ductile when stressed to ideal strength. Gum Metals satisfy both criteria, explaining their remarkable mechanical properties. 相似文献
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Shvartsburg AA Hudgins RR Dugourd P Gutierrez R Frauenheim T Jarrold MF 《Physical review letters》2000,84(11):2421-2424
The hypothesis that fullerenes grow in a carbon plasma by the addition of C2 units (the "fullerene road") has been widely acclaimed as the most plausible mechanism for formation of larger fullerenes including C60 and C70. Calculations suggest that the association of C2 with fullerenes proceeds through two classes of intermediates, "sticks" and "handles." Here we report the observation of these species using high-resolution ion-mobility measurements for C(n) cations generated by laser vaporization of graphite and laser desorption of C60. Sticks with up to eight-atom chains have also been found. 相似文献