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标题: 宇宙暗物质~?求确认 [打印本页]

作者: 战斗扭 时间: 2012-5-9 17:49
标题: 宇宙暗物质~?求确认
V3 by moonrocki

第一题上来就是宇宙dark matter那题那叫一个长啊
就是在探讨说the mass of universe其实重点不在visible particles
而是在invisible particles。而对invisible particles其实我们的研究还不够多。
说proton和neotron(拼错) 他们在很久很久以前跑的比光速还快他们速度很快
然后他们特别轻现在一个standard的hypothesis（有题问这个方法证明的是啥）也无法证明没记清楚反正
后来说发现了一个新的粒子叫neotrolias(拼错，但是有个a)，他们又有mass又有speed
反正能证明dark matter的重量神马的。

V4 by athenelynn 740

那个宇宙射线问题，其实思路很简单，主要讨论的是人眼为什么没有进化出功能来识别可见光之外的其它光，理由就是（1）在这些其它光到达地球之前被吸收了；（2）太阳等散发的光中大部分是可见光，那些其它频率的本来占的也是少数

V5 by yysbinzhou M49 V29

大约就是介绍宇宙有什么暗物质组成然后说这种暗物质里包含了什么，一个一个的提出然后再一个一个的否定，最后好像又讲到一种新的物质
我唯一记得的是，第二段最再否定了第一种之后，然后又提出了新的假设，有可能是有什么什么东西，接着（高亮开始）一个实验表明这种物质的速度比光速还要快blabla~~~ （高亮结束）然后就是说用这实验否定了这种物质题目。问这个高亮的作用，我选的解释前面的假设什么的好像。。。。（不一定对大家谨慎参考）
接下来一段介绍了一种新物质N~~~ 和最开始提到N~~~ 他们的拼写看起来很像，但是他们很不同（这句话不是我的回忆原文就是这么说的）然后说这个物质的特性（此处有题问两种N物质的差别是什么。。。我没读懂，完全不知道，我读了这句话的前后，没感觉有特别明确的答案）
最悲剧的是这片文章问的题目全部都是类似于：关于某物质作者同意以下哪种观点。读不懂文章就确定不下来的那种。希望有天文学方面的N人可以读懂正篇文章，然后造福大众吧。。。。

V6 by cuppyan123

黑物质叫Black Matter。文章还提到一个东西很重要，是“Neutralino”，好像有题。黑物质还分hot 和cold。我找来的Neutralino和black Matter的关系，也就这个还跟原文沾点儿边：
As a heavy, stable particle, the lightest neutralino is an excellent candidate to comprise the universe's cold dark matter. In many models the lightest neutralino can be produced thermally in the hot early universe and leave approximately the right relic abundance to account for the observed dark matter. A lightest neutralino of roughly 10–10000 GeV is the leading weakly interacting massive particle (WIMP) dark matter candidate.
Neutralino dark matter could be observed experimentally in nature either indirectly or directly. In the former case, gamma ray and neutrino telescopes look for evidence of neutralino annihilation in regions of high dark matter density such as the galactic or solar center. In the latter case, special purpose experiments such as the Cryogenic Dark Matter Search (CDMS) seek to detect the rare impacts of WIMPs in terrestrial detectors. These experiments have begun to probe interesting supersymmetric parameter space, excluding some models for neutralino dark matter, and upgraded experiments with greater sensitivity are under development.

V7 by GMAT798
宇宙的dark物质很长很长 2屏吧。说恒星行星小彗星什么的占宇宙总质量不过5个点，其他的是什么捏？那都是dark物质啦（有题）
然后猜想 dark物质是netroxxxxxx 比中子的netro长4个字母的单词，有的特性是（有题）mass，stability，电中性。

V8 by bemyself2010 690

第一段讲:宇宙中大家知道的物质只占了5%,剩下的都是暗物质.剩下的不记得了.第一段没什么出题点
第二段:提问,暗物质是由什么组成的?P和N不是,接下来是"Nor can more than a few of Neutrino怎么怎么的,意思是Neutrino也不是暗物质. 接下来高亮"一个关于newtrino的实验,说它很轻啦,速度很快啦,因此很hot "总之也不是dark matter.
第三段: 记得个fit的词(我理解是根据以上neutrino特征的反面推出的dark matter的特征), 能fit dark matter的物质具有的特点是cold, sluggish等等. 貌似在现在的cosmatic中不存在,但是在standard的假说中有一种neutranilo的物质符合
第四段: 主要讲neutronilo的,这里提到它不被electromagnetic怎么着(在比较俩个N不同的选项里出现),同时它又是最轻的,它又很stable, 因为如果不够轻的话就会不stable从而被分成俩个更轻的(很绕的逻辑),
第二段和第四段非常长,而且有很多细节题.
第一题:高亮的实验的作用
记得的选项是:1,回答段首的问题.2,支持前面那句话"nor more than".3,为了第三段什么的.我选了第二个.
第二题:Neutrino 和 neutranilo的描述哪个正确(以下简称n1,n2)
1,n2在宇宙初期不被electromagnetic影响(我犹豫了下,文中是提到有,但是没有前面的宇宙初期的限定,我没选)
2,n2比n1重.(我选的这个)
3,n1不stable(文中没提)
4,n2在cosmic中实际上还没被发现?(我排除了)

V9 BY lupin 700

狗狗里面考古的V8说的很准确，感谢作者，感谢~~
第三段结尾说，这个物质宇宙中没有发现，但是有一个什么什么的模型吧可以推测好像，然后进入第四段开始推测这种物质的特点。(这个模型有题，其实就是在第四段的内容里面找)
第四段说了symmetric的观点，好像是说宇宙中的物质都有其对称的物质，然后开始根据N推测(哪个N记不得了)，最后结果是这个物质是massive,stable,sluggish的
有一题说下列哪个是正确的，选了一个说Neutrilino比other super**的要stable，不确定
还有一题说关于mass of universe正确的是，好像这么问的，我选的是dark matter的质量那些看的见得gas啊，还什么东东的要重，也不确定

V10 BY 粉红—台灯

dark matters暗物质（1）开头是暗物质的定义：Stars, loose gas,..........5% visual（第一句话有考题第三题我的答案就是把这句话同意改写答案用词invisual）（2）问Neutralino的特点：选项有两个numerous..., mass, not stable,sluggish.

搜索：伍月（待确认）

In the 1980's, astronomer BohdanPaczynski proposed a way of determining whether the enormous dark haloconstituting the outermost part of the Milky Way galaxy is composed of MACHO's(massive compact halo objects), which are astronomical objects too dim to bevisible.

aczynski reasoned that ifMACHO's make up this halo, a MACHO would occasionally drift in front of a starin the Large Magellanic Cloud, a bright galaxy near the Milky Way. The gravity of a MACHO that had so drifted,astronomers agree, would cause the star's light rays, which would otherwisediverge, to bend together so that, as observed from Earth, the star wouldtemporarily appear to brighten, a process known as microlensing. Because many individual stars are ofintrinsically variable brightness, some astronomers have contended that the brighteningof intrinsically variable stars can be mistaken for microlensing. However, whereas the different colors oflight emitted by an intrinsically variable star are affected differently whenthe star brightens, all of a star's colors are equally affected bymicrolensing. Thus, if a MACHO magnifiesa star's red light tenfold, it will do the same to the star's blue light andyellow light. Moreover, it is highlyunlikely that a star in the Large Magellanic Cloud will undergo microlensingmore than once, because the chance that a second MACHO would pass in front ofexactly the same star is minuscule.

Question #55. 639-01 (23881-!-item-!-188;#058&000639-01)
It can be inferred from the passagethat which of the following would constitute the strongest evidence of themicrolensing of a star in the Large Magellanic Cloud?

(A) The brightness of such a staris observed to vary at irregular intervals.
(B) The brightening of such a staris observed to be of shorter duration than the brightening of neighboringstars.
(C) The red light of such a star isobserved to be brighter than its yellow light and its blue light.
(D) The red light, yellow light,and blue light of such a star are observed to be magnified temporarily by thesame factor.
(E) The red light of such a star isobserved to have increased tenfold.

Question #56. 639-04 (23927-!-item-!-188;#058&000639-04)
According to the passage,Paczynski's theory presumes that if MACHO's constituted the Milky Way's darkhalo, occasionally a MACHO would

(A) drift so as to lie in a directline between two stars in the outer Milky Way
(B) affect the light rays of a starin the Large Magellanic Cloud with the result that the star would seem for atime to brighten
(C) become obscured as a result ofthe microlensing of a star in the Large Magellanic Cloud
(D) temporarily increase theapparent brightness of a star in the Large Magellanic Cloud by increasing thegravity of the star
(E) magnify each color in thespectrum of a star in the Large Magellanic Cloud by a different amount

Question #57. 639-06 (23973-!-item-!-188;#058&000639-06)
The passage is primarily concernedwith

(A) outlining reasons why aparticular theory is no longer credited by some astronomers
(B) presenting data collected by aresearcher in response to some astronomers' criticism of a particular line ofreasoning
(C) explaining why a researcherproposed a particular theory and illustrating how influential that theory hasbeen
(D) showing how a researcher'stheory has been used to settle a dispute between the researcher and someastronomers
(E) describing a line of reasoningput forth by a researcher and addressing a contention concerning that line ofreasoning

答案是DBE

今天有些不想学习看不进去。。。。顺便就搜了一下考古= =嗯。。。决定考好了以后留驻CD做一名考古学家

作者: linshenzi 时间: 2012-5-9 17:59
hahah...

作者: dragonbabe 时间: 2012-5-9 18:12
这篇不是prep里的吗？是这个月出现了吗？求确认

作者: Evangeline13 时间: 2012-5-9 19:34
up

作者: 超级无敌萍 时间: 2012-5-9 19:37
up

作者: Roxas605 时间: 2012-5-9 20:54
我也觉得会不会是这一篇，我已经转过去了。

http://forum.chasedream.com/GMAT_Math/thread-712329-21-1.html

作者: Yuke1212 时间: 2012-5-9 22:22
UP 谢谢考古！

作者: irenechl 时间: 2012-5-9 23:05
thx~

作者: chenyao16887 时间: 2012-5-10 09:57
up

作者: ctyl95 时间: 2024-7-22 11:39

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