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标题: 北美下午场 [打印本页]

作者: chanelxql 时间: 2019-10-12 06:38
标题: 北美下午场
术靴
0909库的（部分是变体）
2 6 8 21 23 24 36 47 54 81 87 112
有一个求类似长方形的周长长宽为100和75 但是短边各被一个半圆替代
越堵
0909库
十一
十二
二十四
还有一个超长的暗物质相关的

作者: YvonnePan 时间: 2019-10-12 06:51
暗物质那个我找了19年所有的库都没有可能新题？

作者: Starfish2 时间: 2019-10-12 07:42
多谢lz！

作者: billyisfragile! 时间: 2019-10-12 07:52
是原文吗？

https://www.newscientist.com/article/dn11860-ring-of-dark-matter-surrounds-cosmic-collision/
Ring of dark matter surrounds cosmic collision
SPACE 15 May 2007
By David Shiga

A wispy ring of dark matter, detected indirectly by the way its gravity bends light, frames a pair of galaxy clusters. A map of the dark matter (bluish clouds) was combined with a Hubble image of the galaxy clusters to create this view (Illustrated image: NASA/ESA/M J Jee/Johns Hopkins University)

A cloud of dark matter has been detected expanding like a smoke ring from a giant collision between galaxy clusters, a team of astronomers says. If confirmed, the ring could offer new clues to the nature of the mysterious matter.

Dark matter is an enigmatic material that does not emit, absorb or reflect light. It reveals itself only by the way its gravity influences normal matter around it and seems to outweigh the universe’s normal matter by a factor of six.

Now, astronomers have discovered what looks like a ring of dark matter expanding from a cosmic clash involving two massive galaxy clusters. If confirmed, the ring will help astronomers investigate how dark matter behaves when disturbed, perhaps providing hints to its nature.

Myungkook James Jee of Johns Hopkins University in Maryland, US, led the team of researchers that made the discovery. They detected the ring in Hubble Space Telescope (HST) observations of a galaxy cluster called Cl 0024+17, which is 5 billion light years from Earth in the direction of the constellation Pisces.

They carefully observed how matter in the cluster bends the paths of light rays coming from distant background galaxies. This ‘gravitational lensing’ effect allowed them to map out the distribution of matter, including dark matter, in the cluster.

Colossal collision

They found a curious ring-like structure around the cluster’s outskirts. The researchers believe the ring is made of dark matter, since there is no concentration of visible matter at the location of the ring. Most of the cluster’s ordinary matter is thought to be in the form of hot gas, which was mapped by the Chandra X-ray Observatory, and is concentrated at the cluster’s core.

Previous studies have hinted that Cl 0024+17 is not a single galaxy cluster but a pair of clusters that have collided. Simulations show that when such a colossal collision occurs – in this case, it involved almost 200 billion Suns’ worth of matter – the cluster’s dark matter explodes outwards, forming a roughly spherical shell. Watch an animation of the collision and dark matter explosion.

Projected on the sky, such a shell would look like the ring observed in the gravitational lensing study, the researchers say. They estimate that the collision happened sometime between 1 billion and 2 billion years ago.
Modified gravity

Some scientists have previously suggested that modifications to Newton’s law of gravity could account for anomalies cited as evidence for dark matter (see Equinox challenge to Newton’s law). This possibility can be difficult to rule out, because normally dark matter and ordinary matter are so well mixed together that it is difficult to pin down effects due to dark matter alone.
But because the ring in Cl 0024+17 is separate from any concentrations of ordinary matter, it would be difficult to explain without dark matter, the researchers say. “I think it’s the strongest evidence for the existence of dark matter to date,” Jee told New Scientist.

A previous study revealed the separation of dark matter and ordinary matter in the Bullet Cluster of galaxies, but in the case of Cl 0024+17, the separation is even more complete.
Marusa Bradac of the Stanford Linear Accelerator Center in (SLAC) in Menlo Park, California, US, who co-authored the Bullet Cluster study, says if the dark matter ring is real, it will be an important laboratory for studying the properties of dark matter.

Instrumental effects

That is because the ring’s characteristics, such as its exact shape, depend on the properties of dark matter particles, like whether they bounce off one another when they meet, or just pass right through one another.
“It’s a very exciting result, and if it’s real, its going to give us a ton of information about dark matter,” she told New Scientist.

But she says gravitational lensing effects of the kind used in the study are very subtle and could be confused with slight distortions that can arise in observations because of imperfect instruments.

“I’m not saying that I don’t trust the result, but at this point I would just be slightly sceptical,” she says. She acknowledges, however, that the team “did do a very careful analysis” of the data.

Exotic particles

The team itself initially suspected the ring was some kind of illusion introduced by Hubble’s instruments but could not find any such effects. In any case, Jee says, if the ring were an instrumental effect, it should show up in similar Hubble observations obtained of other galaxy clusters. But those observations show no sign of rings.

He says the mere existence of the ring shows that the dark matter particles do not interact strongly with one another through any force other than gravity. That is true for the most popular candidates for dark matter – exotic subatomic particles with names like axions and neutralinos.

But alternative candidates, such as “mirror matter” – a form of matter that interacts readily with itself through a range of forces – would tend to collide more frequently. “If there is any collisionary interaction between dark matter particles, then it can smear out the very subtle shell-like structure,” Jee says.

作者: billyisfragile! 时间: 2019-10-12 08:32

YvonnePan 发表于 2019-10-12 06:51
暗物质那个我找了19年所有的库都没有可能新题？

https://forum.chasedream.com/thread-1326949-1-1.html

三十、【考古】Dark matter

https://forum.chasedream.com/thread-912608-1-1.html

作者: justinhsh 时间: 2019-10-12 09:33
lz输血部分的题号是CD的0909寂静的题号吗

作者: Starfish2 时间: 2019-10-12 09:44

justinhsh 发表于 2019-10-12 09:33
lz输血部分的题号是CD的0909寂静的题号吗

没错，我已经看了一些了，结合前两位放JJ的帖子，确实有一些跟9.9库重的

作者: 章鱼宝宝o 时间: 2019-10-12 10:35
楼主，阅读工业设计心理学画作还有共同进化吗

作者: chanelxql 时间: 2019-10-12 10:58

bzy! 发表于 2019-10-12 07:52
是原文吗？

https://www.newscientist.com/article/dn11860-ring-of-dark-matter-surrounds-cosmic-collis ...

不是这篇。
只记得最后一段关于一个s开头的术语的阐述。还有两个r开头的词，非常像。

作者: chanelxql 时间: 2019-10-12 10:58

章鱼宝宝o 发表于 2019-10-12 10:35
楼主，阅读工业设计心理学画作还有共同进化吗

是的

作者: billyisfragile! 时间: 2019-10-12 11:34

chanelxql 发表于 2019-10-12 10:58
不是这篇。
只记得最后一段关于一个s开头的术语的阐述。还有两个r开头的词，非常像。 ...

V8 bybemyself2010 690

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)

说明：
1）当时看这里时，有点不理解，为什么是“轻”而stable，而不是“重”而stable。当时以为是狗主笔误。不过原题的英文的确是“轻”，用的是“lightest”这个词。
2）第四段整个都是在论述neutronilo。不过，在正式出现neutronilo之前，第一句里出现了类似于“supersymmetric”这样一个词（可能还要多一两个字母，记不清了，抱歉）。这个词的用意，我说一下我个人的理解。从行文逻辑上推理，第一段说了暗物质，第二/三段分别介绍了porton、neutron和neutrino的特性，由此排除他们不是暗物质之后，第四段就应该说谁可能是暗物质。从第四段的意思看，这个neutronilo是符合暗物质特性的。但是，我之前查过英文背景资料，似乎是说这个neutronilo只是一个理论上存在的物质，并没有真正找到。所以，开头第一句用到的是类似于“supersymmetric”这个词，大概意思是“根据超对称性理论， neutronilo如何如何。”从而给nuetronilo的出场提供一个由头。“supersymmetric”这个词长得很生僻，但应该不影响做题。
3）另外，文章的二/三段里，说到porton和neutron和neutrino时（忘记具体是说这三者中的哪一个）用到了“lightweight”这个词。

作者: 白白er 时间: 2019-10-12 14:13
考古！！

作者: 百万！ 时间: 2019-10-12 17:21
CD0909的寂静库在哪里能看到呀？求助

作者: billyisfragile! 时间: 2019-10-12 17:34

百万！发表于 2019-10-12 17:21
CD0909的寂静库在哪里能看到呀？求助

https://forum.chasedream.com/thread-420286-1-1.html

https://forum.chasedream.com/thread-1351565-1-1.html

作者: 百万！ 时间: 2019-10-12 17:36
小白向各位大佬请教一下

CD的0909寂静库在哪里看呀？我找到了整合贴但是没有看到有题号的整理？

作者: 百万！ 时间: 2019-10-12 17:38
https://forum.chasedream.com/thread-1351297-1-1.html
找到了

感谢楼主！

作者: 百万！ 时间: 2019-10-12 22:42

bzy! 发表于 2019-10-12 17:34
https://forum.chasedream.com/thread-420286-1-1.html

https://forum.chasedream.com/thread-1351565-1 ...

感谢！

作者: yky_yky 时间: 2019-10-13 00:13

bzy! 发表于 2019-10-12 17:34
https://forum.chasedream.com/thread-420286-1-1.html

https://forum.chasedream.com/thread-1351565-1 ...

大神植物那篇文章你有原文吗

作者: billyisfragile! 时间: 2019-10-13 08:38

yky_yky 发表于 2019-10-13 00:13
大神植物那篇文章你有原文吗

which one?

作者: 弱鸡小梁 时间: 2019-10-13 11:16

bzy! 发表于 2019-10-12 08:32
https://forum.chasedream.com/thread-1326949-1-1.html

三十、【考古】Dark matter

Mark一下！

作者: 弱鸡小梁 时间: 2019-10-13 11:16

bzy! 发表于 2019-10-12 08:32
https://forum.chasedream.com/thread-1326949-1-1.html

三十、【考古】Dark matter

感激不尽！求确认是不是这个考题

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