本帖最后由 zerowing 于 2015-11-6 10:48 编辑
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7 j' V* \: y: {8 [- K8 G4 a* m4 S% L恩,以后就以这个为标题形成一个系列了。每周更新一次。感谢关注。7 F7 K7 R" u% ^! C( D1 {
* p( `3 ~$ t1 q6 z; l. `Strong forces make antimatter stick0 u4 Z/ u; F; s# f
强力致使反物质结合 , @; Q, M }' N- C: n: Y) O
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9 o& _2 a q: YPhysicists have shed new light on one of the greatest mysteries in science: Why the Universe consists primarily of matter and not antimatter.. u4 _6 ~! `# _ W3 v% r( g
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Antimatter is a shadowy mirror image of the ordinary matter we are familiar with.
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7 H0 E8 _ } \+ e/ y$ i* oFor the first time, scientists have measured the forces that make certain antimatter particles stick together.
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The findings, published in Nature, may yield clues to what led to the scarcity of antimatter in the cosmos today. / f" f0 O$ H" i! O2 b% N6 J
2 ~2 I' C- `# _" e5 dThe forces between antimatter particles - in this case antiprotons - had not been measured before. If antiprotons were found to behave in a different way to their "mirror images" (the ordinary proton particles that are found in atoms) it might provide a potential explanation for what is known as "matter/antimatter asymmetry".
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* `0 }% u/ Z% j! U5 ` Z/ @At the beginning of the Universe, the Big Bang produced matter and antimatter in equal amounts. But that's not the world we see today: instead antimatter is extremely rare. # r) ]* ?. ~+ P& N( @1 c
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Some phenomenon must have led to the overwhelming dominance of matter; scientists have their theories, but the evidence remains elusive. ) i' Z3 c3 I. {; r
8 B; n3 a w: i, Q$ Q! b6 o: F"Although this puzzle has been known for decades and little clues have emerged, it remains one of the big challenges of science," said co-author Aihong Tang, from the Brookhaven National Laboratory in New York, US.
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"Anything we learn about the nature of antimatter can potentially contribute to solving this puzzle."
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5 C% Q" W1 K8 c. a物理学家新近揭示科学界一大未解之谜:为什么宇宙主要由物质组成,而非反物质。/ U( m9 A( l2 c$ a
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正如我们所熟悉的那样,反物质是物质的一个阴暗镜像(性质相反,但却难以看到)。; |' q0 {. r. C
6 K3 c9 f3 k7 M- ?而也是第一次,科学家们成功测量连接反物质粒子间的结合力。
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- s w/ `3 H. A/ e这篇发表在 自然 网站上的研究,可能会解开导致反物质在现在宇宙中稀缺的秘密。
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反物质粒子之间的力,(例如此次的反质子),以前从未有过测量。如果我们发现反质子表现出同其“镜像粒子(正常质子微粒发现于原子中)“的不同运行方式,则可为我们所知的”物质、反物质不对称性“提供一个合理的解释。" a9 ]1 K; q# j. B' {
; r' h# d) u. c( ]5 L' S宇宙形成之初,”轰隆“一下(好吧,这是直译,指奇点大爆炸)炸出等量的物质和反物质。而这跟我们今天的情况完全不同,我们的宇宙中几乎找不到反物质。: s: ]9 h8 i4 G6 J, h$ u
3 D2 j5 k# E* ?因此,一定发生了一些会导致物质以压倒性优势显现出来的现象。对此,科学家们各执一词,但却一直无法证实。
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”尽管这个难题已经被认知了几十年,而且我们也发现了一些蛛丝马迹,但他依旧是科学届的一大挑战!“合著者,来自美国纽约布鲁克海文国家实验室的 爱红﹒唐介绍说,“任何一个我们发现到的关于反物质的本质都可能帮我们破解这个难题。” l) `, I9 X) }9 c/ A
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Thankfully, antimatter can be produced by particle accelerators - albeit in tiny amounts - giving scientists the opportunity to study its properties. " i- o8 V9 V u
Using a particle smasher called the Relativistic Heavy Ion Collider (RHIC) at Brookhaven, physicists were able to measured the force of interaction between pairs of antiprotons. j5 t6 o1 O u5 L. o
The scientists found that the force between antiproton pairs is attractive, just like the strong nuclear force that holds protons together within atoms. 8 N4 O9 {8 {6 E* N
Antimatter particles have the same masses as their ordinary matter equivalents, but carry opposite charges.
5 j) D* l) }+ |Zhengqiao Zhang, another scientist who studied the antiproton interactions using the RHIC, said: "We see lots of protons, the basic building blocks of conventional atoms, coming out, and we see almost equal numbers of antiprotons.
) m$ c: n! g% w: s: b- ?! k"The antiprotons look just like familiar protons, but because they are antimatter, they have a negative charge instead of positive, so they curve the opposite way in the magnetic field of the detector." Within the accuracy of these measurements, matter and antimatter appear to be perfectly symmetric. There didn't appear to be some asymmetric quirk of the strong force that could account for the continuing existence of matter in the Universe and the scarcity of antimatter. - H2 y( X8 z+ o! ^4 }
That points scientists towards other explanations for the matter/antimatter asymmetry. For example, neutrinos (another fundamental building block of the Universe) might be their own antiparticles. Differences in the way neutrino particles interacted after the Big Bang might have led to a slight matter excess that allowed our Universe to exist.
: K5 w' n5 a/ S% K8 S% r- i1 ]感谢上帝,我们可以通过粒子加速器产生反物质——尽管只有微量,但这也提供了科学家们研究反物质属性的机会。& ^% ?2 @' I( @( @ W( z! p
0 A& [) N) ]3 A, t" y$ @( ?通过使用布鲁克海文国家实验室被称为相对重离子碰撞机(RHIC)的粒子加速器,物理学家得以测定反质子之间的作用力。$ e. p8 b" ~4 l3 ^4 G; v
9 o. W8 H& |9 j) `: P6 q' D科学家发现,反质子之间具有很强的吸引力,就像原子核内质子间的强核力。$ V+ H2 k3 s1 {# G$ h! q# `: }6 j
# \) g. {5 L) w3 M0 F) d9 `$ t8 K反物质粒子同正物质具有相同的质量,但是却携带相反的电荷。$ n) \, [) a9 a6 z
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另一位在RHIC研究中的科学家——张正乔(估计是华裔)介绍说:“我们看到的大量构成基本原子的质子飞出,而这个量与观测到的反质子几乎相等。反质子就像我们熟悉的质子,但因为他们是反物质,因此他们带有一个单位的负电荷,而非正电荷。因此,他们在磁场检测器重划出相反的曲线。“0 r4 [7 C' x0 m5 F
$ {) h6 t, [" }) {2 R基于这些测量的精确性,物质和反物质似乎是完全对称的。没有丝毫与正物质性质完全相悖的转折性证据可以解释为什么宇宙中存在连续物质而鲜有反物质。
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4 a# R& Q9 }. K: G, k+ Y& c' y, F这说明科学家只能寄希望于其他的可以解释物质、反物质不对称性的观点。比如,中微子(另一种宇宙基本粒子)可能就是其本身的反物质粒子。自”大爆炸“后中微子粒子间的不同相互作用方式可能导致我们的宇宙以一种微量不对称的形式存在。
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点评:好吧。到最后,这帮孙子们也没找到答案。只是更精确的又阐述了一遍反物质。
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