博客李淼

（我的《环球科学》第9期的专栏文章出笼了，以下是文章的内容，请勿转。2008年09期）

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欧洲核子中心的大型强子对撞机 (LHC) 的建造一直在稳步前行，虽然注入粒子束的日期不断地被推后。最新的启动日期似乎是八月底九月初，但如果再被推迟一个月我也不会惊讶，毕竟这是人类历史上最大的机器以及最复杂的实验，还是保证万无一失的好。随着启动这台巨大的机器的日子的逼近，网上出现了一首大型强子对撞机的说唱（RAP），背景是大型强子对撞机所在的隧道，舞蹈者匿名。歌词很长，就不将原文歌词写出来了，我只给出我的翻译：

“二十七公里的地下隧道/是为了让质子们互相赛跑/一个跨越瑞士和法国的巨圆/共有60个国家为此出了钱/两束质子在其中转圈振荡/直到到达探测器的中心，然后碰撞/所有被打包到极其微小空间的能量/变成质量和粒子释放/然后……

LHCb盯着反物质去了哪里/ALICE观测铅离子碰撞的游戏/CMS和ATLAS做的事几乎一样/它们抱着发现新粒子的希望/LHC加速质子和铅离子/这台机器的发现将使你兴奋到窒息

我们看到天上的行星和流星，以及更多的恒星/我们也知道黑洞栖息在银河的中心/但是所有这些天体所含物质的引力/不足以解释为什么恒星聚集在一起，必须存在其他东西/这些幽暗的物质只通过引力相互作用/组成他们的粒子很难被捕捉/但能量守恒定定律我们可以利用/能量被它们带走，不用搜索

你看到粒子奔驰，在喷注中飞溅/另一个方向什么都没有，画不出一条线/你说你的定律被破坏，这不太可能/肯定有其他粒子来保持平衡/它可能是暗物质粒子/你将第一次看到充满宇宙的小东西

LHCb盯着反物质去了哪里/ALICE观测铅离子碰撞的游戏/CMS和ATLAS做的事几乎一样/它们抱着发现新粒子的希望

反物质是物质的魔鬼弟兄/表面上看起来就像双胞胎/但是电荷和手征相反/使得反粒子不能被随便携带/反物质遭遇物质互相湮灭/变成能量四处散开

当物质在能量中诞生/这正是LHC中出现的很多过程/你得到一半物质一半反物质/就像宇宙鸿蒙初开之时/大爆炸，爆炸出所有物质/反物质却在早期逐渐消失/因为我们今天找遍宇宙所有角落/却看不到反物质的一点踪迹/这到底……

LHCb盯着反物质去了哪里/ALICE观测铅离子碰撞的游戏/CMS和ATLAS做的事几乎一样/它们抱着发现新粒子的希望/LHC加速质子和铅离子/这台机器的发现将使你兴奋到窒息

所有人都在谈论黑格斯/所有人都相信它逃不了这台机器的检视/如果黑格斯真的存在，我们马上就要看见/如果它不存在，科学家就要声言/“原来它不存在，我们需要别的机制来了解/粒子为何有质量，标准模型并不完美。”

可是黑格斯，我还没有告诉你细节/它如何给别的粒子以质量/如果空间充满了黑格斯场/通过这种媒介，有的粒子艰难有的粒子轻巧/后者如光子，它们没有质量/而重粒子如顶夸克就变得很胖/黑格斯还会传递力量/使得与其耦合的粒子听其号令/变得可以测量

LHCb盯着反物质去了哪里/ALICE观测铅离子碰撞的游戏/CMS和ATLAS做的事几乎一样/它们抱着发现新粒子的希望

也许你会觉得万有引力很强/当你从自行车摔下你会摔得直截了当/你与大地碰撞，摔得真的很痛/可是你错了，如果你以为引力很强/你瞧，引力比弱力更弱/所以科学家们一直在寻找/超出三维的其他空间维/我们看不见它们因为它们很小/引力会逸出三维空间进入高维/使得引力在我们的世界变得虚弱渺小/这些额外维自己卷积起来/日常生活中也就根本看不见它们/可是假如你变成一个引力子/额外维就会为你打开大门/我们就会去那里找你……”

这首说唱的原文视频的地址。

大型强子说唱的作者是CERN的科学作家凯特•麦卡尔平 (Kate McAlpine) ，在一次从日内瓦到核子中心四十分钟的旅行中，她写下了歌词。她虽然轻松地在四十分钟内完成歌词创作，我却花了很长时间来翻译。英文很简单，但转换成中文还要押韵就不简单了。这个说唱可以说是粒子物理前沿的简单介绍，听众在不到五分钟的时间内轻松地弄明白了大型强子对撞机到底是用来干什么的，CERN真的没有白白雇佣她。

麦卡尔平在说唱中反复提到了大型强子对装机的四个探测器，分别是LHCb、ALICE、CMS和ATLAS，她用短短的一段歌词就说清了这些探测器的作用。我们可以解释得更详细一点，LHCb是“The Large Hadron Collider beauty experiment”的缩写，用来测量电荷+宇称不守恒。ALICE这个美丽的名字是“A Large Ion Collider Experiment”的缩写，其中离子这个字 (ion) 泄露了该探测器的秘密，离子是歌词中提到的铅离子，它们的碰撞会形成夸克胶子流体。CMS是“Compact Muon Solenoid”的缩写，翻译成中文就是紧致μ子螺线管。最后，ATLAS是“A Toroidal LHC ApparatuS”的缩写，也是希腊神话中巨人的名字，他用肩旁扛起了天空。CMS和ATLAS这两个探测器是大型强子对撞机的主要探测器，用来探测黑格斯粒子和可能存在的新粒子。

下面是这首RAP的原文：

Twenty-seven kilometers of tunnel under ground
Designed with mind to send protons around
A circle that crosses through Switzerland and France
Sixty nations contribute to scientific advance
Two beams of protons swing round, through the ring they ride
‘Til in the hearts of the detectors, they’re made to collide
And all that energy packed in such a tiny bit of room
Becomes mass, particles created from the vacuum
And then…

LHCb sees where the antimatter’s gone
ALICE looks at collisions of lead ions
CMS and ATLAS are two of a kind
They’re looking for whatever new particles they can find.
The LHC accelerates the protons and the lead
And the things that it discovers will rock you in the head.

We see asteroids and planets, stars galore
We know a black hole resides at each galaxy’s core
But even all that matter cannot explain
What holds all these stars together – something else remains
This dark matter interacts only through gravity
And how do you catch a particle there’s no way to see
Take it back to the conservation of energy
And the particles appear, clear as can be

You see particles flying, in jets they spray
But you notice there ain’t nothin’, goin’ the other way
You say, “My law has just been violated – it don’t make sense!
There’s gotta be another particle to make this balance.”
And it might be dark matter, and for first
Time we catch a glimpse of what must fill most of the known ‘Verse.
Because…

LHCb sees where the antimatter’s gone
ALICE looks at collisions of lead ions
CMS and ATLAS are two of a kind
They’re looking for whatever new particles they can find.

Antimatter is sort of like matter’s evil twin
Because except for charge and handedness of spin
They’re the same for a particle and its anti-self
But you can’t store an antiparticle on any shelf
Cuz when it meets its normal twin, they both annihilate
Matter turns to energy and then it dissipates

When matter is created from energy
Which is exactly what they’ll do in the LHC
You get matter and antimatter in equal parts
And they try to take that back to when the universe starts
The Big Bang – back when the matter all exploded
But the amount of antimatter was somehow eroded
Because when we look around we see that matter abounds
But antimatter’s nowhere to be found.
That’s why…

LHCb sees where the antimatter’s gone
ALICE looks at collisions of lead ions
CMS and ATLAS are two of a kind
They’re looking for whatever new particles they can find.
The LHC accelerates the protons and the lead
And the things that it discovers will rock you in the head.

The Higgs Boson – that’s the one that everybody talks about.
And it’s the one sure thing that this machine will sort out
If the Higgs exists, they ought to see it right away
And if it doesn’t, then the scientists will finally say
“There is no Higgs! We need new physics to account for why
Things have mass. Something in our Standard Model went awry.”

But the Higgs – I still haven’t said just what it does
They suppose that particles have mass because
There is this Higgs field that extends through all space
And some particles slow down while other particles race
Straight through like the photon – it has no mass
But something heavy like the top quark, it’s draggin’ its ***
And the Higgs is a boson that carries a force
And makes particles take orders from the field that is its source.
They’ll detect it….

LHCb sees where the antimatter’s gone
ALICE looks at collisions of lead ions
CMS and ATLAS are two of a kind
They’re looking for whatever new particles they can find.

Now some of you may think that gravity is strong
Cuz when you fall off your bicycle it don’t take long
Until you hit the earth, and you say, “Dang, that hurt!”
But if you think that force is powerful, you’re wrong.
You see, gravity – it’s weaker than Weak
And the reason why is something many scientists seek
They think about dimensions – we just live in three
But maybe there are some others that are too small to see
It’s into these dimensions that gravity extends
Which makes it seem weaker, here on our end.
And these dimensions are “rolled up” – curled so tight
That they don’t affect you in your day to day life
But if you were as tiny as a graviton
You could enter these dimensions and go wandering on
And they’d find you…

When LHCb sees where the antimatter’s gone
ALICE looks at collisions of lead ions
CMS and ATLAS are two of a kind
They’re looking for whatever new particles they can find.
The LHC accelerates the protons and the lead
And the things that it discovers will rock you in the head.

这篇文章发表于 2008年8月27日, 星期三 14:16:58，属于分类 理论物理。 你可以查看 HTML打印版 或通过 新闻聚合(RSS) 来追踪这篇文章的最新评论。