美国国家公共电台 NPR Why Corned Beef Sandwiches — And The Rest Of The Universe — Exist

 

SCOTT SIMON, HOST:

When NPR science correspondent Joe Palca came to us and said he had a story about EDM, we thought (laughter) we could get down with that.

(SOUNDBITE OF SONG, "GRAPEVINE")

TIESTO: (Singing) My mind, my mind, my mind. My mind, my mind, my mind. My mind, my mind, my mind.

SIMON: Then Joe said the story is not about electronic dance music - much favored by BJ Leiderman, who writes our theme music - but instead the electric dipole moment of the neutron¹. We said, what is that? Joe said he'd explain.

JOE PALCA, BYLINE²: When Indiana University physicist³ Chen-Yu Liu is asked why she's interested in the electric dipole moment of the neutron, she's ready with an answer.

CHEN-YU LIU: I say I'm trying to understand why we exist.

PALCA: In fact, she's trying to understand why everything exists - you, me, stars, galaxies⁴, corned beef sandwiches, everything. Theories say the explanation may be hidden in the electric dipole moment of the neutron. It's not a moment as in a moment in time. It refers to the neutron being slightly more football shaped than perfectly⁵ spherical⁶. You see, at the instant the universe came into existence billions of years ago, energy turned into matter.

Now, matter comes in two types - matter and antimatter. And when a particle of antimatter meets a particle of matter, they annihilate⁷ each other, and all that's left is light. So somehow, somewhere there had to be a slight imbalance, a bit more matter than antimatter, to make all the stuff in the universe. Theories predict the signal that explains that imbalance would be found if the neutron had a measurable electric dipole moment. But so far, no one has been able to measure one. Chen-Yu Liu says that maybe because it's small and hard to measure in neutrons⁸.

LIU: To do measurement precisely⁹, we need to be able to slow them down, confine them in space and watch them for a very long time.

PALCA: So basically you're trying to get the neutron to sit still while you study it.

LIU: Exactly.

PALCA: Liu is working on one way to slow down neutrons. At Oak Ridge¹⁰ National Lab in Tennessee, they're working on another.

VINCE CIANCIOLO: All right, so the main target is down there.

PALCA: We're at something called this Spallation Neutron Source at Oak Ridge. It's a cavernous room that throbs¹¹ with energy. Vince Cianciolo is a physicist here. He says when you shoot a beam of protons at a target made of mercury, you get a spray of neutrons that can be diverted into multiple beamlines.

CIANCIOLO: This is the fundamental physics beamline - beamline 13 - and the dipole moment experiment will be mounted next on this beamline.

PALCA: To get the neutrons to slow down so you can study them, you need to build a special chamber¹² where the neutrons can be chilled colder than 450 degrees below zero Fahrenheit¹³. And that's just one of the challenges. Cianciolo points to a spot at the end of the beamline where the chamber will be installed.

CIANCIOLO: The support of this whole foundation has to be non-magnetic, so you can't use standard rebar. You have to use - we'll probably use fiberglass rebar.

PALCA: The construction here will take place over the next couple years. In the meantime, other pieces of the experiment are taking shape. At Caltech in Pasadena, physics grad student Marie Blatnik is working on that chamber that will ultimately go to Oak Ridge. It's a giant aluminum¹⁴ cylinder¹⁵.

MARIE BLATNIK: We get to probe the smallest parts of the universe by making the world's largest machines. I mean, look at this thing (laughter). It's huge.

PALCA: Blatnik's adviser¹⁶ Brad Filippone says people have been trying for decades to find the neutron's electric dipole moment. He says the apparatus¹⁷ they're building here will take the search to the next level.

BRAD FILIPPONE: We believe we'll be able to increase the sensitivity by a factor of 100.

PALCA: But it's possible that even after this more sensitive search, physicists¹⁸ may still come up empty. Filippone says that's OK. Physicists will learn something.

FILIPPONE: Looking for the electric dipole moment is relatively¹⁹ easy to make the science case to other physicists. The question is, how much are you willing to spend?

PALCA: And convincing non-physicists the search is worth the money can be harder. Just ask physicist Leah Broussard at Oak Ridge.

LEAH BROUSSARD: My mom says, why are my tax dollars being wasted on this research?

PALCA: But Broussard has an answer for her mom.

BROUSSARD: Humans are explorers. We explore the unknown frontiers. I want to know how the universe came to be. Don't we all?

PALCA: I imagine so. Joe Palca, NPR News.

1 neutron   

n.中子

参考例句：

• Neutron is neutral and slightly heavier than the proton.中子是中性的，比质子略重。
• Based on the neutron energy,the value of weighting factor was given.根据中子能量给出了相应的辐射权重因子的数值。

2 byline   

n.署名；v.署名

参考例句：

• His byline was absent as well.他的署名也不见了。
• We wish to thank the author of this article which carries no byline.我们要感谢这篇文章的那位没有署名的作者。

3 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

4 galaxies   

星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）

参考例句：

• Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
• We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。

5 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

6 spherical   

adj.球形的；球面的

参考例句：

• The Earth is a nearly spherical planet.地球是一个近似球体的行星。
• Many engineers shy away from spherical projection methods.许多工程师对球面投影法有畏难情绪。

7 annihilate   

v.使无效；毁灭；取消

参考例句：

• Archer crumpled up the yellow sheet as if the gesture could annihilate the news it contained.阿切尔把这张黄纸揉皱，好象用这个动作就会抹掉里面的消息似的。
• We should bear in mind that we have to annihilate the enemy.我们要把歼敌的重任时刻记在心上。

8 neutrons   

n.中子( neutron的名词复数 )

参考例句：

• The neutrons and protons form the core of the atom. 中子和质子构成了原子核。 来自《简明英汉词典》
• When an atom of U235 is split,several neutrons are set free. 一个铀235原子分裂时，释放出几个中子。 来自《简明英汉词典》

9 precisely   

adv.恰好，正好，精确地，细致地

参考例句：

• It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
• The man adjusted very precisely.那个人调得很准。

10 ridge   

n.山脊；鼻梁；分水岭

参考例句：

• We clambered up the hillside to the ridge above.我们沿着山坡费力地爬上了山脊。
• The infantry were advancing to attack the ridge.步兵部队正在向前挺进攻打山脊。

11 throbs   

体内的跳动( throb的名词复数 )

参考例句：

• My finger throbs with the cut. 我的手指因切伤而阵阵抽痛。
• We should count time by heart throbs, in the cause of right. 我们应该在正确的目标下，以心跳的速度来计算时间。

12 chamber   

n.房间，寝室；会议厅；议院；会所

参考例句：

• For many,the dentist's surgery remains a torture chamber.对许多人来说，牙医的治疗室一直是间受刑室。
• The chamber was ablaze with light.会议厅里灯火辉煌。

13 Fahrenheit   

n./adj.华氏温度；华氏温度计(的)

参考例句：

• He was asked for the boiling point of water in Fahrenheit.他被问到水的沸点是华氏多少度。
• The thermometer reads 80 degrees Fahrenheit.寒暑表指出华氏80度。

14 aluminum   

n.(aluminium)铝

参考例句：

• The aluminum sheets cannot be too much thicker than 0.04 inches.铝板厚度不能超过0.04英寸。
• During the launch phase,it would ride in a protective aluminum shell.在发射阶段，它盛在一只保护的铝壳里。

15 cylinder   

n.圆筒，柱(面)，汽缸

参考例句：

• What's the volume of this cylinder?这个圆筒的体积有多少？
• The cylinder is getting too much gas and not enough air.汽缸里汽油太多而空气不足。

16 adviser   

n.劝告者，顾问

参考例句：

• They employed me as an adviser.他们聘请我当顾问。
• Our department has engaged a foreign teacher as phonetic adviser.我们系已经聘请了一位外籍老师作为语音顾问。

17 apparatus   

n.装置，器械；器具，设备

参考例句：

• The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。
• They had a very refined apparatus.他们有一套非常精良的设备。

18 physicists   

物理学家( physicist的名词复数 )

参考例句：

• For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说，这是受挫折的一年。 来自英汉非文学 - 科技
• Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。

19 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。