How we explore unanswered questions in physics | James Beacham

Translator: Leslie Gauthier Reviewer: Camille Martínez

翻译人员: Lipeng Chen 校对人员: Chen Zou

There is something about physics

有一些关于物理方面的事情，

that has been really bothering me since I was a little kid.

从我还是个小孩的时候 就开始并一直困扰着我。

And it's related to a question

它和一个问题有关，

that scientists have been asking for almost 100 years,

科学家们已经在这个问题上 探索了将近100年，

with no answer.

却毫无结果。

How do the smallest things in nature,

自然界中最小的事物，

the particles of the quantum world,

量子世界中的那些粒子，

match up with the largest things in nature --

是如何与自然中最大的事物，

planets and stars and galaxies held together by gravity?

即在万有引力作用维系下的 行星、恒星以及星系相匹配的？

As a kid, I would puzzle over questions just like this.

小的时候，我时常会为 这样的问题感到疑惑。

I would fiddle around with microscopes and electromagnets,

我会不停地摆弄显微镜和电磁铁，

and I would read about the forces of the small

我还会去阅读了解粒子间作用力和

and about quantum mechanics

量子力学，

and I would marvel at how well that description matched up

然后惊叹于那描述

与我们的观察竟如此契合。

to our observation.

Then I would look at the stars,

那时我仰望星空，

and I would read about how well we understand gravity,

读到我们有多了解重力，

and I would think surely, there must be some elegant way

然后我会严肃思考 这一定有一些精巧的地方

that these two systems match up.

使得这两个系统匹配。

But there's not.

但事实上并没有。

And the books would say,

书上会说，

yeah, we understand a lot about these two realms separately,

是的，我们分别在这 两个领域上了解了很多，

但是当我们尝试着将它们 以数学的方式联系在一起的时候，

but when we try to link them mathematically,

everything breaks.

每件事都变得不合逻辑了。

And for 100 years,

而且100年来，

我们关于如何解决这个 几乎是物理灾难的想法

none of our ideas as to how to solve this basically physics disaster,

has ever been supported by evidence.

从没有被证据支持过。

And to little old me --

对于小小的我，

little, curious, skeptical James --

幼小的，好奇的，多疑的詹姆士，

this was a supremely unsatisfying answer.

这个答案绝对满足不了我。

So, I'm still a skeptical little kid.

我仍然是一个充满怀疑的小孩。

Flash-forward now to December of 2015,

快进到现在，2015年12月，

when I found myself smack in the middle

我发现自己突然出现 在物理世界的正中央，

of the physics world being flipped on its head.

并完全沉迷于此。

It all started when we at CERN saw something intriguing in our data:

一切开始于我们在欧洲粒子物理研究所 （CERN）的数据中看到一些有趣的东西，

a hint of a new particle,

某种新的粒子的线索，

an inkling of a possibly extraordinary answer to this question.

也说明这个问题的答案 极有可能是非同寻常的。

So I'm still a skeptical little kid, I think,

所以，我觉得我仍然是 一个小小的怀疑论者，

but I'm also now a particle hunter.

而我现在成为了一个粒子猎人。

I am a physicist at CERN's Large Hadron Collider,

我是CERN大型强子对撞机 （LHC）实验的物理学家，

the largest science experiment ever mounted.

这是有史以来规模最大的科学实验。

It's a 27-kilometer tunnel on the border of France and Switzerland

这个机器是法国和瑞典 交界地区的一个27公里的隧道，

buried 100 meters underground.

深埋于地下100米处。

And in this tunnel,

在这个隧道里，

we use superconducting magnets colder than outer space

我们使用低于外部空间 温度的超导磁体

to accelerate protons to almost the speed of light

来加速质子运动， 使其速度接近光速，

and slam them into each other millions of times per second,

并使得质子以每秒 上百万次的速度互相撞击，

collecting the debris of these collisions

收集撞击后产生的碎片，

to search for new, undiscovered fundamental particles.

来进行新的、未发现的 基本粒子的研究。

Its design and construction took decades of work

它的设计和构造花费了 全世界上千名物理学家

by thousands of physicists from around the globe,

数十年的时间，

and in the summer of 2015,

2015年的夏天，

we had been working tirelessly to switch on the LHC

我们不知疲倦地 以人类曾经在对撞机试验中

at the highest energy that humans have ever used in a collider experiment.

使用过的最高能量 一次次打开LHC的开关。

Now, higher energy is important

更高的能量是必要的，

because for particles, there is an equivalence

因为粒子能量和粒子的质量

between energy and particle mass,

是守恒的，

and mass is just a number put there by nature.

质量只是自然给出的一个数值。

To discover new particles,

为了发现新的粒子，

we need to reach these bigger numbers.

我们要找到更大的数值，

And to do that, we have to build a bigger, higher energy collider,

为了做到这一点，我们要 制造更大更高能量的对撞机，

and the biggest, highest energy collider in the world

而这个世界上最大，能量最高的对撞机

is the Large Hadron Collider.

也就是大型强子对撞机LHC。

And then, we collide protons quadrillions of times,

然后，我们让质子对撞一千万亿次，

and we collect this data very slowly, over months and months.

并在数个月内 慢慢地收集这些数据，

And then new particles might show up in our data as bumps --

然后新粒子猛然出现在我们的数据里，

slight deviations from what you expect,

和你们所期望的有点偏差，

little clusters of data points that make a smooth line not so smooth.

很小的一簇数据表使得 一条平滑的线变得有些粗糙。

For example, this bump,

比如，距离2012年的数据记录

after months of data-taking in 2012,

几个月之后发现的这个碰撞，

led to the discovery of the Higgs particle --

引领我们发现了希格斯粒子

the Higgs boson --

——应该叫希格斯玻色子——

and to a Nobel Prize for the confirmation of its existence.

并因为证明其存在而 获得了诺贝尔奖。

This jump up in energy in 2015

2015年，能量出现了大幅波动，

represented the best chance that we as a species had ever had

这表示我们人类作为一个物种 遇见了有史以来的最佳机会

of discovering new particles --

来探寻新粒子的存在，

new answers to these long-standing questions,

探寻那些存在已久的问题的答案。

because it was almost twice as much energy as we used

因为这次的能量接近两倍于

when we discovered the Higgs boson.

我们曾发现的希格斯玻色子。

Many of my colleagues had been working their entire careers for this moment,

我的许多同僚终身奉献于事业 为的就是这一刻，

and frankly, to little curious me,

坦白讲，对于小小的， 充满好奇心的我来说，

this was the moment I'd been waiting for my entire life.

这就是我一生都在等待的时刻。

So 2015 was go time.

这个时刻就是2015年。

So June 2015,

2015年6月，

the LHC is switched back on.

LHC再一次启动了。

My colleagues and I held our breath and bit our fingernails,

我和我的同僚们一起 屏住呼吸，紧张到咬指甲，

and then finally we saw the first proton collisions

最终我们看到了 第一次质子对撞，

at this highest energy ever.

伴随着有史以来最大能量。

Applause, champagne, celebration.

于是立刻爆发了掌声，欢呼，庆贺。

This was a milestone for science,

这是科学史上的里程碑，

我们完全不知道我们会从 全新的数据当中得出什么。

and we had no idea what we would find in this brand-new data.

And then a few weeks later, we found a bump.

几周过去了， 我们发现了一个碰撞。

It wasn't a very big bump,

这不是一次很大的碰撞，

but it was big enough to make you raise your eyebrow.

但是也足够让你惊讶到挑眉。

但是要给挑眉的幅度 从一到十划分等级的话，

But on a scale of one to 10 for eyebrow raises,

if 10 indicates that you've discovered a new particle,

如果“十”表示你发现了一种新粒子，

那么这次大概只能有“四”。

this eyebrow raise is about a four.

（观众笑声）

(Laughter)

I spent hours, days, weeks in secret meetings,

我花了数小时，数天， 数周时间参加秘密会议，

arguing with my colleagues over this little bump,

和我的同事们讨论这次小碰撞，

poking and prodding it with our most ruthless experimental sticks

用我们最无礼的方式对着它指指点点，

to see if it would withstand scrutiny.

看它能不能经受得住详细的检查。

But even after months of working feverishly --

但是经过了几个月的狂热实验

sleeping in our offices and not going home,

——睡在实验室连家都不回，

candy bars for dinner,

用糖果棒代替晚餐，

喝了一桶又一桶的咖啡——

coffee by the bucketful --

physicists are machines for turning coffee into diagrams --

物理学家变成了把咖啡 转化成了图表的机器。

(Laughter)

（观众笑声）

This little bump would not go away.

这个小碰撞并没有消失。

So after a few months,

所以几个月后，

we presented our little bump to the world with a very clear message:

我们把这个小碰撞非常清楚的 介绍给了全世界。

this little bump is interesting but it's not definitive,

这个小碰撞虽然令人关注， 但它并不是最终结果。

so let's keep an eye on it as we take more data.

所以我们会继续关注它， 记录下更多数据。

So we were trying to be extremely cool about it.

也因冷静我们想以 极度清醒的态度来观察它。

And the world ran with it anyway.

全世界也一直在关注着它。

The news loved it.

新闻界喜爱它。

People said it reminded them of the little bump

人们说这让他们想起了

that was shown on the way toward the Higgs boson discovery.

发现希格斯玻色子的那次碰撞。

Better than that, my theorist colleagues --

比这更令人振奋的是， 我的理论家同事们

I love my theorist colleagues --

——我爱他们——

my theorist colleagues wrote 500 papers about this little bump.

我的理论家同事们写了500篇 关于这个小碰撞的论文。

(Laughter)

（观众笑声）

The world of particle physics had been flipped on its head.

整个粒子物理世界都痴迷于此。

But what was it about this particular bump

但是这次粒子对撞到底为什么

导致了上千名物理学家 都兴奋地难以自抑？

that caused thousands of physicists to collectively lose their cool?

This little bump was unique.

这次小碰撞是独特的。

This little bump indicated

这次小碰撞意味着

that we were seeing an unexpectedly large number of collisions

我们眼见着未曾预期过的 大量粒子对撞，

whose debris consisted of only two photons,

它们的残骸只形成两种光子，

two particles of light.

就是两种光粒子。

And that's rare.

这是很少见的。

Particle collisions are not like automobile collisions.

粒子对撞不像汽车碰撞。

They have different rules.

它们的规则是不一样的。

When two particles collide at almost the speed of light,

当两个粒子以接近光速的速度发生碰撞，

the quantum world takes over.

量子世界就出现了。

And in the quantum world,

在量子世界中，

these two particles can briefly create a new particle

这两个粒子可以简单地 创造出一种新的粒子。

that lives for a tiny fraction of a second

这种新粒子只会有一瞬间存在，

before splitting into other particles that hit our detector.

在它分解成其他的粒子之后 恰好被我们的检测器检测到了。

Imagine a car collision where the two cars vanish upon impact,

想象一下汽车的碰撞， 两辆车因受撞击而消失，

一辆自行车凭空出现——

a bicycle appears in their place --

(Laughter)

（观众笑声）

And then that bicycle explodes into two skateboards,

然后这辆自行车又发生了 爆炸，变成两块滑板

which hit our detector.

撞向我们的检测器。

(Laughter)

（观众笑声）

Hopefully, not literally.

我希望这不是真的。

They're very expensive.

因为它们太贵重了。

Events where only two photons hit out detector are very rare.

两个光子撞击被探测器捕捉到 这种事情太少见了。

And because of the special quantum properties of photons,

并且由于光子的特殊量子特性，

there's a very small number of possible new particles --

极少有可能产生新的粒子——

these mythical bicycles --

也就是那些所谓的“自行车”——

that can give birth to only two photons.

会产生两个光子。

But one of these options is huge,

但是其中一个可能性是很大的。

and it has to do with that long-standing question

它和一个长期存在的问题有关，

that bothered me as a tiny little kid,

从我还是个小孩的时候 就一直困扰着我，

about gravity.

也就是重力。

Gravity may seem super strong to you,

重力对大家的影响太大了。

but it's actually crazily weak compared to the other forces of nature.

但是它同大自然其它的力量 相比又实在太微弱了。

I can briefly beat gravity when I jump,

当我跳起来的时候， 我可以短暂性地克服重力，

but I can't pick a proton out of my hand.

可我却不能从我手里拿起一个质子。

The strength of gravity compared to the other forces of nature?

把引力的强度和其它的 自然力量相比会如何？

It's 10 to the minus 39.

它等于10的负39次方。

That's a decimal with 39 zeros after it.

也就是小数点后39个零。

Worse than that,

更可怕的是，

all of the other known forces of nature are perfectly described

所有我们现在已知的其它自然力量 都能够被一种名叫“标准模型”的东西

by this thing we call the Standard Model,

精确地描述，

which is our current best description of nature at its smallest scales,

这是目前我们所使用的最好的 描述自然的最小模型。

坦白地说，

and quite frankly,

也是人类最成功的成就之一

one of the most successful achievements of humankind --

except for gravity, which is absent from the Standard Model.

——除了重力， 这是被排除在标准模型之外的，

It's crazy.

这太疯狂了。

It's almost as though most of gravity has gone missing.

好像大部分的重力都不知所踪。

We feel a little bit of it,

我们只能感受到一点点，

but where's the rest of it?

但是剩下的部分在哪儿？

No one knows.

没有人知道。

But one theoretical explanation proposes a wild solution.

但是有种理论 提出了一个疯狂的设想。

You and I --

你和我——

even you in the back --

即使你在后面——

we live in three dimensions of space.

我们生活在三维空间里。

I hope that's a non-controversial statement.

我希望这个陈述没有争议。

(Laughter)

（观众笑声）

All of the known particles also live in three dimensions of space.

所有我们现在已知的粒子 都存在于三维空间，

In fact, a particle is just another name

实际上，粒子只是给

for an excitation in a three-dimensional field;

在三维空间产生的碰撞 起的另一个名字，

a localized wobbling in space.

空间中的局部震动。

More importantly, all the math that we use to describe all this stuff

更重要的是，我们学过的 所有用来描述这些东西的数学知识

assumes that there are only three dimensions of space.

都建立在只存在三维空间的假设之上。

But math is math, and we can play around with our math however we want.

但是数学仅仅是数学， 我们可以用任何方式摆弄它。

And people have been playing around with extra dimensions of space

人类幻想着存在额外维度空间

for a very long time,

已经有很长时间了，

但是这始终是一个抽象的数学概念。

but it's always been an abstract mathematical concept.

I mean, just look around you -- you at the back, look around --

我是说，看看你们周围——

there's clearly only three dimensions of space.

你非常清楚这是三维空间。

But what if that's not true?

但是假如这不是真的呢？

What if the missing gravity is leaking into an extra-spatial dimension

假如那些消失的重力 其实都流失到了超三维空间，

that's invisible to you and I?

而你和我都看不到呢？

What if gravity is just as strong as the other forces

假如重力其实和其它的力一样强呢？

if you were to view it in this extra-spatial dimension,

假如你能在超三维空间看到它呢？

and what you and I experience is a tiny slice of gravity

还有，假如你和我经受的重力 其实仅仅是重力的一小部分，

make it seem very weak?

所以看上去这股力才这么微弱呢？

If this were true,

如果这些假设都是真的，

我们就要扩展我们的粒子标准模型。

we would have to expand our Standard Model of particles

to include an extra particle, a hyperdimensional particle of gravity,

让更多的粒子，比如多维重力粒子

a special graviton that lives in extra-spatial dimensions.

这种存在于超维空间的特殊的 引力子也能够被涵盖进来。

I see the looks on your faces.

我看到了你们脸上的表情。

You should be asking me the question,

你们也许会问我这样的问题：

"How in the world are we going to test this crazy, science fiction idea,

“在我们被困于三维空间的情况下， 我们怎么能证实这种疯狂的

stuck as we are in three dimensions?"

科幻小说里的设想？”

The way we always do,

我们经常会用的方法是

by slamming together two protons --

让两个质子互相撞击——

(Laughter)

（观众笑声）

Hard enough that the collision reverberates

很难让碰撞反射到任何

可能存在的超维空间里，

into any extra-spatial dimensions that might be there,

momentarily creating this hyperdimensional graviton

很难随时制造出这种多维引力子，

that then snaps back into the three dimensions of the LHC

然后让其迅速返回到三维空间的LHC上

and spits off two photons,

再分解成两个光子，

two particles of light.

两个光粒子。

And this hypothetical, extra-dimensional graviton

这种假想出来的 超维引力子

is one of the only possible, hypothetical new particles

是假想的可能存在的 所有新粒子中的一种，

that has the special quantum properties

它拥有特殊的量子特性，

that could give birth to our little, two-photon bump.

碰撞后能够分解出两个光子。

So, the possibility of explaining the mysteries of gravity

因此，解释重力的奥秘

and of discovering extra dimensions of space --

以及发现超维空间的可能性

perhaps now you get a sense

——现在你应该有所察觉了，

as to why thousands of physics geeks collectively lost their cool

为什么上千个物理怪才 在小小的，两个光子的碰撞面前

同时失去了冷静。

over our little, two-photon bump.

这种类型的探索将会改写课本。

A discovery of this type would rewrite the textbooks.

But remember,

但是请记住，

the message from us experimentalists

我们这些正在践行的实验主义者

that actually were doing this work at the time,

想要说的是

非常清楚的：

was very clear:

我们需要更多的数据。

we need more data.

With more data,

有了更多数据，

the little bump will either turn into a nice, crisp Nobel Prize --

这个小碰撞就会变成新鲜出炉的 美好的诺贝尔奖了——

(Laughter)

（观众笑声）

Or the extra data will fill in the space around the bump

或者更多的数据将会填满 碰撞数据边上的空白，

and turn it into a nice, smooth line.

然后变成又一条光滑的线条。

So we took more data,

所以我们记录了更多的数据，

and with five times the data, several months later,

七个月后的数据量达到了以前的五倍，

our little bump

这次小小的碰撞

turned into a smooth line.

变成了平稳的线条

The news reported on a "huge disappointment," on "faded hopes,"

新闻上报道着“大失所望”，“希望破灭”，

and on particle physicists "being sad."

还有粒子物理学家们“十分难过”。

Given the tone of the coverage,

在这样的基调下，

you'd think that we had decided to shut down the LHC and go home.

你肯定会觉得我们已经决定 中断LHC试验，各回各家。

(Laughter)

（观众笑声）

But that's not what we did.

但我们不是这样做的。

But why not?

可是为什么不呢？

I mean, if I didn't discover a particle -- and I didn't --

我的意思是，如果我没有发现新的粒子 ——我也确实没有发现——

if I didn't discover a particle, why am I here talking to you?

如果我没有发现新的粒子， 那么我怎么会站在这里发表演讲？

为什么我不羞愧地低下头，

Why didn't I just hang my head in shame

and go home?

然后灰溜溜的离开呢？

Particle physicists are explorers.

粒子物理学家是一群探险者。

And very much of what we do is cartography.

我们工作的大部分内容是绘制图表。

Let me put it this way: forget about the LHC for a second.

我这么解释吧： 暂时先忘掉LHC。

想象你是一个太空探险家， 正踏上一个遥远的星球

Imagine you are a space explorer arriving at a distant planet,

searching for aliens.

寻找外星人。

你的第一个任务是什么？

What is your first task?

To immediately orbit the planet, land, take a quick look around

立即围着整个星球飞一圈， 登陆，然后快速地看看周围环境，

有没有明显的生命迹象，

for any big, obvious signs of life,

and report back to home base.

然后向总部报告。

That's the stage we're at now.

这就是我们现在所处的阶段。

We took a first look at the LHC

我们第一次查看LHC，

for any new, big, obvious-to-spot particles,

看看有没有新的， 大到无法忽视的粒子，

and we can report that there are none.

然后我们可以报告什么也没有。

We saw a weird-looking alien bump on a distant mountain,

我们看见了外表奇特的外星人 出现在遥远的山上，

可是一旦我们靠近了， 看到的只有一块岩石。

but once we got closer, we saw it was a rock.

But then what do we do? Do we just give up and fly away?

然后我们又该怎么做呢？ 就这样放弃然后飞回去吗？

Absolutely not;

当然不能。

we would be terrible scientists if we did.

如果这么做了， 我们就是糟糕的科学家。

不会，我们准备花费 数十年时间来探索，

No, we spend the next couple of decades exploring,

mapping out the territory,

在地图上画出版图，

sifting through the sand with a fine instrument,

用最好的工具筛掉沙子，

peeking under every stone,

检查每一块石头，

drilling under the surface.

挖掘地底深处的秘密。

New particles can either show up immediately

新粒子要么立刻出现，

as big, obvious-to-spot bumps,

像巨大而无法忽视的碰撞一样，

or they can only reveal themselves after years of data taking.

或者它们可以在很多年后的 数据收集过程中才出现。

Humanity has just begun its exploration at the LHC at this big high energy,

人类只能怀着巨大热情 从LHC里探索，

and we have much searching to do.

我们还有许多探索工作要做。

But what if, even after 10 or 20 years, we still find no new particles?

但是假设十年或是二十年后，我们 仍然发现没有新的粒子，那该怎么办呢？

We build a bigger machine.

我们会建造一个更大的机器。

(Laughter)

（观众笑声）

We search at higher energies.

我们会以更高的热情去探索。

We search at higher energies.

我们会以更高的热情去探索。

Planning is already underway for a 100-kilometer tunnel

计划已经开始 在100公里长的隧道里进行，

that will collide particles at 10 times the energy of the LHC.

LHC将会使用十倍的能量 来进行粒子对撞。

We don't decide where nature places new particles.

我们不会决定自然 会把新粒子藏在哪里，

We only decide to keep exploring.

我们只决定要继续探索。

But what if, even after a 100-kilometer tunnel

但是假如用100公里长的隧道

or a 500-kilometer tunnel

或是500公里长的，

or a 10,000-kilometer collider floating in space

甚至是10000公里长的 对撞机，都只能

between the Earth and the Moon,

漂浮在地球和月球之间了，

we still find no new particles?

我们仍然没有找到新粒子 该怎么办呢？

Then perhaps we're doing particle physics wrong.

那么也许我们研究 粒子物理的方法是错误的。

(Laughter)

（观众笑声）

Perhaps we need to rethink things.

也许我们应该重新思考。

Maybe we need more resources, technology, expertise

我们可能需要比我们现在拥有的

than what we currently have.

更多的资源，技术和专家。

We already use artificial intelligence and machine learning techniques

我们已经开始在LHC的 某些部分运用人工智能

in parts of the LHC,

和机器学习技术。

但是想象一下 运用如此复杂的算法

but imagine designing a particle physics experiment

using such sophisticated algorithms

设计一个粒子物理试验，

that it could teach itself to discover a hyperdimensional graviton.

让它自己去探索超维引力子的场景。

But what if?

但是假如可以呢？

What if the ultimate question:

假如这个终极问题：

假如连人工智能都不能 帮助我们解决问题呢？

What if even artificial intelligence can't help us answer our questions?

假如这些存在了几个世纪 的开放式问题

What if these open questions, for centuries,

are destined to be unanswered for the foreseeable future?

注定是没有答案的， 在可预见的未来也不可能被解答呢？

What if the stuff that's bothered me since I was a little kid

假如从我还是个孩子的时候开始 就困扰着我的那些事情

is destined to be unanswered in my lifetime?

注定了我一生都不可能找到答案呢？

Then that ...

那么……

will be even more fascinating.

它就更令人神魂颠倒了。

We will be forced to think in completely new ways.

我们将会被迫从全新的角度去思考。

We'll have to go back to our assumptions,

我们会回到最初的设想，

and determine if there was a flaw somewhere.

来确认某处是否所有缺陷。

And we'll need to encourage more people to join us in studying science

我们需要鼓励更多人 加入我们来进行科学研究，

since we need fresh eyes on these century-old problems.

我们需要用新的眼光 去看待这些世纪问题。

I don't have the answers, and I'm still searching for them.

我没有答案， 我仍然在寻找答案。

But someone -- maybe she's in school right now,

可是某些人 ——也许她现在正在学校里，

maybe she's not even born yet --

也许她现在还没出生，

could eventually guide us to see physics in a completely new way,

——某天可以带领我们 以全新的方式去探索物理世界，

and to point out that perhaps we're just asking the wrong questions.

她可以指出也许 我们其实是问了错误的问题，

Which would not be the end of physics,

导致我们不可能找到 物理上的正确答案，

but a novel beginning.

反而能写出一部虚构小说。

Thank you.

谢谢大家。

(Applause)

（观众掌声）