There is something about physics that has been really bothering me since I was a little kid. And it's related to a question that scientists have been asking for almost 100 years, with no answer. How do the smallest things in nature, the particles of the quantum world, match up with the largest things in nature -- planets and stars and galaxies held together by gravity?
有一些关于物理方面的事情, 从我还是个小孩的时候 就开始并一直困扰着我。 它和一个问题有关, 科学家们已经在这个问题上 探索了将近100年, 却毫无结果。 自然界中最小的事物, 量子世界中的那些粒子, 是如何与自然中最大的事物, 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. I would fiddle around with microscopes and electromagnets, and I would read about the forces of the small and about quantum mechanics and I would marvel at how well that description matched up to our observation. Then I would look at the stars, and I would read about how well we understand gravity, and I would think surely, there must be some elegant way that these two systems match up. But there's not. And the books would say, yeah, we understand a lot about these two realms separately, but when we try to link them mathematically, everything breaks.
小的时候,我时常会为 这样的问题感到疑惑。 我会不停地摆弄显微镜和电磁铁, 我还会去阅读了解粒子间作用力和 量子力学, 然后惊叹于那描述 与我们的观察竟如此契合。 那时我仰望星空, 读到我们有多了解重力, 然后我会严肃思考 这一定有一些精巧的地方 使得这两个系统匹配。 但事实上并没有。 书上会说, 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, 每件事都变得不合逻辑了。
And for 100 years, none of our ideas as to how to solve this basically physics disaster, has ever been supported by evidence. And to little old me -- little, curious, skeptical James -- this was a supremely unsatisfying answer.
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 从没有被证据支持过。 对于小小的我, 幼小的,好奇的,多疑的詹姆士, 这个答案绝对满足不了我。
So, I'm still a skeptical little kid. Flash-forward now to December of 2015, when I found myself smack in the middle of the physics world being flipped on its head. It all started when we at CERN saw something intriguing in our data: a hint of a new particle, an inkling of a possibly extraordinary answer to this question.
我仍然是一个充满怀疑的小孩。 快进到现在,2015年12月, 我发现自己突然出现 在物理世界的正中央, 并完全沉迷于此。 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, 某种新的粒子的线索, 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, but I'm also now a particle hunter. I am a physicist at CERN's Large Hadron Collider, the largest science experiment ever mounted. It's a 27-kilometer tunnel on the border of France and Switzerland buried 100 meters underground. And in this tunnel, we use superconducting magnets colder than outer space to accelerate protons to almost the speed of light and slam them into each other millions of times per second, collecting the debris of these collisions to search for new, undiscovered fundamental particles. Its design and construction took decades of work by thousands of physicists from around the globe, and in the summer of 2015, we had been working tirelessly to switch on the LHC at the highest energy that humans have ever used in a collider experiment.
所以,我觉得我仍然是 一个小小的怀疑论者, 而我现在成为了一个粒子猎人。 我是CERN大型强子对撞机 (LHC)实验的物理学家, 这是有史以来规模最大的科学实验。 这个机器是法国和瑞典 交界地区的一个27公里的隧道, 深埋于地下100米处。 在这个隧道里, 我们使用低于外部空间 温度的超导磁体 来加速质子运动, 使其速度接近光速, 并使得质子以每秒 上百万次的速度互相撞击, 收集撞击后产生的碎片, 来进行新的、未发现的 基本粒子的研究。 它的设计和构造花费了 全世界上千名物理学家 数十年的时间, 2015年的夏天, 我们不知疲倦地 以人类曾经在对撞机试验中 使用过的最高能量 一次次打开LHC的开关。
Now, higher energy is important because for particles, there is an equivalence between energy and particle mass, and mass is just a number put there by nature. To discover new particles, we need to reach these bigger numbers. And to do that, we have to build a bigger, higher energy collider, and the biggest, highest energy collider in the world is the Large Hadron Collider. And then, we collide protons quadrillions of times, and we collect this data very slowly, over months and months. And then new particles might show up in our data as bumps -- slight deviations from what you expect, little clusters of data points that make a smooth line not so smooth. For example, this bump, after months of data-taking in 2012, led to the discovery of the Higgs particle -- the Higgs boson -- and to a Nobel Prize for the confirmation of its existence.
更高的能量是必要的, 因为粒子能量和粒子的质量 是守恒的, 质量只是自然给出的一个数值。 为了发现新的粒子, 我们要找到更大的数值, 为了做到这一点,我们要 制造更大更高能量的对撞机, 而这个世界上最大,能量最高的对撞机 也就是大型强子对撞机LHC。 然后,我们让质子对撞一千万亿次, 并在数个月内 慢慢地收集这些数据, 然后新粒子猛然出现在我们的数据里, 和你们所期望的有点偏差, 很小的一簇数据表使得 一条平滑的线变得有些粗糙。 比如,距离2012年的数据记录 几个月之后发现的这个碰撞, 引领我们发现了希格斯粒子 ——应该叫希格斯玻色子—— 并因为证明其存在而 获得了诺贝尔奖。
This jump up in energy in 2015 represented the best chance that we as a species had ever had of discovering new particles -- new answers to these long-standing questions, because it was almost twice as much energy as we used when we discovered the Higgs boson. Many of my colleagues had been working their entire careers for this moment, and frankly, to little curious me, this was the moment I'd been waiting for my entire life. So 2015 was go time.
2015年,能量出现了大幅波动, 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 来探寻新粒子的存在, 探寻那些存在已久的问题的答案。 因为这次的能量接近两倍于 我们曾发现的希格斯玻色子。 我的许多同僚终身奉献于事业 为的就是这一刻, 坦白讲,对于小小的, 充满好奇心的我来说, 这就是我一生都在等待的时刻。 这个时刻就是2015年。
So June 2015, the LHC is switched back on. My colleagues and I held our breath and bit our fingernails, and then finally we saw the first proton collisions at this highest energy ever. Applause, champagne, celebration. This was a milestone for science, and we had no idea what we would find in this brand-new data. And then a few weeks later, we found a bump. It wasn't a very big bump, but it was big enough to make you raise your eyebrow. But on a scale of one to 10 for eyebrow raises, if 10 indicates that you've discovered a new particle, this eyebrow raise is about a four.
2015年6月, LHC再一次启动了。 我和我的同僚们一起 屏住呼吸,紧张到咬指甲, 最终我们看到了 第一次质子对撞, 伴随着有史以来最大能量。 于是立刻爆发了掌声,欢呼,庆贺。 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。 几周过去了, 我们发现了一个碰撞。 这不是一次很大的碰撞, 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, 如果“十”表示你发现了一种新粒子, 那么这次大概只能有“四”。
(Laughter)
(观众笑声)
I spent hours, days, weeks in secret meetings, arguing with my colleagues over this little bump, poking and prodding it with our most ruthless experimental sticks to see if it would withstand scrutiny. But even after months of working feverishly -- sleeping in our offices and not going home, candy bars for dinner, coffee by the bucketful -- physicists are machines for turning coffee into diagrams --
我花了数小时,数天, 数周时间参加秘密会议, 和我的同事们讨论这次小碰撞, 用我们最无礼的方式对着它指指点点, 看它能不能经受得住详细的检查。 但是经过了几个月的狂热实验 ——睡在实验室连家都不回, 用糖果棒代替晚餐, 喝了一桶又一桶的咖啡—— 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. So after a few months, we presented our little bump to the world with a very clear message: this little bump is interesting but it's not definitive, so let's keep an eye on it as we take more data. So we were trying to be extremely cool about it.
这个小碰撞并没有消失。 所以几个月后, 我们把这个小碰撞非常清楚的 介绍给了全世界。 这个小碰撞虽然令人关注, 但它并不是最终结果。 所以我们会继续关注它, 记录下更多数据。 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. The news loved it. People said it reminded them of the little bump that was shown on the way toward the Higgs boson discovery. Better than that, my theorist colleagues -- I love my theorist colleagues -- my theorist colleagues wrote 500 papers about this little bump.
全世界也一直在关注着它。 新闻界喜爱它。 人们说这让他们想起了 发现希格斯玻色子的那次碰撞。 比这更令人振奋的是, 我的理论家同事们 ——我爱他们—— 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. But what was it about this particular bump that caused thousands of physicists to collectively lose their cool? This little bump was unique. This little bump indicated that we were seeing an unexpectedly large number of collisions whose debris consisted of only two photons, two particles of light. And that's rare.
整个粒子物理世界都痴迷于此。 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? 这次小碰撞是独特的。 这次小碰撞意味着 我们眼见着未曾预期过的 大量粒子对撞, 它们的残骸只形成两种光子, 就是两种光粒子。 这是很少见的。
Particle collisions are not like automobile collisions. They have different rules. When two particles collide at almost the speed of light, the quantum world takes over. And in the quantum world, these two particles can briefly create a new particle that lives for a tiny fraction of a second before splitting into other particles that hit our detector. Imagine a car collision where the two cars vanish upon impact, a bicycle appears in their place --
粒子对撞不像汽车碰撞。 它们的规则是不一样的。 当两个粒子以接近光速的速度发生碰撞, 量子世界就出现了。 在量子世界中, 这两个粒子可以简单地 创造出一种新的粒子。 这种新粒子只会有一瞬间存在, 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。 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——
(Laughter)
(观众笑声)
And then that bicycle explodes into two skateboards, which hit our detector.
然后这辆自行车又发生了 爆炸,变成两块滑板 撞向我们的检测器。
(Laughter)
(观众笑声)
Hopefully, not literally. They're very expensive.
我希望这不是真的。 因为它们太贵重了。
Events where only two photons hit out detector are very rare. And because of the special quantum properties of photons, there's a very small number of possible new particles -- these mythical bicycles -- that can give birth to only two photons. But one of these options is huge, and it has to do with that long-standing question that bothered me as a tiny little kid, about gravity.
两个光子撞击被探测器捕捉到 这种事情太少见了。 并且由于光子的特殊量子特性, 极少有可能产生新的粒子—— 也就是那些所谓的“自行车”—— 会产生两个光子。 但是其中一个可能性是很大的。 它和一个长期存在的问题有关, 从我还是个小孩的时候 就一直困扰着我, 也就是重力。
Gravity may seem super strong to you, but it's actually crazily weak compared to the other forces of nature. I can briefly beat gravity when I jump, but I can't pick a proton out of my hand. The strength of gravity compared to the other forces of nature? It's 10 to the minus 39. That's a decimal with 39 zeros after it.
重力对大家的影响太大了。 但是它同大自然其它的力量 相比又实在太微弱了。 当我跳起来的时候, 我可以短暂性地克服重力, 可我却不能从我手里拿起一个质子。 把引力的强度和其它的 自然力量相比会如何? 它等于10的负39次方。 也就是小数点后39个零。
Worse than that, all of the other known forces of nature are perfectly described by this thing we call the Standard Model, which is our current best description of nature at its smallest scales, and quite frankly, one of the most successful achievements of humankind -- except for gravity, which is absent from the Standard Model. It's crazy. It's almost as though most of gravity has gone missing. We feel a little bit of it, but where's the rest of it? No one knows.
更可怕的是, 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 精确地描述, 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, 也是人类最成功的成就之一 ——除了重力, 这是被排除在标准模型之外的, 这太疯狂了。 好像大部分的重力都不知所踪。 我们只能感受到一点点, 但是剩下的部分在哪儿? 没有人知道。
But one theoretical explanation proposes a wild solution. You and I -- even you in the back -- we live in three dimensions of space. I hope that's a non-controversial statement.
但是有种理论 提出了一个疯狂的设想。 你和我—— 即使你在后面—— 我们生活在三维空间里。 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. In fact, a particle is just another name for an excitation in a three-dimensional field; a localized wobbling in space. More importantly, all the math that we use to describe all this stuff assumes that there are only three dimensions of space. But math is math, and we can play around with our math however we want. And people have been playing around with extra dimensions of space for a very long time, but it's always been an abstract mathematical concept. I mean, just look around you -- you at the back, look around -- there's clearly only three dimensions of space.
所有我们现在已知的粒子 都存在于三维空间, 实际上,粒子只是给 在三维空间产生的碰撞 起的另一个名字, 空间中的局部震动。 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 都建立在只存在三维空间的假设之上。 但是数学仅仅是数学, 我们可以用任何方式摆弄它。 人类幻想着存在额外维度空间 已经有很长时间了, 但是这始终是一个抽象的数学概念。 我是说,看看你们周围—— 你非常清楚这是三维空间。
But what if that's not true? What if the missing gravity is leaking into an extra-spatial dimension that's invisible to you and I? What if gravity is just as strong as the other forces if you were to view it in this extra-spatial dimension, and what you and I experience is a tiny slice of gravity make it seem very weak? If this were true, we would have to expand our Standard Model of particles to include an extra particle, a hyperdimensional particle of gravity, a special graviton that lives in extra-spatial dimensions.
但是假如这不是真的呢? 假如那些消失的重力 其实都流失到了超三维空间, 而你和我都看不到呢? 假如重力其实和其它的力一样强呢? 假如你能在超三维空间看到它呢? 还有,假如你和我经受的重力 其实仅仅是重力的一小部分, 所以看上去这股力才这么微弱呢? 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。 让更多的粒子,比如多维重力粒子 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. You should be asking me the question, "How in the world are we going to test this crazy, science fiction idea, stuck as we are in three dimensions?" The way we always do, by slamming together two protons --
我看到了你们脸上的表情。 你们也许会问我这样的问题: “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 科幻小说里的设想?” 我们经常会用的方法是 让两个质子互相撞击——
(Laughter)
(观众笑声)
Hard enough that the collision reverberates into any extra-spatial dimensions that might be there, momentarily creating this hyperdimensional graviton that then snaps back into the three dimensions of the LHC and spits off two photons, two particles of light. And this hypothetical, extra-dimensional graviton is one of the only possible, hypothetical new particles that has the special quantum properties that could give birth to our little, two-photon bump.
很难让碰撞反射到任何 可能存在的超维空间里, 很难随时制造出这种多维引力子, 然后让其迅速返回到三维空间的LHC上 再分解成两个光子, 两个光粒子。 这种假想出来的 超维引力子 是假想的可能存在的 所有新粒子中的一种, 它拥有特殊的量子特性, 碰撞后能够分解出两个光子。
So, the possibility of explaining the mysteries of gravity and of discovering extra dimensions of space -- perhaps now you get a sense as to why thousands of physics geeks collectively lost their cool over our little, two-photon bump. A discovery of this type would rewrite the textbooks. But remember, the message from us experimentalists that actually were doing this work at the time, was very clear: we need more data. With more data, the little bump will either turn into a nice, crisp Nobel Prize --
因此,解释重力的奥秘 以及发现超维空间的可能性 ——现在你应该有所察觉了, 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。 这种类型的探索将会改写课本。 但是请记住, 我们这些正在践行的实验主义者 想要说的是 非常清楚的: 我们需要更多的数据。 有了更多数据, 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 and turn it into a nice, smooth line.
或者更多的数据将会填满 碰撞数据边上的空白, 然后变成又一条光滑的线条。
So we took more data, and with five times the data, several months later, our little bump turned into a smooth line. The news reported on a "huge disappointment," on "faded hopes," and on particle physicists "being sad." Given the tone of the coverage, you'd think that we had decided to shut down the LHC and go home.
所以我们记录了更多的数据, 七个月后的数据量达到了以前的五倍, 这次小小的碰撞 变成了平稳的线条 新闻上报道着“大失所望”,“希望破灭”, 还有粒子物理学家们“十分难过”。 在这样的基调下, 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. But why not? I mean, if I didn't discover a particle -- and I didn't -- if I didn't discover a particle, why am I here talking to you? Why didn't I just hang my head in shame and go home?
但我们不是这样做的。 可是为什么不呢? 我的意思是,如果我没有发现新的粒子 ——我也确实没有发现—— 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, 然后灰溜溜的离开呢?
Particle physicists are explorers. And very much of what we do is cartography. Let me put it this way: forget about the LHC for a second. Imagine you are a space explorer arriving at a distant planet, searching for aliens. What is your first task? To immediately orbit the planet, land, take a quick look around for any big, obvious signs of life, and report back to home base. That's the stage we're at now. We took a first look at the LHC for any new, big, obvious-to-spot particles, and we can report that there are none. We saw a weird-looking alien bump on a distant mountain, but once we got closer, we saw it was a rock.
粒子物理学家是一群探险者。 我们工作的大部分内容是绘制图表。 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 寻找外星人。 你的第一个任务是什么? 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, 然后向总部报告。 这就是我们现在所处的阶段。 我们第一次查看LHC, 看看有没有新的, 大到无法忽视的粒子, 然后我们可以报告什么也没有。 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 then what do we do? Do we just give up and fly away? Absolutely not; we would be terrible scientists if we did. No, we spend the next couple of decades exploring, mapping out the territory, sifting through the sand with a fine instrument, peeking under every stone, drilling under the surface. New particles can either show up immediately as big, obvious-to-spot bumps, or they can only reveal themselves after years of data taking.
然后我们又该怎么做呢? 就这样放弃然后飞回去吗? 当然不能。 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, 在地图上画出版图, 用最好的工具筛掉沙子, 检查每一块石头, 挖掘地底深处的秘密。 新粒子要么立刻出现, 像巨大而无法忽视的碰撞一样, 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, and we have much searching to do. But what if, even after 10 or 20 years, we still find no new particles? We build a bigger machine.
人类只能怀着巨大热情 从LHC里探索, 我们还有许多探索工作要做。 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? 我们会建造一个更大的机器。
(Laughter)
(观众笑声)
We search at higher energies. We search at higher energies. Planning is already underway for a 100-kilometer tunnel that will collide particles at 10 times the energy of the LHC. We don't decide where nature places new particles. We only decide to keep exploring. But what if, even after a 100-kilometer tunnel or a 500-kilometer tunnel or a 10,000-kilometer collider floating in space between the Earth and the Moon, we still find no new particles? Then perhaps we're doing particle physics wrong.
我们会以更高的热情去探索。 我们会以更高的热情去探索。 计划已经开始 在100公里长的隧道里进行, LHC将会使用十倍的能量 来进行粒子对撞。 我们不会决定自然 会把新粒子藏在哪里, 我们只决定要继续探索。 但是假如用100公里长的隧道 或是500公里长的, 甚至是10000公里长的 对撞机,都只能 漂浮在地球和月球之间了, 我们仍然没有找到新粒子 该怎么办呢? 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. Maybe we need more resources, technology, expertise than what we currently have. We already use artificial intelligence and machine learning techniques in parts of the LHC, but imagine designing a particle physics experiment using such sophisticated algorithms that it could teach itself to discover a hyperdimensional graviton.
也许我们应该重新思考。 我们可能需要比我们现在拥有的 更多的资源,技术和专家。 我们已经开始在LHC的 某些部分运用人工智能 和机器学习技术。 但是想象一下 运用如此复杂的算法 设计一个粒子物理试验, 让它自己去探索超维引力子的场景。
But what if? What if the ultimate question: What if even artificial intelligence can't help us answer our questions? What if these open questions, for centuries, are destined to be unanswered for the foreseeable future? What if the stuff that's bothered me since I was a little kid is destined to be unanswered in my lifetime? Then that ... will be even more fascinating.
但是假如可以呢? 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? 假如这些存在了几个世纪 的开放式问题 注定是没有答案的, 在可预见的未来也不可能被解答呢? 假如从我还是个孩子的时候开始 就困扰着我的那些事情 注定了我一生都不可能找到答案呢? 那么…… 它就更令人神魂颠倒了。
We will be forced to think in completely new ways. We'll have to go back to our assumptions, and determine if there was a flaw somewhere. And we'll need to encourage more people to join us in studying science since we need fresh eyes on these century-old problems. I don't have the answers, and I'm still searching for them. But someone -- maybe she's in school right now, maybe she's not even born yet -- could eventually guide us to see physics in a completely new way, and to point out that perhaps we're just asking the wrong questions. Which would not be the end of physics, but a novel beginning.
我们将会被迫从全新的角度去思考。 我们会回到最初的设想, 来确认某处是否所有缺陷。 我们需要鼓励更多人 加入我们来进行科学研究, 我们需要用新的眼光 去看待这些世纪问题。 我没有答案, 我仍然在寻找答案。 可是某些人 ——也许她现在正在学校里, 也许她现在还没出生, ——某天可以带领我们 以全新的方式去探索物理世界, 她可以指出也许 我们其实是问了错误的问题, 导致我们不可能找到 物理上的正确答案, 反而能写出一部虚构小说。
Thank you.
谢谢大家。
(Applause)
(观众掌声)