100 - 什么是光？从古代哲学到量子物理的旅程

今天，我们知道光是由光子或电磁波片段组成的。

Today, we know that light is made of photons or pieces of electromagnetic waves.

这些光子是粒子，但它们的表现也非常像波，以每秒三亿米的惊人速度在空间中传播。

These photons are particles, but these particles also act very much like waves, which travel through space at an incredible 300,000,000 meters every second.

但在我们了解这些关于光的性质之前很久，人类就一直好奇光到底是什么，它是如何运作的。

But long before we knew any of these things about light, human beings have wondered about what light really is and how it really works.

今天在节目中，我们将讨论一些自古以来人们提出的关于光的理论，探索当我们刚开始了解光时，人们是如何理解它的，以及我们是如何从那时走到今天的。

Today in the show, we're gonna talk about some of the theories of light that people proposed going back ancient times and explore how people made sense of light when we were just starting to learn about it and how we got from where we were then to where we are today.

别走开。

Stick around.

你正在收听《为什么是这个宇宙？》。

You're listening to Why This Universe?

这是一个解析物理学中最宏大思想的播客。

A podcast where we break down the biggest ideas in physics.

我是丹·胡珀。

My name is Dan Hooper.

光这个东西，每个人对它都有一些自己的看法。

Light is one of those things that everyone has some ideas about.

我们都有接触光的经验。

We all have experience with light.

它不像夸克、电子或者弯曲空间那样抽象，那些东西我们得先去发现，才知道它们存在。

It's not like something abstract like quarks or electrons or curved space, which, you know, we had to go out and discover in the world before we even knew they existed.

我觉得，自从有人类以来，人们就对光有某种概念了。

For as long as there have been human beings, I imagine they've had some sort of conception of light.

我能找到的最早关于光的本质的记载，是公元前五世纪的。

The oldest writings that I could find on the nature of light come from the fifth century BCE.

不过，这里说的记载，其实是指后来的人对公元前五世纪那些人所写内容的转述。

And by writings here, I really mean what people later on said about what these people wrote back in the fifth century BCE.

那些原始文献都没有保存到今天。

None of the original writings have survived to the present day.

那我们就从前苏格拉底时期的哲学家恩培多克勒说起吧。

So let's start with the pre Socratic philosopher Empedocles.

恩培多克勒写道，或者说他主张，世界上的一切都是由四种元素以不同的组合构成的。

So Empedocles wrote or said or written that he believed everything in the world was made up of four elements in different combinations.

这四种元素就是火、土、气和水的。

These were fire, earth, air, and water.

他还说，阿佛洛狄忒，就是女神阿佛洛狄忒，用这四种元素造了人的眼睛，并在眼睛里点燃了一种内在的火，这种火会从眼睛里射出来。

And he said that Aphrodite, the goddess Aphrodite made the human eye out of those four elements and lit some sort of inner fire in the eye that would shine out from the eye.

正是这种内在的火使得视觉成为可能。

And it was this inner fire that made sight possible.

我不知道你怎么想，但当我第一次开始思考这个理论时，没过多久我就发现了一些问题。

Now, don't know about you, but when I first started to think about this theory, it didn't take me long before I began to notice some problems with it.

比如说，如果是我们的眼睛发出光线让我们看见东西，那似乎意味着我们在晚上应该和白天一样容易看清东西。

For example, if it's our eye that's sending out the rays that allow us to see, it would seem to imply that we should be able to see just as easily during the night as we can during the day.

但恩培多克勒当然是个聪明人，他也意识到了这一点。

But Empedocles, of course, was a smart guy and he realized this too.

为了解决这个问题，他假设眼睛发出的光线和我们所看物体发出的光线之间，必须发生某种相互作用，他称这些物体发出的光线为“流出物”。

So to solve this problem, he postulated there is some kind of interaction that must take place between the rays that were coming from the eye and then rays that were coming from the things we're looking at, what he called effluences.

这两样东西都必须存在，也就是我们眼睛发出的光线和光源发出的光线。

Both of these things had to be present, the rays from our eye and the rays from the light source.

所以如果缺少了其中任何一样，我们就看不见东西。

So if both of those weren't involved, we wouldn't be able to see something.

至少他是这么想的。

At least that was his idea.

后来柏拉图采纳了其中一些观点，至少部分认同。

Plato later on would take up some of these ideas, endorsing at least parts of them.

他还认为视觉是通过眼睛发出的某种火来实现的，和恩培多克勒的观点很像，这种火与来自各种物体的光相互作用。

And he also argued that vision occurred through some kind of fire emitted by the eyes, a lot like Empedocles interacting with light from various objects.

好，我们再把时间往前推一点，大约到公元前300年，那时候有希腊哲学家欧几里得。

All right, let's step forward a while to about 300 BCE with the Greek philosopher Euclid.

欧几里得最出名的是他的《几何原本》，这本书主要讲几何学。

So Euclid is most famous for his book Elements, which was really about geometry.

他建立的几何体系一直沿用到中世纪，对数学和几何学贡献巨大。

He laid out the geometrical system that persisted in place until the Middle Ages, huge contributions to mathematics and geometry.

但除此之外，他还写了一本关于光的书，叫做《光学》。

But in addition to this, he also wrote a book about light that he called Optica.

在很多方面，欧几里得对光和视觉的看法跟恩培多克勒和柏拉图差不多，但他用了更多的数学，尤其是几何学。

In a lot of ways, Euclid thought about light and vision in the same way that Empedocles and Plato had, but he applied a lot more math to the problem, especially the mathematics of geometry.

他提出光沿直线传播，这基本上是对的。

He did things like argue that light travels in straight lines, which is more or less true.

他还描述了反射现象，并写下了描述光在物体表面反射时行为的数学定律。

And he also described the phenomena of reflection and wrote down mathematical laws that describe how light behaves when it's reflected off the surface of an object.

欧几里得反对恩培多克勒的视觉理论，指出我们抬头看夜空时能立刻看到星星。

Euclid argued against Empedocles' theory of vision, pointing out that we see stars instantly when we look up at the night sky.

如果眼睛发出的光线速度无限快，或者快到我们察觉不到时间延迟，那这也许说得通。但如果你认为视觉是靠眼睛向所看物体发送信号来实现的，那就很难理解为什么我们看到像星星那么远的东西不需要花更多时间。

This might be okay if the rays from our eyes traveled infinitely fast or so fast that we didn't notice any time delay, But if you think sight works by sending signals from our eyes to the thing we're looking at, it might be hard to understand why it doesn't take more time for us to see things that are very far away, like stars.

关于光的最基本、最长久的问题之一，已经开始在这些古希腊哲学家之间引发争论了。

Already one of the most fundamental and long standing questions about light was starting to be debated among these ancient Greek philosophers.

这个问题就是：光是由粒子组成的，还是由某种非粒子的东西组成的。

That question is whether or not light is made up of particles or something else, something non particle like.

一方面，像亚里士多德这样的人认为光必须通过空气或水这样的介质传播。

On the one hand, there were figures like Aristotle who thought that light had to travel through a medium like air or water.

这还不是像现代的光的波动理论。

This wasn't like a modern theory of wave like light yet.

亚里士多德并没有谈论振荡、干涉或其他任何波动特征。

Aristotle wasn't talking about things like oscillations or interference or any other wave like features.

但这至少是朝着可能开始类似光的波动理论的方向迈出的一小步。

But it was at least a small step in the direction of something that could begin to resemble a wave like theory of light.

这场辩论的另一方是希腊的原子论者。

On the other side of this debate were the Greek atomists.

原子论者认为，包括光在内的一切都是由不可分割的粒子组成的，他们称之为原子。

The atomists argued that everything including light was made up of indivisible particles or what they called atoms.

这些并不是我们在现代物理学和化学中讨论的那种原子，但我们的名字就是从那里来的。

These aren't the kind of atoms that we talk about in physics and chemistry in the modern era, but it's where we get the name.

他们基本上就是指那些不能被分解成更小碎片的粒子，你知道，就是不可分割的粒子。

And they basically just mean pieces that can't be broken up into smaller pieces, you know, indivisible particles.

这就让我们想到了卢克莱修。

And that brings us to Lucretius.

卢克莱修不是希腊人。

Lucretius wasn't a Greek.

他是罗马人。

He was a Roman.

他生活在公元前一世纪。

He lived in the first century BCE.

尽管他自己不是希腊人，但他显然受到了早期希腊原子论者的启发。

And Even though he wasn't Greek himself, he was clearly inspired by the earlier Greek atomists.

卢克莱修提出了光的粒子理论，他认为光是由粒子组成的，这些粒子至少运动得非常快，而且如果我没理解错的话，它们是沿直线运动的。

Lucretius had a particle theory of light, so he argued that light was made up of particles that move, at least very quickly, and if I understand them correctly, in straight lines.

这开始有点像我们现在所说的光子了。

This started to look a little bit like what we would now call photons.

显然，我们今天所知道的关于光子的许多东西，卢克莱修并没有提到，但至少光可能由我们称之为粒子的、不可分割的个体组成的这个想法，至少可以追溯到公元前一世纪。

Obviously, a lot of things that we know about photons today Lucretius wasn't talking about, but at least the idea that light could be made up of individual, indivisible things that we might call particles, that goes back to the first century at least.

接下来我们来到公元二世纪，伟大的天文学家和几何学家托勒密，拼写是P-T-O-L-E-M-Y。

Moving on to the second century of the Common Era, we have the great astronomer and geometr, Ptolemy, p t o l e m y.

托勒密最出名的是他在天文学上的成就。

Ptolemy is most famous for his work in astronomy.

他提出的托勒密模型，在西方世界一直是太阳系的主导理论，直到伽利略时代才被取代。

The Ptolemaic model that he developed would remain the predominant theory of the solar system in the Western world up until roughly the age of Galileo.

但他还写了一本叫《光学》的书，据说那是古代关于光的最精深的论述。

But he also wrote a book called Optics, which was said to be the most sophisticated of the ancient treatments describing light.

在那本书里，他描述了自己做的一些关于光的实验，并提出了他关于视觉感知如何运作的理论。

In that book, he described some experiments he conducted with light, and he presented his theory of how visual perception worked.

他还把大量的几何学知识用在这个问题上，让这个领域比他的前辈们有了更坚实的数学基础。

He also brought a lot of geometrical expertise to this problem, placing the subject on a firmer mathematical footing than any of his predecessors.

他像前人一样写了反射之类的内容，但他还讨论了折射。

He wrote about things like reflection, as others had before him, but he also talked about refraction.

折射就是光从一种介质进入另一种介质时发生的弯曲，比如从空气进入水，或者从空气进入玻璃，或者从水进入玻璃。

Refraction is the bending of light as it passes from one medium to another, like from air into water, or from air into glass, or water into glass.

比如，他知道在反射中，入射角等于反射角。

He knew, for example, that when it came to reflection, the angle of incidence would equal the angle of reflection.

他还测量了光线在不同介质之间传播时的弯曲程度。

And he measured how these light rays would bend when they pass between different medium.

并且他把这些行为记录成了数学表格。

And he wrote down mathematical tables to describe this behavior.

总的来说，这些数据已经相当接近准确了。

And, you know, all in all, they were pretty close to accurate.

虽然不是完美，但大致方向是对的。

Not perfect, but in the right ballpark.

这种处理方式相对现代。

The relatively modern approach to that subject.

好了。

Alright.

关于古代世界以及当时人们对光的看法，我要说的就这些。

So that's the last thing I'm gonna say about the ancient world and what people thought during that time about light.

现在我们直接跳到很久以后，远远超过那些被一些人称为黑暗时代的时期，进入早期的启蒙时代。

So we're gonna jump way ahead now, well past the, you know, dark ages as you as some people like to call them and whatever, and into, like, the early age of enlightenment.

对吧？

Okay?

我在这里提到的这些人，当然读过希腊人和其他古代人关于光的论述，但他们打算把这些想法大大推进。

So the people I'm talking about here certainly read what the Greeks and and other ancient people had to say about light, but they were gonna, you know, embark to try to take these ideas considerably farther.

这里，我们先从勒内·笛卡尔开始。

And here, we're gonna start with Rene Descartes.

他生活在十六世纪末和十七世纪上半叶。

So he lived in the late fifteen hundreds and the first half of the sixteen hundreds.

他是一位伟大的哲学家，但至少在我看来，并不是一位特别好的物理学家。

He is a great philosopher, but at least in my opinion, was not a particularly good physicist.

这在一些历史学家中可能有点争议。

That might be a bit of a controversial statement among some historians.

这只是我的个人看法。

It's just my opinion.

但当我读他的物理学著作时，我觉得并不怎么有说服力。

But when I read his physics, it doesn't seem all that compelling to me.

我认为，笛卡尔提出的那些物理理论，实际上并没有把科学推进多远。

Those physical theories, the ones that Descartes proposed, never really turned out to advance science very far, I would argue.

而且他描述的那些东西，结果发现世界上并不存在，至少大多数时候是这样。

And the things they described were turned out to be things that don't really exist in the world, at least most of the time.

事实证明，他在光这个课题上的研究也不例外。

And as it turns out, his work on the topic of light was no exception to this.

尽管如此，笛卡尔是最早用机械论观点来思考世界的重要人物之一。

That said, Descartes was among the first prominent figures to think about the world in mechanical terms.

古希腊人和其他人用几何学的数学术语来谈论世界，但笛卡尔谈论的是机械因果关系，通过这些关系，不同作用的效果可以通过物质传递。

So people, ancient Greeks, others had talked about the world in mathematical terms of geometry, but Descartes was talking about mechanical causal factors through which the effects of different actions can be transmitted through matter.

我认为这是向前迈出的重要一步，即使细节有些模糊，而且和现实世界联系不大。

And I think this was an important step forward, even if the details were kind of muddy and and not really, connected to the real world.

关于光，笛卡尔认为光是由某种通过物质介质传播的压力构成的。

And in the case of light, Descartes thought that it was some kind of pressure that moved through a material medium that constituted light.

这其实并不完全正确，但这是一个重要的进步，而且影响了很多后来的人。

That turns out to not be true exactly, but it was an important step forward, and it influenced a lot of people who would come after him.

1637年，笛卡尔发表了他的折射理论，里面有一些好的想法，但他错误地假设光在密度更大的介质中传播得更快，在密度较小的介质中传播得更慢，而这些假设都不成立。

In 1637, Descartes published his theory of refraction, which had some good ideas in it, but he had to incorrectly assume that light moves faster in denser mediums and less fast in a less dense medium, and none of that turns out to be true.

这让他得出了错误的结论，基本上是因为他认为光很像声音，但实际上光并不太像声音。

And this allowed him to reach false conclusions, basically because he thought that light was a whole lot like sound, and it's not really all that much like sound.

所以，尽管笛卡尔的光理论中有一些真理的影子，但他的理论中仍有很多不正确的地方，我们不得不在此基础上继续前进。

So although there were some inklings of truth in Descartes' theory of light, there was still a lot he didn't get correct in his theory, and we had to kind of move on from there.

大约在同一时期，或者可能比笛卡尔稍晚一些，自然哲学家们追随希腊原子论者的脚步，开始考虑光是由粒子组成的理论。

Around the same time, or maybe a little later than Descartes, natural philosophers were following up on the Greek atomists and were considering theories of light in which light was made up of particles.

这包括皮埃尔·伽桑狄，他提出了一个光由粒子组成的理论，并在1670年他去世后发表。

This included Pierre Gassendi, and he had a theory of light that was made of particles and he published after his death in 1670.

然后，以非常重要和重大的方式继续这一工作的，当然是著名的艾萨克·牛顿。

And then following up on this in a very big and important way was, of course, the famous Isaac Newton.

牛顿研究了笛卡尔和伽桑狄的光理论，并得出结论，光一定是由粒子组成的。

Newton had studied both Descartes and Gessendi's theories of light, and he came to the conclusion that light must be made up of particles.

他提出，如果光是由波组成的，那么这些波在遇到障碍物时应该会比实际弯曲得更厉害。

He argued that if light had been made of waves instead, those waves would bend around obstacles more than they do.

这个论点现在看来大部分是错的，但值得思考的是，牛顿为什么会得出这样的结论。

This argument turns out to be mostly wrong, I would say, but it's worth thinking about why Newton reached this conclusion.

他错的原因非常微妙。

He was wrong for very subtle reasons.

所以基本上可以归结为这一点。

So it basically comes down to this.

光似乎以非常直的直线传播，尤其是与其他类型的波相比。

Light seems to move in remarkably straight lines, especially compared to other kinds of waves.

打个比方，想象一下一个水面上有一艘船，然后有一些波浪经过那艘船。

For comparison, picture a body of water with a boat in it and then some waves that are passing by that boat.

船会稍微扰动那些波浪，改变它们的形状。

The boat is gonna disturb those waves a bit and change their shape.

然后，如果你在船的另一边，波浪朝你涌来，你只会看到一片混乱的波浪。

And then if you were on the opposite side of the the boat and those waves are coming from you, you just kinda see a mess of waves.

现在想象一下，光波经过一个物体，照到另一边的墙上。

Now picture light waves passing by a an object and shining onto a wall on the other side.

明白吗？

Okay?

这样就会投下影子。

That will cast a shadow.

在合适的条件下，你可以看着那个影子，辨认出物体的形状，可能还有一些清晰的边缘。

And under the right conditions, you can look at that shadow and, like, make out the shape of the object, maybe with some sharp edges.

你光看影子就能真正搞清楚光波绕过的是什么物体。

You can, like, really understand what the thing is that the light waves are are projected around just by looking at the shadow.

我觉得船和水面就做不到这一点。

I don't think you can do that to the boat and the body of water.

那些水波经过时会被抹开或模糊掉。

Those water waves get smeared out or blurred out as they pass by.

这完全是两种不同的表现。

It's just not the same sort of behavior.

牛顿看到水波的行为和光的性质后，就认为光不可能是由波组成的。

And when Newton looked at what water waves did and how light behaved, this led him to think that the the light couldn't be made of waves.

相反，光一定是由粒子构成的。

It had to be made up of particles instead.

实际上，事情要复杂得多。

In reality, this is all a bit more complicated.

毕竟，事实证明，光在物体边缘附近会稍微发生偏折。

Light after all is, as it turns out, slightly deflected near the edges of bodies.

这就是我们所说的衍射现象，也就是光波在绕过障碍物或穿过狭窄缝隙时发生的弯曲和扩散。

This is the phenomena we call diffraction, or the bending and spreading out of light waves as they pass around obstacles or through narrow openings.

但这种衍射远没有水波那么明显。

But this diffraction is just not nearly as pronounced as it is for water waves.

为了解释这一点，牛顿在他的理论中提出了一种临时性的假设。

And to explain this, Newton proposed kind of an ad hoc part of his theory.

他说，光的粒子在靠近物体边缘时，会受到某种力的作用。

He said that particles of light were somehow acted on by some force or forces as they get close to the edge of an object.

而且，你知道，牛顿在这里就是错了。

And, you know, here, Newton was just wrong.

他编造了一些不真实的东西。

He just made up something that isn't real.

事实证明，我们现在知道，光经历的这种衍射实际上是由于它的波动性质。

And as it turns out, we now know that this kind of diffraction that light experiences is in fact due to its wave like nature.

但就像我说的，这并不是对牛顿的重大批评。

But like I said, this isn't a big critique of Newton.

他错了，但他错在非常微妙且远非显而易见的原因上。

He was wrong, but he was wrong for very subtle and far from obvious reasons.

总的来说，我认为牛顿提出了一个相当不错的光理论，至少在他那个时代是这样。

All in all, I would say that Newton had put forward a pretty good theory of light, at least for the time that he was working in.

他的理论可以解释光的反射，对折射也有很好的解释，但那部分并不完全正确。

His theory could explain the reflection of light, and it had a pretty good explanation for refraction, but that part wasn't exactly correct.

它只能解释折射。

It could only explain refraction.

因为他错误地假设了光从密度较低的介质进入密度较高的介质时会被加速。

If he incorrectly assumed that light was somehow accelerated when it passed from a lower density medium into a higher density medium.

这跟之前笛卡尔在他的理论中所假设的有些相似。

This was kind of similar to what Descartes had assumed earlier in his own theory.

在接下来的大约一个世纪里，也就是基本上整个18世纪，牛顿的理论大致上还是光学的领先理论。

Throughout the next century or so, like basically the 1700s, Newton's theory was more or less the leading theory of light.

如果你问一群自然哲学家光是什么，他们会告诉你光是由粒子组成的，就像牛顿说的那样，并且他们会指着牛顿的书《光学》来证明这一点。

If you asked a bunch of natural philosophers what light was, they would tell you it's made of particles, like Newton had said, and they would point to Newton's book Optics on this topic.

这也有一些合理的理由。

And this was for some good reasons.

就像我说的，牛顿的理论整体上还是相当不错的。

Like I said, Newton's theory was pretty good overall.

但这也可能很大程度上是因为艾萨克·牛顿当时已经非常出名了。

But it also probably had a lot to do with just how famous Isaac Newton had become by this point.

他的万有引力理论和三大运动定律是当时科学史上最大的成就，真的是前所未有的。

His theory of gravitation and his three laws of motion were the biggest success, well, really the biggest success in the history of science up to that point.

所以，你知道，他的名声相当好。

So, you know, he had a pretty good reputation.

基于这些原因，当时的主流观点认为光可能是由粒子组成的，而不是波。

And for all these reasons, the dominant view of that time was that light was probably made of particles and not waves.

这就引出了光的另一个特性，那就是偏振。

This brings us to yet another property of light, and that property is that of polarization.

用现代的话说，当光波的振动受到限制时，我们就说光是偏振的。

So in modern language, we say that light is polarized when the vibrations of a light wave are restricted.

它们只能沿特定方向或特定模式振动。

They can only vibrate in a certain direction or in a particular pattern.

有些光源，比如太阳光，是非偏振的。但你可以拿太阳光，让它通过某些材料，使其只沿特定方向振动。

Some sources of light, like sunlight, is unpolarized But you can take sunlight, for example, and pass it through certain materials, causing it to only vibrate in certain directions.

然后我们就说它是偏振的。

And then we say that it's polarized.

牛顿做过实验，让光通过一种叫做冰洲石的透明晶体。

Newton had conducted experiments where he passed light through a transparent crystal known as Iceland spar.

冰洲石有时候也被称为维京太阳石，之所以这么叫，是因为早期的斯堪的纳维亚航海者在他们的船或小船上发现，即使太阳被云层遮住，他们也能用这种材料来判断太阳的方向。

Iceland spar is also sometimes called the Viking sunstone, and it's called this because the early Scandinavian navigators on their ships or boats found that they could use this material to tell the direction of the sun even when it was obscured by the clouds.

这当然对在水路上导航非常重要。

And this was of course very important for trying to navigate waterways.

冰洲石有一种特性，我们现在知道它叫双折射。

Iceland's spar is a property we now know is called birefringence.

双折射的意思是，当一束非偏振光穿过这种晶体时，会被分成两束相互垂直偏振的光线。

What birefringence means is that when the ray of unpolarized light passes through this crystal, it gets divided into two separate rays of mutually perpendicular polarization.

所以，其中一束光在一个方向上偏振，另一束则在与之垂直的相反方向上偏振。

So, one of the rays is polarized in one orientation and then the other in the perpendicular kind of opposite polarization.

这会导致透过晶体看到的物体出现两个分开的影像。

This causes objects that are seen through the crystal or viewed through the crystal to have two separate images.

所以，如果你是一个维京人，在阴天试图在水路或海上导航，你会拿出你的太阳石，然后在晶体内部寻找阴影。

So if you're a Viking trying to navigate your, you know, waterways or seas on a cloudy day, you take out your sunstone, and you would look for shadows inside of the crystal.

然后你会在晶体顶部画一个点，再从晶体底部看过去。

You'd then draw a dot on the top of the crystal and look through the bottom of the crystal.

然后你旋转晶体，直到两个点看起来完全一样。

You then rotate the crystal until the two dots look exactly the same.

一旦你做到了这一点，晶体就应该指向太阳的方向。

And once you've done that, the crystal should be pointing in the direction of the sun.

好，我们回到牛顿。

Okay, so back to Newton.

牛顿发现，当光穿过这种冰岛晶石时，它会处于偏振状态。他认为这个事实支持了他的假设，即光是由粒子组成的。

Newton figured out that when light passed through this Iceland spar crystal, it was left in a polarized state, And he argued that this fact favored his hypothesis that light was made up of particles.

当然，这与现代人的说法相反。

Of course, this is opposite to what modern people would say.

现代物理学家会说，这恰恰证明了光是一种波，可以被偏振。

Modern physicists would say this is just proof that light is made of a wave and can be polarized.

但从牛顿的角度来看，他认为像粒子这样的东西可能有不同的侧面、形状、轴或极。

But from Newton's perspective, he argued that something like a particle could have different sides or shapes or axes or poles.

这可以解释为什么只有部分光粒子能够穿过偏振介质。

And this could explain why only some of the particles of light were able to pass through the polarizing medium.

当时，除了他之外，没有人明白光波是如何导致偏振现象的。

He and no one else understood at the time yet how light waves could lead to the phenomena of polarization.

我们现在明白了，但当时这还不是一个能讨论的话题。

We get it now, but that just wasn't something on the table yet.

而且我觉得，除非你理解了电和磁这些东西，否则你不可能真正理解偏振。

And I don't think it's possible to really understand that until you understand things like electricity and magnetism.

而电和磁的发现还要再等大约一个世纪，也就是在十九世纪中期。

And that stuff wouldn't happen for another century or so in the middle of the eighteen hundreds.

艾萨克·牛顿关于光最著名的发现与颜色有关。

Isaac Newton's most famous discovery regarding light has to do with color.

牛顿意识到，不同颜色的光在从一种介质进入另一种介质时，折射的角度是不同的。

Newton realized that different colors of light were refracted by different angles whenever they passed from one medium into another.

例如，牛顿用玻璃棱镜证明，你可以把白光分解成各种颜色的独立光线。

Using a glass prism, for example, Newton was able to show that you could take white light and break that white light up into separate rays of all colors.

这当然是一个巨大的进步，而且这确实是光颜色理论开始发展的第一次。

This was a big advance, of course, and it was really the first time that the color theory of light started to be advanced.

牛顿在主张光是由粒子组成的同时，其他自然哲学家也在提出相反的观点，试图论证光是一种波。

While Newton was arguing that light must be made up of particles, other natural philosophers around the same time were making the opposite case, trying to argue that light was some kind of wave.

比如罗伯特·胡克，他把光波比作水波，并提出光的振动方向可能垂直于传播方向。

This included Robert Hooke, for example, who compared light waves to water waves and suggested that light's vibrations could be perpendicular to the direction of propagation.

这已经开始预示了十九世纪将盛行的光的理论。

That was starting to foreshadow the theories of light that would come to prominence in the nineteenth century.

还有克里斯蒂安·惠更斯，差不多同一时间，他发表了《光的波动理论》。

Was also Christian Huygens, around the same time he published A Mathematical Theory of Light Waves.

正是在那本书里，他提出了一个概念，叫“光以太”。

And it was in that book that he introduced a concept called the luminiferous ether.

好。

K.

所谓“光以太”，就是他设想的一种假想介质，光波在其中传播，就像水波在水中传播、声波在空气中传播一样。

So luminiferous was this hypothetical medium that he thought light waves moved through, an analogy to water waves moving through water or sound waves moving through air.

当时很多物理学家认为，波必须要有介质才能传播。

A lot of physicists at this time thought that in order for something to be a wave, it had to have a medium.

它必须通过某种介质来传播。

It had to move through something.

根据惠更斯的说法，这种介质就是所谓的“发光以太”。当时支持光的波动性的最强论据之一与衍射现象有关。

In this case, that's something, according to Huygens, was the luminiferous One of the strongest arguments in favor of the wave like nature of light at the time had to do with the phenomena of diffraction.

牛顿不得不引入一种新的假想力来解释光的衍射，但如果你认为光是由波组成的，那么这种力就不必要了。

Newton had to introduce a new hypothetical force to explain the diffraction of light, but if you thought that light was made up of a wave, that sort of force wasn't necessary.

所以即使在牛顿时代，也至少有一些支持光的波动性的论点。

So there were at least some arguments being made in favor of the light wavelike nature of light, even in the Newtonian era.

现在我们跳到大约一个世纪后，也就是1800年左右，我们要讲一个叫托马斯·杨的人。

So we're gonna jump forward about a century or so now, around the year 1800, and we're gonna talk about a guy named Thomas Young.

托马斯·杨当时指出，如果光确实是由波组成的，那么这些波应该能够相互干涉，就像声波或水波一样。

So Thomas Young pointed out around this time that if light is in fact made of waves, those waves should be able to interfere with each other, just like sound waves or water waves can.

这里的想法是，如果你有两个波，把它们叠加在一起，如果它们的波峰和波谷对齐，那么波会变得更亮或至少更强。

The idea here is that if you have two waves and you put them on top of each other, if their peaks and troughs align, that wave will get brighter or at least stronger.

如果波峰和波谷不对齐，一个波的波峰叠在另一个波的波谷上，它们就会相互抵消，变得暗淡或更暗，甚至完全抵消，形成没有波的状态。

And if the peaks and troughs don't align, if the peaks of one wave are put on top of the troughs of another, they'll cancel each other out and they'll become fainter or dimmer or maybe cancel each other out entirely, the absence of a wave.

于是托马斯·杨做了一些实验来验证这个假设，试图寻找光波产生的干涉图样。

So Thomas Young carried out some experiments to test this hypothesis and try to look for the interference patterns you'd get from light waves.

他在实验中观察到了衍射图样，我认为这相当有说服力地证明了光确实具有波动性。

And he saw diffraction patterns in his experiments that showed, I think pretty conclusively, that light does in fact behave like a wave.

他在这方面最著名的实验叫做双缝实验，现在我们也称之为杨氏双缝实验，这是他在1801年进行的。

His most famous experiment in this direction was something called the double slit experiment, which we now call Young's double slit experiment, which he carried out in 1801.

在这个实验中，一束光穿过一块带有两个狭缝的屏幕，然后从这两个狭缝发出的光照射到后面更远的一块屏幕上。

In this experiment, a source of light was passed through a screen with two slits in it, and then the light from those slits shone onto a second more distant screen.

如果光是由粒子组成的，你原本会预期在第二个屏幕上看到两个亮斑，一个在第一道狭缝的正前方，另一个在第二道狭缝的正前方。

If the light was made of particles, you would expect this to lead to two bright spots on the second screen, one in front of the first slit and another one in front of the second slit.

但如果光其实是波，结果就会不一样了。

But if light instead is a wave, the result would be expected to be different.

这是因为当来自两道狭缝的波叠加时，如果它们的波峰对波峰，就会产生相长干涉；如果一个波的波峰对着另一个波的波谷，就会产生相消干涉。

This is because when you combine those waves from the two slits, they might combine constructively if their peaks are on top of their peaks, or destructively if their peaks from one are on top of the troves of the other.

所以在杨氏双缝实验中，他并没有看到像光由粒子组成时预期的那两个亮斑。

So in Young's double slit experiment, he didn't see two bright spots like you'd expect if light had been made of particles.

相反，他看到的是一明一暗交替出现的图案。

Instead, he saw an alternating pattern of bright and dim spots.

这是因为两列波在某些地方对齐，在另一些地方错开了。

This was resulting from the places where the two waves were aligned or misaligned with each other.

我觉得这很明显，至少现在对我来说是这样，当时的人们应该也觉得很明确，这基本上就是光像波一样行为的决定性证据了。

And I think it's pretty clear, at least it is to me now, I think it was pretty clear to people at the time that this was more or less definitive proof that light behaved like a wave.

这当然是个大事件，但这并不是杨对光理解的全部贡献。

This was a very big deal, of course, but it wasn't Young's only contribution to our understanding of light.

他还提出，不同颜色的光其实是波长不同的光波。

He also proposed that different colors of light are light waves with different wavelengths.

牛顿已经证明了不同颜色的光在从一种介质进入另一种介质时会有不同的折射，但并没有说明光的颜色属性到底是什么。

So Newton had shown that different colors of light would be refracted differently when they pass from one medium to another, but there was no reference to what the properties of the colors of light were.

杨指出，这跟它们的波长有关，也就是每一列波的长度。

Young showed that this had to do with their wavelengths, how long their individual waves were.

他还有一个关于颜色感知的理论，认为人眼必须有三种不同类型的颜色感受器，这个理论后来被证明基本是正确的。

He also had a theory of color perception, in which he argued that the human eye must have three different kinds of color receptors, which turns out to be pretty much true.

所以，光具有波动性的证据在19世纪初不断积累，而且越来越有力。

So the evidence for light's wave like behavior accumulated, and it got stronger and stronger throughout the early 1800s.

这个理论仍然留给我们的主要问题或弱点，就是光波到底是在什么介质中传播的。

The main problem or weakness, the main question that this theory still left us with, is what the light waves were moving through.

物理学家知道的其他类型的波都需要介质来传播。

Other kinds of waves that physicists knew about required a medium for their transmission.

水波需要水来传播，声音需要像空气这样的介质，等等。

Water waves need water to move through, sound needs something like air, and so on and so forth.

没有人知道光波是在什么介质中传播的。

And no one knew what the light waves were rippling through.

当然，有人提出了以太这种假说，但从来没有人见过或测量过这种假想介质的任何东西。

The luminiferous ether, of course, had been proposed, but no one had ever seen or measured anything about that hypothetical medium.

所以它仍然只是一个假设，除非你能测量光传播所经过的介质，否则它真的只是猜测。

So it was still just a hypothesis, and until you could measure that medium that light was traveling through, it was really just speculation.

这就把我们带到了光与电和磁的深层联系上。

And this brings us to light's deep connections with electricity and magnetism.

1845年，迈克尔·法拉第发现了我们现在所说的法拉第旋转现象。

In 1845, Michael Faraday discovered the phenomenon that we now call Faraday rotation.

法拉第旋转发生在光穿过充满带电粒子和磁场的空间时。

Faraday rotation happens when light passes through a volume of space that's filled with electrically charged particles and a magnetic field.

例如，当偏振光穿过磁化的气体云时，偏振方向会慢慢旋转。

As polarized light travels through a magnetized cloud of gas, for example, the direction of that polarization slowly twists.

这个现象被观测到了，这是第一个真正表明光与电和磁有关的迹象。

This was observed, and it was the first real indication that light had something to do with electricity and magnetism.

我觉得1845年时细节还没搞清楚，但这给法拉第指明了正确的方向。

I don't think the details were figured out in 1845, but this, like, pointed Faraday in the right direction.

仅仅几年后，这促使法拉第在1847年提出，光可能是某种高频电磁振动。

And only a couple years later, this led Faraday to propose in 1847 that light might be some kind of high frequency electromagnetic vibration.

如果真是这样，这种振动可能甚至能在真空中传播。

If that were true, it's possible that such a vibration could propagate even through empty space.

换句话说，它可能根本不需要任何介质。

In other words, it might not require any kind of medium at all.

与此同时，詹姆斯·克拉克·麦克斯韦正在推导他完整的电磁学数学理论，包括我们现在所说的麦克斯韦方程组的四个方程：比如高斯定律、法拉第定律等等。

In the meantime, James Clerk Maxwell was working out his full mathematical theory of electromagnetism, including the four equations that we now call Maxwell's equations: things like Gauss's law and Faraday's law, and things like this.

麦克斯韦用这些方程证明了，即使没有介质存在，电场和磁场的波也应该能够在空间中传播。

Maxwell used these equations to show that it should be possible for waves of electric and magnetic fields to propagate through space even if there weren't a medium present.

而且这些波在空间中应该以恒定的速度传播，这个速度他可以用自己的方程计算出来。

And these waves should move through space at a constant speed, a speed that he could use his equations to calculate.

所以，故事讲到这里，我们得暂时把电和磁放一放。

So at this point of the story, we need to take a step away from electricity and magnetism for a second.

我们一会儿再回来讲这个。

We'll come back to it in just a minute.

但是，要理解麦克斯韦关于电磁波速度的发现有多重要，我们得回头聊聊光速。

But to understand the significance of Maxwell's realization about the speed of electromagnetic waves, we have to go back and talk about the speed of light.

早在1676年，奥勒·罗默——我觉得我那个丹麦名字念得没错，奥勒·罗默，差不多这样——第一次测量了光速。

Way back in 1676, Olle Romer, and I think I'm saying that Danish name right, something Olle Romer, something like this, made the first measurement of the speed of light.

他是通过观察木星的卫星做到的。

He did this by observing the moons of Jupiter.

当木星最内侧的卫星的轨道周期，在地球靠近木星时看起来会变短，好像它移动得更快；而当地球远离木星时，它的周期看起来又会变长。

The period of Jupiter's innermost moon appears to be shorter, or it looks like it's moving faster when Earth is approaching Jupiter, and it appears to be somewhat longer in its period when it's moving away from Jupiter.

随着时间的推移，这颗卫星的轨道周期会看起来时快时慢，这种视周期的变化让罗默得以估算光从木星传到我们这里的速度。

Over time then, the period of this moon's orbit shifts to faster and slower, and this shifting of the apparent period allowed Romer to estimate how fast the light was traveling from Jupiter to us.

他由此估算出光速，得到了每秒2.2亿米的结果，这比实际值每秒3亿米大约小了25%左右，但已经相当接近了。

From this, he estimated the speed of light, and he got a number of 220,000,000 meters per second, which is about, you know, 25 or so percent smaller than the actual value of 300,000,000 meters per second, but it's pretty close.

后来在18世纪及以后，这个测量不断改进，最终误差缩小到了真实光速的1%以内。

And then later in the eighteenth century and beyond, this measurement was improved, getting within a percent or so of the true value of the speed of light.

现在，想象你身处19世纪中叶的麦克斯韦的位置，他刚刚用他的方程计算出电磁波在真空中传播的速度。

So now put yourself in Maxwell's position in the middle of the eighteen hundreds, and he has just used his equations to calculate the speed at which electromagnetic waves should propagate through empty space.

他从这些方程中得知，电磁波不需要介质，能以恒定速度传播，而且令人惊讶的是，他计算出的速度与罗默等人测得的光速几乎完全一致。

He knew from these equations that electromagnetic waves didn't need a medium and they could propagate at a constant speed, and amazingly enough, the speed that he calculated was almost identical to the speed that Romer and others had measured for the speed of light.

要么这纯属巧合，而且概率极低，要么麦克斯韦刚刚意识到或得知，光其实就是一种电磁波。

Either this was a total and highly unlikely coincidence, or Maxwell just realized or just learned that light is in fact an electro magnetic wave.

不久之后，海因里希·赫兹在实验室中产生并检测到了无线电波，证明了它们的行为与其他类型的光完全一致，从而证实了麦克斯韦的理论。

Soon after this, Heinrich Hertz confirmed Maxwell's theory by generating and detecting radio waves in the laboratory and showing that they behave just like other kinds of light.

毕竟，无线电其实就是波长非常非常长的光。

Radio, after all, is just light with really, really long wavelengths.

而且他还能证明这些无线电波表现出反射、折射、衍射和干涉等现象，这些都是用可见光能看到的现象。

And he could show that these radio waves exhibited phenomena like reflection, refraction, diffraction, and interference, all the stuff that you could see with optical light.

到这个时候，已经很清楚了，光其实就是电场和磁场的振荡波。

And it was clear by this time that light really was an oscillating wave of electric and magnetic fields.

我刚才说过，麦克斯韦证明了电磁波即使在没有介质的情况下也能在空间中传播。

I said a moment ago that Maxwell showed the electromagnetic waves could propagate through space even if there was no medium present.

但这其实是事后回顾时才会这么说的话。

But this is kind of something one would say looking back in hindsight.

在当时，我觉得物理学家们并不觉得这是那么明确的事情。

At the time, I don't think physicists thought that was so clear.

特别是，麦克斯韦并不是在说光波不需要介质。

In particular, Maxwell wasn't arguing that light waves didn't require a medium.

他仍然认为可能某种介质是存在的。

He he still thought maybe there was some sort of medium involved.

所以麦克斯韦方程组描述了电场和磁场如何变化和表现，但我不会说它们确定了这些场的物理本质，或者它们到底是由什么构成的。

So Maxwell's equations describe how electric and magnetic fields change and behave, but I wouldn't say that they establish what those fields physically were, what they really were made of or something.

当时很多物理学家想象电场和磁场是以太中的某种应力或运动，那种发光的以太。

And many physicists at the time imagined that electric magnetic fields were somehow stresses or motions in the luminous brisk ether.

所以他们是在用介质来讨论这些场，也就是光传播所依赖的那种介质。

So they were talking about these fields in terms of a medium, the medium that light would propagate through.

基于这个想法，在1880年代，阿尔伯特·迈克耳孙和爱德华·莫雷用他们制造的干涉仪，试图以比之前任何人都更高的精度来测量光速。

So with this in mind, in the eighteen eighties, Albert Mikkelsen and Edward Morley used a device they built called an interferometer to try to measure the speed of light with much greater precision than anyone had been able to do up until that point.

干涉仪的工作原理是把一束光分成两束。

The interferometer worked by taking a beam of light and splitting it into two separate beams.

然后这些光束通过镜子等装置被引导，使它们相互垂直传播一段时间，然后再合并成一束光。

Then those beams would be directed with mirrors and things so that they would travel perpendicular to each other for a while and then get recombined into a single beam.

就像在杨氏双缝实验中一样，当这两束光合并时，会产生干涉图案，也就是他们所说的条纹图案。

Just like in the Young's double slit experiment, when these two beams of light were combined, they would produce interference patterns, or what they called fringe patterns.

因为地球以每秒约30公里的速度绕太阳运行，迈克耳孙和莫雷预期会看到干涉图案会随着他们仪器指向的方向而改变。

Because the Earth is moving at about 30 kilometers a second around the Sun, Mikkelsen and Morley expected to see an interference pattern that would change depending on which direction they pointed their instrument.

比如说，如果地球是朝着发光以太的方向运动，那他们测到的速度应该是一个值。

For example, if, you know, the earth was moving into the, luminaverse ether, then they should measure one speed.

如果地球是背离发光以太运动，那测到的光速应该不一样。换句话说，光速应该会随着你是朝着还是背着光传播的介质运动而改变。

If it was moving away from the luminaverse ether, they should get a different measurement of the In other words, the speed of light should, you know, change depending on if you're moving into or away from the medium that the light was traveling through.

但他们看到的并不是这样。

But this isn't what they saw.

他们从来没有观察到任何这样的变化。

They never saw any change like this.

他们测到的光速是恒定的，不管地球怎么动，或者他们能想到的其他任何因素，光速都一样。

The light that they measured was moving at a constant speed, the same speed regardless of the Earth's motion or anything else that they could put their finger on.

如果地球是在某种发光以太或者其他介质中运动，那就不应该是这个结果。

This is not what you would expect if the Earth were moving through some kind of luminous ether or some other kind of medium.

因为这个实验结果，也就是迈克耳孙-莫雷实验的结果，再加上其他一些原因，当时的物理学家越来越难为这种假想介质的存在辩护了。

Because of this experimental result, the Michelson Morley result, and for other reasons, it was becoming increasingly difficult for physicists at the time to defend the existence of this hypothetical medium.

要让光波从遥远的恒星传到我们这里，这种介质就得充满整个宇宙空间。

To carry light waves from distant stars, this would have to fill the entirety of space.

在我们和所观察的星星之间，不可能有任何空荡荡的区域。

There couldn't be any empty pockets between us and the stars we're looking at.

但与此同时，为了支撑这些波，这种以太的刚性必须比任何已知材料高出数百万倍。

And yet at the same time, to support these waves, this ether would have to be millions of times more rigid than any known material.

以太还必须允许行星穿过它，而不产生任何可观测的摩擦。

The ether also had to allow planets to pass through it without producing any observable amount of friction.

而且，再加上迈克尔逊-莫雷实验没有探测到以太的影响，这真的迫使人们去做一些相当激进的事情。

And, you know, that combined with the fact that Michelson Morley didn't detect the effects of the ether, it was really forcing people to do some pretty radical things.

他们当时想象，比如，也许地球会拖着以太一起运动，或者给以太理论添加其他各种花哨的假设，试图解释所观察到的现象。

They were imagining, for example, that maybe the earth dragged the ether along with it, or other sorts of bells and whistles that they had to add to these ether theories to try to explain what had been observed.

由于这些和其他原因，到十九世纪末，支持以太的论据变得越来越站不住脚。

For these reasons and others, the case for the ether was growing increasingly precarious by the end of the nineteenth century.

现在我们来到了故事中最离奇的部分，也就是光与我们所知的量子力学交织在一起的部分。

And now we get to the weirdest part of our story, the part of the story where light becomes intertwined with what we know as quantum mechanics.

1900年，马克斯·普朗克试图解释我们称之为黑体辐射的现象，也就是我们从炽热物体上看到的光谱。

In 1900, Max Planck was trying to explain the phenomena we call black body radiation, the spectrum of light we see from hot objects.

他提出，为了解释在辐射中观察到的现象，光波可能只能以有限且离散的量来获得或失去能量。

And he suggested, in order to explain what had been observed in this radiation, that light waves might be able to gain or lose energy only in finite and discrete amounts.

这些量与其频率成正比。

These amounts were proportional to their frequency.

普朗克把这些能量单位称为光量子。

Planck called these pieces of energy light quanta.

大约在同一时期，科学家们在实验室里注意到了一种奇怪的现象，他们称之为光电效应。

Around the same time, businesses had noticed in a laboratory something kind of strange that they called the photoelectric effect.

在这个实验中，光被照射到一块金属板上，这块金属板连接着一个有断口的电路。

In this experiment, light was shined or illuminated onto a metal plate, which was connected to an electric circuit with a break in that circuit.

入射光的能量可以产生电子，从金属板上释放出自由电子，并导致电流开始在电路中流动。

The energy of the incident light could create electrons, free electrons off the metal plate, and cause electric current to start to move around the circuit.

当时人们认为，或者至少设计这个实验的人预期，这样产生的电流量会与所看到的光的强度成正比。

It was thought at the time, or at least expected by the people who designed this experiment, that the amount of electric current that would be generated in this way would be proportional to the intensity of the light you saw.

这在某种程度上是对的，但这种效应只有在光的频率足够高时才会发生。

That was true up to a point, but this effect turned on only if the light was high enough in frequency.

一开始，这真的让人摸不着头脑。

At first, this was really confusing.

光的频率按理说跟这个没关系。

The frequency that light wasn't expected to have anything to do with this.

但爱因斯坦在1905年解释了这一点，他借鉴了普朗克的光量子假说，基本上是说，如果光是由粒子或量子组成的，那么一个低频光的单个粒子就没有足够的能量从金属板上打出一个电子来。

But Einstein explained this in 1905, drawing on Planck's hypothesis of light quanta, basically arguing that if light was made up of particles or quanta, then an individual particle of low frequency light wouldn't have enough energy to break even a single electron off of the metal plate.

所以不管你把多少低频光照在金属板上，都不会产生电流。

So no matter how much low frequency light you shined in the metal plate, no electric current would be generated.

这是第一个确凿的证据，表明光不仅是一种波，而且也是由粒子组成的。

This was the first concrete evidence that light was not only a wave, but was also made up of particles.

这里要理解的一个重要点是，虽然普朗克是第一个提到光量子的人，但他当时并不认为光真的是由粒子组成的。

An important thing to appreciate here is that although Planck was the first to talk about light quanta, he didn't at the time think that light was really made up of particles.

他只是提出，也许光只能以这种离散的量来获得或失去能量。

He was only suggesting that perhaps light could only gain and lose energy in these kind of discrete amounts.

他觉得这可能跟光在物质中产生的方式有关，或者别的什么。

He thought it might have something to do with how light was created in matter or something.

相比之下，爱因斯坦提出的观点要激进得多。

Einstein, in contrast, was proposing something much more radical.

他认为光本身就是由离散的、粒子状的光量子组成的。

He was saying that light itself was made up of discrete pieces, or particles, quanta.

而且，尽管光由粒子组成，爱因斯坦仍然坚持认为它同时也表现出波的特性。

And still, despite being made of particles, Einstein still argued that it was also behaving like a wave.

虽然花了一些时间，但爱因斯坦的光量子假说最终在1923年由阿瑟·康普顿进行的实验中得到直接证实。

It took a while, but Einstein's light quanta hypothesis was directly confirmed in an experiment that was conducted in 1923 by Arthur Compton.

康普顿的做法是，将X射线形式的光照射到物质上，然后测量散射出来的光的波长。

What Compton did was direct light in the form of X rays at matter, and he measured the wavelengths of the light that came out.

结果表明，单个光量子可以与单个电子碰撞，并携带确定的动量。

The results showed that individual light quanta can collide with an individual electron and carry a definite amount of momentum.

正如爱因斯坦在1905年所假设的那样，他证明了光是由单个粒子组成的。

Just as Einstein had postulated back in nineteen o five, he showed that light was made up of individual particles.

而这一点，我认为，让我们回到了原点。

And this, I'd argue, brings us full circle.

几百年来，甚至几千年来，科学家和哲学家一直在争论光是由粒子组成，还是由波组成。

For hundreds, if not thousands of years, scientists and philosophers argued whether light was made up of particles or instead consisted of waves.

我们现在知道，答案是肯定的。

The answer we now know is yes.

奇怪的是，它两者都是。

Strangely enough, it is both of those things.

物理学家们已经不再争论这个问题了。

This isn't debated anymore by physicists.

我们知道答案很明确。

We know the answer is clear.

光的粒子，以及所有其他形式的物质和能量，实际上都是量子力学对象。

Particles of light, and for that matter all other forms of matter energy, are in fact quantum mechanical objects.

量子力学对象由离散的粒子组成，但这些粒子可以像波一样发生干涉。

And quantum mechanical objects consist of discrete pieces or particles, but those particles can undergo interference like a wave.

这告诉我们，光子和其他量子对象可以同时出现在许多不同的地方。

This tells us that photons and other quantum objects can be in a lot of different places at the same time.

它们可以在空间中沿着不同的路径从一点移动到另一点，而且总的来说，量子世界是一个非常非常奇怪、非常非常反直觉的地方。

They can take different paths through space as they move from one point to another, and in general, the quantum world is a very, very strange and very, very counterintuitive place.

这个故事里我最喜欢的部分是，在长达数千年的关于光的本质的猜测之后，最终真相竟然比任何人之前想过的都要离奇、都要反直觉。

My favorite part of the story is knowing that in the end, over thousands of years speculation about the nature of light, the truth turned out to be more bizarre and more counterintuitive than anything anyone had ever come up with before.

说白了，这就是像我这样的人如此热爱物理学的原因。

This, put plainly, is why people like me love physics so much.

这个节目是由我和Shalma Wegsman制作的，由我们的好朋友Basal Distortion编辑。

Why this universe is produced by myself and Shalma Wegsman and edited by our good friend Basal Distortion.

我叫Dan Hooper，是威斯康星大学麦迪逊分校的物理学教授，也是威斯康星冰立方粒子天体物理中心的主任。

My name is Dan Hooper, and I'm a professor of physics at the University of Wisconsin in Madison, and I'm the director of the Wisconsin Ice Cube Particle Astrophysics Center.

如果你想支持我们，可以订阅我们的Patreon，每月只需3美元。

If you want to support us, subscribe to our Patreon for as little as $3 a month.

作为回报，你将获得无广告的节目，并且可以在我们的“随便问我们”环节中直接向我们提问。

And in return for your support, you'll get ad free episodes and the ability to ask us questions directly for our Ask Us Anything segments.

你可以在patreon.com/whythisuniverse找到我们。

You can find that at patreon.comwhythisuniverse.

感谢收听。

Thanks for listening.