Name: 物理學中最詭異的難題！| Sean Carroll (The weirdest problem in physics | Sean Carroll)
Uploaded: 2026-01-19T18:30:46.000Z
Duration: 50 min 19 s

Quantum mechanics is weird because despite the fact that we're celebrating its hundredth anniversary right now, we still don't understand it.

量子力學很奇怪，因為儘管我們現在正在慶祝它的百週年，我們還是不懂它。

What is really going on in this, our best, most important framework for doing fundamental physics?

在我們這個進行基礎物理學研究最棒、最重要的框架裡，到底發生了什麼事？

We understand, on the basis of quantum gravity, why the Earth moves around the sun or apples fall from trees.

我們基於量子重力，瞭解地球為何繞著太陽轉，或是蘋果為何從樹上落下。

But we don't understand what happens when gravity becomes strong, like in a black hole or near the Big Bang.

但我們不瞭解當重力變得非常強時會發生什麼事，像是黑洞裡或大爆炸附近。

So basically, nature uses every trick that it can think of to make physics work in interesting ways.

所以基本上，大自然會用盡牠能想到的各種方法，讓物理學以有趣的方式運作。

And it really does give physicists a sense of accomplishment at the end of the day, to figure it all out.

而最終，搞懂這一切確實能讓物理學家們感到很有成就感。

I'm a physicist and philosopher at Johns Hopkins University, host of the Mindscape podcast and also author of a bunch of books, most recently the Biggest Ideas in the Universe series, including Space, time and motion and quanta and fields.

我是約翰霍普金斯大學的物理學家兼哲學家，Mindscape 播客的主持人，也是許多書籍的作者，最近的作品是《宇宙中的最大想法》系列，包括 Space, time and motion 和 量子與場。

I'd like to think if you were a physicist circa 1895, okay, the very end of the 19th century, you would have been forgiven for thinking that we were almost there.

我想，如果你是 1895 年左右的物理學家，也就是 19 世紀末，你會被原諒認為我們差不多就快要懂了。

We were almost having a complete theory of nature in our grasp because they had the idea of particles right.

我們差不多已經掌握了完整的自然理論，因為他們對粒子的概念是正確的。

You know, the idea of an atom was a little bit sketchy to a lot of physicists in the 1800s, but they eventually caught on and they were beginning to realize that atoms were made of other particles.

你知道，在 1800 年代，很多物理學家對原子的概念還有些模糊，但他們最終還是明白了，並開始意識到原子是由其他粒子組成的。

Protons, neutrons, electrons, and so forth.

And then the particles which make up matter are pushed around by fields, by the electric field, by the magnetic field, by the gravitational field, and so forth.

然後構成物質的粒子是由場推動的，像是電場、磁場、重力場等等。

So you have this sort of two part harmony.

所以你有這種雙軌並行的和諧。

Matter is made of particles, forces come from fields.

物質由粒子組成，力由場產生。

And all the effort in the future of physics would be figuring out what are all the particles, what are all the fields.

而未來物理學的所有努力，就是要弄清楚所有的粒子和所有的場是什麼。

There were a couple of clouds on the horizon.

The fact that the symmetries of Maxwell's theory of electromagnetism were different than the symmetries of Newton's theory of classical mechanics.

麥克斯韋電磁學理論的對稱性與牛頓經典力學的對稱性不同。

But the others were that there were certain properties of matter and materials that didn't quite seem to make sense.

但其他幾點是，物質和材料的某些特性似乎不太合理。

They were putting together the picture of the atom.

當時大家正在拼湊原子的樣貌。

That is the cartoon you've always seen, right?

這就是大家一直看到的那個卡通圖，對吧？

There's a little nucleus at the center of the atom and electrons are circling around it like planets orbiting a star.

原子中心有個小小的原子核，電子就像行星繞著恆星一樣繞著它轉。

This is called the Rutherford atom model, after Ernest Rutherford, who was a brilliant experimental and theoretical physicist.

這叫做拉塞福原子模型，以歐內斯特·拉塞福命名，他是一位傑出的實驗物理學家和理論物理學家。

And people liked the idea that electrons were kind of like little planets.

大家喜歡電子就像小行星這樣的想法。

But they instantly figured out it can't possibly be right because that electron orbiting the nucleus would give off electromagnetic waves.

但他們立刻就發現這根本不可能對，因為繞著原子核轉的電子會放出電磁波。

All of the light you're looking at right now came from some electron in motion moving around.

你現在看到的所有的光，都來自於某個運動中的電子。

So you can calculate, you can say if the electron is moving around in orbit around the atomic nucleus, if it gives off light, it will lose energy and spiral into the nucleus.

所以你可以計算，你可以說，如果電子繞著原子核運行，放出光，它就會失去能量，然後螺旋式地墜入原子核。

And the answer is, every atom in the universe, including the ones in the chair you're sitting on or even in your own body, should collapse to a point in a hundredth of a billionth of a second.

答案是，宇宙中的每一個原子，包括你坐的椅子上的原子，甚至你身體裡的原子，都應該在百分之一十億分之一秒內塌縮成一個點。

The idea that electrons are like little planets in the solar system is just wrong.

電子像太陽系裡的小行星這樣的想法，根本就是錯的。

And this and other things, black body radiation and other experimental results convinced people that there wasn't this clean division between particles and forces.

這以及其他像是黑體輻射等實驗結果，讓大家確信粒子和力之間並沒有這麼清晰的劃分。

They said there's aspects of light which is supposed to be a wave, which are particle, like.

他們說光有波動的面向，也有粒子的面向。

Einstein said that there are aspects of particles like electrons that are wavelength.

愛因斯坦說，像電子這樣的粒子也有波長的面向。

Louis de Broglie, following work by Niels Bohr and others, said that.

路易·德布羅意繼尼爾斯·波耳等人的研究之後，提出了這個說法。

And this whole thing Coalesces almost exactly 100 years ago, in 1925, in the theory of quantum mechanics, and almost right at the same time, two different versions of it came out.

這一切大約在100年前，也就是1925年，在量子力學理論中幾乎完全成形，而且差不多在同一時間，出現了兩個不同的版本。

Werner Heisenberg had his version called matrix mechanics.

維爾納·海森堡的版本叫做矩陣力學。

Erwin Schrodinger had his version called wave mechanics.

埃爾溫·薛丁格的版本叫做波動力學。

They showed that they were actually mathematically equivalent.

他們證明瞭這兩種說法在數學上其實是等價的。

But quantum mechanics, I like to say it was the second of two big ideas in the history of physics.

但我喜歡說，量子力學是物理學史上兩個偉大想法中的第二個。

The first big idea in physics was classical mechanics.

物理學上的第一個偉大想法是古典力學。

Relativity is a pretty big idea, but not as big as classical mechanics or the second big idea, which is quantum mechanics.

相對論是個很偉大的想法，但不如古典力學或第二個偉大想法量子力學來得重要。

Quantum mechanics throws away classical mechanics and replaces it with something very different.

量子力學捨棄了古典力學，取而代之的是一個非常不同的概念。

It says that electrons are not particles or waves.

They act like waves until you look at them, and then they look like particles.

在你觀察它們之前，它們表現得像波，一旦你觀察它們，它們就表現得像粒子。

That is a very, very difficult thing to swallow.

And physicists are still trying to figure out what to make of it.

物理學家們至今仍在努力理解它到底是什麼意思。

It's so much fun reading the history of how these ideas developed, because today we're just taught the final result.

閱讀這些想法發展的歷史真的很有趣，因為我們今天學到的都是最終的結果。

But, you know, they didn't know what was going on back in the early days.

但你知道嗎，在早期，他們根本不知道發生了什麼事。

In 1926, Erwin Schrodinger presents an equation for what we now call the wave function.

1926年，埃爾溫·薛丁格提出了我們現在稱為波函數的方程式。

It's a dopey name for a very important idea.

對於一個非常重要的想法來說，這名字有點遜。

所以，想像一下那個小小的電子。

Instead of orbiting in a circle, it's a wave.

它不是繞著原子核畫圈，而是一種波。

It has a profile around the center of the atom.

它在原子中心周圍有一個輪廓。

It's still the equation that we use today.

這仍然是我們今天在使用的方程式。

But then you have to ask, okay, semi philosophical question, what is the wave function?

但接著你必須問，好，一個有點哲學性的問題，什麼是波函數？

And Schrodinger thought, well, okay, in some cases, electrons act like waves.

而薛丁格認為，嗯，好吧，在某些情況下，電子就像波一樣。

在其他情況下，它們就像粒子一樣。

Maybe the equation says that if you start with an electron wave all spread out, it will sort of localize itself near some point and it will look like a particle.

也許這個方程式說，如果你從一個分散開來的電子波開始，它會有點在某個點附近自我定位，看起來就像一個粒子。

The equations don't care about your feelings.

If you start out with a localized electron wave, it will spread out all over the place.

如果你從一個局域化的電子波開始，它就會散開到各處。

So it was yet another physicist, Max Born, different than Niels Bohr, who pointed out the right way to think about Schrodinger's wave function.

所以是另一位物理學家 Max Born，跟 Niels Bohr 不同，他指出了理解薛丁格波函數的正確方法。

He said, think about what happens when you measure a property of the electron, like its position, position or its velocity or whatever you want to measure.

他說，想想當你測量電子的某個性質時會發生什麼，像是它的位置、位置或速度，或是任何你想測量的東西。

He says, what the wave function is doing is it's telling me the probability of getting a different measurement outcome.

他說，波函數的作用是告訴我得到不同測量結果的機率。

In particular, if you want the math, you square the wave function.

具體來說，如果你想知道數學，你會把波函數平方。

That tells you the probability of seeing the electron somewhere.

那告訴你看到電子的機率在哪裡。

And this was just bizarre and crazy for all sorts of reasons.

這因為各種原因都非常奇怪和瘋狂。

People didn't like the idea that probabilities were involved at all.

人們根本不喜歡機率會被牽涉進來的想法。

Of course, there's probabilities when you flip a coin, but that's just because you just don't know everything there is to know about the coin.

當然，拋硬幣也會有機率，但那只是因為你對硬幣的瞭解不夠全面。

Since the time of Newton and Laplace, we thought that physics deep down was perfectly deterministic.

自從牛頓和拉普拉斯的時代以來，我們一直認為基礎物理學基本上是完全決定論的。

And here's Max Born saying, no, it's not.

而現在馬克斯·玻恩說，不行，它不是。

But the other thing that's difficult to swallow is, why in the world is the idea of measuring or observing something showing up in the fundamental laws of physics?

但另一件難以接受的事是，為什麼測量或觀察某樣東西的想法會出現在基礎物理學的定律裡？

Of course, you have to think about measuring things and observing things.

當然，你必須考慮測量和觀察事物。

But it was always imagined that if I measure the position of a planet or something like that, in principle, I can do that measurement completely benignly, without disturbing the system in any way at all.

但人們一直認為，如果我測量一顆行星的位置等等，原則上，我可以完全不幹擾地進行測量，而不會以任何方式擾亂系統。

And what Born is saying is that when you measure an electron, you instantly and dramatically change its wave function.

而玻恩說的是，當你測量一個電子時，你會瞬間且劇烈地改變它的波函數。

And to tell me what the fundamental laws of physics are, according to what became known as the Copenhagen interpretation of quantum mechanics, after the city where Niels Bohr and Werner Heisenberg and others were doing their work, part of those fundamental laws are a set of rules that say, here's what's happened.

而且，根據後來被稱為量子力學哥本哈根詮釋的說法，也就是尼爾斯·波耳和維爾納·海森堡等人在他們工作過的城市之後的詮釋，基礎物理學的定律的一部分就是一套規則，說明發生了什麼。

What happens when you measure the properties of a system.

當你測量一個系統的性質時，會發生什麼事。

So quantum mechanics is the only theory in the history of physics that has rules about measurement outcomes and has measurement playing an important role in what those laws are.

所以量子力學是物理學史上唯一一個有關於測量結果的規則，並且測量在這些定律中扮演重要角色的理論。

And if you ask, well, what is a measurement?

如果你問，好吧，什麼是測量？

The answer is, we're not going to tell you the answer to that.

答案是，我們不會告訴你這個問題的答案。

We don't have an agreed upon set of criteria for when a measurement happens.

我們沒有一套大家同意的標準，來說明什麼時候發生了測量。

And this is known, cleverly as the measurement problem of quantum mechanics.

這就是所謂的量子力學測量問題。

There's various plausible resolutions to it, but we don't agree with on what the right one is.

對這個問題有各種可能的解決方法，但我們並沒有對哪個是正確的達成共識。

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