Name: 【TED-Ed】愛因斯坦聰明的錯誤：「纏結現象」 Einstein's brilliant mistake: Entangled states - Chad Orzel
Uploaded: 2014-11-17T09:27:45.000Z
Duration: 5 min 10 s

Albert Einstein played a key role in launching quantum mechanics to his theory of photoelectric effect.

阿爾伯特˙愛因斯坦是把量子力學引進光電效應的關鍵人物

But remains deeply bothered by its philosophical implications.

卻對其中隱含的達觀意義百思不得其解

And though most of us still still remember him for deriving e equal m c square.

愛因斯坦以相對論(E=mc2)聞名世界

His last contribution to physics was actually a 1935 paper.

但他和另外兩位年輕同事鮑里斯˙波多爾斯基、納森˙羅森在1935年合著的論文

Co-author with his young colleague - Boris Podolsky and Nathan Rosen.

才是他在世時對物理學的最後一個貢獻

Regarded as an art philosophical foot note well into the 1980s.

論文堪稱1980年代詮釋藝術哲學的代表之作

This EPR paper has recently become central to a new understanding of quantum physics.

我們現在知道論文提到的怪異現象叫做「糾纏狀態」

With its description of a strange phenomenon now known as entangled states.

進而對量子物理學有了新的認識

The paper begins by considering a source that splits out the pair of particles

EPR開頭說一個母體分裂出兩個粒子

Each of these measurements has two possible results of equal probability.

Let’s say zero or one for the first probability and A or B for the second.

假設第一種結果叫做0或1，第二種結果則稱為A或B

Once a measurements is performed, subsequent measurement of the same properties in the same particle will yelled the same result.

第一種量測方法結束後 執行第二種量測方法 測量同個粒子的同個性質 會得到相同結果

The strange application of this scenario is not only the state of the single particle

But that the measurement then determine the state

What’s more the measurements affect each others.

If you measure a particle as being in state one and followed it up with the second type of measurement

例如: 測量後發現粒子的狀態是1 此時再用第二種標準測量

You’ll have a fifty percent chance of getting either A or B.

But if you then repeat the first measurement,

You’ll have a fifty percent chance of getting zero

得到的結果卻不一定是1 雖然第一次測的結果是1

Even that the particle have already been measured one.

So switching the properties been measured scramble the original results.

所以突然變換測量的屬性可能顛覆最初結果

Things get even stranger when you look at both particles.

Each of the particle will produce random results, but if you compare the two

You’ll find that they’re always perfect league correlated.

For example, if both particle are measured at zero.

Measuring one will tell you the other with absolute certainty.

測量其中一個 就能準確預測另一個

But this entanglement seems to defy Einstein’s famous theory of relativity

但量子糾纏說 似乎違背了鼎鼎有名的相對論

Because there is nothing to limit the distance between particles.

因為後者說 粒子間的距離不受控制

If you measure one in New York at noon, and the other in San Fransinco and then the second later

舉例來說: 中午在紐約的測量 和稍後在舊金山的測量結果

But if the measurement does the terminate value then this will require one particle sending some sort of signal to the other

測量若真能決定某些數字 就代表粒子能以光速1300萬倍的速度

At thirteen million time the speed of light which according to relativity is impossible.

傳達某種信號給別的粒子 在相對論裡 這是不可能的事

For this reason, Einstein dismiss entanglement as ‘spuckhafte ferwirklung’

因此愛因斯坦認定量子糾纏是「spuckhafte ferwirklung」

He decided that the quantum mechanics must be incomplete a mere approximation of a deeper reality.

他說量子力學無法解釋的 只有那粗略評估出的深奧現實

In which all particles have pre-determine states that are hidden from us.

所有粒子都處於特定的狀態 只是我們沒注意到

So porter of orthodox quantum theory led by Neil Bohr maintain that quantum state really are fundamentally indeterminate

尼爾斯˙波爾是傳統量子力論的擁護者 他始終認為粒子原來沒有特定性質

And entanglement allows the states of one particle to depend on that the distance partner

而量子糾纏說允許這顆粒子受到那顆粒子的影響

For thirty years, physics remained at in past until John Bell

30年來 物理學家也都深信不疑 直到約翰˙貝爾發現

Figured it out that the key to testing the EPR argument was to look in cases involving different measurements on the two particles

探討EPR論調的關鍵是「用兩種方法測量兩個粒子」

The local hidden variable theories favored by Einstein Podolsky and Rosen

愛因斯坦和另兩人偏好的隱變量理論

Strictly limited how often you can get results like 1A or B0

Because the outcome would have to be defined in advance

因為該理論把結果都先設定好了

Bell showed that the purely quantum approach where the state is truly indeterminate until measured has different limits

貝爾說之前的量子力學假設粒子的狀態要測量後才能得知 這樣有諸多限制

And predicts measurement results that are impossible in the pre-determine scenario

如果粒子本身有特定性質 那假設結果就沒有意義

Once Bell had worked out how to test the EPR argument physicists went out and did it.

貝爾發現驗證EPR論點的方法後 物理學家紛紛跟進

Beginning with John Clauster in the seventies and Alain Aspect in the early 80s

70年代打頭陣的約翰˙克勞澤(註: 美國物理學家)、80年代初期的阿蘭˙阿斯佩(註: 法國物理學家)

Dozens of experiments has tested the EPR prediction and all have found the same thing

許多人都實驗了論文中的假設 結果如出一轍

The correlations between the indeterminate states of entangle particles are real

糾纏的兩粒子之間那未確定狀態的關聯 也正確

And cannot be explained by any deeper variable

The EPR paper turned out to be wrong but brilliantly sell

EPR論文有紕漏 卻曾為許多人稱頌

By leading physicists to think deeply about the foundations of quantum physics

領頭的物理學家們藉由思考量子物理學的基礎

It led to further elaborations of the theory and help launch research into subjects like quantum information

讓理論更完善 也開啟了量子資訊之類的研究

Now a thriving field with the potential to develop computers of unparallel power

現在這領域日漸茁壯 將來可能開發出能力無與倫比的電腦

Unfortunately, the random of measure results prevent science fiction scenario like using entangle particles

不幸的是 測量結果的隨機性證明了科幻小說中

「糾纏粒子可超越光速傳遞訊息」的情節安排是個錯誤

So relativities is save for now but the quantum universe is far stranger than Einstein wanted to believe

相對論的地位目前還不可動搖 但量子宇宙可比愛因斯坦想的還要複雜太多了