Name: 費米悖論的量子級解答！ (A Quantum Solution to the Fermi Paradox)
Uploaded: 2026-02-12T18:24:13.000Z
Duration: 5 min 18 s

Why hasn't extraterrestrial life contacted us yet?

外星生命為什麼還沒聯繫我們？

Is the core question of the Fermi paradox.

In short, the observable universe contains so many millions of billions of stars and planets that the chances of intelligent life arising elsewhere, and

簡單來說，可觀測宇宙中有數百萬兆顆恆星和行星，其他地方出現智慧生命的機率，

probably many, many, many places elsewhere, seems almost inevitable.

而且很可能在很多很多地方都出現，似乎是勢在必行的。

And yet we haven't heard from any aliens.

然而，我們卻沒有收到任何外星人的消息。

One possible explanation is that we're overlooking quantum mechanics.

一種可能的解釋是，我們忽略了量子力學。

Here's the to communicate long distances in space, it may be that you need to be using quantum communication.

在太空中進行遠距離通信，可能需要使用量子通信。

A fundamental problem with interstellar communication is the speed of light.

星際通信一個根本性的問題是光速。

The distances between stars are just so big, and light takes so long to get there.

恆星之間的距離實在太大了，光到達那裡需要很長時間。

You have to be really efficient with your communication.

You don't want to wait a decade to hear back.

你總不能等個十年才收到回覆吧。

And it turns out that quantum communication, where you send photons that are entangled or in a carefully superimposed quantum state, quantum communication can be incredibly more information dense than non quantum communication.

結果發現，量子通信，也就是傳送糾纏或處於精心疊加的量子態的光子，量子通信能比非量子通信傳送更多資訊。

In one protocol, any number of quantum bits can be used to transmit twice as many non quantum bits.

在一種協定中，任何數量的量子位元都可以用來傳輸兩倍數量的非量子位元。

And in another setup, it takes exponentially more non quantum bits than quantum bits to transmit a particular type of information.

在另一種設定中，傳輸特定類型的資訊需要指數級更多的非量子位元而非量子位元。

Though both of these quantum efficiency gains have caveats that we'll explain later.

不過，這兩種量子效率增益都有一些我們之後會解釋的注意事項。

But regardless, quantum communication being more efficient doesn't, on its own, explain Fermi's where are all the aliens Paradox.

但無論如何，量子通信更有效率，本身並不能解釋費米「外星人在哪裡？」悖論。

Quantum communication, it turns out, has some very particular requirements, and

結果發現，量子通信有一些非常特別的要求，

it's those that might help solve the Fermi paradox.

而正是這些要求，可能能幫助我們解決費米悖論。

Specifically, to send quantum information to someone else, you can't just broadcast a signal out in all directions like you can with radio waves or whatever.

具體來說，要把量子資訊傳送給別人，不能像用無線電波那樣隨便往四面八方廣播訊號。

The laws of physics require the person receiving the quantum information to get over 50% of photons you send in order to reconstruct the info.

物理定律規定，接收量子資訊的人必須收到你發送的超過 50% 的光子，才能重建資訊。

So instead of broadcasting a quantum signal, you have to narrowcast, I mean, focus it.

所以，我們不能廣播量子訊號，而是要定向傳輸，也就是聚焦。

The equation for this tells us that the size of the transmitting and receiving telescopes must be really, really big.

這個公式告訴我們，發射和接收望遠鏡的大小必須非常非常大。

Exactly how big depends on how far you're sending the message and what wavelength of light you're using.

具體多大，取決於你要傳送訊息的距離，以及你使用的光的波長。

And the 50% receipt requirement means you have to send a quantum signal using photons with wavelengths that'll pass undisrupted both through the Earth's atmosphere and across interstellar space, rather than getting scattered off of interstellar dust or whatever.

而且 50% 的接收要求意味著，我們必須使用波長能夠不受幹擾地穿過地球大氣層和星際空間的光子來傳送量子訊號，而不是被星際塵埃之類的散射掉。

And the numbers work out such that if you want to do quantum communication with Alpha Centauri, the nearest star system to, you'd need a telescope around 100 km in size and a bigger one from more distant locations.

數字算出來是這樣，如果你想和離我們最近的星系半人馬座進行量子通信，就需要一個大約 100 公里大小的望遠鏡，而更遠的地方則需要更大的望遠鏡。

And this is not like the Very Large Array where they have radio dishes really far apart to simulate having a large telescope.

這跟「非常大型陣列」那種把無線電碟分散得很遠來模擬大型望遠鏡的做法不一樣。

In this case, you actually have to build the whole telescope because you have to get more than 50% of the photons.

這種情況下，我們真的必須建造整個望遠鏡，因為我們需要接收超過 50% 的光子。

Interstellar quantum communication is a hard thing to do.

星際量子通信是件很難做到的事。

Perhaps now you can start to see how this explains the Fermi paradox.

或許你現在開始能理解這如何解釋費米悖論了。

Suppose that widespread alien civilizations are using interstellar quantum communication with huge oversized telescopes.

假設廣泛存在的異星文明正在使用超大型望遠鏡進行星際量子通信。

And for their quantum communications to work, each transmission has to get the majority of the transmitted photons into the receiving telescope.

為了讓他們的量子通信奏效，每次傳輸都必須讓大部分傳輸的光子進入接收望遠鏡。

Which means that very few would stray off by having happenstance to be detected by our undersized telescopes.

這意味著，只有極少數光子會偶然被我們小型望遠鏡偵測到而散射掉。

And because we wouldn't receive more than 50% of the photons from a transmission, both because we don't have a big enough telescope and the signal wouldn't be pointed at us anyway, it wouldn't be possible to understand any of the information we received.

而且因為我們無法接收超過 50% 的傳輸光子，一方面是我們的望遠鏡不夠大，另一方面訊號也不是指向我們，所以我們收到的任何資訊都無法理解。

Basically, aliens communicating quantumly could be sending messages whizzing past us all the time, and we wouldn't know.

基本上，正在進行量子通信的外星人可能一直有訊息從我們身邊呼嘯而過，而我們卻渾然不知。

Plus, any aliens that had telescopes powerful enough for quantum communication with us would also consequently have telescopes good enough to see that we don't have telescopes powerful enough for quantum communication.

此外，任何擁有足夠強大望遠鏡與我們進行量子通信的外星人，也會是以擁有足夠好的望遠鏡來發現我們沒有足夠強大望遠鏡進行量子通信。

So they would know that sending us a message is futile and therefore perhaps wouldn't bother.

所以他們會知道傳送訊息給我們是徒勞的，是以或許就不會費心了。

In summary, our theoretical and experimental understanding of quantum information suggests that aliens might be likely to use quantum interstellar communication rather than non quantum communication.

總結來說，我們對量子資訊的理論和實驗理解表明，外星人可能傾向於使用量子星際通信，而不是非量子通信。

Which means aliens would be sending narrow cast messages that would mostly pass us.

這意味著外星人會發送定向傳輸的訊息，而這些訊息大多會錯過我們。

And even if we could intercept them, we wouldn't have the capacity to intercept enough to receive the message, and

而且就算我們能攔截到，也沒辦法攔截到足夠的量來接收訊息，

therefore we would expect not to hear anything.

所以我們預期會聽不到任何聲音。

Like if aliens wanted to communicate with us and could tell we couldn't receive a quantum message, why wouldn't they just send us a regular signal, like with radio waves or something?

像是如果外星人想跟我們溝通，而且知道我們接收不到量子訊息，為什麼他們不直接用無線電波之類的普通訊號傳送呢？

And also, if aliens had traveled through the galaxy to set up a network of giant telescopes, couldn't they just come visit?

而且，如果外星人已經在銀河系裡建立了一整個巨型望遠鏡網路，他們不能直接來拜訪嗎？

But answering those is beyond the scope of this video.

不過這些問題的解答就超出這支影片的範圍了。

Whether you're an alien learning to build an interstellar quantum communication network, or simply a human like me wanting to excel at learning science, I recommend Brilliant, this video's sponsor.

無論你是想建立星際量子通信網路的外星人，還是像我一樣想在科學學習上表現出色的人類，我都推薦 Brilliant，這支影片的贊助商。

Brilliant allows you to learn by doing, utilizing step by step interactive lessons that guide you to understand from first principles, such as their scientific thinking course, which teaches logical and scientific problem solving through the lens of everyday physics and engineering puzzles.

Brilliant 讓你透過動手做來學習，利用一步一步的互動式課程，引導你從基本原理開始理解，像是他們的科學思維課程，透過日常的物理和工程謎題，教你邏輯和科學的解題能力。

Brilliant makes it easy for anyone, whether you're 10 or 100, to learn in a more fun and effective way than just watching videos.

Brilliant 讓任何人，不論是 10 歲還是 100 歲，都能用比只看影片更有趣、更有效的方式學習。

To sign up for Brilliant for free and get 30 days of full access to all of their courses, go to brilliant.org minutephysics or scan the QR code on screen or click on the link in the description.

想免費註冊 Brilliant 並享有 30 天所有課程的完整存取權，請前往 brilliant.org minutephysics，或掃描螢幕上的 QR code，或點擊說明中的連結。

You'll also get 20% off an annual premium subscription for all of Brilliant's content.

你還能享有 Brilliant 所有內容年訂閱方案 8 折優惠。

Again, that's brilliant.org minutephysics and thanks to Brilliant for their support.

再次提醒，網址是 brilliant.org minutephysics，感謝 Brilliant 的支持。

The protocol, called super dense quantum coding allows you to send two non quantum bits of information from each quantum bit you send, which seems like a 2x speedup, except it requires the receiver to already be in possession of an entangled quantum bit from the sender in order to receive the message.

這個稱為「超密集量子編碼」的協定，能讓你透過傳送的每個量子位元，傳送兩個非量子位元的資訊，這看起來像是速度加倍，但前提是接收者必須已經持有傳送者提供的糾纏量子位元，才能接收訊息。

So you'd either have to bring a big supply of pre entangled quantum bits with you when you built the receiving telescope, or the sender would still have to send two quantum bits to transmit two non quantum bits, in which case they could just send the non quantum ones.

所以，你可能得在建造接收望遠鏡時，帶一大批預先糾纏好的量子位元過去，或者傳送者為了傳送兩個非量子位元，還是得傳送兩個量子位元，這樣的話，他們乾脆直接傳送非量子位元就好了。

The other procedure called the hidden matching problem, which requires exponentially more non quantum bits to be sent than quantum ones.

另一個稱為「隱藏匹配問題」的程序，需要傳送的非量子位元數量是量子位元的指數級倍數。

This procedure also requires the receiver to already be in possession of some information, and

這個程序也要求接收者必須預先持有某些資訊，而且

it's not clear exactly how it would be turned into a general communication protocol, but

目前還不清楚具體要如何將它轉化為一個通用的通信協定，但是

it has been proven that this procedure is exponentially faster when you communicate quantumly than non quantumly.

已經證實，當你用量子方式通信時，這個程序比非量子通信快上指數級。

字幕列表影片播放

費米悖論的量子級解答！ (A Quantum Solution to the Fermi Paradox)

capacity

brilliant

fundamental

suppose