Hawking's black hole paradox explained - Fabio Pacucci

譯者: Lilian Chiu 審譯者: Harper Chang

Scientists work on the boundaries of the unknown,

科學家致力於探索未知的邊界，

where every new piece of knowledge forms a path into a void of uncertainty.

每一次新知的發現

都開啓一條通往未知可能性的路。

And nothing is more uncertain–

沒有什麼比悖論更不確定的了——

or potentially enlightening– than a paradox.

或，更有啟發的潛力。

Throughout history,

縱觀歷史，悖論一直挑戰著 我們所知的一切，

paradoxes have threatened to undermine everything we know,

and just as often, they’ve reshaped our understanding of the world.

但它們同樣經常重新建構 我們對世界的了解。

Today, one of the biggest paradoxes in the universe

現今，宇宙中最大的悖論之一

threatens to unravel the fields of general relativity and quantum mechanics:

威脅著廣義相對論與量子力學領域：

the black hole information paradox.

黑洞資訊悖論。

To understand this paradox,

要了解這個悖論，

we first need to define what we mean by "information."

我們先要定義這裡 所謂的「資訊」是什麼。

Typically, the information we talk about is visible to the naked eye.

通常，我們所說的資訊 是用肉眼可以看見的。

For example,

比如，這種資訊告訴我們：

this kind of information tells us that an apple is red, round, and shiny.

蘋果是紅色的、圓形的、有光澤。

But physicists are more concerned with quantum information.

但物理學家更在乎的是量子資訊。

This refers to the quantum properties of all the particles that make up that apple,

也就是：構成這顆蘋果的 所有粒子有什麼量子特性，

such as their position, velocity and spin.

比如它們的位置、速度、自旋。

Every object in the universe is composed

宇宙中的所有物質

都由具有獨特 量子特性的粒子所構成。

of particles with unique quantum properties.

This idea is evoked most significantly in a vital law of physics:

一個重要的物理定律 體現了這個想法：

the total amount of quantum information in the Universe must be conserved.

宇宙中所有量子資訊的 總量必須守恆。

Even if you destroy an object beyond recognition,

即使我們把物體摧毀到無法辨識，

its quantum information is never permanently deleted.

它的量子資訊也永遠不會消失。

And theoretically, knowledge of that information

理論上，一旦知道那些資訊，

would allow us to recreate the object from its particle components.

我們就可以用該物體的粒子元件 將該物體重建出來。

Conservation of information isn’t just an arbitrary rule,

資訊守恆並不只是 任意的一條法則，

but a mathematical necessity, upon which much of modern science is built.

它在數學上有其必要性，

且是大部分現代科學的建構基礎。

But around black holes, those foundations get shaken.

但在黑洞附近， 那些根基受到動搖。

When an apple enters a black hole,

當一顆蘋果進入黑洞，

it seems as though it leaves the universe,

它就好像離開了這個宇宙，

and all its quantum information becomes irretrievably lost.

它會失去它所有的 量子資訊，且無法挽回。

However, this doesn’t immediately break the laws of physics.

然而，這不會馬上 破壞物理的法則。

The information is out of sight,

資訊雖然看不見，

but it might still exist within the black hole’s mysterious void.

但它可能仍然存在於 黑洞的神秘空洞當中。

Alternatively, some theories suggest

另一種說法是，

那些資訊甚至根本 沒有進入到黑洞中。

that information doesn’t even make it inside the black hole at all.

Seen from outside, it’s as if the apple’s quantum information

從外面看，似乎蘋果的量子資訊

is encoded on the surface layer of the black hole, called the event horizon.

被編碼在黑洞的表層上，

也就是事相面（事件視界）。

As the black hole’s mass increases,

當黑洞的質量增加，

the surface of the event horizon increases as well.

事相面的表面也會增加。

So it’s possible that as a black hole swallows an object,

所以，的確有可能， 當黑洞吞噬物體時，

it also grows large enough to conserve the object’s quantum information.

它也會長大到一個程度， 讓該物體的量子資訊可以守恆。

But whether information is conserved inside the black hole or on its surface,

但，不論資訊守恆是 發生在黑洞內或黑洞表面，

the laws of physics remain intact–

物理的定律仍然不受影響——

until you account for Hawking Radiation.

除非你要去說明霍金輻射。

Discovered by Stephen Hawking in 1974,

1974 年史帝芬霍金 發現了這種現象，

this phenomenon shows that black holes are gradually evaporating.

它顯示黑洞會漸漸蒸發。

Over incredibly long periods of time

經過非常長的時間之後，

black holes lose mass as they shed particles away from their event horizons.

黑洞的事相面會散失粒子， 因而失去一些質量。

Critically, it seems as though the evaporating particles

重要的是，蒸發的粒子看起來

are unrelated to the information the black hole encodes–

似乎和黑洞編碼的資訊沒有關聯——

suggesting that a black hole and all the quantum information it contains

這就意味著，黑洞 和它含有的所有量子資訊

could be completely erased.

能被完全抹除。

Does that quantum information truly disappear?

那些量子資訊真的會消失嗎？

If not, where does it go?

如果不會，它們到哪裡去了？

While the evaporation process would take an incredibly long time,

雖然蒸發過程會花非常長的時間，

the questions it raises for physics are far more urgent.

它帶給物理的問題更急迫。

The destruction of information

資訊的毀滅會迫使我們

would force us to rewrite some of our most fundamental scientific paradigms.

重寫我們最基礎的科學範式。

But fortunately, in science,

但，幸運的是，在科學上，

every paradox is an opportunity for new discoveries.

每一個範式都是新發現的機會。

Researchers are investigating a broad range of possible solutions

針對資訊悖論，研究者在探究

to the Information Paradox.

各種可能的解決方案。

Some have theorized

有些研究者推理說資訊 其實是被編碼在逃逸輻射上，

that information actually is encoded in the escaping radiation,

in some way we can’t yet understand.

用的是我們尚無法理解的編碼方式。

Others have suggested the paradox is just a misunderstanding

其他研究者則認為悖論只是誤解，

of how general relativity and quantum field theory interact.

誤會了廣義相對論和量子場論 如何產生交互作用。

Respectively,

這兩種理論分別描述了

these two theories describe the largest and smallest physical phenomena,

最大和最小的物理現象，

and they’re notoriously difficult to combine.

這兩者本來就是出了名的難結合。

Some researchers argue that a solution to this and many other paradoxes

有些研究者主張，對這個悖論 及許多其他悖論而言，

will come naturally with a “unified theory of everything.”

解決方案自然會隨著 「統一的萬物論」出現。

But perhaps the most mind-bending theory to come from exploring this paradox

但，也許在探究這個悖論時，

最難以理解的理論是全像原理。

is the holographic principle.

Expanding on the idea that the 2D surface of an event horizon

事相面的 2D 表面 能夠儲存量子資訊，

can store quantum information,

這個想法延伸出了全像原理，

this principle suggests that the very boundary of the observable universe

該原理指出，可觀測宇宙的

每一條邊界也都是 2D 表面，

is also a 2D surface encoded with information

且有關於真實 3D 物體的資訊 被編碼在這表面上。

about real, 3D objects.

If this is true, it’s possible that reality as we know it

如果這是真的， 有可能我們所知道的真實

is just a holographic projection of that information.

只是那些資訊的全像投影。

If proven, any of these theories would open up new questions to explore,

如果得到證明，上述任一個理論 都能夠開啟探索的新方向，

while still preserving our current models of the universe.

同時還能沿用我們目前的宇宙模型。

But it’s also possible that those models are wrong!

但，也有可能那些模型是錯的！

Either way, this paradox has already helped us take another step

不論如何，這個悖論已經協助我們

向未知又邁進了一步。

into the unknown.