Can a black hole be destroyed? - Fabio Pacucci

譯者: Lilian Chiu 審譯者: Bruce Sung

Black holes are among the most destructive objects in the universe.

黑洞是宇宙中 最有毀滅性的物體之一。

Anything that gets too close to the central singularity of a black hole,

任何東西，如果太靠近 黑洞的中心奇點，

be it an asteroid, planet, or star,

不論是小行星、行星、恆星，

risks being torn apart by its extreme gravitational field.

都有很高的風險可能會因為 它的極端重力場而四分五裂。

And if the approaching object happens to cross the black hole’s event horizon,

如果靠近黑洞的物體 剛好穿過了黑洞的事件視界，

it’ll disappear and never re-emerge,

它就會消失，永遠不會再出現，

adding to the black hole’s mass and expanding its radius in the process.

在過程中，還會增加 黑洞的質量並擴大它的半徑。

There is nothing we could throw at a black hole

不論我們朝黑洞丟什麼，

that would do the least bit of damage to it.

都無法對它造成一點損傷。

Even another black hole won’t destroy it–

就連另一個黑洞也無法摧毀它，

the two will simply merge into a larger black hole,

兩個黑洞只會融合成 一個更大的黑洞，

releasing a bit of energy as gravitational waves in the process.

在過程中以重力波的 形式釋放出一點能量。

By some accounts,

有人說，

it’s possible that the universe may eventually consist entirely of black holes

最終，宇宙有可能滿滿都是黑洞，

in a very distant future.

發生在非常遙遠的未來。

And yet, there may be a way to destroy, or “evaporate,” these objects after all.

但，也許還是有辦法可以摧毀

或「蒸發」這些物體。

If the theory is true,

如果理論沒錯，

all we need to do is to wait.

我們要做的就是等待。

In 1974,

在 1974 年，史帝芬霍金 推論出一個過程，

Stephen Hawking theorized a process

that could lead a black hole to gradually lose mass.

可能會導致黑洞漸漸失去質量。

Hawking radiation, as it came to be known,

它就是漸漸被大家 所知的霍金輻射，

is based on a well-established phenomenon called quantum fluctuations of the vacuum.

它的基礎是一個已被大家接受的 現象，叫做真空量子漲落。

According to quantum mechanics,

根據量子力學，

a given point in spacetime fluctuates between multiple possible energy states.

在時空中給定的一個點 會在數種可能的能態間起伏漲落。

These fluctuations are driven by the continuous creation and destruction

驅動這些起伏漲落的是

虛粒子對的不斷創造和摧毀，

of virtual particle pairs,

which consist of a particle and its oppositely charged antiparticle.

虛粒子對包含了一個粒子 和一個帶相反電荷的反粒子。

Normally, the two collide and annihilate each other shortly after appearing,

正常情況下，這兩者出現後 沒多久，就會相撞並毀滅，

preserving the total energy.

總能量維持不變。

But what happens when they appear just at the edge of a black hole’s event horizon?

但，當它們出現在黑洞事件視界 邊緣時，會發生什麼事？

If they’re positioned just right,

如果把它們放對位置，

one of the particles could escape the black hole’s pull

其中一個粒子可以 逃離黑洞的引力，

while its counterpart falls in.

另一個粒子則會掉進去。

It would then annihilate another oppositely charged particle

接著，它就會在黑洞的事相面內，

摧毀另一個帶相反電荷的粒子，

within the event horizon of the black hole,

reducing the black hole’s mass.

因而減少黑洞的質量。

Meanwhile, to an outside observer,

此時，從外部觀察者來看，

it would look like the black hole had emitted the escaped particle.

就像是黑洞放射出了 逃離的那個粒子。

Thus, unless a black hole continues to absorb additional matter and energy,

因此，除非黑洞持續 吸收額外物質和能量，

it’ll evaporate particle by particle, at an excruciatingly slow rate.

不然它就會以極緩慢的速度， 一個粒子一個粒子地蒸發。

How slow?

多慢？物理有一個分支 叫做黑洞熱力學，

A branch of physics, called black hole thermodynamics, gives us an answer.

它就可以給我們答案。

When everyday objects or celestial bodies release energy to their environment,

當日常的物體或是天體 釋放能量到它們的環境中時，

we perceive that as heat,

我們會感受到熱能，

and can use their energy emission to measure their temperature.

並能用它們放出的能量 來測量它們的溫度。

Black hole thermodynamics

黑洞熱力學指出，

suggests that we can similarly define the “temperature” of a black hole.

我們可以用類似的方式， 定義黑洞的「溫度」。

It theorizes that the more massive the black hole,

它的理論是，黑洞的質量越大，

the lower its temperature.

它的溫度就越低。

The universe’s largest black holes

宇宙中最大的黑洞

would give off temperatures of the order of 10 to the -17th power Kelvin,

發出的絕對溫度會是 10 的 -17 次方，

very close to absolute zero.

非常接近絕對零度。

Meanwhile, one with the mass of the asteroid Vesta

如果黑洞的質量 和灶神星（小行星）一樣，

would have a temperature close to 200 degrees Celsius,

溫度就會接近攝氏 200 度，

thus releasing a lot of energy in the form of Hawking Radiation

因此會以霍金輻射的形式 釋放許多能量

to the cold outside environment.

到寒冷的外在環境。

The smaller the black hole,

黑洞越小，

the hotter it seems to be burning–

它似乎燃燒得越熱——

and the sooner it’ll burn out completely.

也會更快完全燒盡。

Just how soon?

有多快？不用期待了。

Well, don’t hold your breath.

First of all, most black holes accrete, or absorb matter and energy,

首先，大部分的黑洞長大 或是吸收物質和能量的速度，

more quickly than they emit Hawking radiation.

都比它們發散 霍金輻射的速度更快。

But even if a black hole with the mass of our Sun stopped accreting,

但，即使質量和我們太陽 一樣大的黑洞停止成長了，

it would take 10 to the 67th power years–

也需要花上 10 的 67 次方年——

many many magnitudes longer than the current age of the Universe—

比宇宙目前的壽命還要長許多——

to fully evaporate.

才會完全蒸發。

When a black hole reaches about 230 metric tons,

當黑洞達到大約 230 公噸時，

it’ll have only one more second to live.

它就會只剩下一秒鐘可以活。

In that final second,

在那最後一秒鐘，

its event horizon becomes increasingly tiny,

它的事件視界會越來越小，

until finally releasing all of its energy back into the universe.

直到最後，將它所有的 能量釋放回宇宙。

And while Hawking radiation has never been directly observed,

雖然從來沒有人 直接觀察到霍金輻射，

some scientists believe that certain gamma ray flashes detected in the sky

有些科學家相信，在空中 偵測到的某些伽瑪射線閃光

are actually traces of the last moments

其實就是在時間之初 所形成的小型原始黑洞

of small, primordial black holes formed at the dawn of time.

在其最後時刻留下的蹤跡。

Eventually, in an almost inconceivably distant future,

最終，在幾乎無法 想像的遙遠未來，

the universe may be left as a cold and dark place.

宇宙可能會變成只是 一個寒冷、黑暗的地方。

But if Stephen Hawking was right,

但，如果史帝芬霍金 是對的，在那發生之前，

before that happens,

the normally terrifying and otherwise impervious black holes

平常十分嚇人，且在其他情況 都不會受到影響的黑洞，

will end their existence in a final blaze of glory.

在發出最後的光輝之後， 將不復存在。