And also the most mysterious.

不過也是最神秘的。

A black hole is a region in space where the force of gravity is so strong not even light, the fastest known entity in our universe, can escape.

黑洞是一個外太空的地帶，引力大到就連我們認知最快的光速也沒有辦法逃脫。

The boundary of a black hole is called "the event horizon", a point of no return, beyond which we truly cannot see.

黑洞的範圍被稱為是「視界」，一個沒辦法返回，我們真的看不見的東西。

When something crosses the event horizon, it collapses into the black hole's singularity.

當有物體越過視界時，它會跌入黑洞的奇點裡。

An infinitely small, infinitely dense point where space, time, and the laws of physics no longer apply.

一個非常迷小、非常密集的點讓空間、時間和物理規則都不再適用。

Scientists have theorized several different types of black holes, with stellar and supermassive black holes being the most common.

科學家推理出許多種不同的黑洞，最常見的是恆星黑洞和超大質量黑洞。

Stellar black holes form when massive stars die and collapse.

恆星黑洞是由大質量恆星死亡和衰退而成。

They're roughly 10 to 20 times the mass of our sun and scattered throughout the universe.

大概比太陽大 10 到 20 倍，散佈在整個宇宙。

There could be millions of these stellar black holes in the Milky Way alone.

光是銀河系就有上百萬個這種恆星黑洞。

Supermassive black holes are giants by comparison, measuring millions, even billions of times more massive than our sun.

相比之下，超大質量黑洞是比太陽還要再大上數百萬，甚至數十億倍。

Scientists can only guess how they form, but we do know they exist at the center of just about every large galaxy, including our own.

雖然科學家只能推測他們是如何形成，但我們可以知道的是，他們存在於每個大星系的中心，包括我們自己的。

Sagittarius A, the supermassive black hole at the center of the Milky Way, has a mass of roughly four million suns, and has a diameter about the distance between the earth and our sun.

人馬座 A 是銀河系中心的一個超大質量黑洞，大小約是太陽的四百萬倍，直徑是大概是地球到太陽的距離。

Because black holes are invisible, the only way for scientists to detect and study them is to observe their effect on nearby matter.

因為黑洞是看不見的，科學家唯一的偵測和研究的方法是觀察他們對周遭事物的影響。

This includes accretion disks, a disk of particles that form when gases and dust fall toward a black hole, and quasars, jets of particles that blast out of supermassive black holes.

包括吸積盤，由氣體和塵埃掉進黑洞後形成的粒子盤和類星體，超大質量黑洞噴射出的粒子氣流。

Black holes remained largely unknown until the 20th century.

直到二十世紀，人類對大部分的黑洞還是未知的。

In 1916, using Einstein's general theory of relativity, a German physicist named Karl Schwartzschild calculated that any mass could become a black hole if it were compressed tightly enough.

1916 年時，一位德國物理學家卡爾·史瓦西使用愛因斯坦的廣義相對論，推算出任何質量只要被壓縮得夠緊，就可以變成黑洞。

But it wasn't until 1971 when theory became reality.

但直到 1971 年，這個推論才變成事實。

Astronomers studying the constellation Cygnus discovered the first black hole.

天文學家研究天鵝座時發現第一個黑洞。

An untold number of black holes are scattered throughout the universe, constantly warping space and time, altering entire galaxies, and endlessly inspiring both scientists' and our collective imagination.

無數個黑洞散佈在整個宇宙中，不停地扭曲空間和時間，改變整個星系，並不斷地激起我們和科學家的共同想像力。