From thousands of galaxies, each with billions of stars.

在這幾千個包含幾十億個恆星的銀河系中

Imagine, you could take this kind of power, and use it to fire the biggest super-weapon in the universe.

然後用這些能量在宇宙中做出一個超級兵器

Imagine the damage you could do.

能夠造成多少破壞呢？

It turns out, you don't need to imagine it.

不用想了，你根本不需要想像

These exist, and they're called gamma ray bursts.

這真實存在的！它被稱為『伽瑪射線爆發』

But what are these cosmic snipers?

這些宇宙狙擊手是甚麼呢？

And what happens if one takes a shot at Earth?

如果地球不小心被射到會發生甚麼事呢？

To understand gamma ray bursts, we first have to understand gamma rays.

要了解伽瑪射線爆發，首先我們要先了解伽瑪射線

Gamma rays are electromagnetic radiation – waves which carry energy just like visible light.

伽瑪射線是一種如同可見光一樣攜帶著能量的電磁波

Visible light is a tiny part of the electromagnetic spectrum: it's the part your eyes can see.

可見光是指電磁波光譜中可以被你看見的一小部分

At lower energies, there are radio waves, microwaves and infrared.

比可見光低能量的有無線電波、微波跟紅外線

And at higher energies: ultraviolet, x-rays and gamma rays.

能量大於可見光的有紫外線、X光跟伽瑪射線

Gamma rays are incredibly powerful.

伽瑪射線非~常~的強大

A single gamma ray photon, is more energetic than a million visible photons combined.

一個伽瑪射線光子的能量比起一百萬個可見光子的能量總和還多！

Their high energy makes gamma rays a form of ionizing radiation.

這樣的高能量讓他成為游離輻射

Meaning they are energetic enough, to break apart atomic bonds.

意思是他有足夠的能量可以打斷原子間的鍵結

This makes them dangerous to you and me.

這讓它對於你我來說非常的危險

Ionizing radiation disrupts the delicate biochemical machinery that keeps us alive,

游離輻射會破壞維持我們生命的生物機制 （意指會破壞人體中DNA的排序）

like a 9mm bullet through a clock.

就像9釐米口徑的子彈射穿掛鐘一樣

Fortunately, on Earth, the ozone layer blocks gamma rays. Filtering them out before they can harm us.

幸運的是，地球的臭氧層幫我們抵擋了伽瑪射線， 在他可以傷害我們之前先濾掉了

But if the atmosphere blocks gamma rays from space,

但是如果大氣層幫我們擋掉了伽瑪射線，

how were gamma ray bursts (or GRBs) from space ever discovered?

我們怎麼發現他的呢？

During the Cold War,

在冷戰期間

the USA sent up spy satellites, which could detect gamma rays from Soviet nuclear tests in space.

美國的間諜衛星其中有一個功能是 用來探測蘇聯核子實驗所放出來的伽瑪射線

They didn't see any bombs, but they did observe faint bursts coming from space,

這些衛星沒發現任何炸彈，卻發現了微弱的脈衝從遙遠的宇宙而來

lasting only a few seconds.

並只持續了幾秒

To date, this may be the only major scientific discovery made by spy satellites (that we know about anyway).

至今，這是間諜衛星唯一的科學貢獻了 （至少我們知道的是這樣XD）

Astronomers use telescopes see different kinds of light to make their discoveries.

天文學家用天文望遠鏡分析各種光線來找出端倪

And these spy satellites gave them a new pair of eyes.

這些間諜衛星就像是給了他們另一雙眼睛

They were a mystery for thirty years but eventually,

直到30年後這些神祕的伽瑪射線爆發

we discovered the source of a GRB: a galaxy six billion light years away.

才被找出真正的源頭：一個60億光年外的星系

If a GRB can be seen from such a distance, then it must be incredibly energetic.

這些伽瑪射線爆發能夠被這麼遙遠的我們觀測到， 代表他的能量是無法想像的大

Releasing more energy in a second than the sun will, in its entire ten billion year lifetime.

短短一秒所釋放的能量等於太陽一生一百億年所發出來的全部能量

Making GRBs, the brightest events in the universe.

讓伽瑪射線爆發成為宇宙中最亮的一個東西

So, where do they come from?

所以，他們從哪裡來呢？

GRBs, accompany some of the most violent, cataclysmic deaths in the universe,

伽瑪射線爆發伴隨著宇宙中最劇烈的死亡災難

and the birth of black holes.

與黑洞的生成一起發生的

There are two types of gamma ray bursts:

伽瑪射線爆發有兩種：

short and long, and each has their own source.

短的和長的，分別來自不同的地方

Long GRBs last about a minute, and scientist think they are produced by supernova:

長伽瑪射線爆發持續大約一分鐘， 科學家認為它們是由超新星產生的：

when the core of a massive star collapses to become a black hole.

一顆大質量恆星的核心坍縮成黑洞

Short GRBs last a second, and are produced when two neutron stars in a binary merge.

短伽瑪射線爆發只會持續一秒鐘， 產生兩個互繞的中子星

Over millions of years, their orbits decay by emmiting gravitational waves.

經過數百萬年，它們的軌道會因為重力波的釋放而變小

Once they are close enough to touch, they crash and splash into each other, forming a black hole.

當他們夠近的時候，兩個會撞在一起並形成黑洞

Both supernova and neutron star mergers the same thing:

超新星和中子星合併都會造成同樣的結果：

black holes, surrounded by a magnetized disc of gas left over from their parent stars.

一個圍繞著被磁化氣體盤的黑洞

In these environments, the rotation winds up the magnetic field, which funnels hot jets of particles,

在這樣的環境中，高速的旋轉帶起了強大的漏斗狀磁場，射出炙熱的粒子

traveling at nearly the speed of light.

以接近光速飛行

The gas in this funnel creates two tight jets of high energy gamma rays,

在漏斗中的氣體創造了前後兩道高能量的伽瑪射線爆發

like a celestial laser gun.

就像一個星際雷射槍

So unlike other cosmic explosions, which spread out and fade,

所以不像其他宇宙中的爆炸是分散的

GRBs say focused, and can been seen from much further.

伽瑪射線爆發更加集中，所以可以射的更遠

Any more detail would require too much mathematics for a YouTube video.

至於更詳細的數學運算恐怕 不適合在YouTube影片上出現^ ^

The universe is full of these cosmic snipers, firing blindly and randomly into the dark,

宇宙充滿了這些隨機且漫無目的星際狙擊手

and they're hitting us all the time.

一直打到地球上

On average, we detect one per day. Fortunately, most are harmless.

平均每天都可以發現一個，還好幾乎都無害

All the bursts we have detected so far, originated outside the Milky Way,

目前所發現的所有伽瑪射線爆發都源於銀河系之外

too far away to hurt us.

這遠到無法傷害我們

But a nearby GRB could be disastrous,

但是如果伽瑪射線爆發發生在我們附近，那會是個大災難

if one goes off within a few light years of us, it would totally cook the surface of the Earth.

如果其中一個發生在幾光年附近，那會把地球表面整個烤乾

Or at least, the half that's facing it.

或者至少是面對他的那面~

But even a more distant GRB could still end life on Earth.

但即使是更遠的伽瑪射線爆發仍然可以毀滅地球上的生物

And it wouldn't need to score a head-shot to kill us.

而且不需要爆頭！

If originating from a few thousand light years away,

如果從幾千光年外發射

it would be a hundred light years wide by the time it reaches us,

當他到達這裡時會變成幾百光年寬

washing over the Solar System like a tidal wave.

如同潮水一樣沖過太陽系

Again, the ozone layer protects us, but it's better equipped to handle the trickle of ultraviolet from the sun.

臭氧層會再次的保護我們，不過他還是比較適合 處理涓涓細流般的太陽紫外線

A gamma ray burst would overwhelm it, leaving us exposed to deadly solar radiation.

伽瑪射線爆發會壟罩整個臭氧層，讓我們直接曝露在致命的太陽射線下

Ozone takes years to replenish itself by natural processes,

臭氧層需要很多年才會自動補充

which is more than enough time for the sun to burn the Earth sterile.

比其太陽要把地球燒成無菌室的時間還長

Or at least, to kill most complex life.

或者至少可以殺掉最複雜的生物~

In fact, this may have already happened.

事實上這可能已經發生過了

A GRB has been suggested as one possible cause of the Ordovician extinction 450 million years ago,

伽瑪射線爆發也被認為是4.5億年前奧陶紀大滅絕一個可能的原因

that eradicated almost 85% of all marine species.

那殺死了近85％的海中物種

Although it's pretty much impossible to prove.

雖然這幾乎不可能證明

Gamma ray bursts could even be one reason we don't see life anywhere else in the universe.

伽瑪射線爆發可能也是我們在宇宙中 看不到其他生命的原因之一

They might be wiping clean huge chucks of it, on a regular basis.

他們會定期清掉星球上大部分的生命

It's been suggested, that because of GRBs, only 10% of all galaxies might be hospitable to life,

因為伽瑪射線爆發，可能只有10％的星系適合生命居住

similar to us.

就像我們一樣我們

So, are they going to kill us?

所以，他們會殺死我們嗎？

Probably not.

可能不會

In a galaxy like ours, there may only be one GRB per millennia.

在像我們這樣的星系一千年只會有一個伽瑪射線爆發

And to harm us, they must be close and directed at us.

要對我們造成傷害，他要夠近而且還要面向我們

But since gamma rays travel at the speed of light, we won't know when it's headed our way until it arrives.

但是伽瑪射線爆發是以光速前進，我們在他抵達之前根本沒辦法預測

So, there could already be a GRB on its way to kill us all, and we won't know it, until it hits us,

所以可能早就有一個會殺死我們的伽瑪射線爆發 朝著我們過來，直到他到之前我們都無從得知

and we're dead.

然後我們就死了

This video was sponsored by squarespace.com/nutshell

這部影片由squarespace.com/nutshell贊助 中文字幕由Jason Haung@NCKU提供

Death from the sky could come around any second.

從空中降臨的死亡可能隨侍會到達

Maybe, even now!

也許，就是現在！

So you don't have any time to waste.

所以你沒有任何時間可以浪費！

Learning to set up a website, portfolio or blog is usually hard and time consuming.

學習建立了一個網站或部落格通常很花時間

Not so with Squarespace though.

Squarespace讓他不會是如此

They let you set up a page with easily understandable tools, very quickly,

他們用很容易理解的工具讓你很快建立一個網頁

and without any knowledge of web design.

而且不需要網頁設計的知識

You can use the code "NUTSHELL" to save 10% and support Kurzgesagt.

您可以使用序號“NUTSHELL” 獲得10％折扣並支持Kurzgesagt。

Squarespace have been a great sponsor, so give them some love.

Squarespace是一個偉大的贊助商， 所以給他們一些愛吧 <3

You can support us directly at Patreon or get Kurzgesagt merch here:

您可以直接在Patreon支持我們，或者在這裡得到Kurzgesagt專賣品：

it really helps.

這對我們很有幫助

Over the next few months, we'd like to make more videos about cataclysmic destructive events,

在接下來的幾個月中我們會做更多災難性的破壞影片

because, honestly, it's a lot of fun to make these.

因為，老實講，做這些很有趣^ ^

If you have any ideas about what kind of doomsday scenario you'd like to learn about,

如果你有甚麼末日場景想要了解的話

let us know in the comments.

讓我們知道你的意見

And if you need to kill a little more time now, here are few related videos.

如果你現在需要閒晃時間，這裡有一些相關的影片可以看

Or maybe...

或者可能...

NOW!

現在！