Up to two trillion galaxies made up of something like 20,000 billion billion stars

環繞著我們所居的星系，約有兩兆的星系，其中又有兩十垓的行星

surround our home galaxy.

而光是於我們所居的星系“銀河”中，科學家們就找出了適居帶中約略四百億個類地行星

In the Milky Way alone,

從這個數字去推測的話，很難想像銀河裡沒有任何其他鄰居

scientists assume there are some 40 billion earth-like planets

如果科學家找到了其他的生命體，將顛覆我們對於自己的認知

in the habitable zone of their stars.

光是知道這個巨大的空間不是只有死寂就能增加我們對於外在的認知

When we look at these numbers, it's hard to imagine that there is nobody else out there.

但在尋找我們的太空友敵之前，該解決的問題是：我們到底該由何找起？

It would change our perception of ourselves forever if we found others.

在這樣一個古老又浩大的宇宙中

Just knowing that this vast place is not dead would shift our perspective outward,

我們得假設文明生成之間都差了千萬載，以不同的速度，朝著截然不同的方向發展

and could help us get over our irrelevant quarrels.

所以我們的搜索範圍不僅涵蓋相距千百光年的眾行星，也包含了從石器時代到超高科技文明社會

But before looking for our new best friends, or worst enemies,

所以我們需要有一套理論、系統來有計畫性的搜尋

we have a problem to solve: What are we actually looking for?

宇宙中的智慧生命體是否皆遵守某種通則？

[Kurzgesagt intro]

由於目前我們的樣本只含自己，由此所推斷或許會有一些偏誤

In a universe that big and old,

但總比沒有好！

we have to assume that civilizations start millions of years apart from eachother,

我們已知人類文明始於有創造能力的手與腦

and develop in different directions and speeds.

我們已知人類有競爭資源、擴張棲息地的天性

So not only are we looking over distances of dozens to hundreds of thousands of light years,

有著越多這些特質的人種

we're looking for a civilization ranging from cavemen to super advanced.

就越有可能在這場文明遊戲中勝出

So, we need a conceptual framework to enable us to think better thoughts

依天而存的自然之道或許聽起來不錯，

that make us able to search better.

但其終究不是通往農業，火藥，或現代都會的道路

Are there universal rules that intelligent species follow?

因此，我們可以合理的假設

Currently our civilization sample size is only one,

能在其他星球稱霸的外星生物也有這些共同特質

so we may make incorrect assumptions based solely on ourselves.

而在進一步假設我們的物理法則也適用於他們

Still, better than nothing.

那麼我們便可以用“能源來源”來分類他們的文明

We know that humans started out with nothing but minds and hands that could build tools.

人類的社會可以由能源的來源、使用方式來準確分類發展階段

We know that humans are curious, competitive, greedy for resources, and expansionist.

我們使用體能，到掌握火焰

The more of these qualities our ancestors had,

接著我們製造機器利用起了風和水的動能

the more successful they were in the civilization building game.

隨著對機器的改進和知識領域不斷的擴張，

Being one with nature is nice,

我們盯上了從地底下挖出的古老植物屍體

but it's not the path to irrigation systems, or gunpowder, or cities.

而隨著從消耗能源的能力快速成長還有的是我們的文明

So it's reasonable to assume that aliens able to take over their home planet also have these qualities.

於1800至2015之間，世界人口倍增六倍

And, if aliens have to follow the same laws of physics,

然而，能量的使用量卻增長至25倍

then there is a measurable metric for progress: Energy use.

這樣的人口-能量消耗 成長模式 很有可能在未來繼續出現

Human progress can be measured very precisely by how much energy we extracted from our environment,

由此成長模式，科學家Nikolai Kardashev（尼古拉·卡爾達肖夫）

and how we made it usable to do things.

發明出了一套方法來分類山頂洞人到宛若神明的文明

We started with muscles, until we learned to control fire.

卡爾達肖夫指數

Then we made machines that used kinetic energy from water and wind.

由一個文明的能源使用狀況來進行分類

As our machines got better and our knowledge of materials expanded,

這個分類表其經數十年不段的改良、進步

we began to harness the concentrated energy from dead plants we dug up from the ground.

總的來說有四個文明的等級

As our energy consumption grew exponentially, so did the abilities of our civilization.

一個等級一的文明

Between 1800 and 2015, population size had increased sevenfold,

能使用自身星球的能源

while humanity was consuming 25 times more energy.

一個等級二的文明

It's likely that this process will continue into the far future.

能利用恆星、和恆星系內所生成的能量

Based on these facts, scientist Nikolai Kardashev developed a method of categorizing civilizations,

一個等級三的文明

from cave dwellers to gods ruling over galaxies:

能使用其星系內的能量

The Kardashev Scale; a method of ranking civilizations by their energy use.

在一個等級四的文明

The scale has been refined and expanded on over the decades,

能掌握多個星系能量

but in general it puts civilizations into four different categories.

每一個等級之間的差距極大

A Type 1 civilization is able to use the available energy of their home planet.

在不同等級之間相比，就好像拿螞蟻社會來跟都市人類社會相比

A Type 2 civilization is able to use the available energy of their star and planetary system.

對螞蟻來說人類的複雜度與力量遠大於他們，宛若他們的神明

A Type 3 civilization is able to use the available energy of their galaxy.

為了讓這個分類系統能有用，

A Type 4 civilization is able to use the available energy of multiple galaxies.

我們需要再去切割出更小的間隔，繼續分類

These levels differ by orders of magnitude.

在分類表小的那端有著零級到一級的文明

It's like comparing an ant colony to a human metropolitan area.

代表著從狩獵撿採社會，到我們未來數百年的發展

To, ants we are so complex and powerful, we might as well be gods.

而銀河中就可能有好幾個這樣程度的文明

So to make the scale more useful, we need subcategories.

但一個文明並不是隨時都在向外發射訊號

On the lower end of the spectrum, there are Type 0 to Type 1 civilizations:

即使外星人位在很近的鄰星系 Alpha-人馬座

Anything from hunter-gatherers, to something we could achieve in the next few hundred years.

我們也幾乎沒辦法得知他們的存在

These might actually be abundant in the Milky Way.

但即使他們就像人類一樣向外發射訊號

But a civilization that is not actively transmitting radio signals into space

可能也沒辦法幫助讓我們探測到

might be as close as our nearest stellar neighbor, the Alpha Centauri system,

以星系的尺度而言，人類所發散出的信號幾乎等同於不存在

and we would have no way of realizing they exist.

我們的訊號或許可以發射到驚人的200光年外

But even if they transmitted radio signals like we do, it might not be very helpful.

然而對於整個銀河系來說，這就好像沙粒般微小

On an interstellar scale, humanity is practically invisible.

這種狀況下，即使對方收到了

Our signals may extend over an impressive 200 light years,

在經過幾光年後我們的訊號就可能會衰變為噪聲

but this is only a tiny fraction of the Milky Way.

變得不可能被辨識出這是一個由智慧生物發出的訊號

And even if someone were listening,

今日的人類文明社會大約位在0.75級

after a few light years our signals decay into noise,

我們對地球做了很多的改變

impossible to identify as the source of an intelligent species.

我們創造了巨大的建築、開鑿地下資源等

Today, humanity ranks at about level 0.75.

伐去了雨林，抽乾了池塘

We have altered our planet:

我們創造了河流和人工湖

we've created huge structures, mined and stripped mountains,

改變了大氣層的成分和溫度

removed rainforests, and drained swamps.

如果我們持續進步

We've created rivers and lakes,

而且我們也沒有毀了地球

and changed the composition and temperature of the atmosphere.

在接下來的幾百年內我們就能成為一個真正的第一級文明

If progress continues, and we don't make Earth uninhabitable,

任何一個第一等級的文明

we will become a full Type 1 civilization in the next few hundred years.

一定會持續探索外在

Any civilization that becomes a Type 1 is bound to look outside,

因為他依然好奇貪婪而且渴望擴張

because it's likely that it's still curious, competitive, greedy and expansionist.

下一個合理的升級為第二等級的方式

The next reasonable step towards transitioning to Type 2 is trying to alter and mine other planets and bodies.

是試著開採和改變其他星球

This might start with outposts in space, transition to infrastructure and industries near the home planet,

這會促使原先單純的太空前哨站

move on to colonies, and end with terraforming other planets,

逐漸轉為建立鄰近母星的基礎設施和工業設施

by changing their atmosphere, their rotation, or position.

接著成為殖民地

As a civilization expands and uses more and more stuff and space,

最終藉由改變大氣組成或旋轉軌道完成地球化

its energy consumption scales with them,

隨著一個文明空間不斷的擴張

so at some point, they may embark on the largest project a lower Type 2 civilization can take on:

能源的需求也在快速上升

harnessing the energy of their star by building a Dyson Swarm.

或許到了某個時間點

Once this megastructure is finished,

他們開始了一個二級文明能夠建造的最大設施

energy has become practically unlimited for molding the home system however they see fit.

建造戴森網來利用整個恆星的能量

If they are still curious, competitive, greedy and expansionist,

一但這個巨構建築完成

and now have complete control over their home system,

就能夠獲取看似無窮無盡的能量

stellar infrastructure in place, and the energy output of a star,

來驅動他們的家鄉星系

the next frontier moves to other stars light years away.

如果它們依然好奇，貪婪地想要擴張

For a Type 2 civilization,

現在他們已經完全掌握了母星系的所有能源

the distance to other stars might feel like the distance between Earth and Pluto does to us today:

下一個目標將是數個光年外的另一個星系

Technically within reach,

對於一個等級二的文明來說

but only with immense investments in terms of time, ingenuity, and resources.

這個距離或許就和我們今天感受到地球到冥王星的距離一樣

This begins their transition towards Type 3.

雖然看似伸手可及

This step is so far beyond us

但必須要投入巨量的時間、資源、和創新性

that it becomes hard to imagine what exactly these challenges will look like,

這開啟了他們通往第三級文明的道路

and how they'll be solved.

到了這個階段 對我們來說是如此遙不可及

Will they be able to find a solution to the vast distances

讓我們無法想像他們會遭遇甚麼困難

and travel times of hundreds or thousands of years?

還有它們是如何解決的

Will they be able to communicate and keep a shared culture and biology between colonies light years apart?

它們究竟是否會找到方法

Or will they split into separate Type 2 civilizations?

穿越巨大的空間並旅行數百上千年

Maybe even different species?

它們還能和數光年外的殖民地溝通

Are there deadly challenges between the stars?

並分享文化和生物學知識嗎?

So the closer a species gets to Type 3,

還是它們會分裂成數個等級二的文明?

the harder it becomes to fathom what it might actually look like.

甚至成為一個完全不同的物種?

They might discover new physics, may understand and control dark matter and energy,

在星系之間有甚麼隱藏的死亡挑戰嗎?

or be able to travel faster than light.

當一個物種越接近等級三

We might be unable to grasp their motives, technology, and actions.

越難以猜測出他真正的程度

Humans are the ants, trying to understand the galactic metropolitan area.

或許它們發現了新的物理原理

A high Type 2 civilization might already consider humanity too primitive to even talk to.

或許理解並運用了暗物質和暗能量

A Type 3 civilization might feel about as like we feel about the bacteria living on the anthill.

或許它們能以超光速行進

Maybe they wouldn't even consider us conscious, or our survival relevant.

我們可能無法猜測到它們的動機、科技還有活動

We could only pray that they're nice gods.

人類就像那時的螞蟻一樣

But the scale doesn't necessarily end here.

試著了解宇宙超級都市群

Some scientists suggest there might be Type 4 and Type 5 civilizations,

一個二級的文明

whose influence stretches over galaxy clusters or superclusters,

可能已經認為人類是如此原始以致於不屑溝通

structures comprising thousands of galaxies and trillions of stars.

一個三級的文明看待我們

Ultimately, there might be a Type Omega civilization,

可能就像我們看待於蟻丘上面的細菌一般

able to manipulate the entire universe, and possibly others.

他們可能不會考慮我們的感受

Type omega civilizations might be the actual creators of our universe,

或是我們的生存條件

for reasons beyond our comprehension.

我們只能祈禱

Maybe they were just bored.

他們是一個善良的神明

As flawed as this classification may be,

但是等級分類表並不止步於此

this thought experiment is already telling us interesting things.

有些科學家認為還有等級四甚至等級五的文明

If our ideas about the nature of species that form interstellar civilizations is sort of correct,

他的影響力遍布星系團

then we can be pretty sure that there are no civilizations of Type 3 and beyond near the Milky Way.

甚至是那個由上千個星系和上兆的恆星系所組成的

Their influence would in all likelihood be so all-encompassing,

超星系團

and their technology so far above our own, that we couldn't miss them.

最終，或許有一個等級Omega的文明

The galaxy should flash with their activity in thousands of star systems.

能夠操縱整個宇宙

We should be able to see or detect their artifacts or movements between different parts of their empire.

或甚至其他的宇宙

Even if a Type 3 civilization did exist in the past, and died a mysterious death,

Omega文明可能是那個真正的創造我們宇宙的造物主

we should be able to detect some of the remnants of their empire.

為了一個我們不能理解的理由

But when scientists looked, they didn't find remnants of harvested stars,

可能他們只是無聊了!

decaying megastructures or scars of great interstellar wars.

就算這個分類表可能有缺陷

So they're very likely not out there and never were.

這個思想實驗已經告訴我們

In a sense, this is very sad, but also very reassuring.

一些有趣的事

It leaves the galaxy to us and others similar to us.

如果我們對於自然生物所創造的跨星系文明的假設是正確的

So the most promising civilizations to look for may be somewhere in the spectrum from Type 1.5 to Type 2.5.

我們可以確定在銀河系附近沒有三級和更高的文明存在

They wouldn't be too advanced to understand them and their motives.

因為他們的影響會如此巨大

They may have finished their first megastructures,

還有他們的科技會凌駕於我們以至於我們不會忽略

and they might be in the process of moving staff between stars,

星系中的上千個恆星系應該會閃爍著它們的活動痕跡

transmitting enormous amounts of information into space,

我們應該能在它們的帝國各處

by accident, or on purpose.

看見或偵測到他們的作品或活動

They would probably also look to the stars and look for others.

就算過去曾經存在一個三級文明，並結束於一場謎團

Then again, maybe we've got it all wrong.

我們也應該能發現他們帝國的遺跡

Maybe progress to Type 2 does not mean expanding outwards,

但是當科學家們進行觀測時

and humanity is still too immature to imagine otherwise.

並沒有發現被挖掘過的行星，破損的巨構建築

For now, all we really know is that we haven't seen anybody yet.

或巨大的星系戰爭遺跡

But, we've only just started looking.

所以它們很有可能不在那裡，也不曾在那裏

Until we finally find friendly super aliens and can ask them to explain the rules of the universe to us,

這可能令你難過，但也同時令人放心

most of us have to make do with learning stuff ourselves.

這代表銀河系的空間留給了我們和發展度相似的外星人

Whether you're going back to school leaving home for the first time,

所以最應該尋找的是位於某處的1.5級到2.5級的文明

or if you're just entering a new phase in your life,

他們對於人類來說不會太過於先進以致於無法理解

our shop is stocked and ready for all your back-to-school needs.

他們可能剛剛完成第一個巨構建築

Notebooks and notepads to organize your work,

而且可能正在恆星之間轉移他們的工人

stickers and mugs to make things look nice,

並正在轉譯大量的訊息並發送至宇宙深處中

lots and lots of posters to turn your dorm or room into an inspiring oasis of knowledge.

「意外地」或是「故意地」

We have new shirts and for the first time, a Kurzgesagt Earth sweater.

它們可能也正在看著星空並尋找其他的存在

All of these products are designed and produced with love by the Kurzgesagt merch birbs.

當然，也有可能我們全都搞錯了

Our merch is the easiest way to support what we do and keep our videos free for everyone.

或許進化到第二等級不代表著向外擴張

Thank you for watching.

而人類還是太不成熟來想像其他的存在

*duck noise*

至於現在，我們知道我們還未遇見其他人

Subtitles by: Bruno Andre Fernandes Ortega and others

但，我們才剛開始