If you come too close, they'll devour you and add your energy to their collection.

近づき過ぎればあなたの エネルギーは吸い取られ

And so, the energy is lost to us forever.

永遠に失われる

Or is it? It turns out there's a universe cheat code.

違うだろうか?

A way of powering civilizations until the very death of everything, or of constructing the largest bomb in the universe.

抜け道があることがわかった

But how?

宇宙の最後まで文明に エネルギーを供給する方法

Didn't we learn that all energy is trapped forever in black holes, even light?

あるいは宇宙最強の 爆弾を作る方法だ

This is true.

どうやって?

Everything you think you know about the weirdest thing in the universe is about to get weirder, for one simple reason:

すべてのエネルギーが取り込まれ、 光ですら逃げ出せないのでは?

Black holes are spinning.

その通り

When really really massive stars die, their cores collapse under their own gravity into black holes.

だが宇宙一奇妙なものが、 実はもっと奇妙なものになる

This means something very big becomes very, very tiny. Like the tiniest anything can be in this universe.

単純な理由で

But stars are rotating and a fundamental property of our universe is that things that are spinning don't want to stop spinning.

ブラックホールは 回転しているのだ

We call this: angular momentum.

ブラックホールは なぜ回転するのか

And this angular momentum can't go away. A big thing that spins and becomes smaller, spins faster.

大質量の星が死ぬ時

So, as the core of a star collapses, its momentum makes it spin faster and faster and faster, until it collapses into a black hole .

核が重力で潰れて ブラックホールとなる

And the black hole keeps on spinning, inconceivably fast.

巨大だったものがすごく 小さくなるということだ

Some of them spin millions of times a second.

宇宙で最も小さく なるといっていい

Just like non spinning black holes,

しかし星は回転しており、

...spinning black holes have an event horizon and a singularity at their core, where all of their mass is concentrated.

宇宙の基本法則によれば 回転しているものは止まらない

The singularity is usually described as a single infinitely small point with no surface area.

これを角運動量と呼ぶ

But points can't rotate, so a rotating singularity can't be a point.

角運動量は保存される

Instead, it's a RINGularity.

回転しているモノ が小さくなると

A ringularity is a ring with a thickness of zero and no surface, spinning extremely fast, containing all the mass of the black hole.

回転は速くなる

The black hole is spinning so fast, that it morphs space and time itself.

なので星の核が崩壊すると、

It literally drags space with it, such is its power.

ブラックホールになる過程で 回転はどんどん速くなる

This creates a new and super weird region of space-time: the Ergosphere, which envelops the black hole.

ブラックホールは想像も つかない速度で回り続ける

If space and time are completely broken inside the event horizon, then they're only half broken inside the ergosphere.

毎秒数百万回も 回転するものもある

Inside the ergosphere, nothing makes sense.

回転するブラックホールは なぜ特別なのか

It's possible to enter it and then leave it again, but it's probably not a great experience.

回転しないブラックホールと同様

You can imagine it like this: Falling into a static black hole is like sliding down a hole.

回転するブラックホールにも 事象の地平線があり

Being inside the ergosphere of a spinning black hole is like spiraling down a deadly drain.

核には質量の全てが凝縮した 特異点がある

The black hole transfers its own kinetic energy in the form of rotation, to everything that enters the ergosphere.

特異点はふつう、無限に小さく

The ringularity makes you dance whether you want to or not.

表面を持たない点 として描かれる

You need to move faster than the speed of light just to stand still here, which is impossible.

しかし点は回転 できないので

But here's our cheat code: We can steal this energy, and there's a lot of energy to steal.

回転する特異点は 点ではありえず

Take the supermassive black hole at the center of the Milky Way.

かわりにリング状特異点となる

We could steal as much energy from it as every single star in the Milky Way emits in a billion years combined.

リング状特異点は厚みがゼロで 表面を持たず、

The easiest way to steal this energy is, oddly enough, to drop something into the black hole.

極端に速い速度で回転し

We've seen that the ringularity forces energy on us when we enter the ergosphere,

ブラックホールの 質量の全てを持つ

...which is a lot like being in a whirlpool, with space-time rushing around and around.

ブラックホールの回転は あまりに速いため

If you're clever you can use the water to your advantage, and swim faster than before.

時間と空間そのものを ゆがませる

In practice, this means sending a rocket into the ergosphere, and making a trade with the black hole:

空間は文字通り 引きずり回され

We give it some mass-energy, and it gives us some of its rotational energy.

新たに超奇妙な時空が 作り出される

But it's not a fair trade, we get the better deal.

ブラックホールを取り囲む 「エルゴ球」である

Normally, if you fire a rocket, you exchange chemical energy for kinetic energy.

事象の地平線の内側では時空が 完全に壊れているとするなら

This is like pushing yourself forward in a swimming pool.

エルゴ球の内側では 半分だけ壊れている

But if you fire a rocket inside the ergosphere, it's like pushing yourself forward in a wave pool.

エルゴ球の内側では 全てのものが意味を失う

The rotational energy of the waves gives you a much stronger boost than you could get just by pushing yourself.

そこに進入して離脱 することも可能だが

The boost from the rotation of the back hole is so big, that you leave the ergosphere with much more energy than you entered it.

たぶん大した経験では ないだろう

The black hole gives a tiny amount of its rotational energy to you, and slows down a little.

回転しないブラックホールに 落ちることは

Obviously, this requires a lot of food.

穴にすべり落ちるようなものだ

Fortunately, black holes aren't picky eaters.

回転するブラックホールの エルゴ球の内側に入るのは

An advanced future civilization would probably harvest asteroids to drop them into the black hole when they needed an energy boost.

排水口に飲み込まれる ようなものだ

But there's an even better way to get energy from a black hole, and oddly enough, it builds the biggest bomb any living thing could ever hope to build:

ブラックホールは自らの 回転エネルギーを

We only need two things to build a black hole bomb: a fast-spinning black hole, and a big mirror.

エルゴ球に進入した 物に受け渡す

The mirror has to completely envelop the black hole,

リング状特異点はあなたを 激しく動かすだろう

...which is similar to a Dyson Sphere, a mega structure that harvests the energy of an entire star.

その場に留まるためには 超光速で動く必要があるが

Although, our mirror would be easier to build.

それは不可能だからだ

Mirrors are simpler, and black holes are much, much more compact than stars.

そこで抜け道である

If we made the mirror 10 centimeters thick, the metal of a big asteroid would probably be enough material for a black hole with the mass of our Sun.

このエネルギーを頂くのだ

Once our mirror is in place, we only need to open a window, and shoot electromagnetic waves at the black hole.

かなりのエネルギーを 取り出せる

You can imagine what happens next, by imagining tossing a ball at a wall, and it coming back faster than a bullet.

怪物からエネルギーを 取り出す方法

The waves hit the black hole at light speed.

天の川銀河の中心にある 超大質量ブラックホールなら

A small proportion of the waves falls past the event horizon to disappear forever.

銀河の個々の星が何十億年もかけて 放出するのと同等のエネルギーを

But a much larger amount sloshes through the ergosphere,

取り出すことができる

...where the black hole forces some of its rotational energy on them, and amplifies them.

いちばん簡単な方法は

They now begin superradiant scattering, which are fancy science words meaning:

なにかをブラックホールに 落とすことだ

"Bouncing around between mirror and black hole and getting stronger."

リング状特異点はエルゴ球に 入ったものにエネルギーを渡す

Every time they go around, they are getting exponentially stronger.

時空がぐるぐる回れば回るほど

By opening some windows in the mirror, we can extract the energy from the waves as fast as they grow.

水を賢く使えば前より 速く泳げるはずだ

Which we could use, in theory, to create what would be for all practical purposes, an endless source of energy for trillions of years.

実際にはロケットを送ってうまく ブラックホールとやりとりして

Or, we could blow it up.

なにがしかの質量エネルギーを与える 見返りとして回転エネルギーをもらう

If the waves are not released, they will continue to get stronger and stronger,

実はこれは等価交換より割がいい

...and take more and more energy from the black hole, until the mirror shatters.

ロケットを飛ばす場合

A supermassive black hole would release as much energy as a supernova,

化学エネルギーを 運動エネルギーに交換する

...making the bomb the largest explosion any living being could ever create.

これはプールで自力で 前進するようなものだ

The beauty of the black hole bomb, the Penrose process, and the super radiant scattering, is that they are not science-fiction.

エルゴ球の中を ロケットで進むのは

In the far far future, this might be the only way to survive in our dying universe.

流れるプールで 前進するようなもので

After all the red dwarfs have cooled down, and all the white dwarfs transformed into black dwarfs, the universe will turn dark forever.

回転エネルギーのぶんだけ 自力で飛ぶより後押しされる

Rotating black holes might be the only sources of energy in the entire universe that life could harvest.

ブラックホールの 回転は強力なので

If so, the last living being in existence might one day end its life around a black hole.

エルゴ球から出る時には かなり加速されている

Which is equally chilling and uplifting.

ブラックホールは微量の 回転エネルギーを失い

It turns out that even without any light, there are places we can go.

回転はごくわずかに 遅くなる

Black holes are as interesting as they are mysterious, but there's actually a surprising amount we do know.

明らかにこれには多くの エサが必要になる

Using math we can calculate things and come up with theories about how we die if we fall into them.

さいわいブラックホールは 何でも食べる

If you're the sort of person who gets excited about maths and calculating these things for yourself,

たぶん進歩した未来の文明は 小惑星を捕獲して

...our friends at Brilliant have put together a fantastic black hole quiz to help you get your head around them.

ブラックホールに 落とすのに使うのかも

Brilliant is a problem-solving website that teaches you to think like a scientist, by guiding you through the problems.

ブラックホールからエネルギーを 取り出すもっといい方法もある

They take concepts like these, break them up into bite-sized pieces, present clear thinking in each part, and then build back up to an interesting conclusion.

生ける者が望みうる 最大の爆弾を作る方法だ

If you visit Brilliant.org/nutshell or click the link in the description, you can sign up for free and learn all kinds of cool stuff.

ブラックホール爆弾

And as a bonus for Kurzgesagt viewers, the first 688 people will also get 20% off their annual membership.

必要なのは2つ:

If you want to truly learn about black holes and support Kurzgesagt, this is one of the best ways to do it.

高速で回転するブラックホールと 大きな鏡だ