字幕表 動画を再生する
-
Is there a border we will never cross?
人が行けない場所はあるか
-
Are there places we will never reach, no matter how hard we try?
頑張っても届かない場所はあるか
-
Turns out there are.
答えは「ある」
-
Even with science fiction technology, we are trapped in our pocket of the Universe.
SF的な技術があっても
-
How can that be? And, how far can we go?
出られない領域がある
-
We live in a quiet arm of the Milky Way; A spiral galaxy of average size,
それはなぜか
-
– about 100,000 light years across –
どこまで行けるのか
-
consisting of billions of stars, gas clouds, dark matter, black holes, neutron stars,
私たちは天の川銀河にいる
-
and planets, with a supermassive black hole in the galactic centre.
直径約10万光年の渦巻き銀河で
-
>From afar, our galaxy seems dense, but in reality, it consists, mostly, of empty space.
ここにたくさんの星 ガス雲
-
With our current technology, sending a human to the closest star, would take thousands of years.
ダークマター ブラックホール
-
So, our galaxy is pretty big.
中性子星 惑星があり
-
The Milky Way is not alone, though.
中心には巨大ブラックホールがある
-
Along with the Andromeda galaxy, and more than fifty dwarf galaxies,
密度が濃く見えるが
-
it's a part of "The Local Group";
実際はほとんどが空の空間だ
-
a region of space about ten million light years in diameter.
現在の技術では近くの星まで
-
It is one of the hundreds of galaxy groups in the "Laniakea Supercluster",
数千年かかる
-
which, itself is only one of millions of superclusters,
それくらい銀河は大きい
-
that make up the observable universe.
銀河は他にもある
-
Now, let's assume, for a moment, that we have a glorious future;
アンドロメダや他の銀河が合わさり
-
humanity becomes a type three civilisation,
局部銀河群となり
-
does not get wiped out by aliens,
その直径は1000万光年
-
and develops interstellar travel based on our current understanding of physics.
ラニアケア超銀河団の中の一つだ
-
In this best case scenario, how far could we possibly go?
これも超銀河団の中の一つで
-
Well; the local group.
それらが宇宙を構成する
-
It's the biggest structure that humanity will ever be a part of.
ここで 輝く未来が来たと仮定しよう
-
While it's certainly huge, the local group accounts for only 0.00000000001 % of
人類はタイプ3の文明となり
-
the observable universe.
宇宙人にも潰されず
-
Let this number sink in for a moment.
現代物理で可能な技術を発展させた
-
We are limited to a hundred billionth of a percent of the observable universe.
この場合 どこまで行けるのか?
-
The simple fact that there is actually a limit for us, and that there is
銀河群の中までだ
-
so much universe that we will never be able to touch, is kind of frightening.
これが人類に支配できる最大領域だ
-
Why can't we go further?
十分広いが これは宇宙全体の
-
Well, it all has to do with the nature of nothing.
0.00000000001%
-
Nothing, or empty space, isn't empty but has energy intrinsic to itself;
でしかない
-
so-called "quantum fluctuations".
想像できるだろうか
-
On the smaller scale, there is constant action, particles and antiparticles
人類が行けるのは
-
appearing and annihilating themselves.
宇宙の10兆分の1に限られている
-
You can imagine this quantum vacuum as a bubbling part:
これが限界ということは
-
with denser, and less dense regions.
宇宙の大きな可能性にも
-
Now, let's go back 13.8 billion years when the fabric of space
触れられないことになる
-
consisted of nothing at all.
なぜそこが限界か
-
Right after the big bang, in an event known as cosmic inflation, the observable universe
それは無の性質と関係している
-
expanded from the size of a marble to trillions of kilometres, in fractions of a second.
空の空間は実際は空ではなく
-
This sudden stretching of the universe was so fast and extreme,
エネルギーを持っている
-
that all those quantum fluctuations were stretched as well,
量子ゆらぎという現象だ
-
and subatomic distances became galactic distances,
小さな世界は常に活動し
-
with dense and less dense regions.
粒子と反粒子が現れては消えている
-
After inflation, gravity began to pull everything back together.
この量子的な真空は 言わば
-
At the largest scale, the expansion was too quick and powerful
密度の偏った泡だ
-
to overcome but in smaller scales, gravity emerged victorious.
ここで 宇宙が真に無だった
-
So, over time, the denser regions, or pockets, of the universe,
138億年前に戻ってみよう
-
grew into groups of galaxies, like the one we live in today.
ビッグバン直後 空間は膨張して
-
Only stuff inside our pocket – The Local Group – is bound to us gravitationally.
宇宙はビー玉大から1兆キロまで
-
But wait, what is the problem then?
一瞬で広がった
-
Why can't we travel from our pocket, to the next one?
この宇宙の膨張が急激だったため
-
Here, dark energy makes everything complicated.
量子ゆらぎも引っ張られ
-
About six billion years ago, dark energy took over.
その密度の偏りが宇宙に反映された
-
It's basically an invisible force or effect, that causes,
濃い所と薄い所ができた
-
and speeds up the expansion of the universe.
膨張後は 重力が物同士を引っ張った
-
We don't know why, or what dark energy is, but we can observe its effect clearly.
大きい規模では膨張力が強かったが
-
In the early universe, there were larger, cold spots around the local group,
小さい規模では重力が勝った
-
that grew into clusters with thousands of galaxies.
そしてその後密度が濃かった所には
-
We are surrounded by a lot of stuff, but none of those structures and galaxies
現在のような銀河群ができあがった
-
outside of the local group are gravitationally bound to us.
集まった銀河群は
-
So the more the universe expands, the larger the distance between
重力によって繋がっている
-
us and other gravitational pockets becomes.
では 何が問題なのか
-
Over time, dark energy will push the rest of the universe away from us,
なぜ別の群に行けないのか
-
causing all the other clusters, galaxies, and groups to eventually become unreachable.
ダークエネルギーが原因だ
-
The next galaxy group is already millions of light years away,
約60億年前 それは始まった
-
but all of them are moving away from us, at speeds we can't, ever, hope to match.
目に見えない力によって
-
We could leave the local group, and then fly through intergalactic space,
膨張が加速を始めたのだ
-
into the darkness, but we would never arrive anywhere.
なぜなのかはわからないが
-
While we will become more and more stranded, the local group will become more tightly bound,
影響は確かにある
-
and merge together to form one giant elliptical galaxy, with the unoriginal name "Milkdromeda"
最初 銀河群の周りには空間があり
-
in a few billion years.
銀河は集団で存在していた
-
But it becomes even more depressing:
周りにもそんな集団があった
-
at some point, the galaxies outside the local group, will be so far away,
しかしそれらの外の銀河団とは
-
that they will be too faint to detect, and the few photons that do make it to us,
重力では繋がらないため
-
will be shifted to such long wavelengths, that they will be undetectable.
宇宙が膨張するほど
-
Once this happens, no information outside of the local group will be able to reach us.
その距離は離れていくことになる
-
The universe will recede from view.
ダークエネルギーはこれを加速させ
-
It will appear to be dark and empty in all directions, forever.
他の銀河群への旅を不可能にする
-
A being born in the far future in Milkdromeda,
数百万光年先の銀河群が
-
will think there is nothing but its own galaxy in the entire universe.
さらに加速的に遠ざかっているのだ
-
When they look far into empty space, they will only see more emptiness and darkness;
銀河群を出て 闇の中までは行けるが
-
they won't be able to see the cosmic background radiation,
辿り着く場所はない
-
and they won't be able to learn about the Big Bang.
一方 時間が経つにつれて
-
They will have no way of knowing what we know today;
銀河群はより密集し
-
the nature of the expanding universe, where it began, and how it will end.
数十億年後 合体して一つの巨大銀河
-
They will think the universe is static and eternal.
ミルクドロメダになる
-
Milkdromeda will be an island in the darkness, slowly getting darker and darker.
別のことも起きる
-
But still, with its trillions of stars, the local group is certainly
他の銀河群は遠く離れていくと
-
large enough for humanity.
見えなくなっていく
-
After all, we still haven't figured out how to leave our solar system,
光子が少なくなり 波長も伸びるため
-
and we have billions of years to explore our galaxy.
見づらくなるのだ
-
We have the incredible luck to exist at the perfect moment in time to see,
やがて外からの情報は届かなくなり
-
not only our future but also our most distant past.
宇宙の景色は変わる
-
As isolated and remote as the local group is, we can perceive the entire universe,
暗くて 何も見えなくなる
-
grand and spectacular as it is right now.
永遠に
-
This video was sponsored by SquareSpace.com/nutshell
将来 ミルクドロメダ人は
-
Do you feel isolated in a humongous universe?
宇宙はこの銀河だけだと思うだろう
-
Why not set up a website or blog and share your thoughts with other
宇宙を見てみても
-
humanoids around you?
何もない暗闇があるだけだ
-
Squarespace lets you do that with easy-to-understand tools
宇宙背景放射もないため
-
very quickly and without any knowledge of web design.
ビッグバンに気づかない
-
You can also use the code "NUTSHELL" to save 10 % and support Kurzgesagt
私たちが知ることを知らない
-
in making more videoes about our place in the universe.
宇宙の膨張も
-
Thanks so much for the help with the video to Ethan Siegel.
始まりも 終わり方も
-
Follow his astronomy blog here.
彼らは宇宙は永遠だと考えるだろう
-
You can support us directly at Patreon or get Kurzgesagt merch here.
そして孤独なミルクドロメダは
-
It really helps.
ゆっくり闇に包まれていく
-
It is awesome that you watched this far, so we have made a playlist for you about more universe stuff.
それでもこの銀河群の星は
-
Subtitles made by Sebastian Winkelmann
人間にとって十分多い
-
Subtitles by the Amara.org community
と言っても 太陽系から出る方法も