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  • 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 pocketThe Local Groupis 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

Is there a border we will never cross?

人が行けない場所はあるか

字幕と単語

動画の操作 ここで「動画」の調整と「字幕」の表示を設定することができます

B2 中上級 日本語 銀河 宇宙 膨張 密度 光年 重力

どこまで行けるのか?人間性の限界 (How Far Can We Go? Limits of Humanity.)

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    mommy に公開 2021 年 01 月 14 日
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