字幕表 動画を再生する
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Whoa, dude.
翻訳: Satoshi Tatsuhara 校正: Lily Yichen Shi
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(Laughter)
おぉすごいな! このすごい方程式を見て いいねぇ
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Check out those killer equations. Sweet.
今から18分 できる限り式を使わず
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Actually, for the next 18 minutes I'm going to do the best I can
素粒子物理の美を説明します
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to describe the beauty of particle physics without equations.
サンゴは 学ぶ所が多く
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It turns out there's a lot we can learn from coral.
とても美しい 特異な生物です
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A coral is a very beautiful and unusual animal.
サンゴの突起は 無数のポリプの集合体です
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Each coral head consists of thousands of individual polyps.
ポリプは出芽と分岐を繰り返し
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These polyps are continually budding and branching
同じ遺伝子をもつ複製を作ります
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into genetically identical neighbors.
これを高知能なサンゴだとして
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If we imagine this to be a hyperintelligent coral,
個体を一つ選んで 気になる質問をしましょう
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we can single out an individual and ask him a reasonable question.
みんなと違って ちょうどその位置にいるのは
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We can ask how exactly he got to be in this particular location
なぜ?
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compared to his neighbors --
単なる偶然? 運命か何か?
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if it was just chance, or destiny, or what?
ポリプは 温暖化に苦言を呈してから
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Now, after admonishing us for turning the temperature up too high,
ばかな質問だと言うでしょう
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he would tell us that our question was completely stupid.
サンゴは意地悪になるんです
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These corals can be kind of mean, you see,
私もサーフィンで傷を負いました
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and I have surfing scars to prove that.
ポリプは続けます
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But this polyp would continue and tell us
「隣のポリプは 私の完全な複製物だ 私は
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that his neighbors were quite clearly identical copies of him.
すべての場所に
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That he was in all these other locations as well,
同時に存在し それぞれを体験する」
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but experiencing them as separate individuals.
サンゴにとって 多くの複製に分岐することは
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For a coral, branching into different copies
当然なので
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is the most natural thing in the world.
人類とは違い 高知能なサンゴらしく 量子力学を
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Unlike us, a hyperintelligent coral
理解します
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would be uniquely prepared to understand quantum mechanics.
量子力学の数学で 宇宙の仕組みが
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The mathematics of quantum mechanics
正確に表現され
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very accurately describes how our universe works.
現実が多くの可能性に分岐し続けることがわかります
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And it tells us our reality is continually branching into different possibilities,
まさにサンゴのようです
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just like a coral.
人類がこれを理解しがたいのは
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It's a weird thing for us humans to wrap our minds around,
一つの可能性しか経験しないからです
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since we only ever get to experience one possibility.
量子力学の奇妙さを示したのは
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This quantum weirdness was first described
シュレーディンガーの猫が最初です
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by Erwin Schrödinger and his cat.
猫なら
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The cat likes this version better.
こっちのほうが好きでしょう(笑)
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(Laughter)
放射性物質とシュレーディンガーが 箱に入っています
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In this setup, Schrödinger is in a box with a radioactive sample
量子力学の法則によれば 試料から
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that, by the laws of quantum mechanics, branches into a state
放射線が出る状態と
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in which it is radiated and a state in which it is not.
出ない状態に分岐します(笑)
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(Laughter)
放射した方では
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In the branch in which the sample radiates,
毒が放出されて シュレーディンガーは死んでいますが
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it sets off a trigger that releases poison and Schrödinger is dead.
他方の現実では生きたままです
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But in the other branch of reality, he remains alive.
二つの現実は 各シュレーディンガーが別々に経験します
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These realities are experienced separately by each individual.
各世界に 相手の世界は存在しません
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As far as either can tell, the other one doesn't exist.
人は一つの現実しか経験できず
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This seems weird to us,
別の現実を見られないので
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because each of us only experiences an individual existence,
奇妙に感じます
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and we don't get to see other branches.
シュレーディンガーと同様 私たちはサンゴのように
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It's as if each of us, like Schrödinger here,
多くの可能性に分岐します
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are a kind of coral branching into different possibilities.
量子力学の数学でわかるように
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The mathematics of quantum mechanics tells us
これが微小世界の仕組みです
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this is how the world works at tiny scales.
一言でいうと
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It can be summed up in a single sentence:
「起こりうる全てが起こる」
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Everything that can happen, does.
これが量子力学です
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That's quantum mechanics.
でも 全て起こるわけではありません
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But this does not mean everything happens.
ほかの物理学は 起こる事と起こらない事を
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The rest of physics is about describing what can happen and what can't.
示します
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What physics tells us is that everything comes down to geometry
物理学が示すのは 素粒子の相互作用と幾何学に
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and the interactions of elementary particles.
すべて行き着くということです
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And things can happen only if these interactions are perfectly balanced.
何かが起こるのは 相互作用が完全に平衡な場合
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Now I'll go ahead and describe how we know about these particles,
だけです
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what they are and how this balance works.
その粒子を知る方法 その実体
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In this machine, a beam of protons and antiprotons
平衡がどう作用するのか説明します
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are accelerated to near the speed of light
この装置では 陽子と反陽子のビームが
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and brought together in a collision, producing a burst of pure energy.
光速近くまで加速して衝突し
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This energy is immediately converted into a spray of subatomic particles,
一体化して 混じりけのないエネルギーが放射されて
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with detectors and computers used to figure out their properties.
原子より小さな粒子の放射に
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This enormous machine --
変換され
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the Large Hadron Collider at CERN in Geneva --
検出器とコンピュータで解析されます
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has a circumference of 17 miles and, when it's operating,
この巨大な加速器LHCは
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draws five times as much power as the city of Monterey.
ジュネーブのCERNにあり
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We can't predict specifically
一周27km
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what particles will be produced in any individual collision.
稼働時にはモントレー市の
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Quantum mechanics tells us all possibilities are realized.
5倍の電力を消費します
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But physics does tell us what particles can be produced.
衝突ごとに どの粒子が生まれるかは
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These particles must have just as much mass and energy
予測できません
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as is carried in by the proton and antiproton.
量子力学は すべての可能性が
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Any particles more massive than this energy limit aren't produced,
実在するといい 物理学は生成可能な粒子を示します
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and remain invisible to us.
生成された粒子のエネルギーは必ず
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This is why this new particle accelerator is so exciting.
陽子と反陽子が運ぶエネルギーに等しく
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It's going to push this energy limit seven times
このエネルギー限界を超える粒子は
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beyond what's ever been done before,
生まれず 目にできません
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so we're going to get to see some new particles very soon.
この新型加速器がすごいのは そこです
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But before talking about what we might see,
エネルギー限界が従来より7倍
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let me describe the particles we already know of.
高いのです
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There's a whole zoo of subatomic particles.
新しい素粒子はすぐ見つかります
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Most of us are familiar with electrons.
予測する前に
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A lot of people in this room make a good living pushing them around.
既知の素粒子について説明します
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(Laughter)
いわゆる「素粒子動物園」です
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But the electron also has a neutral partner called the neutrino,
電子は身近ですね
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with no electric charge and a very tiny mass.
みなさんは
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In contrast, the up and down quarks have very large masses,
これを使って
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and combine in threes to make the protons and neutrons inside atoms.
いい暮らしをしています(笑)
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All of these matter particles come in left- and right-handed varieties,
電子には中性の仲間がいます
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and have antiparticle partners that carry opposite charges.
無電荷で質量がとても小さいニュートリノです
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These familiar particles
アップクォークとダウンクォークは 質量が膨大で
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also have less familiar second and third generations,
三つで 陽子と中性子を作ります
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which have the same charges as the first but have much higher masses.
物質の素粒子には
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These matter particles all interact with the various force particles.
右回りと左回りがあり
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The electromagnetic force interacts with electrically charged matter
逆の電荷をもった反粒子が相棒です
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via particles called photons.
身近な素粒子には
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There is also a very weak force
聞き慣れない第2 第3世代があります 第1世代と電荷は同じですが
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called, rather unimaginatively, the weak force ...
質量ははるかに大きいものです
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(Laughter)
物質の素粒子は 力の素粒子と相互作用します
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that interacts only with left-handed matter.
「電磁力」は 電荷をもつ物質と相互作用します
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The strong force acts between quarks
光子という素粒子が媒介します
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which carry a different kind of charge, called color charge,
非常に弱い力もあります
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and come in three different varieties: red, green and blue.
安直に「弱い力」と呼ばれていて
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You can blame Murray Gell-Mann for these names -- they're his fault.
左回りの物質とだけ相互作用します
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Finally, there's the force of gravity,
「強い力」は クォークに働きます
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which interacts with matter via its mass and spin.
クオークは 色荷というチャージをもち
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The most important thing to understand here
色荷には 赤 緑 青の3種があります
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is that there's a different kind of charge associated with each of these forces.
この命名はマリー・ゲルマンの
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These four different forces interact with matter
あやまちです
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according to the corresponding charges that each particle has.
最後は「重力」です 質量とスピンを介して
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A particle that hasn't been seen yet, but we're pretty sure exists,
物質と相互作用します
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is the Higgs particle, which gives masses to all these other particles.
一番重要なのは 力ごとに
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The main purpose of the Large Hadron Collider
別のチャージが対応する
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is to see this Higgs particle, and we're almost certain it will.
ということです
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But the greatest mystery is what else we might see.
4種の力は その力に対応した
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And I'm going to show you one beautiful possibility
各素粒子のチャージに応じて 物質と作用します
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towards the end of this talk.
未発見ながら確実に存在するのが
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Now, if we count up all these different particles
ヒッグス粒子です 他の素粒子に質量を与えます
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using their various spins and charges,
LHCの主目的は
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there are 226.
ヒッグス粒子の発見です ほぼ確実ですが
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That's a lot of particles to keep track of.
ほかに何を発見できるかが 最大の神秘です
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And it seems strange
ここからは すごい可能性を一つ
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that nature would have so many elementary particles.
お話しします
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But if we plot them out according to their charges,
素粒子を
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some beautiful patterns emerge.
スピンやチャージを考慮して数え上げると226個です
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The most familiar charge is electric charge.
多いのです
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Electrons have an electric charge,
自然界にそれほど多種の素粒子が
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a negative one,
あるのは奇妙にも思えますが
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and quarks have electric charges in thirds.
チャージに基づいて描画すると
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So when two up quarks and a down quark are combined to make a proton,
美しいパターンが現れます
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it has a total electric charge of plus one.
一番身近なのは電荷ですね
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These particles also have antiparticles, which have opposite charges.
電子の電荷はマイナス1
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Now, it turns out the electric charge
クォークの電荷は1/3の倍数
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is actually a combination of two other charges:
アップクォーク二つと ダウンクォーク一つで
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hypercharge and weak charge.
陽子を作ります 電荷の合計はプラス1です
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If we spread out the hypercharge and weak charge
素粒子には 逆の電荷をもつ反粒子が存在します
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and plot the charges of particles in this two-dimensional charge space,
電荷は
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the electric charge is where these particles sit
別の二つのチャージの組み合わせです
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along the vertical direction.
ハイパーチャージとウィークチャージです
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The electromagnetic and weak forces interact with matter
2次元チャージ空間に
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according to their hypercharge and weak charge,
ハイパーチャージとウィークチャージを展開して 各粒子のチャージをプロットすると
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which make this pattern.
電荷は
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This is called the unified electroweak model,
縦方向に示されます
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and it was put together back in 1967.
ハイパーチャージとウィークチャージに基づいて
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The reason most of us are only familiar with electric charge
電磁力と弱い力が物質と
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and not both of these is because of the Higgs particle.
相互作用します
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The Higgs, over here on the left, has a large mass
これは
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and breaks the symmetry of this electroweak pattern.
1967年に統一された電弱統一モデルです
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It makes the weak force very weak by giving the weak particles a large mass.
身近なのは電荷だけで
-
Since this massive Higgs sits along the horizontal direction in this diagram,
両方ではないのは ヒッグス粒子が原因です
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the photons of electromagnetism remain massless
左側にあるヒッグスは質量が大きくて
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and interact with electric charge along the vertical direction
電弱パターンの対称性を破ります
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in this charge space.
弱い素粒子の
-
So the electromagnetic and weak forces
質量を大きくし 弱い力を弱めます
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are described by this pattern of particle charges
大質量のヒッグスが図の横方向に位置しているので
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in two-dimensional space.
電磁力を担う光子は質量をもたずに チャージ空間の縦方向で
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We can include the strong force by spreading out its two charge directions
電荷と相互作用を
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and plotting the charges of the force particles in quarks
します
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along these directions.
電磁力と弱い力は 2次元空間で
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The charges of all known particles
素粒子のチャージのパターンとして示されます
-
can be plotted in a four-dimensional charge space,
強い力を2チャージ方向に展開して
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and projected down to two dimensions like this so we can see them.
クォークに働く力の素粒子のチャージを描くと
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Whenever particles interact, nature keeps things in a perfect balance
強い力を導入することができます
-
along all four of these charge directions.
既知のすべての素粒子の
-
If a particle and an antiparticle collide,
チャージを 4次元チャージ空間に描画して
-
it creates a burst of energy and a total charge of zero
2次元に投影できます
-
in all four charge directions.
素粒子が相互作用するとき 4チャージ方向で
-
At this point, anything can be created
完全に平衡が保たれます
-
as long as it has the same energy and maintains a total charge of zero.
粒子と反粒子が衝突すると エネルギーが放出されて
-
For example, this weak force particle and its antiparticle
全4チャージ方向でチャージの和がゼロになります
-
can be created in a collision.
エネルギーが同じで チャージの和がゼロであれば
-
In further interactions, the charges must always balance.
何でも作れます
-
One of the weak particles could decay into an electron and an antineutrino,
例えば この弱い力の粒子と反粒子は
-
and these three still add to zero total charge.
衝突で生まれます
-
Nature always keeps a perfect balance.
さらに相互作用しても チャージは常に平衡します
-
So these patterns of charges are not just pretty.
弱い力は 電子と反電子ニュートリノに
-
They tell us what interactions are allowed to happen.
崩壊しますが
-
And we can rotate this charge space in four dimensions
三つのチャージの和はゼロのままです
-
to get a better look at the strong interaction,
いつも完全に平衡が保たれます
-
which has this nice hexagonal symmetry.
チャージパターンは綺麗なだけでなく
-
In a strong interaction, a strong force particle,
どんな相互作用が発生し得るかを読み取れます
-
such as this one,
4次元でこのチャージ空間を回転させれば
-
interacts with a colored quark, such as this green one,
強い相互作用を見られます
-
to give a quark with a different color charge -- this red one.
六角形状に対称です
-
And strong interactions are happening millions of times
強い相互作用では 例えばこの強い力の素粒子が
-
each second in every atom of our bodies,
例えばこの緑のカラークォークと相互作用して
-
holding the atomic nuclei together.
別の色荷をもつ この赤いクォークとなります
-
But these four charges corresponding to three forces
体中の原子では 毎秒
-
are not the end of the story.
強い相互作用が 無数に発生して
-
We can also include two more charges corresponding to the gravitational force.
原子核を一体に保っています
-
When we include these,
3種の力に対応した4種のチャージだけでは
-
each matter particle has two different spin charges,
終わりません
-
spin-up and spin-down.
重力に対応した
-
So they all split and give a nice pattern in six-dimensional charge space.
2チャージも導入できます
-
We can rotate this pattern in six dimensions
このとき 物質の素粒子は それぞれ
-
and see that it's quite pretty.
上下二つのスピンチャージをもちます
-
Right now, this pattern matches our best current knowledge
6次元チャージ空間にすべて分かれて
-
of how nature is built at the tiny scales of these elementary particles.
きれいなパターンを描きます
-
This is what we know for certain.
6次元でパターンを回転させると
-
Some of these particles are at the very limit
かなり綺麗になります
-
of what we've been able to reach with experiments.
素粒子レベルの微小スケールで自然の仕組みを示す最有力の思想と
-
From this pattern
これが一致
-
we already know the particle physics of these tiny scales --
しています
-
the way the universe works at these tiny scales is very beautiful.
確かに一致しています
-
But now I'm going to discuss some new and old ideas
いくつかの素粒子で
-
about things we don't know yet.
すでに装置限界に達しています
-
We want to expand this pattern using mathematics alone,
微小スケールでの素粒子物理は
-
and see if we can get our hands on the whole enchilada.
このパターンから明らかとなりました
-
We want to find all the particles and forces
微小スケールの宇宙の仕組みは とても美しいのです
-
that make a complete picture of our universe.
未知の世界について 新旧交えて
-
And we want to use this picture to predict new particles
お話しします
-
that we'll see when experiments reach higher energies.
数学だけを使い パターンを拡張して
-
So there's an old idea in particle physics
全体像をつかめるか試します
-
that this known pattern of charges,
宇宙を完璧に描く 素粒子と力を
-
which is not very symmetric,
すべて見つけたいのです
-
could emerge from a more perfect pattern that gets broken --
もっと高エネルギーの実験で見つかる
-
similar to how the Higgs particle breaks the electroweak pattern
新しい素粒子を予測したいのです
-
to give electromagnetism.
素粒子物理学には昔から
-
In order to do this, we need to introduce new forces
対称性に欠ける この既知のチャージパターンは
-
with new charge directions.
完璧なパターンが崩壊して生まれたという考えがあります
-
When we introduce a new direction,
ヒッグス粒子が電弱パターンを破って
-
we get to guess what charges the particles have along this direction,
電磁力を生むのと
-
and then we can rotate it in with the others.
似ています そのためには 新しい力とチャージ方向を
-
If we guess wisely, we can construct the standard charges
導入する必要があります
-
in six charge dimensions as a broken symmetry
新しいチャージ方向を導入すれば
-
of this more perfect pattern in seven charge dimensions.
素粒子のチャージが明らかになり ほかと一緒に
-
This particular choice corresponds to a grand unified theory
回転可能になります
-
introduced by Pati and Salam in 1973.
上手くやれば6チャージ次元の標準的なチャージが
-
When we look at this new unified pattern,
もっと綺麗な7チャージ次元パターンの対称性を