磁性曾被判不可能？自旋给出答案
字幕摘录
| 时间 | 英文 | 中文 |
|---|---|---|
| 0:00 | In the early 1900s, physicists Niels Bohr and Hendrika Johanna van Leeuwen | 1900年代初,物理学家尼尔斯·博尔和亨德丽卡·约翰娜·范·李尤文 |
| 0:07 | separately discovered something shocking. | 发现了一些令人震惊的东西。 |
| 0:10 | According to every known rule of physics, magnetism was impossible. | 根据物理学的每一个已知规则,磁学是不可能的. |
| 0:17 | This finding made no sense. | 这个结论毫无意义。 |
| 0:19 | Humans had relied on magnetic compasses for a thousand years, | 人类依赖磁性指南针已有一千年了 |
| 0:23 | and anyone who'd ever held two magnetized metals | 和曾经持有过两种磁化金属的人 |
| 0:27 | could tell you that some invisible force was acting on them. | 可以告诉你,一些无形的力量 在对他们采取行动。 |
| 0:31 | Bohr和van Leeuwen知道他们错过了什么 | |
| 0:34 | But what? | 但是怎样? |
| 0:36 | By the 1920s, physicists had learned quite a bit about the fundamentals of matter. | 到20世纪20年代,物理学家们已经对物质的基本原理有了相当的了解. |
展开字幕全文（66 条）
| 序号 | 英文 | 中文 |
|---|---|---|
| 1 | In the early 1900s, physicists Niels Bohr and Hendrika Johanna van Leeuwen | 1900年代初,物理学家尼尔斯·博尔和亨德丽卡·约翰娜·范·李尤文 |
| 2 | separately discovered something shocking. | 发现了一些令人震惊的东西。 |
| 3 | According to every known rule of physics, magnetism was impossible. | 根据物理学的每一个已知规则,磁学是不可能的. |
| 4 | This finding made no sense. | 这个结论毫无意义。 |
| 5 | Humans had relied on magnetic compasses for a thousand years, | 人类依赖磁性指南针已有一千年了 |
| 6 | and anyone who'd ever held two magnetized metals | 和曾经持有过两种磁化金属的人 |
| 7 | could tell you that some invisible force was acting on them. | 可以告诉你,一些无形的力量 在对他们采取行动。 |
| 8 | Bohr和van Leeuwen知道他们错过了什么 | |
| 9 | But what? | 但是怎样? |
| 10 | By the 1920s, physicists had learned quite a bit about the fundamentals of matter. | 到20世纪20年代,物理学家们已经对物质的基本原理有了相当的了解. |
| 11 | They knew that every material is made of atoms, | 他们知道每个材料都是由原子组成的, |
| 12 | each comprised of a nucleus containing protons and orbited by electrons. | 每一个由含有质子的核组成,并由电子轨道组成。 |
| 13 | They also knew that both of these particles have a few fundamental properties, | 他们还知道,这两个粒子 有一些基本性质, |
| 14 | including a small amount of mass, an electrical charge, and some amount of magnetism. | 包括少量质量,电荷,以及一定的磁性. |
| 15 | The origin of these intrinsic properties remains an ongoing mystery. | 这些内在属性的起源仍是一个持续存在的谜. |
| 16 | But the result is that every electron and proton is a tiny magnet | 但结果是每个电子和质子都是微小的磁铁 |
| 17 | that works just like their full-size counterparts. | 这就像他们的全尺寸对应。 |
| 18 | Both have invisible magnetic fields that radiate out in closed loops from one end to the other. | 两者都有隐形磁场,在从一端到另一端的闭环中辐射出来. |
| 19 | These magnetic poles are attracted to the dense field lines at the opposite pole of other magnets | 这些磁极被其他磁铁的对角的密集场线所吸引 |
| 20 | and repelled by fields flowing in the opposite direction. | 被相反方向的田地所击退。 |
| 21 | Of course, researchers still had questions. | 当然,研究人员仍然有疑问。 |
| 22 | What determines the direction of these magnetic fields? | 是什么决定了这些磁场的方向? |
| 23 | And if every atom is composed of tiny magnets, why isn't everything magnetic? | 如果每个原子都由微小的磁体组成, 为什么不是所有磁体? |
| 24 | The answers emerged with the birth of quantum mechanics, | 答案随着量子力学的诞生而出现 |
| 25 | a new branch of physics exploring how the laws of nature work differently at the subatomic level. | 探索自然规律如何在亚原子层面 发生不同作用 |
| 26 | In 1926, a pair of Dutch physicists discovered that, in addition to mass, charge, and magnetism, | 1926年,一对荷兰物理学家发现, 除了质量,电荷,和磁性, |
| 27 | particles had another fundamental property – quantum spin. | 粒子有另一个基本属性——量子旋转。 |
| 28 | This is a confusing label because while nothing is actually spinning, | 这是一个令人困惑的标签 因为虽然没有什么是实际上旋转, |
| 29 | spin does refer to a kind of innate direction that influences a particle's behaviour. | 旋转确实是指一种影响粒子行为的固有方向. |
| 30 | And in the 1930s, Nobel Prize laureate John H. van Vleck discovered that this property | 而1930年代,诺贝尔奖获得者约翰·H·范·弗莱克(John H. |
| 31 | held the answer to countless questions about magnetism, including Bohr and van Lewens. | 对无数有关磁性的问题,包括博尔和范勒文斯,都持有答案. |
| 32 | Basically, the direction of a particle's spin determines the direction of its magnetic field. | 基本上,粒子旋转的方向决定了它的磁场方向. |
| 33 | And since electrons have much stronger magnetic fields than protons, | 由于电子磁场比质子强得多, |
| 34 | the direction of their spin determines whether or not something is magnetic. | 他们旋转的方向决定了东西是否具有磁性。 |
| 35 | If enough of a material's electrons spin in the same direction, | 如果一个物质的电子 足够向同一方向旋转, |
| 36 | their many tiny magnetic fields will align, turning the material into a magnet, | 他们的许多微小的磁场会合起来 把材料变成磁铁 |
| 37 | with a field pointing in that direction. | 并有一个球场指向那个方向。 |
| 38 | The more aligned electrons, the stronger the magnet. | 相对应的电子越多,磁力就越强. |
| 39 | On the other hand, if a material is full of electrons with competing spins, | 另一方面,如果一个材料充满了电子,有相互竞争的旋转, |
| 40 | their fields cancel each other out, leaving you with something non-magnetic. | 他们的球场相互抵消 留下一些非磁性的东西 |
| 41 | Most elements have electrons that come in pairs and spin in opposite directions, | 大部分元素都有电子,它们成对地出现,旋转方向相反, |
| 42 | which is why most materials aren't magnetic. | 这也是为什么大多数材料不是磁性。 |
| 43 | But iron, nickel, cobalt, and a few rare metals prefer to leave some of their electrons unpaired. | 但铁,镍,钴,以及少数稀有金属更倾向于留下部分电子未发酵. |
| 44 | This doesn't automatically make them magnetic. | 这不会自动使它们产生磁性. |
| 45 | Just because their electrons are unpaired doesn't mean they always spin in the same direction. | 仅仅因为它们的电子没有被激发,并不意味着它们总是朝同一个方向旋转. |
| 46 | However, they can be nudged into alignment by interacting with neighbouring atoms. | 然而,它们可以通过与相邻原子的相互作用来调整。 |
| 47 | And researchers can kickstart this process by applying a strong magnetic field, | 研究人员可以通过应用强磁场启动这个过程, |
| 48 | or by heating and cooling the material inside a weaker magnetic field. | 或者在较弱的磁场内加热和冷却材料。 |
| 49 | These metals will stay magnets permanently, | 这些金属会永远保持磁性 |
| 50 | unless their electrons are scrambled by intense heat or an extremely strong magnetic field. | 除非它们的电子被强烈的热量或极强的磁场所挤压. |
| 51 | But this magnetization process can make anything magnetic, temporarily. | 但这种磁化过程可以使任何磁性,暂时. |
| 52 | Felix Bloch和Edward Mills Purcell 在1945年利用了这一点, | |
| 53 | when they invented nuclear magnetic resonance spectroscopy. | 他们发明了核磁共振光谱 |
| 54 | This technology uses a strong magnetic field to temporarily align a material's protons, | 这种技术使用强磁场来暂时对齐材料的质子, |
| 55 | then a weaker field to knock specific molecules out of alignment. | 然后是一个较弱的场 将特定分子从对齐中击退 |
| 56 | The machine then tracks the electromagnetic energy expended by the jostled protons as they realign, | 机器跟踪振动质子在调整时 消耗的电磁能 |
| 57 | allowing researchers to map the material's molecular structure. | 允许研究人员绘制材料的分子结构图. |
| 58 | This invention laid the groundwork for MRI machines, | 这个发明为核磁共振机器奠定了基础 |
| 59 | which use a similar approach to magnetise the water in our bodies and map our tissues. | 它们使用类似的方法 磁化我们体内的水 并绘制我们的组织。 |
| 60 | Of course, NMR and MRI are just two of countless modern technologies that rely on magnetism. | 当然,NMR和核磁共振只是依赖磁学的无数现代技术中的两种. |
| 61 | Computer hard drives, electric motors, speakers, wireless communication. | 计算机硬盘,电动机,扬声器,无线通信. |
| 62 | All these inventions prove that not only does magnetism exist, | 所有这些发明都证明 磁性不仅存在, |
| 63 | but studying this phenomenon remains endlessly attractive. | 但研究这一现象仍然无休止地吸引人。 |
| 64 | From new technologies to anti-poverty programs and mapping the way we think, | 从新技术到除贫计划 以及绘制我们的想法, |
| 65 | the research of Nobel Prize laureates has led to incredible breakthroughs. | 诺贝尔奖得主的研究 带来了不可思议的突破 |
| 66 | Learn more with these videos. | 学习更多这些视频。 |
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