百科知识视频之煎蛋小学堂40 平行世界与多重世界

One of the biggest secrets of physics is that we still don't fundamentally understand what happens when the smallest things interact with big things,that is when quantum mechanics meets our everyday world.

物理学的最大秘密之一便是，我们仍然没有从根本上理解 当极小的物体和大物体相互作用时会发生什么 也就是说，当量子力学和我们的日常生活相遇时，会发生什么。

You've probably heard of the "Schrodinger's Cat"experiment where a particle (in this case a cat)is in a superposition of two states (both dead and alive)at once,until it interacts with the outside world,normally a photon of light that we send in to see what's going on (but it could also just be a random particle that has nothing to do with us).Upon interaction with the outside world,the cat is observed as being either dead,or alive,but not both.

你也许听说过“薛定谔的猫”的实验。一个粒子(在这个实验中是一只猫) 同时处于两种状态的叠加(即死又活)中，直到它 与外界相互作用，通常是我们为了探清内部情况发送的一束光子 有可能是一个与我们没有任何关系的随机粒子。在与外界 相互作用之后，人们认为这只猫或活或死，但非即死又活的状态 .

The problem is,physics can't explain how the cat,or particle,goes from being in a combination of two states at once to being in "just one",or "just the other";nor do we know how the "decision"is made.This isn't just a problem with cats,either,It plagues every single quantum mechanics experiment,famous or otherwise,from the double slit experiment and quantum teleportation to the Stern-Gerlach experiment and tests of the Bell inequalities.In every case,we can predict how likely it is for a particle to be in one state or another,but have no clue how it actually ends up that way,That's where the many-worlds picture of quantum mechanics comes in-basically,"many-worlds"proposes the idea that the quantum system doesn't actually decide-rather,at every junction where large everyday stuff interacts with a quantum system,the timeline of history splits and both possibilites happen on different,alternate branches,You know,a choose-your-own-adventure where every possible story happens.

问题是，物理学不能解释猫，或者粒子是如何 怎么从两种状态的叠加一下子变为 一种状态，或另一种，我们亦无从得知这样的“决定”是怎么做出的 这也不只是猫的问题，它困扰着每一个量子力学实验 无论实验是否知名，从双缝，干涉实验，量子隐形传送实验 到斯特恩-盖拉赫实验，贝尔不等式的检验。在每一种情况下，我们 都能预测粒子在不同状态下的可能性，但无法知道 它实际上是怎么达到这个状态的。量子力学的多重世界的图景就是这么 被引入的。基本上说，“多重世界”推崇的是量子系统 并不做出最终的“决定”，相反，在每个交汇处 当生活中常见的大物体和量子系统相互作用时，历史的时间轴 分成两半，事物的两种可能性发生于 两个不同的，相互间隔的分支。就是在一个什么都有可能 发生的故事里选择自己的命运。

In this scenario,we'd think that only one possibility happened because we'd be stuck on one of the branches,in a version of ourselves that only sees one possibility happen.In some ways,this sounds pretty fishy,I mean,it's hard to test the reality of a universe that hides its true nature from us by not allowing us to test or observe its true nature.But anyway,in the many-worlds picture of quantum mechanics,"branch-points"are predicted to happen all the time,everywhere.Pretty much any time subatomic particles interact with each other,or with anything else,anywhere in the universe,there are multiple possible outcomes.Which means a LOT of branching of history.There may even be infinitely many branches.

在这种情况下，我们 认为只有一种情况发生了，因为 我们最终停在了一个分支上，也就是说我们仅仅看到一种可能性 成为现实。这似乎听上去有些不对劲。我的意思是，想要考证 一个不容我们考证或者观察其本质的宇宙的真实面貌 的确很难。但不论如何，在量子力学的多重世界图景中，“分支点”一直在产生，无论任何时间或任何地点。正如 亚原子粒子在宇宙中任何地点与任何一个亚原子或者其他物质 相互作用时，会产生多种可能的结果。这对于历史“分支”来说 意义重大。这种分支的数量可能有无穷多。

So is the Many Worlds hypothesis true?We don't know -it hasn't yet been tested experimentally.There's a bit of mathematics that supports it,and there are also a number of mathematical models that don't require such an extravagantly big & complex picture of the universe,But luckily,physics is science,not speculation,and eventually,someone,maybe even you,will perform an experiment that helps us discover the truth.

所以“多重世界”假说是真的么 我们并不知道尚无实验对其作出证明。有很多数学公式支持它存在。同时，也有许多数学模型 并不支持如此挥霍无度而又复杂的 宇宙图景。幸运的是，物理是一门科学而非投机活动，最终 会有人，甚至可能是你能够设计出一个实验来帮助我们 探索出真相。