The Boltzmann brain paradox - Fabio Pacucci

翻译人员: Yip Yan Yeung 校对人员: Yuwei Wu

How do you know you’re a person who has lived your life,

你该如何得知 你是过着现有人生的一个人，

rather than a just-formed brain full of artificial memories,

还是一个装满人工记忆的 初生大脑，

momentarily hallucinating a reality that doesn't actually exist?

用不存在的现实暂时迷惑着你呢？

That may sound absurd,

听起来可能有些奇怪，

but it’s kept several generations of top cosmologists up at night.

但是这让好几代 顶级宇宙学家彻夜难眠。

They call it the Boltzmann brain paradox.

他们将其称为玻尔兹曼大脑悖论 （Boltzmann Brain Paradox）。

Its namesake, Ludwig Boltzmann, was a 19th century physicist

它的名字源自 一位 19 世纪的物理学家

路德维希·玻尔兹曼 （Ludwig Boltzmann），

operating in a period when scientists were passionately debating

当时，科学家们激烈地讨论着

whether the universe had existed for an infinite or finite time.

宇宙已经存在了无限长的时间， 还是有限长的时间。

Boltzmann’s main claim to fame was revolutionizing thermodynamics,

令玻尔兹曼成名的主要成就是 他为热力学带来了革命性突破，

the branch of physics that studies energy.

热力学是物理学中研究能量的分支。

He put forward a new interpretation of entropy,

他创造了熵的全新阐释，

which is a measure of the disorder of a system.

熵描述了系统的无序程度。

A glass is an ordered system, whereas a shattered glass is disordered.

一块玻璃是一个有序系统， 而一块碎玻璃是一个无序系统。

The second law of thermodynamics states that closed systems tend towards disorder:

热力学第二定律主张 一个孤立系统会向无序状态演变，

you won’t see a shattered glass return to its pristine state.

比如，一块碎玻璃不会回到原状。

Boltzmann’s insight was applying statistical reasoning to this behavior.

玻尔兹曼的发现是 利用统计原理解释这一现象。

He found that a system evolves to a more disordered state because it’s more likely.

他发现之所以说一个系统会逐渐 趋于无序，只是因为可能性更大，

However, the opposite direction isn’t impossible,

然而，逆向也是有可能的，

just so unlikely that we’ll never witness things like scrambled eggs turning raw.

只是可能性微乎其微，所以 我们从未见证过炒蛋变生的情况。

But if the universe exists over an infinitely long time,

但是，如果宇宙已经 存在了无限长的时间，

extremely unlikely events will happen,

极端不可能事件也有可能发生，

including complex things forming out of random combinations of particles.

包括从粒子的随机组合中 形成复杂物体。

So what does that look like in a hypothetical infinitely old universe?

那么在一个假想的无限宇宙中 是什么样的呢？

In this unremarkable stretch of near-nothingness,

在这接近虚无的历史长河中，

about eight octillion atoms randomly come together to form a replica

大约 8 乘 10 的 27 次方个原子 随机组合到一起，形成了一个

of the Thinker made of pasta.

由意面做成的《思想者》复制品。

It instantly dissolves.

然后它瞬间分解了。

Over here, these particles suddenly form something like a brain.

接着，这些粒子突然组成了 一个类似大脑的东西。

It’s filled with false memories of a lifetime up to the present moment,

它盛满了虚假的一生记忆， 直到此时此刻，

when it perceives a video saying these very words,

直到在它消失前接收到这个视频，

before decaying.

说着这些话。

And finally, by random fluctuations, all the particles in the cosmos

再举个例子，宇宙中的 所有粒子随着随机波动

concentrate in a single point,

汇集到一个点，

and an entire new universe spontaneously bursts into existence.

然后一个全新的宇宙 自发地横空出世。

Of those last two, which is more likely?

刚说的两个想法， 哪个更有可能呢？

The brain, by far—

大脑的可能性大得多，

despite all its complexity, it’s a blip compared to an entire universe.

虽然非常复杂，比起 整个宇宙可太微不足道了。

Every one universe produced by random fluctuations has equivalent odds

每一个由随机波动产生的宇宙 有同样的可能性

to heaps upon heaps of insta-brains.

在这些速成大脑上层层堆叠。

So by this reasoning, it seems extremely more likely

因此，非常有可能

that everything you believe to exist is actually a brief illusion,

所有你相信存在的物体 都是一个短暂的幻象，

soon to be extinguished.

稍纵即逝。

Boltzmann didn’t get quite that far in his thinking;

玻尔兹曼在他的想法中 并没有到达这一步，

the brains themselves were introduced by later cosmologists building on his work.

大脑本身的理论由后续宇宙学家 基于他的成果得出。

But they, like just about everyone else,

但是这些宇宙学家们， 就和大多数人一样，

were pretty sure that they themselves weren't just ephemeral brains.

非常确信他们本人 并不只是转瞬即逝的大脑。

So the paradox was: how could they be correct and the universe be eternal?

因此，这个悖论为：如果他们是对的， 宇宙怎么会是永恒的呢？

The resolution is something most take for granted today:

答案是我们如今 默认的一个“事实”：

that our universe has not existed forever,

我们的宇宙不是永恒存在的，

but rather time and space started with a Big Bang.

时间和空间始于宇宙大爆炸。

So that’s the paradox over and done with, right?

悖论就这么被解决了，对吧？

Well, maybe not.

不一定。

In the last century, scientists have found evidence supporting the theory

上个世纪，科学家们 发现了一些证据

of the Big Bang everywhere we look.

处处证明了宇宙大爆炸理论。

Yet while we know that the Big Bang happened,

然而，虽然我们知道 宇宙大爆炸发生了，

no one knows what, if anything, preceded and caused it.

但是无人知晓在它之前发生了什么， 或者由什么导致。

Why did the universe begin in such an extremely ordered, and unlikely, state?

为什么宇宙始于如此 极端有序又不太可能的状态呢？

Is our universe in an unending cycle of creation and collapse?

我们的宇宙是不是处于一个 创造崩塌的循环之中呢？

Or might we be in one of many universes expanding within a multiverse?

我们的宇宙会不会是多元宇宙 正在膨胀的其中之一呢？

In this context, Boltzmann’s paradox has found renewed interest

在这种环境下，当代宇宙学家

对玻尔兹曼悖论产生了新的兴趣。

by contemporary cosmologists.

Some argue that leading models for where the universe came from

有人说，宇宙来源的主流模型

still imply that Boltzmann brains are more likely than human brains,

依旧在说明玻尔兹曼大脑 比人脑更有可能，

suggesting something’s amiss.

说明了有什么东西不对。

Others counter that slight modifications of the cosmological models

有人反对说，对宇宙论 模型的轻微修改

would avoid the problem,

就能避免这个问题，

or that Boltzmann’s brains can’t actually physically form.

或者证明玻尔兹曼大脑 无法从实际上物理存在。

Some researchers even attempted to calculate the probability

有的研究人士甚至试图计算出

of a brain popping out of random quantum fluctuations

从随机量子波动中 产生一个大脑的概率，

long enough to think a single thought.

时间足以思考一个想法。

They got this incredible number

他们得到了 这样一个惊人的数字，

whose denominator is 10 to a number about a septillion times larger

分母为 10，次方为

比宇宙恒星数量大 10 的 24 次方的数字。

than the number of stars in the universe.

The Boltzmann brain paradox, despite its absurdity,

尽管玻尔兹曼大脑悖论 有点离谱，

is useful because it creates a bar that models have to rise to.

但是由于它为模型创造了一个标杆， 还是十分有用的。

If, compared to numbers like this one,

如果参照这个数字，

the current state of the universe is exceedingly unlikely,

宇宙现在的状态 极为不可能出现，

something in the model is almost certainly wrong.

证明这个模型 肯定有地方不对。

Unless you’re the one who is wrong...

除非你就是那个不对的人……