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时空难道只是个幻想? – 译学馆
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时空难道只是个幻想?

Are Space and Time An Illusion? | Space Time | PBS Digital Studios

[序曲音乐]
[INTRO MUSIC]
今天的内容是关于
Today’s episode is about
空间
space,
时间
time,
与现实的本质
and the nature of reality.
我是戴夫
My name is Dave,
这次是真正的“时空”
and this time, it really is ‘Space Time.’
[主题音乐]
[THEME MUSIC]
如果你用心的话 这一集
If you pay attention,this episode
将会颠覆你的观念
is going to blow your mind,
所以 我们会慢慢来
so we’re going to take it slow.
时空究竟是什么
What is spacetime, exactly?
在我回答这个问题之前
Before I can answer that,
我需要大家为我做些事情
I need you to do something for me.
抛弃你对时间和空间
Give up your intuitions about
是如何运转的直觉认知
how time and space work.
首先 你的大脑也许会抗拒
At first, your brain might resist and
会拼命地紧紧抓住那些直觉不放
hold onto those intuitions for dear life.
别担心啦
Don’t worry.
这是正常的
That’s normal.
这对每一个人来说都是挑战
This is challenging for everyone,
就算是爱因斯坦
even Einstein.
准备好了吗
Ready?
好的
OK.
时空就是
Spacetime refers to
构成我们对事物之间的空间和事件之间的时间的
whatever external reality underlies our collective experiences of the space
认知集合的任何外界现实
between things and the time between events.
为什么时间和空间不能单独成为实体?
Why can’t space and time just be a reality?
为什么要增加时空这一额外的概念
Why add spacetime as an extra concept?
我来告诉你原因
Here’s why.
假设有两个观察者在做相对运动 粒子作为观察者
Suppose two observers are moving relative to each other, and particles count as observers.
事实是——两个观测者就事件发生所经历的时间会产生分歧
Fact– those observers don’t agree about how much time passes between events.
同样 他们也不会就给定任意时刻事物之间的空间完全达成一致
Fact– they don’t fully agree on how much space there is between things at any given moment.
并且 他们甚至不会对所有事件发生的先后顺序取得一致意见
Fact– they don’t even agree on the chronological order of all events.
然而 每个观察者
And yet, each observer
都是合理度量的
measures things properly
与观测事实是完全相符的
and is entirely consistent,
这也就意味着没有一个人是错的
which means neither of them is wrong.
虽然听起来很荒谬
Now that sounds absurd,
但这的确是事实
but it’s true.
大量其他人力物力 其中一些我们链接到了描述中
Plenty of other resources, some of which we link to in the description
讨论了这些差异和差异的实验证据
discuss these discrepancies and the experimental evidence for them.
今天啊
For today,
我们仅从表观价值来看待时空
we’ll just take them at face value
并集中关注
and focus on
时空对于自然现实究竟意味着什么
what they imply about the natural reality
因为如果你认真思考
Because if you think about it,
其中的意义是令人难以置信的
some of the implications are staggering.
比如说事件发生时间的顺序的分歧
Take this disagreement about sequence of events, for instance.
这个问题很严峻
It is severe.
如果两个观测者连事件发生的顺序都不能达成一致
If two observers can’t agree on the sequence of events,
也就意味着当前
it means that at present,
有些人的过去在其他人的未来
someone’s past is in someone else’s future.
由于对非常临近的事件来说 这种影响微乎其微
Now for nearby events, the effect is microscopic,
但是那又怎样
but so what?
任何不一致都意味着
Any disagreement means that
对将事件划分为过去 现在和将来
there is no universal division
没有统一的标准
of events into past, present, and future,
这将接二连三地引起关于事物的哲学的大麻烦
which opens major philosophical cans of worms for things
比如自由意志以及我们能够改变未来这样的信念
like free will and our belief that we can change the future.
所以每个人对宇宙的感受
So is everyone’s experience
是完全主观的吗?
of the universe entirely subjective?
或换种说法
Or phrased another way,
如果我们通常想象的时间和空间
if time and space as we usually conceive of them
不是客观现实的一部分
aren’t part of objective reality,
那么 它们是什么?
then what is?
个中缘由
Causality.
由我来解释
Let me explain.
客观现实的一个重要出发点是
A good starting point for objective reality
它在宇宙中任意处都是一致的
is universal agreement.
如果幸运的话
And as luck would have it,
所有的观测者都将对此达成一致
all observers do agree about this thing.
这被称作时空间隙
It’s called the spacetime interval,
或两个事件的时空间隔
or spacetime separation between two events.
即使在相对运动中 两个观测者会测出不同的距离
Even though two observers in relative motion will measure different distances
并在相同的两个事件之间测出不一样的历时
and different elapsed times between the same two events,
他们总会对两个事件的时空间隔达成一致
they always agree about the spacetime interval between those events.
现在 如果每个人都对时空间隔达成一致
Now if everyone agrees about spacetime intervals,
他们必定意味着什么
they must signify something.
但是是什么?
But what?
我们注意到
We’ll notice that
既然其中涉及到了差值
since it involves subtraction,
一个时空间隔可以是正数 零 或是负数
a spacetime interval can be positive, zero, or negative.
当它为正数时
When it’s positive,
两个事件毫无关联
nothing can get from one event to the other,
观测者永远不会对哪个事件先发生达成一致
and there are always observers who disagree about which one happens first.
当它为零或负数时
When it’s zero or negative,
信号或事物可以在两个事件中传递
signals or things can get from one event to the other
所有人都同意它们的发生次序
and everyone agrees on their sequence.
所以看上去好像
So it appears
甲乙两个事件的时空间隔
that the spacetime interval between events A and B
告诉你甲事件能否影响乙事件
tells you whether A can influence B.
换句话说
In other words,
即使我们不能就过去 现在 未来 时间或距离达成一致
even though we can’t agree about past, present, future, time,or distance,
我们也似乎都同意它们的因果关系
we all appear to agree about causality.
这似乎是违反直觉的
Now that may seem counterintuitive.
通常我们认为时间决定因果关系
Normally we think that time is responsible for causality.
但实际上是相反的
But actually it’s the other way around.
就我们对当前的事物取得相同看法来说
To the extent that we agree about temporal anything,
这仅仅是因为因果关系
it’s only because of causality.
因果关系是真实的
Causality is what’s real.
所以因果关系和时空有什么联系呢?
So what does causality have to do with spacetime?
正如它所呈现出来的的 休戚相关
As it turns out, everything.
看 在相对论问世不久以后
See, shortly after relativity first came out,
爱因斯坦的前任数学教授 赫尔曼·闵可夫斯基注意到
a former math professor of Einstein’s named Hermann Minkowski noticed that
时空间隔像是非欧几里得空间距离公式的一个怪异变式
the spacetime interval resembles a weird version of a distance formula in what’s called a non-Euclidean space.
所以他提出了如下的激进观点
So he proposed the following radical idea–
现实或许并不是一个在时间中发生着的三维空间
maybe reality is not a three dimensional space that evolves in time.
而是
Instead,
一个四维的非欧几里得的数学空间
it’s a four dimensional non-Euclidean mathematical space that’s just there.
没有进化论
No evolution.
没有时间
No time.
数学意义上的四维空间就是时空
That 4D mathematical space is spacetime.
空间中的点相当于事件
Its points correspond to events.
整个空间包含着从始至终的所有事件
All events, everywhere, ever.
而且这样看来
And in this view,
只有符合四维空间的几何关系的事物
only things that correspond to geometric relations in that 4D space
才是客观实在的
are objectively real,
比如说 因果关系
like for instance, causal relations.
它们相当于时空间隔
They correspond to spacetime intervals,
是几何关系
which are geometric relations,
点点之间的非欧几里得的距离
a non-Euclidean version of the distances between points.
相比较
In contrast,
我们的经验 对时间和空间的测量
our experiences and measurements of time and space
不代表什么 而只是它本身
don’t correspond to anything, per se.
它们更像是数学课上的坐标系
They’re more like the XY grid we use in math class,
在黑板上谈论时是有用的 但任意性强
useful for talking about the board, but arbitrary
并且固有地缺乏意义
and inherently meaningless.
黑板上的点和几何事实
The board, its points and geometric facts,
就在那儿 无论我们是否在上面画坐标轴
are simply there whether we put axis on that board or not.
那么 你是客观现实的吗?
So are you objectively real?
好的 有几分是
Well, kind of.
如果你是所有
If you are the sequence of all the events
你在场的事件的关联 那么
of which you were present, then you
你是一个时空中的几何物体 一条线段
are a geometric object in spacetime, a line segment
将代表你的出生与死亡的两个事件的点
joining the points representing the events
连接到一起
of your birth and your death.
你在那条线段上移动吗?
Do you move along that line segment?
并不是这样
No, no.
你就是那条线段
You are the line segment.
时空间是静止的
There’s no motion through spacetime.
跟我们所在的空间不太一样
It’s not this kind of space.
它没有时态
It’s tense-less.
你的未来不仅仅是先决的
And your future isn’t merely predetermined.
它已经存在着
It already exists.
有些禅宗试着去在不误导你的前提下
There’s some zen in trying to express what spacetime
表达和解释什么是时空 但是我认为接下来的表述
is without misleading you, but I think the following
抓住了关键特点
gets the flavor right.
想象一下我们都在读一本由方格纸组成的数码翻页电子书
Imagine we’re are all reading a flip book made of graph paper.
对于书中都讲了哪些故事 我们达成了一致
We agree on the events of the story,
但我们没有达成共识的是这些故事具体写在书中的哪一页上
but we don’t agree where they happen
以及事件与事件之间有多少页
on the page, on how many pages there
甚至对于一些事件发生的顺序
are between events, or even on the order of some
我们也没有一致的答案
of those events.
但是 我们读的是同一本书
And yet, we’re all reading the same book,
只是纸上没有图 没有页
only there’s no graph on the paper, there are no pages,
也没有这么一本书
and there is no book.
所有这些只是我们大脑做出的联想
All of that is just an imposition
为的是理解它到底是什么
our brains make in order to perceive whatever ‘it’ is.
我们为什么要通过这种生动的时间与空间的方式
So why do we perceive reality in such a vividly spatial
理解现实呢?
and temporal way?
问的好
Good question.
没有人能给出确切的答案
No one really knows.
我是否已经把所有有关时空的都告诉你了呢?
So have I told you all there is to know about spacetime?
没有 这只是冰山一角
No, far from it.
所有这一切都只是对所谓的平直时空的
All of this has just been a loose introduction to what’s
一个不太严谨的介绍
called a flat spacetime.
一旦与广义相对论扯上关系
Once general relativity entered the mix,
我们就会发现还有许多拥有不同几何形状的
we’ll find that there are many possible spacetimes
可能的时空 这就使得它很难确定
with different geometries, making it hard to ascertain
到底哪一个才是
which one this is.
但是我们要一步步地慢慢来
But we got to crawl before we walk.
我相信最终我们会得到有趣的结果的
We will get to that fun stuff eventually though,
赶快订阅吧
so subscribe.
和往常一样 在评论区写下你的问题
And as always, the comments are for your questions.
我会尽最大努力在下一次的时空因果连接点处
I’ll do my best to answer them at the next causally-connected
回答它们
point of spacetime.
上一周 我们提出的问题是NASA是否可以
Last week, we asked whether NASA could
引发僵尸大灾变
start a zombie apocalypse.
你们和往常一样都有很多话要说
You guys, as usual, had a lot to say.
Daniel Jenkins 评论说到太空僵尸爆发
Daniel Jenkins commented that a space-based zombie outbreak
说明一种更致命的生物体
assumes that a more virulent organism would actually
更迅速地传播了开来
spread better.
首先 这个假设是不必要的
First of all, that assumption is unnecessary.
对病菌来说 变得更加有害
It’s enough for the bug to just be more harmful
以及更有力地对抗你的空间有限的免疫系统绰绰有余
and harder fight off with your space-depressed immune system.
第二 正如Nicholas Garrison 指出的那样
But second, as Nicholas Garrison pointed out,
细菌就更容易在空间胶囊内传播
germs do spread more easily space capsules
由于一系列的原因
for a variety of reasons, including
其中包括你打的喷嚏和咳嗽
the fact that the gunk in sneezes and coughs
不会落下去而是留在原地
just hangs there instead of falling.
真够恶心的
Pretty nasty.
Joe G.P.和Dikasad2都问到了
Joe G.P. and Dikasad2 both asked what
太空中造成毒性增强的原因是什么呢?
it is about space exactly that enhances virulence?
是低重力还是辐射?
Is it the low gravity or the radiation?
到底是什么?
What is it?
沙门氏菌的研究发起人
Well, the authors of salmonella study
认为在微重力环境中细菌接收到的信号
theorised that the signal to bacteria in microgravity
可能是其细胞膜所受到来自表面和环绕在其周围的流体的
might be lower shear forces on their cell membranes
较小的剪切力
from the surfaces and fluids that surround it.
但是基于我读的期刊文章
But based on the journal articles I read,
这只是若干建议之一
that’s only one of several suggestions
至今悬而未决
and the jury is still out.
我们还不知道
We just don’t know.
Joey Broda和McKnowledge1000都问了
Joey Broda and McKnowledge1000 both asked
为什么人类的基因表达不会改变轨道
why human gene expression isn’t altered in orbit
而细菌的基因表达却会
if bacterial gene expression is.
这是个好问题 但我不是一个微生物学家
That’s a great question, but I’m not a microbiologist.
也许人类的细胞确实改变了
Maybe human cells do change.
我不知道
I don’t know.
确实是好问题 但我无法解答
It’s a great question, but I have no idea.
DHGameStudios说到令人感到耻辱的是
DHGameStudios said that it’s a shame we
我们给这个视频加了一个僵尸标签
put a zombie tag on this video.
你是什么意思?
What do you mean?
《芝麻街》中用吸血鬼和
Is it a shame that ‘Sesame Street’
肢端肥大的金丝雀来教授我们阅读和算术
teaches reading and arithmetic with a vampire and a canary
也让人感到耻辱吗?
with acromegaly?
开心一点 伙计
Have some fun, man.
别这么严肃
Lighten up.
僵尸真是好极了
Zombies are the best.
最后 At-Bristol Science Centre
Finally, At-Bristol Science Centre
很想看到“好奇号”火星车与火星的僵尸
really wants to see the Curiosity rover battling
对战的电影
martian zombies in a movie.
是的 你想看
Yeah, you do.
你知道还有谁也想看吗?
You know who else does?
Bjs301的孩子和朋友们 因为我确信
Bjs301’s kids and their friends, because I’m
他们明白 虽然僵尸都不是真的
pretty sure they understand that even though zombies
但依旧超级棒
aren’t real, they’re still super awesome.
最后播送一条简短的通知
Finally, quick announcement.
PBS Digital Studios
The PBS Digital Studios Network has
获得了威比奖在科学教育领域的提名
been nominated for a Webby award in the science and education category.
感谢您的支持和您在webbyawards.com上的投票
We’d appreciate your support and your vote at webbyawards.com.
你可以点击链接查看详情
You can check out the link in the description.

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视频概述

一起看看神奇的太空新理论吧,全新地去感受宇宙,或许能够给你带来启发

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翻译译者

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视频来源

https://www.youtube.com/watch?v=YycAzdtUIko

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