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物理学已经到达极限了吗?

Why Do People Say We've Reached the End of Physics?

[♪ INTRO]
[开场曲]
《科学秀》
The whole point of physics has always been to understand
物理学最重要的 从来都是在于理解
what the universe is made of
宇宙是由什么构成的
and how the stuff in it interacts.
以及其中物质如何相互作用
You know, like how Isaac Newton wanted to figure out
就像牛顿想弄清楚
why apples always fell straight toward the ground.
为什么苹果总是直直掉在地上
And we’ve come a really long way over the years.
这些年来我们也取得了长足的进步
These days, after about a century of
如今经过近一个世纪的
incredible research in fundamental physics,
出色的基础物理研究
we have a pretty good idea of the building blocks that make up everything
我们已对构成万物的基础
and the rules that describe how they interact.
以及它们相互作用的规律有了清晰的了解
In fact, our fundamental picture of the universe
事实上 我们对宇宙的基本认知
seems so nearly complete
似乎已趋于完整
that it’s led some people to suggest
以至于有些人认为
that we’re arriving at some version
我们已经快达到所谓的
of “the end of physics.”
“物理学的极限”
And for sure, physics is at a turning point,
毫无疑问 物理学正处于一个转折点
but before researchers pack it up and head home,
但在科研人员放弃研究回家之前
it’s worth understanding
我们还是有必要了解一下
what the so-called “end of physics” is really all about.
什么是所谓的“物理学的极限”
As far as anyone can tell, every single thing in our entire world
据我们所知 世界上的所有物质
is made up of a small handful of elementary particles,
都是由少数基本粒子组成的
like electrons and quarks.
比如电子和夸克
And they obey very strict rules when they interact with each other.
这些粒子之间的反应遵循十分严谨的规律
Starting with those basic particles and the rules they follow,
从这些基本粒子及其遵循的规律出发
you can build up to all sorts of things—
你可以构建起各种理论
like the physics of baseball,
比如棒球物理学
the chemistry of pie-baking, or the biology of cell division.
烘焙中的化学或细胞分裂中的生物学
Of course, it doesn’t make much sense to explain
当然用夸克这类基本粒子
how something like the brain works using elementary particles like quarks.
去解释大脑的工作这样的事并不怎么合理
It usually makes more sense to describe reality
通常用分子或细胞这样
with bigger things, like molecules or cells.
更大的物质描述这类事实更合理
But the point is,
但关键是
no matter what unit makes the most sense to use,
无论用多大的物质解释事物最合理
that unit still obeys the same basic principles
那种物质依然遵守同样的基本原则
Like, you’re not going to need a brand-new elementary particle
比如你并不需要一种全新的基本粒子
to make sense of some everyday thing,
来理解一些日常事物
like how a bird flies.
例如鸟是如何飞翔的
Most of the basic rules that describe the stuff in our everyday world
日常事物遵循的大多数基本规律
are part of a framework called the Standard Model
都是一个名为“标准模型”的框架的一部分
This framework is essentially a set of math and physics principles
此框架实质上就是一系列数学与物理原理
that describe the fundamental structure of the world as we know it.
它们描绘了我们所了解的世界的基本结构
It includes three of the world’s four fundamental forces
这个框架包括宇宙四种基本力中的三种
and the couple dozen particles related to them.
以及与此相关的十几种粒子
Those three forces are the electromagnetic force, the strong force, and the weak force
这三种力分别是电磁力 强力和弱力
and they fit neatly into the Standard Model.
它们刚好能放进标准模型
But there is one more fundamental force: gravity.
除此之外还有一种基本力:重力
And it’s a little bit of an oddball because it’s not neatly described
它有点异类 因为它不像其他基本力一样
by the physics of elementary particles, like the other forces are.
严格遵循基本粒子的物理规律
So it doesn’t fit into the Standard Model.
所以它不适合放到标准模型里去
And that’s part of the reason there’s no theory of everything
这也是为什么没有一个万物理论
that neatly ties up all the forces and particles in the universe.
能统一解释宇宙中的所有力和粒子
But, even without a theory of everything,
但即便没有万物理论
the Standard Model and general relativity
标准模型和广义相对论
do a solid job of describing almost everything in our world.
比较不错地解释世上绝大多数事物了
Which is a pretty tall order, all things considered.
总的来看这已经是很难做到的事了
These theories are the culmination of a century’s worth
这些理论是一个世纪以来基础物理研究
of research into fundamental physics.
达到顶峰之后的结晶
And it can be tempting to see fundamental physics
很多人倾向于认为基础物理
as a puzzle with almost all the pieces in place.
就像一个已经快拼完的拼图
Which kind of sounds like the end of the road for physicists.
听起来好像物理学家已经没事可做了
But before anyone calls it a day or, like, converts to a biologist,
但在物理学家辞职或转行做生物学家之前
there are a few things to consider.
大家还得考虑这几件事
First of all, there have been plenty of times throughout history
首先 历史上有过很多次
when scientists thought physics was basically complete…
科学家们认为物理学已经基本完善了
and each time, they were extremely wrong.
结果每次他们都大错特错
For example, in the 1920s,
比如上世纪20年代
even after we discovered the mysteries of quantum mechanics and relativity,
即便量子力学和相对论已经被提出
the physicist Max Born still had the nerve to say that
这位物理学家马克思·玻恩居然还有脸说
“physics, as we know it, will be over in six months.”
“大家都知道物理学在半年内就会终结”
Spolier! It wasn’t.
剧透警告!并没有
Then, there was that time at the end of the 19th century
然后就是十九世纪末那次
when the physicist Albert Michelson said,
物理学家阿尔伯特·迈克耳逊说
“It seems probable that most of the grand underlying principles
“大部分重要的基本原理基本上”
have been firmly established.”
“都已经站住脚跟”
This guy was ready to call it quits before we even knew about
量子力学和相对论甚至都还没出现
quantum stuff and relativity!
他就准备好等物理学终结了
Physicists at the time had been so used to
那时的物理学家太习惯于
the laws of motion discovered by Isaac Newton
牛顿发现的运动定律
that they expected them to work forever, for everything.
以至于他们指望这永远适用于所有事物
The thing was, by the time he’d said that,
问题是 迈克耳逊说这话的时候
Michelson himself had already conducted an experiment
他自己已经做了一个实验
that would go on to prove him
后来会证明他自己的话
and the whole Newtonian worldview—wrong.
以及整个牛顿世界观都是错的
The Michelson-Morley experiment, as it’s called,
该实验史称迈克尔逊—莫雷实验
provided strong evidence that there isn’t any
它有力地证明了不存在
universal, absolute reference frame that everything can be measured relative to,
统一的 适用于所有物体的绝对参考系
as Newton’s way of thinking suggested.
这和牛顿力学恰恰相反
That experiment was crucial in paving the way for relativity.
这个实验为相对论的提出作了重要铺垫
And the move from an absolute to a relativistic way of thinking about motion
人们对于运动的思考方式由绝对转变成了相对
totally upended what we’d thought for centuries
这完全颠覆了几个世纪以来人们对于
about how the universe works.
世界运转规律的认知
As a result, Einstein had to come in
后来爱因斯坦出现了
and invent a whole new way to describe space and time.
并发明了一种全新的空间和时间描述方法
So, back in Michelson’s day,
所以在迈克尔逊的时代
the “grand underlying principles” of physics
物理学还有很多“重要的基本原理”
still had a long way to go.
没被发现
Basically, every time someone like Born or Michelson
基本上每次有玻恩或迈克尔逊这种人
thought they had all the answers,
认为他们能解释万物
they realized that their framework
后来都会发现他们的框架
was just a really good approximation of reality.
实际上只是比较接近现实而已
Once you got out to certain extremes,
一旦到达某些极限
that approximation started to break down.
他们的框架就会土崩瓦解
In other words, their frameworks did a good job
也就是说他们的框架
of describing the world under certain conditions,
在一定条件下能清楚解释这个世界
but they weren’t perfect explanations.
但是并不能完美解释
And the same thing is likely true
标准模型和广义相对论
of the Standard Model and general relativity.
应该也是这样
They seem fundamental
它们看起来很接近基本原理
because they describe the universe really well,
是因为它们很好地解释了这个世界
but in extreme environments like black holes or the Big Bang,
但在黑洞或宇宙大爆炸这样的极端条件下
those frameworks still seem to break down.
这些框架似乎还是会崩塌
And there are still some problems with the laws we call fundamental.
另外我们所谓的基本定律还是存在一些问题
I mean, just the fact that gravity doesn’t mirror the other three fundamental forces
就拿重力跟其他三种基本力不同来说
suggests that some piece of the story is still missing.
还是说明这个理论存在缺陷
And there are other imperfections that
还有很多其他类似缺陷
constantly remind us that
这都不断提醒我们
our fundamental theories are just really good approximations of reality.
我们的基本理论只是非常接近现实
Meaning it’s almost certainly not the end of the road.
这意味着物理学远远没有到达极限
Instead, we’re in a kind of weird, unprecedented era
相反 我们处在一个前所未有的奇怪时代
where physicists know our theories aren’t complete,
物理学家都知道我们的理论并不完整
but they also have very little evidence for anything beyond it.
但是理论之外的事他们又几乎没法证明
That makes it much harder to make progress now
所以现在在物理学上取得进步
than it wasa hundred years ago.
比一百年前难多了
Because the thing is, Michelson and Morley were able
因为问题在于 迈克尔逊和莫雷
to disprove the fundamental laws of their time using a lab experiment
推翻当时物理学基本定律的实验室实验
that can now be done in a college classroom.
现在在大学教室都能做
But the times have changed.
不过时代也变了
People have plucked all the low-hanging fruit.
低处的果实都被人摘完了
If you want to make discoveries about fundamental physics these days,
现在如果你想要在基础物理学上有所发现
you need really big experiments.
那你得做超大规模的实验
In 2012, the Large Hadron Collider at CERN in Switzerland
2012年 瑞士CERN的大型强子对撞机中
discovered the last particle
发现了标准模型中缺失的
missing from the Standard Model, the Higgs boson.
最后一种粒子 希格斯玻色子
That was a gargantuan international collaboration
那是次超大规模的国际合作
involving billions of dollars,
耗资数十亿
and thousands of scientists and engineers,
联合了数千位科学家和工程师
and an army of support staff.
还有一支后勤队伍
You’re simply not going to find an undiscovered particle without that kind of tech,
没有那种技术 你是不可能发现新粒子的
because you need something
因为你需要那种设备
that can create conditions way more extreme than you get in everyday life.
去制造日常生活中不存在的极端条件
And as much as theoretical physicists hoped
尽管理论物理学家们都希望
that the Large Hadron Collider would find evidence of physics beyond the Standard Model
大型强子对撞机能在标准模型之外有所发现
, it simply hasn’t.
但是并没有
But the fact that it’s difficult
很难有所发现
doesn’t mean that there is nothing left to find.
并不意味着没有事物在等待发现了
And the good news is, modern physicists
好消息是现代物理学家
understand this better than people like Michelson did back in the day.
比过去迈克尔逊那帮人更明白这点
So they’re not claiming that the job is done.
所以他们没有宣称物理学已经完事
They know that there are still “grand underlying principles” that haven’t been discovered,
他们知道还有“重要的基本原理”待发现
and tons of ways that our current theories are incomplete.
以及现有理论很多方面的不完善
Just like what happened with relativity back in the day,
就跟当时的相对论一样
the solution to the problem will likely be a whole new theory
这个问题的答案很可能是一个全新的理论
that only looks like the Standard Model or general relativity
但这个理论在特定条件下看起来就是
under the right conditions.
标准模型或广义相对论
Fundamental physics has reached a very high plateau
就现有理论来说 基础物理学
with our current theories.
已经达到非常高的水准
But without enough experimental evidence to guide it higher,
但如果没有足够的实验证据把它推向更高水准
it’s also kinda stuck in a rut.
它就会被困在过去的车辙里
The good news is, there are still lots of ways
好消息是 理论物理学家
theoretical physicists are pushing forward.
还是在多方面推动物理学进步
For one, finding ways to unify the fundamental laws of physics
比如如何去统一这些物理学基本定律
is still a huge area of research.
仍然是一个很重要的研究方向
In some cases, physicists know
有些情况下 物理学家们知道
where the fundamental laws break down—like in black holes.
基本定理在哪些环节会失效 比如在黑洞里
There, both relativistic effects and quantum mechanical effects are relevant,
相对论效应和量子力学效应都存在
so they don’t agree on what should happen.
但是它们的效果并不一致
General relativity says black holes should evaporate into nothing,
按照广义相对论 黑洞应该蒸发消失
but quantum mechanics says that’s not possible.
但是按照量子力学这是不可能的
So we simply don’t know what’s right.
所以我们根本不知道哪个是对的
But scientists have begun figuring out ways
但是科学家们已经开始想办法
to research those kinds of environments.
对那种环境进行研究
Like, to get around the fact
比如为了解决
that they can’t exactly study things like black holes in labs,
无法在实验室研究黑洞之类的东西这个问题
they sometimes use what are called analogous physical systems.
他们有时候会采用所谓的模拟物理系统
So rather than study, say, a black hole directly,
就是他们并不直接研究一个黑洞
physicists study a system that has similar properties.
而是研究一个具有相似性质的系统
For instance, one of the most important properties of black holes
比如 黑洞最重要的性质之一
is that they don’t let light escape.
是它们不会让光逃逸
So physicists found a way
然后物理学家们发现一种办法
to make a similar system in a lab
能够在实验室模拟一个类似系统
except instead of trapping light, their system traps sound.
只不过这个系统不捕获光线而是捕获声音
This is called an acoustic black hole.
这被称为声黑洞
And these things actually reproduce properties
这类系统的确会复制
we’d expect to see in real black holes.
我们会在真实黑洞中见到的特性
Scientists are hoping that they can help figure out the real fate of black holes,
科学家们希望能借此了解黑洞真正的生命历程
since relativity and quantum mechanics disagree.
因为相对论和量子力学在黑洞中并不统一
Another team of researchers found a way to put ultracold helium atoms in a state
另一组科研人员发现一种能让超冷氦原子
where they behave like Higgs boson particles,
表现得像希格斯玻色子一样的方法
and they were able to use that to study properties of the Higgs
他们得以在希格斯玻色子被发现之前
even before they had discovered the Higgs boson itself.
就开始用氦原子研究它的性质了
In general, you can use the concept of analogous systems
总得来说 模拟系统的概念可以被用来
to invent all sorts of unusual environments
制造各种非常规条件
that’ll make particles behave in ways they normally wouldn’t,
在这些条件下粒子的表现非同寻常
and that’s been one way for physicists
这是物理学家们
to push the limits of fundamental physics.
挑战基础物理学极限的一种方法
But these days, it’s not the only way
但如今 这已经不是
to study the fundamentals of reality.
研究现实世界基本原理的唯一方法了
As computers get more and more powerful,
随着计算机变得越来越强大
simulations of physical systems
基础物理学研究中的模拟物理学系统
have become much more common in fundamental physics research.
已经变得越来越普及
And simulations have been a total game-changer,
这种模拟改变了整个游戏规则
because in the past,
因为在过去
just knowing the basic rules that govern a system
单靠了解统治着一个系统的基本规则
wasn’t enough to tell how the system would behave in practice.
是不足以判断该系统在现实世界中的表现的
For instance, it would take way too much number-crunching for a human
比如一个人要想搞清宇宙演化数十亿年来
to figure out how the laws of physics would play out
物理学定律发展到什么地步
over billions of years of galactic evolution.
需要处理太多太多数据
But with simulations, computers do the work
但通过模拟 计算机很短时间
of figuring out how the laws of physics play out under certain conditions in a fraction of the time.
就能算出物理学定律在特定条件下的表现
Based on the results, scientists make predictions about
根据计算结果 科学家们再预测
how those systems behave in the real world.
那些系统在现实世界中的表现
And that can take us a long way!
这可以带来很多进步
Like, predicting the chaotic movement of weather systems
比如 没有先进的计算机模拟
would be close to impossible without advanced computer simulations,
无论你多么精通粒子运动的规律
no matter how well you understand how particles work.
都基本不可能预测混乱的天气系统活动
And simulations are currently the only way to test theories
并且要想检验早期宇宙演化之类的理论
about things like the evolution of the early universe.
当下只能靠模拟
So even without new particles or forces,
所以即便发现不了新粒子或新的力
fundamental physics is still pushing forward.
基础物理还是在不断向前推进
Clearly, theoretical physics isn’t done.
很明显 理论物理并没有完事
But it has changed, for sure.
可以肯定的是 它是在变化的
The next plateau in our search for the theory of everything
只靠一两个异见者在实验室孤军奋战
isn’t going to be reached by a lone maverick working alone in a lab.
是不可能到达寻找万物理论的下个高峰的
It’s going to take contributions from thousands of researchers across the globe,
这需要全球上千位科研人员共同努力
doing everything from writing equations
从写公式到检验天文数据
to examining astronomical data to programming computers.
到计算机编程 所有这些事 亲力亲为
The plateau we’ve reached with our latest theories is exciting,
我们最新理论的水准之高是令人兴奋的
but in some ways the things a theory can’t explain
但是某种程度上 理论解释不了的东西
are more exciting than the things that it can.
比它能解释的东西更令人兴奋
Thanks for watching this episode of SciShow!
感谢收看本期《科学秀》
If you’re interested in learning more about fundamental physics,
如果你想学习更多有关基础物理学的知识
you can check out our four-part series
可以看看我们那系列四集视频
that covers each one of the fundamental forces.
每集分别讲一种基本力
It begins with the strong force,
第一集讲的是强力
and you can get started with that video right after this.
本视频结束之后下一个就是啦
《科学秀》

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视频概述

物理学已经没有可研究的东西了?来听听物理学家怎么说。

听录译者

收集自网络

翻译译者

Han

审核员

审核员SR

视频来源

https://www.youtube.com/watch?v=DGS2aWUKZ38

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