与摩根·弗里曼一起穿越虫洞（2010）

Through The Wormhole With Morgan Freeman S01E03

Part 5 April 19, 2021, 2:23 p.m.

量子力学的最奇怪特点之一
One of the strangest properties of quantum mechanics
称作“非定域性”
is called "nonlocality."
两个粒子彼此存在感应
It's when two particles instantly affect each other,
即使它们相隔数英里甚至一光年之远
even when they're miles or light-years apart.
相当像是巫毒巫术
It's a bit like voodoo.
当你刺人偶，人就马上感到疼痛
When you stab the doll, the human being is also affected.
可与巫毒巫术不同的是
But unlike voodoo,
量子非定域性根正苗红是经过科学证明的
quantum nonlocality is scientifically proven.
今天，瑞士银行基金资助相关研究
Today, Swiss banks fund experiments
看看非定域性能否用于开♥发♥
to see if nonlocality can be used
某种无法破解的
to make one-of-a-kind, crack-proof security keys
电子转账密钥
for computer transactions.
尼古拉斯·吉辛教授领导这项研究
Professor Nicolas Gisin leads the way.
量子物理和光纤专家吉辛
A quantum physicist and fiber-optic specialist,
他测试了量子非定域性
Gisin has tested quantum nonlocality
距离遥远的光子之间
by showing the perfect synchronization of photons,
具有完美的同步性
particles of light, separated by great distances.
量子物理说，呃，实际情况是
Quantum physics says, well, what happens
当你对一个光子施加影响
is that whenever you do something on one photon,
有反应的并不只是这个光子
the reaction is not on this photon only,
这两个光子会产生一个整体反应
but there's a global reaction of two photons.
这意味着，这两个光子
In some sense, the two photons,
虽然远隔千山万水
although they are at this large distance,
它们仍然构成了一个系统
they still constitute one system.
这个整体的系统会立即反应
And so the global system reacts at once.
这就是量子非定域性
And this is quantum nonlocality.
吉辛通过横穿日内瓦的光纤
Gisin sends photon signals
发送光子信♥号♥♥
through fiber-optic cables stretched across Geneva.
一端的一对光子被激光激活
A pair of photons on one end is activated with a laser.
另一端的光子马上反应
And the photons on the other end instantly react.
看上去没有东西移♥动♥过，没有能量交换
Nothing seems to move, and no energy is exchanged.
然而，粒子以某种方法共享信息
Yet somehow, the particles share information.
爱因斯坦称之为“跨越距离的幽灵反应”
Einstein used the word "spooky action at a distance."
跨越距离的幽灵反应
So this spooky action at a distance
并不是在时空传播
is not something that travels in space-time.
它不是在时空中发生的
It's not something that happens in space-time.
没有时空理论能够解释
There's no story in space-time
这种非定域性怎么发生的
that can tell us how these nonlocal correlations happen,
我们可以得出结论
and that's why we conclude
非定域性源于时空之外
that they seem to emerge somehow from outside space-time.
于是，必然的，这种情况
So that has, of course, deep implication
影响了我们对时空的理解
for our understanding of space-time
实际上，更精确的说
or actually, more precisely,
影响了我们对时空的不理解
for our non-understanding of space-time.
有些人相信量子非定域性
Some believe that quantum nonlocality
能够用于向过去发送信息
can be used to send messages backward in time.
在华盛顿大学
At the University of Washington,
物理学家约翰·克莱默正在验证这一理论
physicist John Cramer is putting this idea to the test.
和吉辛相似，他也用处于缠绕态的光子
Like Gisin, he's experimenting with entangled photons --
利用非定域性绑定的光子对进行试验
photons bound by nonlocality.
不同的是，克莱默试图将光子信♥号♥♥
The twist is that Cramer is trying to send photon signals
从当前传递到非常近的过去
from the present back to the very recent past.
这些定制的激光和测量设备
These custom-made lasers and measuring devices,
叫做干涉仪
called interferometers,
是克莱默的时间机器的核心
are the heart of Cramer's time machine.
一个干涉仪叫做艾丽丝
One interferometer called "Alice"
将光子信♥号♥♥传给另一个叫鲍勃的干涉仪
sends photon signals to another interferometer called "Bob."
如果克莱默的理论是正确的
If Cramer's theory is correct
仪器的标定也没有问题
and the calibration is just right,
鲍勃会在艾丽丝发消息的很短时间之前
Bob will get a message from Alice
就收到这个消息
a fraction of a second before she sends it.
因与果要颠倒了
Cause and effect will be reversed.
艾丽丝控制
So Alice has control
我们观察到粒子相
over whether we have particle-like behavior
或者波动相
or wavelike behavior over here.
因为光子纠缠于空间中
Because the photons are entangled in space,
鲍勃，在那边接受信♥号♥♥
Bob, who wants to receive the signal over here,
可以观察并看到
can look and see
它是否同时具有干涉模式
whether he has an interference pattern at the same time.
现在，这个距离是几厘米
Now, this distance is a few centimeters.
并不大
It's not very big.
但是距离不一定要是几厘米
But it doesn't have to be a few centimeters.
也可以是上光年的距离
This could be a light-year down the line,
试验的结果
and she could still do the same thing
不会有什么不同
and cause the same effect over here.
这是纠缠态的工作方式
And that's the way entanglement works.
如果我在这里放一卷光纤
And so if I put a spool of fiber optics in here
有10千米长，艾丽丝会在鲍勃接到信♥号♥♥
that's, say, 10 kilometers long, then she would send the signal
之后50微秒发射信♥号♥♥
50 microseconds after Bob received it.
这样她就向50微秒以前的世界
So she would be sending messages backwards in time
发射消息
by 50 microseconds.
这样，理论上
So one could use it, in principle,
某人可以用它实现与过去通信
for backwards-in-time communication.
如果克莱默的装置正常工作
If Cramer's device works,
它会在信息发射之前就发射信息
it will only send messages back
虽然只是百万分之一秒之前
a millionth of a second before they're sent,
但是一个出现在过去的信♥号♥♥
but a signal showing itself even a tiny bit in the past
哪怕再微小，也将给我们的时间观带来革命性的改变
would revolutionize our understanding of time.
这会证明，逆因果律是真实的
It would prove that retrocausality,
即未来事件会影响过去
the theory that events in the future
这个理论是真实的
affect events in the past, is true.
如果它真的起作用了那会是很有意义的
If it does work, it would be quite remarkable,
是物理学的大事件
be a big deal in physics.
是信息工程的大事件
It would be a big deal in the communication industry.
如果你能向过去发送消息
And if you could send messages backwards in time,
这对一切来说都是大事件
it would be a big deal everywhere.
这会改变我们的文明
It would change our civilization
我都无法设想会发生什么
in ways I have trouble imagining.
但是这也许是个迹象
But all of that is probably just an indication
这个试验恐怕不会成功
that the experiment probably won't work,
因为自然恐怕不会允许人类
because nature probably doesn't want to allow you
向过去发送信息
to send messages backwards in time.
我并不真的认为
I don't really see retrocausality
逆因果律是一个很可信的假设
as a very plausible assumption.
我是说，很明显，时间向着未来演化
I mean, time clearly evolves or gets constructed
或者说构造着未来
towards the future.
另一方面，我也会说
On the other side, I will also say
对现代的物理学家和物理学理论
that time is certainly a very poorly understood concept
时间是一个很不被理解的概念
in physics by physicists today,
我们应该期望，在未来
and one can certainly expect that in the future
我们能够更好和更深刻的理解时间
we'll have a much better and deeper understanding of time
和今日的理解大不相同
and possibly a very different one from the one we have today.
让我们说，总有一天
So let's say that someday
我们发展了更好的时间观
we develop that better understanding of time.
在解决了量子引力之谜后
After solving the riddle of quantum gravity,
我们建造一个能用的时间机器
we build a working time machine.
那会发生什么事呢？
What would happen then?
我们能够改变过去吗？
Would we be able to change the past?
这个答案很炫，也很恼人
The answers are fantastic, disturbing,
还有一点
and a little...
怪异…怪异…怪异……怪异
...Strange. ...Strange. ...Strange....Strange.
我们试图向过去发信♥号♥♥
We're trying to send signals back in time.
如果成功
And if that works,
也许有一天我们能把人送回过去
perhaps one day we can send humans back in time.
一个令人激动的想法
An exciting idea,
但它开启了一扇悖论问题的大门
but it opens the door to the problem of paradox.
悖论是一个自相矛盾的情况
A paradox is a situation that contradicts itself --
悖论本身不合情理
doesn't make any sense.
你从未来向过去发送一个治疗癌症的药方
Say you send a cure for cancer from the future to the past.
现在的死人会活吗？
Would the dead now be alive?