与摩根·弗里曼一起穿越虫洞（2010）

Through The Wormhole With Morgan Freeman S01E03

Part 1 April 19, 2021, 2:23 p.m.

时间——我们对它总是贪得无厌
Time -- We all wish we had more of it.
是否有方法能够跳出时间界限
If only there was a way to escape its bounds
如我们所愿自♥由♥穿行于时间长河
and travel through time as we please,
回到遥远的过去
Back into the distant past...
或者访问几百年后的未来
or hundreds of years into the future.
地球上最聪明的大脑致力于此
The greatest minds on earth have spent decades
几十年来，屡败屡战
trying to make this dream come true without success.
可近来，新的科学透露出
But now new science reveals strange paths
通向这个问题终极答案的怪异之路
that may finally answer the question,
时间旅行可能吗？
is time travel possible?
如果可能，我们怎么才能做到？
And if so, how will we do it?
空间，时间，生命本身
Space, time, life itself.
宇宙之谜，尽在穿越虫洞
The secrets of the cosmos lie through the wormhole.
与摩根·弗里曼一起穿越虫洞（S01E03）
Through The Wormhole With Morgan Freeman (S01E03)
时间旅行可能吗？
Is Time Travel Possible?
某种意义上，地球上的每一个男人、女人和儿童
In a way, every man, woman, and child on this earth
都是时间旅行者
is a time traveler.
不管是否愿意，我们都要经历从生到死的旅程
Like it or not, we're all being shot relentlessly forward,
持续前行，永不间断
making the journey from birth to death,
没有回头路
and there's no going back.
无法预知未来
And there's no way of looking into the future.
是吗？
Or is there?
如果我们能够回到从前
What if we could travel back
见证过去发生的事件
to witness events in the distant past
或者飞向未来，目击自己的命运
or journey into the far future, see our destiny?
想想看，我们可以
Just think what we might learn
亲眼观察历史
if we could watch history unfold right before our eyes...
或者我们有机会改变
...Or what we could change in our own lives
我们自己的生活
if we had the chance?
对多数人来讲，生命中最痛苦的，是失去心中挚爱
For many, life's greatest sorrow is losing a loved one.
小时候，与祖母共渡的时光
The time I spent with my grandmother when I was a child
塑造了今天的我
helped make me the man I am today.
我经常希望能够再见到她老人家
I often wish I could see my grandmother again,
或者回到过去
or go back in time and show her who I am
让她看看成年的我
and what I've become as an adult.
似乎此梦难圆啊
Seems like an impossible dream.
真的吗？
But is it?
科学能够找到
Can science find a way
摧毁横亘在现在和未来之间的时间壁垒，的方法吗
to tear down the walls between now and then?
时间旅行可能吗？
Is time travel possible?
为了找到答案
To find the answer,
我们必须先理解自然的时间
we must first understand the nature of time.
这可比听上去难多了
And that's a lot harder than it sounds.
斯蒂夫·斯科利是一个原子物理学家兼大♥师♥级计时员
Steve Jefferts is an atomic scientist and master timekeeper.
俺认为，我们所有人
We all, I think,
都天生以为自己了解时间
have some innate feeling that we understand time.
时间似水，从身边流逝
It flows past us.
韶华易逝
Time goes on, we get older,
故梦难温
things that happened yesterday are not happening today,
等等等等
et cetera.
但是我不认为
But I don't think that any of us,
有人能够真正理解时间
whether we're physicists who study time
无论是我们这些研究时间的物理学家
or just somebody who lives his life
还是那些打酱油的普通人
really, truly understands time.
斯蒂夫供职于
Steve works at
科罗拉多博尔德的
the National institute of Standards and Technology
国家标准和技术学院
in Boulder, Colorado.
这是世界上6个
It's one of six labs around the world
提供宇宙协调时的实验室之一
that calculate coordinated universal time,
宇宙协调时就是世界标准时间
the official world time.
这些激光装置
This tableful of lasers
是NIST-F1型铯原子钟
is the NIST-F1 cesium fountain atomic clock.
测量原子的振动
Measuring the nuclear vibrations of atoms,
每秒钟“滴答”90亿次
this clock ticks at 9 billion times per second.
即1纳秒的十万分之一
That's one ten-millionth of a nanosecond.
这台钟以16位的精度
This clock will measure frequency, or time interval,
测试频率，也就是时间间隔
out to almost 16 digits.
这有啥子重要的？
Why is that important?
要以如此高的精度测量时间或者频率的原因是
The reasons to measure time or frequency this accurately --
小子，原因可太多了
boy, there are a bunch of them.
有些是出于纯科学原因
Some of them are scientific,
还有些可是实际需要
but some of them are really practical.
像全球定位系统这样的玩意儿
Systems like the global positioning system,
即GPS系统
the GPS system --
实际上就是一个授时系统
it's fundamentally a time-keeping system.
我们所做的，就是把原子钟放到那些卫星上去
And so what we do is we put atomic clocks on satellites,
确定它们都是同步的
make sure they're all synchronized,
这样，当我站在地球表面
and now I stand on the surface of the earth
拿着GPS接收器
with my GPS receiver,
会收到每个卫星发来的时间信♥号♥♥
and it gets time signals from each of these satellites,
接收机测量到抵达时刻
and it just measures the arrival times.
如果从那颗卫星来的信♥号♥♥
And so if the signal from that satellite
比这颗卫星的信♥号♥♥晚到了5纳秒
arrives five nanoseconds before the signal from that satellite,
这说明“哦，我离那颗卫星
it says, "oh, I must be 5 feet further from that satellite
比离这颗要远5英尺”
than that satellite."
这样，如果有4颗卫星的信♥号♥♥
So it does that with four satellites,
接收器就能计算出你所在的经纬度和海拔了
and it computes your "x" and "y" position and your altitude,
你通过时间计算位置
and now you've got your position from time.
这个方法很不同寻常，要成功定位
And the fact that this works at all is just remarkable,
必须达到纳秒级的
but it absolutely depends on
计时精度
having time at the nanosecond level,
如果你达不到纳秒级精度
because if you don't have time at the nanosecond level,
你就无法区分卫星的远近
then you can't tell which satellite you're closer to.
像这样的精确计时，使我们依赖于电脑的
Precision timekeeping like this makes our high-tech,
高科技生活方式变得可能
computer-driven lifestyles possible.
可是当我们的计时系统越来越精确
But as our timekeeping systems become ever-more accurate,
我们发现时间流逝的方式和我们的固有观念不同
we find that time does not flow the way we think it does.
时间并不是统一的
Time is not universal.
怪异的事实是，时间是个性化的
The strange truth is that time is personal.
时间是什么？
What time is it?
呃，这取决于你身处何处
Well, that depends on where you are
以及你脚下的大地
and what the ground beneath your feet is doing.
当你在一个引力场中放置一个钟时
Anytime you put a clock in a gravitational field,
引力场越强
as you get closer to the strong part of the gravitational field,
钟就会越慢
the clock slows down.
事实是，地球并不是坚固不变的
What ends up happening is that the earth is not rigid.
地球实际上比较柔软，像果冻之类的东西
The earth is sort of a squishy, firm ball of jello or something,
每天，当潮起潮落时
and every day, when the tides go in and out,
地球外形也随之变化
the earth deforms sort of like a ball,
你脚下的地壳
and the earth under your foot
也多多少少的有所升降
goes up and down by a foot more or less --
升降程度各地不同
depends on where on the earth you are.
如果我把这个钟拿起来，举高
So if I pick this clock up and move it up by a foot,
它离地心远了一点
it's further from the center of the Earth,
引力也小了一些
the gravitational force goes down a little bit,
钟摆也会快一点
and the clock ticks a little bit faster.
如果你有一个17位精度的表
So now if you have a clock which is accurate to 17 digits,
在一天之中
all of a sudden, every day,
你会看到它实际上忽快忽慢
you can see the rate of the clock speed up and slow down
因为地球是在变化
and speed up and slow down relative to what it should be,
引力也在变化
because the Earth is squishing by this kind of one-foot level.
人类无法察觉这种微小变化
Humans don't perceive these miniscule time differences,
但是我们最准确的计时器
but our very fastest clocks
能够将1秒分为一千兆兆份
can cut a second into a quadrillion pieces.
在这个精度上
And at that scale,
我们会看到时间处处不同
we see that time differs from place to place.
时间和空间，孟不离焦，焦不离孟
Time and space are tightly locked together.
很快，我们觉悟了
Quickly, we're getting to the point
我们开始统一考虑时空
where we're gonna have to start thinking about
而不再是时间和空间
space-time together, rather than space and time,