BBC 地平线系列：时空谜团（2008）

就会比你预计的时间提前一点
compared to the time that you expect it to.
那么某种意义上 每天的长度是摇摆不定的啦？
So the day is, in a sense, the length of day is wobbling?
是的 每天的长度并非恰好是24小时
Yes, the length of the day is not 24 hours exactly.
出乎意料的是 地球每日飘忽不定的速度变化
Surprisingly, earth's daily erratic speed changes
主要是由风造成的
are mostly caused by wind.
随着风速的加强与减缓 通过推向山脉
As the winds speed up or slow down, by the way they push on the mountains
对地球表面产生摩擦 就减缓或加速了地球的固体部分
or the friction on the surface of the earth, they then slow down or speed up the solid part of the earth.
在控制室里 阿瑟掌握着每天最新的时间
Down in the control room, Arthur has the most recent timing for a day.
最新的测量成果就是两天前的
The latest measurement that came back was from just two days ago,
每天的长度是约24小时多出1.9毫秒
and the length of day was about 1.9 milliseconds more than 24 hours.
24小时 1.9毫秒？
So, 24 hours, 1.9 milliseconds?
对 蛮要紧的 一旦累加起来的话
Right. Makes a difference, it all adds up.
因为地球的旋转不稳定 利用太阳
Because the earth doesn't spin at a steady rate, using the movement
和邻近的天体的运行来告诉你时间
of the sun or other nearby celestial bodies to tell you what time it is,
那是非常不可靠的
is not going to be very reliable.
地球的旋转不稳定
The earth's spin's erratic.
每天都在变化
It changes from day to day,
所以你无法利用古老的方法来掌握时间
so you can't use that age-old way of telling the time.
为了知道时间 你不得不停止观看天空
To know what time it is, you have to stop looking into the sky
观看恒星和行星 不得不低下头来观看微观世界
and looking at the stars and the planets, and you have to look down into the world of the small.
你必须通过原子世界来掌握时间
You have to look into the world of the atom to tell the time.
树挡住了！
The tree's in the way!
地球上能找到时间的地方
If there's one place on earth where you can come to find the time,
就在华盛顿
it's here in Washington DC.
这里是美国海军天文台的总部
This is the home of the US Naval Observatory,
一帮遍布地球的严格挑选的时间主宰之一
one of a select bunch of time lords
他们是地球时间的管理人...
dotted across the planet who are the keepers of time on earth...
格林威治时间 19时54分整
Universal Time, 19 hours, 54 minutes exactly.
...这里的时间来自原子钟
.. a time now derived from atomic clocks.
丹尼斯·麦卡锡 时间的主管
Dennis McCarthy, director of time.
我们在1950年代确定时间是基于月亮相对恒星的位置
We defined a time in the 1950s based on the position of the moon with respect to the stars.
我们需要更精确的时间
We needed a more accurate kind of time.
不仅需要更加准确
Not only does it have to be more accurate
而且要更加容易获得
but it has to be more accessible.
那种容易获得的时间是由原子钟提供的
That accessible kind of time is provided by atomic clocks.
我们所要获得的时间要很有规律地重现 是你能倚靠的
What we need to tell time is something which repeats with great regularity, that you can count on.
我们获得的时间的质量取决于所使用的原子
How well we can tell time depends on which atom you're using.
所以我们会有所选用 以保持原子时间
So we choose certain ones to use for keeping atomic time.
那么 原子是如何告诉我们时间的呢？
So, how can atoms give us the time?
你能做的...
What you can do...
原子是
An atom is
非常天然的...
very crudely...
原子核在这里 电子在围绕着原子核的轨道上
The atomic nucleus sits there and electrons sit in orbit around the nucleus.
然而它们只能在确定的地方 所以你无法随意安排它们
But they only sit in specific places, so you can't have them anywhere.
你让它们在这里 这里
You can have them here and here and here.
当它们跳到这里时
And when they jump up to there,
它们就会重新回到这里 会发光
and then back down to there again, they emit light.
这光有特定的频率
And that light has a particular frequency.
就是这光让我们获得的时间十分地精准
And it's this light that allows us to tell the time so precisely.
在这钟里 是叫做铯的稀有金属的原子
Inside the clocks are the atoms of a rare metal called caesium.
让铯原子里的电子跳起
The electrons in the caesium atoms are made to jump up.
然后 随着它们落回去 就会发出光
Then, as they fall back down, they give out light.
这些光波的峰值超过每秒钟90亿次
These light waves peak over nine billion times every second.
就是这个光驱动着时钟
And it's this light that drives the clock,
每一个原子秒实际发出90亿次滴答声
effectively producing nine billion ticks for each atomic second.
这个数目从没有变化 从不改变 这就是其如此精准的原因
This number never changes, never alters, and that's why it's so accurate.
所以 原子钟实际上是在发出电子信♥号♥♥
So, the atomic clock is actually putting out an electronic signal
实际上类似于摆钟的钟摆
which is essentially analogous to the ticking of a pendulum clock,
要知道 摆钟有可能是每一秒或每两秒钟摆动一次
you know, a pendulum clock which might tick once every second or once every couple of seconds.
我们所掌握的这个东西可以每秒钟摆动90亿次
This thing is providing us something which is going nine billion times per second.
因此就为我们提供了高精度的时间
So it provides us with a very fine definition of time.
我们实际上在世界各地有好多海军天文台里的时钟
We actually have a number of clocks at the Naval Observatory located all over the grounds.
这是其中之一
Here's one of them.
这是标准时间系统一
This is the Master Clock System One.
这是标准时间系统二
This is the Master Clock System Two.
如果我想问个问题 “时间是什么？”
So if I want an answer to the question, "What time is it?",
这就是答案吗？ 那就是
there it is? That's it.
格林威治时间 20时0分整
'Universal time, 20 hours, 0 minutes exactly. '
原子钟时间驾驶现代生活的心跳
Atomic time is the heartbeat driving modern life.
它作为独唯一的全球时帧 校准世界的时间
It acts as a single global time frame, a way to synchronise
其精度达到了十亿分之一秒
the world with a time stamp accurate to a billionth of a second.
它在导航 全球通信安排等各方面发挥了关键的作用
It plays a key role in everything from navigation and scheduling to global communication.
这就是地球时的定义
It is THE definition of time on earth.
问题解决了！
Problem solved!
啊 不完全是
Well, not quite.
了解了原子钟时间其实与回答“时间是什么”这个问题有点不搭界
Knowing atomic time is actually somewhat irrelevant to answering the question, "What time is it?"
如果你给出2008年5月21日..
The labels you give to time 2008, May the 21st - it's...
今天是几号♥？
What day is it today?
12号♥ 12号♥ 对
12th. 12th, right.
对于我们 今年是2008年 因为教皇在500年前就规定了
To us, this is the year 2008 because a Pope defined it to be so about 500 years ago.
在伊♥斯♥兰♥历里 今年是1429年
In the Islamic calendar, it's 1429.
在犹太历里 今年是5768年
In the Jewish calendar, it's 5768.
2012年 在玛雅历里 可是一长串数目的最后一年 - 130000
And in 2012, in the Mayan calendar, it'll be the end of the long count - 130000.
各不相同 各行其是
All different, all arbitrary.
所以 如果你真要知道时间是什么 那么我们还得再深入一点
So, if you really want to know what time it is, then we're going to have to go a little deeper.
你手表上的时间是现在的时间 当前的时间
The time that ticks on your watch is the time now, the time of the present.
然而我们的经验感受是 当前的时间不应该是想当然的东西
But the feeling we experience as the present time is something we shouldn't take for granted.
我们所认为的当前的许多东西是与过去一脉相承的
Much of what we believe is in the present is drawn from the past.
我们感觉当前进行的事情是不久前所发生的
What we feel is happening now happened a little while ago.
我们感觉到我们现在所经历的周围的一切
We feel that we experience a now around us -
就是我们现在所看到的结果
everything we see happen now.
然而实际上 远处物体发出的光到这里 被你看到 是需要时间的
But actually, the light coming from distant things into your eye takes time to get there.
所以 你看到的太阳
So, you look at the sun.
在930哩外
The sun is 93 million miles away.
这就意味着光从发出 化了8分多钟才被你看到
That means light takes over eight minutes to get from it into my eyes.
因此 我见到的太阳是8分钟前的
So I'm seeing the sun as it was eight minutes in the past.
它可能爆发了 而我在8分钟里是观察不到的
It could explode and I wouldn't notice for eight minutes.
我只看到美丽的日落景象
I'd just see that beautiful image of the setting sun.
为了回答时间是什么 我们就需要知道时间是什么时候开始的
To answer the question what time is it, we need to know when time began.
光以有限的速度传播的事实 给了我们一个独特的机会
The fact that light travels at a finite speed offers us a unique opportunity.
让我们能够回头看 不光8分钟 而是数百万 甚至数十亿年
It allows us to look back, not just eight minutes, but millions, even billions of years.
我来到巴尔的摩来回首时间
I've come to Baltimore to look back in time.
哈勃太空望远镜前主任史蒂夫·贝克威什
Former director of the Hubble space telescope Steve Beckwith
负责过摄取特别的相片
was responsible for taking an extraordinary photograph.
作为主任 我每年有10%的望远镜观察时间的自♥由♥裁量权
As a director, I had at my discretion
可以用来做任何事情
10% of the telescope time per year that I could use for anything.
有一年 我化了自己所有的时间 事实上稍微超过了自己的时间
One year, I took all of my time, in fact I took a little bit more
决定专致于获取宇宙最深处的照片
than all of my time and decided that we would devote it to the deepest picture ever taken of the universe.
2004年 史蒂夫把哈勃望远镜指向夜空的一小部分
In 2004, Steve pointed the Hubble telescope at a tiny piece of the night sky
拍摄所谓的超深场的照片
and took a picture called the Ultra-Deep Field.
哈勃望远镜曝光了100万秒
It took a million seconds of exposure on the Hubble space telescope,
那是世界上最强大的望远镜
the world's most powerful telescope.
在这个图像中 我们可以看到130亿年的情景
And in this image, we can look back in time 13 billion years.
这图像很难理解 对吧？
It's a difficult picture almost to comprehend, isn't it?
因为某种意义上 它是...
Because in some sense, it's...
3D这词不对 但是它是某种...
3D is the wrong word, but it's some sense...
噢 不 用词准确 它就是3D 我们看到了过去
Oh, no, it IS the right word. It IS 3D. We are looking back in time.
这张图片上的每个星系可能都是过去的
Every single galaxy in this image can be dated.
这个星系发出的光是宇宙在8.8亿岁时的
This galaxy emitted its light when the universe was 8.8 billion years old.
然后 随着你的时间倒♥退♥ 这个星系发出的光
Then, as you go back in time, this is a galaxy that emitted its light
是宇宙在3.3亿岁时发出的
when the universe was 3.3 billion years old.
你可以看到 看上去完全不一样 确实很无序
You can see it looks completely different. It's really very chaotic.
这个是大爆♥炸♥10亿年后的 红红的 有个小尾巴 很小
And this is one billion years after the Big Bang, very red, a little tail, very small.
超深场里最遥远的星系是红的 就在那里 是这个吗？
The most distant galaxy in the Ultra-Deep Field is a red one that's right over here. This one here?
它的光发出时 是宇宙7亿到8亿岁之间
The light from that was emitted when the universe was 700 to 800 million years old.
那么 真的
So, really,
这就是宇宙中形成的最早的结构之一吗？
this is one of the first structures that formed in the universe?
最早形成的之一 我们所能见到的最早的一个
One of the first formed and one of the first we've been able to see.
某种程度上 你看这个几乎...
In a sense, you see this almost...
我原来想说很荒谬
I was going to say paradoxical,