BBC.地平线.2012.宇宙何其大

大卫·施莱格尔博士
劳伦斯·伯克利国家实验室
那是当时最棒的全天图
that was the best picture that we had of the full sky.
帕洛玛巡天着实是一件老古董
The Palomar Survey was practically a museum piece -
用的还是易碎的玻璃底片
photographed on fragile glass negatives.
直到1998年
Even by 1998,
宇宙之图上的星系也不过三万个
only 30,000 galaxies had been placed on the map of the universe.
就在那时
That's when
大卫加入了附近阿帕奇波因特天文台的
David joined the Sloan Digital Sky Survey
斯隆数字化巡天计划
at the nearby Apache Point Observatory.
我们当时有预感 这件事将会意义非凡
We had the sense that it was going to be this great thing
千里之行始于足下 但第一步还未迈出
that was starting, but it hadn't actually started yet.
我们的凌霄之志不限于此
What we wanted to do was something much more ambitious
而是绘制成
and actually get a map of
包含一百万个最亮星系的星图
the million brightest galaxies on the sky.
这一任务需要测量距离
The task required measuring the distance,
因此要观测每一个星系的红移
and therefore red shift, for every single one of these galaxies.
显然一次要观测不止一个星系
Obviously you need to look at more than one galaxy at a time,
这就需要诀窍了
so that's the trick.
若你是未来主义者 你也许会说
If you were a futurist you'd say,
已经是20世纪90年代了
"Well, it's the 1990s,
我们有电脑和机器人
"we have computers and we have robots."
而设计斯隆的人们
The folks designing the Sloan, though,
决定采用最实用的方法
decided to take the pragmatic approach and say,
我们只是希望它能干活就行了
well, we actually want this thing to work.
实际上
Instead of robots,
这套精密的系统需要大量的
the ingenious system they came up
人工操作而非机器控制
with required a far more human touch.
他们得对整个宇宙进行两次观测
And they would have to go round the universe not once, but twice.
实际上绘制了两幅星图
It's really doing two maps of the sky.
第一次观测 并没有测量任何红移
The first time round, they didn't measure any red shifts.
望远镜只是用来照相
The telescope simply took photographs...
一幅二维的宇宙之图
A map of the sky, but in two dimensions only.
其中还没有各星系间距的信息
It doesn't give the distance to each galaxy
暂时没有
yet.
从这些图中 我们无法掌握
We actually have from those images not very much idea
星系在三维世界中的位置
of where these things are in three dimensional space.
从某种程度上说 只不过是些美丽的照片
So at some level, it's just a pretty picture.
但是下一阶段就是点睛之笔了
But the next stage was the trick.
他们将二维照片印在金属板上
They printed the pretty pictures in metal.
这里每个孔都对应着
Each of these holes corresponds to
某一星系的二维位置
our two dimensional location of a galaxy on the sky,
以这个孔为例
where if I look at this hole,
我们可以得到它的经度坐标
we have the longitude on this coordinate,
以及纬度坐标
the latitude in this coordinate,
所以该系统的设计目的
and so the whole design of this system
在于尽可能地让星系发出的光
is to as efficiently as possible get the light from that one galaxy
全部射入特定的孔中
into that specific hole.
镇上的插线小组用光纤
The plugging team from town connected every galaxy
将每个星系连接起来
with a fibre optic cable,
然后将金属板固定回望远镜上
then fitted the plate back over the telescope.
在第二次观测时
Second time around,
望远镜对特定星系的红移
the telescope measures the red shifts
进行测量
for these specific galaxies alone.
一块金属板上有一千个星系
1,000 galaxies on a plate,
一晚上测量九块
nine plates a night
人工观测的星系总数
and one million galaxies in total
已达一百万个
on a map crafted by human hands.
真是不可思议
It's hard to wrap my head around
看着一千根光纤
the idea that we're looking at...
就等于面对一千个星系
you know, with 1,000 fibres, we're looking at 1,000 galaxies,
我一度难以相信
and it's... I have a hard time wrapping my head around
宇宙居然如此之大
that the universe is that big.
斯隆数字化巡天是精密宇宙学的
The Sloan Survey is one of the great achievements
巨大成就之一
of Precision Cosmology.
红移测量出距离
Red shift measures the distance -
用作每个星系的最后一维坐标
the third and final co-ordinate for every galaxy...
二维平面一跃而成磅礴浩瀚的三维空间
to make a 3D Movie on a colossal scale.
也许你曾在《星际迷航》或《星球大战》
Maybe you've seen things like this in the opening of Star Trek
影片开场见过类似的壮美画面
or Star Wars or whatever, and that all looks great,
但那不是真的
but it's not real.
你现在看到的画面才是真实的宇宙
This movie - it is the real Universe.
星图上每个光点就是类似银河的星系
Every point of light on the map is a galaxy like the Milky Way.
现在 宇宙学家可以一探
Cosmologists can now see at a glance
太空中星系的空间分布了
how the galaxies are arranged in space.
这些星图使我们能够检验
What these maps let us do, is it really allows us to test
所有已知的自然力量
all the forces of nature we know about.
各种尺度下都存在着物质结构
There is structure, really, on all scales.
星系的分布并非随机而成
The galaxies are not just placed at random -
而是由引力相互约束
they're bound together by gravity,
编织成一张巨大的宇宙之网
in a vast cosmic web.
这一规律雷打不动
This goes on and on,
即使放眼视线所及的最大尺度 依然如此
and in fact up to the largest scales that we can see.
你仍可以找到这些星系间的结构
You can still trace these structures of galaxies.
但最惊奇的莫过于发现了不可见的事物
But the most surprising discovery is what can't be seen.
绝大部分的宇宙 从我们的视线中消失了
Most of the universe is missing.
光凭星系和恒星一类的可见物
The gravity, due to the stuff that we see,
所产生的引力无法实现这种效果
due to say the galaxies and stars, can't do the job.
这些引力
It's simply not enough stuff
还不足以保持如此模式
to arrange things into the patterns that we see,
让星系以各自方式旋转运动
have galaxies spinning in the way that they do.
一定存在别的东西
There's something else there.
除了可见星系 可见物质
There's something beyond the galaxies that we see,
同样存在的东西
the visible matter.
那里存在着某种暗物质
There's some sort of Dark Matter out there.
现代宇宙学需要新一代的制图师
Modern cosmology needs a new kind of map maker.
因为绝大部分的宇宙都藏于黑暗之中
Because most of the universe is hiding in the dark.
我们不知道暗物质是什么
We don't know what Dark Matter is
因为地球上还从未检测到过
because it's never been detected on Earth.
但它一定存在于宇宙中
We know it must be out there,
因为其引力保证了
because its gravity is holding
宇宙这张大网的稳定
the cosmic web of galaxies together.
但我们无法看见 因为它并不发光
But we can't see it, because it doesn't give off light.
必须有人找到它 并将其绘于星图上
Someone has to find it and put it on the map.
英国天文学家理查德·梅西
British astronomer Richard Massey
是不可见物质的专家
is a master of the invisible.
他是探寻暗物质小组的成员
He's a member of a team hunting for Dark Matter,
大部分组员在加州理工学院
based at the California Institute of Technology.
为此 他常常飞往洛杉矶
So, he's a frequent flyer to the city of Los Angeles.
夜晚飞过美国上空时
When you're flying over America at night,
理查德·梅西
英国杜伦大学
你会看到纵横交错的街灯
you see these criss-crossing lanes of street lights
布满整片大♥陆♥
spread out across the continent.
道路被灯光照亮 但显然会有些趣事
There's obviously some interesting stories going on down there,
发生在道路之间
in between these roads.
事实上 大部分在美国发生的故事
In fact, most of the story of what's going on in America
都在你看不见的空白区域
is actually happening in those empty spaces that you can't see.
理查德的任务就好像
Richard's task is like
为这些表面上看似空白的区域绘图
mapping those apparently empty spaces.
一座座城市仿佛隐藏于黑暗之中
It's as if whole cities were hiding in the dark.
当我们开车越过美国大♥陆♥
If we're driving across America,
设法为新边疆绘制地图时
and trying to map out a new frontier,
我们能看到山脉河谷
we can see mountains and valleys
潺潺溪水 可以将它们一并画入地图
and streams and we can draw them all on a map.
但当我们设法测绘宇宙时
But when we're trying to map out the universe,
多数区域都是不可见的
most of its contents are invisible.
在黑暗宇宙中探索 需要想象力的辅佐
It takes imagination to find your way in a Dark Universe.
你必须创造出新方法来检测不可见的事物
You have to dream up new ways to detect what can't be seen.
一种可能是 暗物质如果不发光
One possibility is that if Dark Matter doesn't give off light
那它可能会吸收光
maybe it absorbs light.
普通的物质
Ordinary matter,