银河系 NARRATOR: The Milky Way galaxy...
一个汇集2千亿颗恒星的巨大城市 a vast cosmic city of 200 billion stars.
我们生活在一个安静的环境里 We live in a quiet neighborhood,
藏匿在并肩的丛林中 tucked away in a safe neck of the woods.
但如果我们的行星 穿越过整个星系会怎样呢 But what if we could take our planet on a journey across the galaxy?
从逐渐老去的数十亿年的恒星 From the violent graveyards where stars, billions of years old,
遍布的废墟 go to die...
到广袤的孕育新星之地 to the cosmic cradles where new stars burst to life.
穿越数十亿年的空间和时间 Dare to travel through billions of years of space and time
去发掘我们星系的来源 to find out how our galaxy came to be...
和等待我们的黑暗命运 and the dark fate that awaits us.
这是揭开银河系秘密的 It's the ultimate journey to uncover the secrets that lie...
终极旅程 inside the Milky Way.
现代城市是人类文明中最伟大成就 Modern cities are a testament
的一个明证 to some of the greatest accomplishments of human civilization--
在数百万电灯的照耀下 建筑物光辉灿烂 feats of engineering that dazzle with millions of lights.
但是这明亮的光源掩盖了 一些更为人惊奇的事情 But the bright lights conceal something even more amazing.
把它们熄灭然后注视着… 空中有一座伟大之城 Turn them off and behold... a great city in the sky.
这是什么？嗯，这是银河 JAMES BULLOCK: What is this? Well, this is the Milky Way.
这是我们的星系 This is our galaxy.
如果你想的话，可以把 星系想象为一座恒星之城 Well, if you'd like, you could think of the galaxy as a city of stars.
我们的太阳只是 NARRATOR: Our sun is just one of the 200 billion stars
广阔无垠的星城中的一颗 that make up a vast cosmic city.
我们刚开始了解这城市 A city we're just beginning to know.
做一名天文学家可真不错 BULLOCK: It's really a wonderful time to be an astronomer,
尤其是研究银河时 especially in studies of the Milky Way.
我们正在经历一项变革 We're undergoing something of a revolution.
事实上，我们可以带 你们到非同凡响之地 In fact we can take you places that are really quite remarkable.
我们正要迈出一大步 NARRATOR: We're about to make a major move.
我们正带着地球 We're picking up the earth
穿越数千光年 and traveling across thousands of light years--
将其放置于这星系中遥远的一处 relocating to distant neighborhoods of the galaxy.
从我们新的所在之处 天空看起来很不同 From our new address the sky looks different...
充满了奇迹和美丽 full of wonder and beauty...
被众多灿烂的太阳所照亮 lit by a multitude of brilliant suns...
从而彰显出数十亿岁恒星的力量 ...revealing the power of stars that lived billions of years ago.
在这里，我们将瞥见当 我们的太阳不存在时的未来 Out here we'll get a glimpse of the future, when our sun exists no more.
这是一次揭示宇宙中 一些最伟大秘密的旅程 It's a journey to unravel some of the greatest mysteries of the universe:
银河系如何产生 how the Milky Way was born,
如何存在如此之久 how it survived for so long
以及最终它将如何灭亡 and how it will eventually die.
但在我们的旅程开始之前 But before our trip can begin,
我们需要一张前行的地图 we need a map of where we're headed.
而做出这张地图是天文学家 And making one is the job of astronomers
罗伯特·科什那和 詹姆斯·波洛克的任务 like Robert Kirshner and James Bullock.
第一个障碍是要搞清楚 银河系究竟是怎样的星系 The first obstacle is simply figuring out what kind of galaxy the Milky Way is.
哈勃空间望远镜 The Hubble Space Telescope
可以让天文学家们 看到数十亿其他的星系 gives astronomers the capability to see billions of other galaxies.
每一个都是不同的 Each one is different.
但结果却发现存在一个模式 But it turns out there is a pattern.
当我们去研究宇宙中其他的星系时 BULLOCK: When we look out to study other galaxies in the universe,
我们发现主要有两种星系 We see that there are basically two types of galaxies.
第一种，椭圆星系 NARRATOR: The first type, elliptical galaxies,
看起来像恒星构成的巨大球体 appear as large balls of stars,
无论从什么角度观察 and no matter what angle they're viewed from,
他们看起来总是圆的 they always look rounded.
另外一种是所谓的：”螺旋星系” The other main class is the so-called “spiral galaxies,“
因为构成它们的恒星 从中心开始螺旋外散 because their stars are contained in arms that spiral out from their centers.
从远处看，螺旋星系像一个飞碟 From a distance, a spiral galaxy looks something like a Frisbee.
正确定义银河的关键 The key to correctly identifying the Milky Way
就呈现在我们的夜空 is written across our night sky.
我们相信银河系是一个螺旋星系 BULLOCK: The Milky Way, we believe, is a spiral galaxy.
所以我们在夜晚 So what we're really seeing,
真实看到的 when we look up at night at this band,
是我们在宇宙中看到的我们的所在 is we're seeing our place in the universe.
我们是一个巨大盘面星系中的一部分 We're part of a giant disc of stars.
但是从内部看才是这样 NARRATOR: But that's just an insider's view.
当然，现在我无法给你们 展示一张星系光芒万丈的图片 BULLOCK: Now, of course I can't show you a picture of the galaxy in all its glory.
我们无法飞跃星系之上 然后拍照给你看 We can't fly above the galaxy and take a picture of it and show you.
我们处于星系盘面之上 We're stuck in the disc of the galaxy,
但我们仍然可以从地面摄图 but we can still image it from the ground.
事实上，这张图片就是从地面拍摄的 In fact, this image is a picture of our galaxy, the Milky Way,
我们的星系，银河系 taken from Earth.
这是最详细的图片之一 NARRATOR: This is one of the most detailed images
取自于我们的星系 of our galaxy ever created.
它是由8亿像素构成 It's made from 800 million pixels
包含1千多张独立图片 contained in over a thousand individual photographs,
拍摄于地球中最黑暗的地方 taken from the darkest places on Earth.
这些图片被煞费苦心的整合在一起 The photos have been painstakingly stitched together
创造出了这幅壮观的画面 to create this breathtaking view.
尽管已经如此令人印象深刻了 但它还只是其中一部分 But impressive as it is, it's only part of the picture.
它就像个比萨 ROBERT KIRSHNER: It's something like a pizza.
如果你处于比萨当中 如果你是个意大利辣香肠 And if you were in the pizza, if you were a pepperoni,
你就无法看清整个事物 your view would not be a very clear one of what the whole story was.
同样的，我们无法看到整个银河 In the same way, we don't see the whole reach of the Milky Way.
天文学家非常需要鸟瞰 NARRATOR: What astronomers really need is a bird's eye view.
你会需要离开银河 KIRSHNER: You would need to get out of the Milky Way
然后真切的看清它的样子 to really see what it looks like.
我们无法那样做 We don't have a way to do that,
但是我们可以观测其他星系 然后看它们的样子 but we can look at other galaxies and see what they look like.
哈勃的照相机惊人 详细的捕捉到临近星系 NARRATOR: Hubble's cameras capture nearby galaxies in amazing detail--
譬如，梅西耶74 like Messier 74.
尽管它有超过3千万光年远 Although it's over 30 million light years away,
它仍是我们的近邻之一 it's one of our closest neighbors.
梅西耶74是一个美丽的螺旋星系 Messier 74 is a beautiful spiral galaxy.
它巨大、闪亮的臂膀从 一个明亮的中心旋出 Its large, starry arms sweep out from a bright core.
这是一个星系的例子 BULLOCK: This is an example of a galaxy
天文学家认为它看起来 很像我们的星系，银河系 that astronomers think looks a lot like our galaxy, the Milky Way.
这是我们自己星系城市的伟大展现 This is a great representation of our own star city.
在中心地带，我们有市中心 In the central region we have the downtown.
这是突起部分，中间的闪亮点 This is the bulge, this bright spot in the middle,
从那里我们看到，这些分支螺旋而出 and from that we see, spiraling out, these arms,
在这个星系中我们看到了 这些美丽的螺旋结构 these beautiful spiral structures we see in this galaxy.
天文学家用哈勃拍摄到的 NARRATOR: Astronomers compare Hubble's incredibly detailed images
其他星系的详尽图片 of other spiral galaxies
和我们从地球拍摄的 with the best images of our own galaxy
自身星系的最好图片作对比 taken from the ground.
用卫星来测量不同方向的 Using satellites to measure the distance and density
恒星的距离和密度 of stars in different directions,
天文学家揭示了我们 星系城市隐含的壮观图纸 astronomers reveal the grand plan underlying our star city.
在它的心脏部位 一个明亮的中心地带 At its heart, a bright central region--
星系核心 the galactic core--
我们星系的中心城区 our galaxy's downtown district.
从这里伸出的两个巨大旋臂 数十亿恒星的集合 From here two majestic spiral arms, bright bands of billions of stars,
旋转而出 sweep out--
长形盾一半人马座 Scutum Centaurus
和英仙臂 and the Perseus arm.
还有其他三个小臂 There are also three smaller arms.
从一端到另一端 From one end to the other,
我们星系的长度为 惊人的60万万亿英里 our galaxy measures a staggering 600,000 trillion miles.
光要花费10万年 才能穿过我们的星系 BULLOCK: it takes light 100,000 years to cross our galaxy.
这是个巨大的星系 This is a big galaxy,
并且如果你想想的话，会非常惊人 and it's quite amazing, if you think about it,
我们对这个天体系统尽力的了解 that we understand as much as we do about this system.
我们的太阳和太阳系位于这里 NARRATOR: Our sun and the solar system are located here--
在两个旋臂之间 in a quiet neighborhood nestled between two spiral arms.
这是我们所熟知的星系位置 This is the galactic home address that we know so well.
但是我们周围的环境却非常不同 But our surrounding neighborhoods are wildly different.
如同其他大城市 存在活力的工业区 Like any large city, there are dynamic industrial zones...
在那里，热量和压力迫使新星 where heat and pressure forge new stars
和其他恒星在猛烈的爆炸中灭亡 and others die in violent explosions.
市中心，在星系的心脏地带 Downtown, in the very heart of the galaxy,
恒星被神秘的力量驱使着去争夺空间 stars jostle for space, pulled by mysterious forces.
[人们的叫声] [people screaming]
我们的星系也有古怪 有历史性的周边环境 Our galaxy also has quaint, historic neighborhoods
讲述出我们的恒星之城是 如何被建造的 that tell the story of how our star city was founded.
现在我们朝向银河中 最壮观的地点之一进发 Now we head to one of the most spectacular locations in the Milky Way--
这里有着线索 a place that holds the clue
关于星系中2千亿颗恒星 to how the 200 billion stars of the galaxy
最初如何被创造出来 were first created--
在太阳系所在的角落里 and it's just around the corner.
我们收拾好然后起程 We're picking up and leaving home.
我们带着我们的行星上路 We're taking our planet on a journey.
目的地？ The destination?
是恒星诞生的地方 A place where stars are born.
它可能看起来很近，但即使以 It may look close by, but even traveling at the speed of light--
186000英里每秒的光速 186,000 miles a second--
也要花上1500年 the trip takes 1,500 years.
我们到达了一团炙热的 气体和尘土云团 We arrive at a vast glowing cloud of gas and dust:
猎户座大星云 the Great Orion Nebula.
美丽的新色彩充满了我们的夜空 Beautiful new colors fill our evening sky.
但这团云不只是艺术品 But this cloud isn't just a work of art.
它关乎我们的太阳和 星系中的每颗恒星 It holds the key to how our sun, and every star in the galaxy,
是如何产生的 came to be.
银河充斥着数十亿颗恒星 The Milky Way is filled with billions of stars in every direction.
从地球上，肉眼也能看到 From Earth the naked eye
巨大，阴暗，表明没有恒星的斑块 also picks out large, dark, seemingly starless patches.
对于天文学家波洛克来说 To astronomer James Bullock,
在这些地区 事情并不象初看到的那样简单 in these areas, there's more than meets the eye.
也许这幅图中最美丽的部分 BULLOCK: Perhaps the most beautiful part of this image
是我们关于黑暗和光亮地区的对比 is that we have this contrast of dark and light regions
汇集在平面之上 running through the plane of the disc.
它其实就是，尘土 What that really is, it's dust.
有很多尘土团 There are clouds of dust
在恒星图片背景上留下的阴影 that are casting a shadow from the back of the stars,
恒星试图发散的光亮 and the stars are trying to shine their light through,
那里的尘土团把光线阻隔 there are dust clouds there that are blocking the light,
很像地面上阻挡太阳的云团 much like a cloud on Earth would block the Sun.
这些巨大的气体尘土团 NARRATOR: These vast clouds of cosmic gas and dust
延伸过银河数千光年 stretch thousands of light years across the Milky Way.
哈勃在大部分螺旋星系中 发现了它们 Hubble finds them in most spiral galaxies.
黑暗，可怕的地带，横扫过旋臂 Dark, ghostly bands, woven through the spiral arms--
延伸至整个盘面 and spreading across the entire disc.
但是这团气体尘土很奇怪 But there's something strange about this gas and dust.
有时它会发光 Sometimes it glows.
这些明亮的发光云团被称为星云 These bright glowing clouds are called nebulas.
每一个都是独特的，并且惊人的美丽 Each one is unique... and breathtakingly beautiful.
鹰星云，有着4光年向上 支撑的塔柱体积 The Eagle Nebula, with towering pillars up to four light years in size,
而船底座星云，有着独特的绿光 and the Carina Nebula, with its distinctive green glow.
这些震撼的颜色揭示出 这些星云是由什么气体组成的 These vibrant colors reveal what gases nebulas are made of.
那么，例如，如果有氧气 KIRSHNER: So, for example, if there's oxygen gas,
你会看到绿光 YOU get a green glow.
如果有氢气，你有看到红光 If there is hydrogen gas, you get a red glow.
所以研究星云散发的 光是非常有益的 So analyzing the light from a nebula turns out to be very instructive.
它告诉我们有什么 还告诉我们物质状况如何 It tells us what's there, it tells us what the physical conditions are,
我们可以分辨出它的密度 它的热量 we can tell how dense it is, how hot it is
和它的组成部分 and what it's made of.
我们可以从周边搞清楚很多 We can find out a lot about the neighborhood
通过查看发光气体直接给出的线索 by looking at these clues that come directly from the glowing gas.
这些气体以数千度发热 NARRATOR: The gases glow at thousands of degrees,
从这些星云深处的神秘源头发热 heated from a mysterious source hidden deep within the nebulas.
要搞清楚源头是什么 我们需要深入窥视 To figure out what the source is, we need to peer deep inside.
但是，当然了 气体和尘土阻挡了我们 KIRSHNER: But of course the gas and dust is in the way.
所以，这并不容易 So it's not so easy.
这是星系中的神秘部分 It's a very mysterious part of the galaxy.
这是我们不得不用 独特技巧去探寻的地方 It's a place that we have to use these special tricks to look into.
金伯利．韦弗是个天体物理学家 NARRATOR: And Kimberly Weaver is an astrophysicist
她有着很多技巧 who's got a few tricks up her sleeve.
我可以很简洁的给你们展示 KIMBERLY WEAVER: I've got a really neat way to show you this.
这是个你用肉眼看不穿的包 This is a bag that you can't see through with your eye.
所以一架普通光源的望远镜 So a normal telescope that looks at optical light
是看不到这里面的． could not see through this.
红外线望远镜 则可以看见里面． In infrared light, a telescope can see through it.
红外摄像机， The infrared camera,
如果我把手放在里面， 就可以看见我的手． if I put my hand inside, can see my hand.
我来扭动手指 演示给你看． I'll wiggle my fingers to show you.
但是你看到的是 我的手在袋子里发出的热量， But you're seeing the heat from my hand inside the bag,
这就像那些藏在气体和尘埃云团 后面的星体． and this is just like a star that's hidden inside a cloud of gas and dust,
天文学家可以通过红外线望远镜 来观测它们． that infrared astronomers can detect by using an infrared telescope.
这是在可见光下 看到的猎户星云． This is a picture of the Orion Nebula in visible light.
看这些气体 We can see all of the gas here
挡在被遮蔽的星体 的前面， located in front of what we know are stars in the background,
我们想透过星云 去观察那些星体． and we want to be able to look inside this nebula and see the stars.
这是红外图， In infrared light, in this image,
我们现在可以 看到星云里面的星体了． we can now pick out the stars inside the nebula,
而且我们可以看到星体 周围有一层尘埃的茧． and we can see dusty cocoons around the stars.
但是科学家依旧需要找到 去除那些留下来的尘埃的方法 NARRATOR: But scientists still need a way to strip away the remaining dust.
我们怎么样才能 避开这些雾气？ WEAVER: How do we get rid of all this haze and fog?
方法是X射线成像． The way to do that is with an X-ray picture.
现在我们换到 X射线图像， Now when we transition into the X-ray image,
你就能只看到 星体本身了． you can see just the stars themselves,
X射线来自 星体的表面， the X-rays coming from the surfaces of the stars,
现在我们能 研究它们的细节了． and now we can study them in great detail.
通过分析 这些星体发出的光， NARRATOR: By analyzing the light from these stars,
天文学家能 有很多惊人的发现． astronomers make an astounding discovery.
在猎户星云里能发现一些 迄今为止发现的最年轻的恒星 Hidden within the Orion Nebula are some of the youngest stars ever found--
它们只有几十万年的历史－ stars just a few hundred thousand years old--
只是银河系生命长河 中的一次心跳． a mere heartbeat in the life of the galaxy.
而且不仅仅猎户星云是这样． And it's not just the Orion Nebula.
在星系的每一支旋臂上星云里 都藏着处在幼年期的星体 Nebulas house baby stars in every spiral arm of the galaxy.
这些区域是 新星的育儿室． BULLOCK: These regions are the nurseries for new stars.
这些区域里 有一些年轻的星 There are young stars in these regions
它们在加热它们周围 的气体云 that are heating up gas clouds that surround them
并且让气体云 发出粉色的光． and making those gas clouds glow pink.
基本上，恒星由气体构成， Stars are made out of gas, basically,
而我们的星系有很多气体． and our galaxy has gas.
事实上，我们的星系，你能想见 In fact, our galaxy, you can think of it
有一个由气体和尘埃 组成的气层 as having an atmosphere of gas and dust
包围着我们在整个星盘上 能看见的所有的恒星， that surrounds all of the stars that we see in the disc,
并且新星从这些 气体中诞生． and it's from this gas that new stars are born.
通过观察星云进化 的不同阶段， NARRATOR: By observing nebulas at different stages in their evolution,
星体诞生的过程 便浮出水面． the story of a star's birth begins to emerge.
所有的一切开始于一团由尘埃和 氢气组成的又冷又暗的云， It all starts inside a cold, dark cloud of dust and hydrogen gas,
一场拔河赛在这里展开． where a quiet tug of war begins.
云想要散去， 像空气中的烟雾一般， The cloud wants to dissipate, like smoke in the air,
但重力却想把它们 拉到一起． but gravity wants to pull it together.
在重力和气体张力之间 KIRSHNER: They're in a kind of balance
有一种 平衡． between gravity pulling in and gas pressure pushing back out.
重力胜利了，物质 开始塌陷成一个圆盘 Gravity wins, and the material crunches down into a disc
这就是一颗恒星 形成的开始． that is the beginning of becoming a star.
当重力将越来越多 的气体拽向 NARRATOR: As gravity pulls more and more gas
圆盘的中心， towards the center of the disc,
气体变得越来越稠密， 越来越热…… it gets denser and denser and hotter and hotter...
……直到最后， 到了1800万度的时候， ...until finally, at 18 million degrees,
一场奇迹般的 转变发生了． a miraculous transformation takes place.
氢气原子 融合成氦― Hydrogen atoms fuse together to form helium--
随着一次核爆炸， 一颗新星开始闪耀光芒． and with a burst of nuclear energy, a star begins to shine.
最终这些星体会在 它们的核心燃烧核能． KIRSHNER: These stars eventually get their nuclear fires going in the core.
当它们那么做时，它们变热 And when they do, they heat up,
它们可以赶走 它们周围的物质 they can expel the material that's around them
好像在清理 自己的邻居一样． so that it kind of clears up the neighborhood.
剩下的 几百万年， NARRATOR: Over the next few million years,
风把周围的气体 吹成壮观的旋涡形状． winds blow the surrounding gas into spectacular swirling patterns.
它把气体吹走， 把尘埃吹走 KIRSHNER: it blows away the gas, it blows away the dust
它让我们能 看见这美丽的东西， and it lets us see this beautiful new thing,
这块新星 诞生的地方． this place where the star has been born.
人的一生太短暂， NARRATOR: A human lifetime is too short
看不到旋臂上 恒星诞生的奇迹景观． to witness the wonder of a star's birth in the spiral arms.
但是把宇宙的几百万年 浓缩至几分钟， But by speeding up millions of years of cosmic time into just a few seconds,
我们就能看见 恒星纷纷诞生． we can see one star born after another.
到处都有更耀眼的亮光， Here and there are even more brilliant flashes of light,
在整个银河系最危险 coming from some of the most violent and dangerous neighborhoods
最恐怖的区域中闪现， in the entire Milky Way galaxy.
在这些地方恒星不再诞生，…… Here stars aren't born...
它们死去． they die.
我们把地球 We're taking the Earth
带出太阳系 的熟悉区域 from the familiar neighborhood of the sun
去拜访一下英仙臂 的胜景， to visit the wonders of the Perseus Arm,
大约6500光年之外． nearly 6,500 light years away.
这里有着银河系 最美的风景之一― Here lies one of the galaxy's most beautiful sights--
蟹状星云． the Crab Nebula.
虽然是由气体和尘埃组成的， 这个星云尚未创造任何新星． Although it's made of gas and dust, this nebula hasn't created stars...yet.
但是对亚历克斯弗利宾可来说， But for Alex Filippenko,
这个区域 代表着我们星系的工业区， this area does represent the industrial zone of our galaxy,
很久以前，建造地球的积木 从这里被生产出来． where the building blocks of Earth were manufactured long ago.
看那熔化的铁． 我的上帝！ ALEX FILIPPENKO: Look at that molten iron. Holy moly!
蟹状星云非常迷人． The Crab Nebula is a fascinating object.
我们可以看见这些 快速扩张的气体． We see these very rapidly expanding gases.
星云看起来是静止的，但是气体 在以每小时300万英里的速度 NARRATOR: The crab may look static, but gases are racing out from its center
从中心向外扩散， at over three million miles an hour,
这股力量来自于以前的一次爆炸． put into motion by a phenomenally powerful and violent event in the past.
当我们检查 那些向外扩散的 FILIPPENKO: When we examine the gases of the Crab Nebula,
蟹状星云的气体， which are expanding outward,
我们回溯到 扩张开始的时间， and we extrapolate that expansion backward in time,
发现所有的气体 在大约一千年前 we find that all of the gases were at a common point
是在同一个地点的． about a thousand years ago.
回到地球上， 大约一千年前， NARRATOR: Back on Earth, a thousand years ago,
人类早期的文明 曾仰望过星空． early civilizations watched the heavens.
在1054年，一部中国文献描述了 一颗明亮新星的出现． In 1054, Chinese manuscripts describe the sudden arrival of a brilliant new star.
它比其他恒星更亮， 在白天都可以看到． It shines brighter than any other star, so brightly it's visible during the day.
但是它神秘地消失了． But then it mysteriously disappears.
今天，蟹状星云 在天空中的位置 Today, the Crab Nebula lies in exactly the same part of the sky
和中国人看到那颗 明星的地方一样． where the Chinese observed their brilliant star.
他们看到的是 蟹状星云诞生的瞬间． What they witnessed was the moment the crab was born.
蟹状星云是 诞生于 FILIPPENKO: The Crab Nebula was produced
一颗恒星在生命终结时 所产生的巨大的爆炸． by the colossal titanic explosion of a star at the end of its life.
它是一颗超新星的残余． It's a supernova remnant.
我们银河系 的旋臂上 NARRATOR: The spiral arms of our Milky Way
到处漂浮着这些 缤纷的残余物． are littered with these colorful remnants.
在恒星们通过剧烈的爆炸 Tombstones of stars that died violently
死亡后留下的墓碑 被叫做超新星． in cataclysmic explosions called supernovas.
要探索这背后神秘的故事， 天文学家需要找到下一个受难者 To figure out this mystery, astronomers need to locate the next victim--
一颗苟延残喘的巨星． a massive star at the brink of death.
天文学家 就像侦探． FILIPPENKO: Astronomers are like detectives.
我们要弄明白 在这个宇宙发生的一切 We have to figure out what's going on in the universe
有时候只能 依据一些极少的线索 sometimes based on a minimal number of clues,
而对大多数天文学家来说， 线索只来自于光． and in the case of most astronomers, the clues come from only the light.
安迪豪威尔知道 要抓住一颗新星的光， NARRATOR: Andy Howell knows catching light from a supernova
时机最为重要． is all about timing.
一个星系中 ANDY HOWELL: Supernovae happen about once every 70 years
出现超新星的间隔是70年， in a galaxy on average,
即大约一个人的一生． so about the human lifetime.
所以可能你一生 都不会看见一次． So chances are you're not going to see one in your lifetime.
实际上银河系 上一次出现超新星 In fact the last one in our galaxy that anybody saw
是在400年前 was about 400 years ago.
所以已经过去了很久， So it's been a long time,
而且，你知道，我以 研究超新星为生． and, you know, I study supernovae for a living.
如果我只等着银河系能出现一次 超新星，我的工作就没法做了． I couldn't do this if I had to just wait for one in our galaxy.
但是值得豪威尔和弗利宾可 感激的是， NARRATOR: But thankfully for Howell and Filippenko,
他们不缺可供研究的星系． there's no shortage of galaxies.
所以我们做的就是 观察其他星系，更远的星系． HOWELL: So what we do is we look at other galaxies, more distant galaxies.
宇宙中有 几十亿星系， There are billions of galaxies out there,
我们可以观察在那些 星系中的超新星． and we see the supernovae that happen in those galaxies.
如果你观察70个星系， 平均一年可以发现一颗． And if you look at 70 galaxies, on average you'll find one a year.
如果你观察700个星系， 你平均一年能发现10颗，以此类推． If you look at 700 galaxies, you'll find ten a year, and so on.
数字带有某种力量． FILIPPENKO: There's power in numbers.
如果我观察成千上万的星系， 我们就能得到非常多的机会． If we look at thousands of galaxies, we improve our odds tremendously.
这是弗利宾可和他的同事 NARRATOR: This is a supernova
幸运地抓拍到的 一颗超新星…… that Filippenko and his colleagues are lucky enough to catch--
在一个5500万光年以外的星系 的外围的一颗正在爆炸的星体． an exploding star on the outskirts of a galaxy 55 million light years away.
它在短暂的时间里比整个 星系都要亮 It briefly outshines the entire galaxy--
几十亿恒星的光芒 浓缩到了一颗正在死亡的恒星身上． the light of a billion suns distilled into one dying star.
几百万或几十亿光年之外 HOWELL: it takes supernova light
的超新星的光 a million, or even a billion years to get here
需要一百万年 或者甚至十亿年才能到达这里． if they're millions or billions of light years away.
但是它们只发光一个月， But they only shine for about a month,
所以在那光永远消失之前 so we have this little tiny window to study these things
我们可以通过这些小窗口 来研究它们． before that light is gone forever.
在工作室里， 豪威尔和他的团队 NARRATOR: In the workshop, Howell and his team
正在忙着 准备他们的望远镜． are busy preparing their telescopes.
很酷啊． 没错． HOWELL: Pretty cool. WOMAN: That's right.
我们在建立 一个天文望远镜网络 HOWELL: We're building a network of telescopes
比以前 so that we can study supernovae in greater numbers,
更细致地研究更多的超新星． in greater detail, than we've ever been able to before.
让我给你看 我们正在建的望远镜． Let me show you the telescopes we're building.
这些是0.4米望远镜 These are the 0.4 meter telescopes
这里有四台， and there are four of them here,
我们一共 在建造20台这样的， and we're building them, 20 of them in total,
把他们安装在 世界的各个角落． and putting them all around the world.
先做好的这些 会安装在智利， So some of these first ones will go to Chile,
夏威夷已经有了一些． we have some in Hawaii already.
让我来给你看 我们正在建造的 So let me show you one of the bigger telescopes
最大的望远镜的其中之一 we're building here.
这里我们有 一米望远镜． Here we have the one meter telescope.
我们大概要造15架． We're building about fifteen.
镜片还没装上， 但这里是装镜片的地方． The mirror's not here yet, but this is where it's going to go.
那可以反射我们从超新星 上收集到的光． That will reflect the light we gather from the supernova.
我们必须让它 可以指向天空的任何地方 We have to be able to point anywhere in the sky,
你就能看见 望远镜跟着轴一起转动， and so you can see that the telescope pivots along this axis,
走C状的轨道． and this C ring moves.
这种观察方法 的好处就是 The great thing about this kind of observing
它是完全机械化的， is that it's totally robotic,
我只用坐在 圣巴巴拉市的这个地方 and I can just sit here in Santa Barbara
喝点小酒吃块披萨 而望远镜在做它们的工作． and have a beer and pizza while the telescopes do their work.
就能发现宇宙各处 所有跟超新星有关的情况． All new discoveries about supernovae from all different places in the universe.
一旦他们抓拍到 一颗正在死亡的恒星的光芒， NARRATOR: Once they've caught the light of a dying star,
侦查工作就开始了． the detective work begins.
我们收集光 并对它做十分仔细的分析 FILIPPENKO: We collect that light and we analyze it in great detail
来推断出 发生了什么情况， in order to determine what's going on,
星体的 化学构造 what's the chemical makeup of the star,
内部压力如何， 温度如何， what's the pressure inside, what's the temperature,
正在发生 怎样的核反应， what kind of nuclear reactions are going on,
一颗恒星是怎样爆炸的． how does a star explode.
所有这些 我们通过对光的分析来得出结果． All of these things we figured out through the analysis of light.
天文学家推测 只有巨大的星球 NARRATOR: Astronomers deduce that only stars with a huge mass
会爆炸． go out with a bang.
一颗巨大的恒星 有它有趣而有力的一生． FILIPPENKO: A massive star has a very interesting and vigorous life.
最初它会将氢聚变 组成氦． Initially it fuses hydrogen to form helium,
那样会产生能量． and that produces energy.
那样会让星体发光． That makes the star shine.
然后那种反应的结果， 氦， Then the ashes of that reaction, the helium,
聚变成 碳和氧， fuse together to form carbon and oxygen,
然后释放更多能量． releasing yet more energy.
而碳和氧能够 聚变成更多重元素， Then the carbon and oxygen can fuse into still heavier elements,
镁，钠，氖 之类的， magnesium and sodium and neon and things like that,
然后硅和硫， 最后是铁． and then silicon and sulfur, and finally iron.
当开始产生铁， 这颗巨星就难逃一死了． NARRATOR: When it starts to make iron, the giant star is doomed.
在星体内核 正发生一场能量战： In the core a fierce battle takes place:
能量想往外走， 支撑着， energy pushes outwards, holding it up,
而重力想 让它往里面坍塌． while gravity wants to crush it inwards.
能量战继续着 直到星体制造出更重的元素― The battle continues as the star makes heavier and heavier elements--
制造更多能量 来抵抗完全的崩塌． producing energy while fending off total collapse.
但是一旦铁开始形成， 能量在战役中就走向失败了． But once it starts to form iron, the battle is lost.
铁核子聚变 成更重的元素时， FILIPPENKO: Fusion of iron nuclei into heavier things
就不再释放能量， 它开始吸收能量． does not release energy, it absorbs energy.
所以从一颗铁核形成 So an iron core builds up,
到它最后变得太大了 而引力最终取得胜利． but finally it becomes so massive that gravity wins.
铁核开始坍塌． The iron core collapses.
一秒不到的时间 外层向里坍塌． In less than a second the outer layers collapse inward,
然后反弹回去 化作无数碎片． then rebound and get blown to smithereens.
但是这死亡将 带来新生． NARRATOR: But from this death comes new life.
[火车鸣笛] [train horn blows]
[鸣笛声] [horn blows]
我们现在在一个铸造厂， FILIPPENKO: We're at a foundry here,
他们正在熔化 废旧机器上的铁， and they're pouring molten iron from old machinery,
他们要用那些铁 制造新的机器． and they're going to make parts for new machines out of that iron.
他们在循环利用． So they're recycling it.
但是所有被喷射到 宇宙中的铁 But all that iron was created and ejected into the cosmos
都是来自于巨大恒星的 超新星爆炸． by gigantic stars that exploded as supernovae.
那些爆炸制造了铁， 并把它们扫卜到宇宙中， Those explosions created the iron, ejected it into the cosmos,
然后它们组成了 像我们这样的行星系统的一部分． and then it got incorporated into planetary systems like ours.
但是总的来说铁原子 都是来自于这些爆炸的星球． But ultimately the atoms of iron were created by exploding stars.
超新星是我们星城 的工业区― NARRATOR: Supernovas are the industrial zones of our star city--
制造新元素的 宇宙铸造厂． cosmic foundries that forge new elements.
在灾难性的爆炸中 In catastrophic explosions
重元素被喷射 到宇宙中， heavy elements are spewed out into our galaxy,
在几十亿年的时间中 充实着这片星系． enriching it over billions of years.
所以如果这些恒星 FILIPPENKO: So if some stars were not to explode
不在这些工业区爆炸的话， in the industrial zones of galaxies like our Milky Way,
比如说我们银河系， then we wouldn't have these industrial zones here on Earth.
那我们在地球上 也不会有这些工业区了． It all is linked.
一切皆有联系． We're all linked to the cosmos.
我们跟宇宙联接在一起． NARRATOR: Our lives today are only possible
因为这些十亿百亿 年前发生的事 because of events that happened thousands of millions of years ago
才让我们今日 在地球上的生活 in the hearts of supernovas.
成为了可能． [horn blows]
这令人着迷，意识到我们身体 中的重元素， FILIPPENKO: It's fascinating to realize that the heavy elements in our bodies,
细胞里的碳， 骨头里的钙， the carbon in our cells, the calcium in our bones,
呼吸的氧气， 血细胞中的铁 所有 the oxygen that we breathe, the iron in our red blood cells,
所有这些重元素 all of those heavy elements were synthesized,
都是通过星球的核反应 合成，创造的 created through nuclear reactions in stars
被超新星喷射 到宇宙之中． and ejected into the cosmos by supernovae.
但是只有某些 星球大到可以作为超新星死去． NARRATOR: But only a handful of stars are massive enough to die as supernovas.
大多数的恒星，像我们的太阳 会经历更温和的死亡． Most stars, like our sun, suffer a more gentle death.
大多数恒星 不会大爆炸而死． FILIPPENKO: Most stars don't die in a cataclysmic explosion.
比如，我们的太阳， 一颗典型的恒星， Our own sun, for example, a typical star,
会在一声口乌咽中死去， 而不是爆炸而死． will die with a whimper, not a bang.
当重力向内拉拽时死亡便来临 NARRATOR: Death comes when the gravity pulling in
向外推的核能最终屈服． finally succumbs to the nuclear energy pushing out.
这时，任何星球， 甚至是我们的太阳，也会死去． When this happens, any star, even our sun, will die.
40或50亿 年间 FILIPPENKO: In about four or five billion years
它会长成一个比原先更大的星球 叫作红巨星． it'll grow into a much bigger star, a star called a red giant,
而外层气体 and the outer atmosphere of gases
会松弛地 聚在太阳周围 will be held so loosely by the sun at that time
那些气体会被轻轻吹散， 我称之为“宇宙之嗝”. that the gases will be blown away gently, in what I call a cosmic burp.
这些宇宙之隔 离开死去的星球 NARRATOR: These cosmic burps leave behind dying stars
这些星球正在舒展他们的旋臂， 慢慢褪去层层元素． that litter the spiral arms as they slowly shed layers of elements.
有些层是氧气 有些层是硅 HOWELL: Some layers are oxygen and some layers are silicon
有些是硫， and some layers are sulfur,
那些 就是我们 and those are the different colors we see
在哈勃望远镜上 看到的不同色彩． in the Hubble Space Telescope images.
离我们的太阳不远处 有颗恒星正在死亡： NARRATOR: Not far from our sun is a place where a star is dying:
螺旋星云． the Helix Nebula.
它展现了 大部分恒星是怎样结束生命的． It sheds light on how most stars end their lives.
我们的太阳 会在50亿年后， Our sun is destined to follow a similar path when it dies,
以相似的方式死去． five billion years from now.
但是在银河系的 其他区域， But in other neighborhoods in the galaxy,
星球正在经受比死亡 更严酷的命运． stars suffer a fate worse than death.
在银河系的中心 At the center of the galaxy
恒星在一个地方 一起消失． lies a place where stars disappear altogether.
[人群的叫声] [people screaming]
我们将地球 带出安全的家园 We're taking the Earth from the safety of home
去市中心， 去银河的心脏． to go downtown, to the heart of the Milky Way.
这是一个有活力，刺激的地区 但同时也危机四伏． It's a dynamic, exciting district, but it's also a risky place to hang out.
[叫声] [screaming]
安德里亚·盖茨花了15年多 的时间来探索这片区域． Andrea Ghez has spent over 15 years exploring this neighborhood.
如果我们从 旋臂开始旅行， ANDREA GHEZ: If we were to take a trip from the spiral arms,
从太阳附近， out where we are by the sun,
到银河系的中心， 那会是一次很有趣的行程． down to the center of the galaxy, it would be an interesting trip.
那很像是 从郊区 It would be very much like moving from the suburbs
搬到繁忙的 大都会的中心地带． into the heart of a very busy metropolitan area.
当我们往市中心进发， 我们会看到更多的星体． NARRATOR: As we head downtown, the number of stars increases.
在银河系中心 星体的密度很高． GHEZ: So the density of stars is tremendous at the center of the galaxy.
比太阳附近的密度 高大概10亿倍． It's about a billion times higher than out here by the sun.
这里，在银河系的中心， NARRATOR: Here, at the center of the galaxy,
天空中有很多恒星 there are so many stars in the sky
地球沐浴 在一片永恒的亮光中． that the Earth is bathed in perpetual light.
这看起来非常美 同时很危险． It's a stunning but dangerous sight to behold.
这些恒星不只是靠近彼此． The stars aren't just close together.
它们以极快的速度移动着． They're moving at super speed.
去银河系的心脏 GHEZ: Going to the heart of the galaxy
可能跟去一个游乐场 相差不远． might not be dissimilar to going to an amusement park.
过山车跟 The rides are somewhat similar
那些银河系中心 恒星的环状轨道运行的方式相似． to how the stars orbit the center of the galaxy.
每小时一千万英里的速度， 比如，跟我们的太阳比， Ten million miles per hour, compared to, say, our sun,
快了50倍． is about a factor of 50 times faster.
所以我们银河系的中心 肯定发生了什么 So something has to be going on at the center of our galaxy
导致了这种现象． to make that happen.
但是要弄明白发生了什么 不是一件小事． NARRATOR: But figuring out what is no small task.
银河系的中心 在两万六千光年之外． The heart of our galaxy lies 26,000 light years away.
很难透过 It's difficult to observe
大量的恒星，气体和尘埃 看个究竟． through the vast amounts of stars, gas and dust.
而且靠近我们的家园 有另外一个问题： And there's another problem even closer to home:
地球的大气层． the Earth's atmosphere.
大气层 对我们很有利． GHEZ: The atmosphere is great for us.
它让我们 能在地球上生存． It allows us to survive here on Earth,
但是它对天文学家 来说绝对是个头疼的课题． but it's an absolute headache for astronomers.
就像想要看到 It's very much like the problem
溪流里的 一颗卵石一样难． of looking at a pebble at the bottom of a stream.
溪水不停地流动， 汹涌 The water in the stream is moving by and it's turbulent
让我们很难 有一个清晰的视角． and it makes it very difficult to get a clear vision.
同样的， 从地球的大气层向外看 In the same way, looking through the Earth's atmosphere
它阻止了我们看到 银河系中心星体的清晰图像． prevents us from getting clear pictures of the stars at the center of the galaxy.
所以像盖茨这样的天文学家 NARRATOR: So astronomers like Ghez
求助于 自适应光学这样的技术 turn to a technique called adaptive optics
来得到更好的视野． to get a better view.
通过测量大气湍流 如何扭曲了激光， By measuring how a laser beam is distorted in moving air,
来矫正 大气的抖动所造成的模糊． it's possible to compensate for the atmosphere's blurring effect.
让我给你举个例子 GHEZ: So let me show you an example
来证明自适应光学技术 多么强大． of how powerful adaptive optics is.
我们想看的星体 The stars that we want to see
是在中心 的这几个， are the ones that are at the very center,
我们认为 银河系的中心 and we think the heart of the galaxy
是在这个盒子的中央 被显现出来． is right within the center of this box, which is panned out here.
没有自适应光学技术 这片区域会变模糊． Without adaptive optics, this region looks completely blurry.
你看不到每一颗恒星． You don't see the individual stars.
有了自适应光学技术 你能看清每一颗． With adaptive optics you see the individual stars.
15年来盖茨 拍了银河系中心 NARRATOR: For 15 years Ghez has taken infrared images
的星体的红外图像， of the stars at the heart of the galaxy
并制作出一部 特别的延时电影． to produce an extraordinary time-lapse movie.
如果我们 把银河系中心放大 GHEZ: So if we zoom in to the very heart of the galaxy
实际上可以看到 过去15年来 we can actually see the data that we've taken
我们掌握的数据， over the last 15 years,
并且你能看见星体 and you can see the stars
能看见它们正在 大幅度地运动． and you can see the tremendous motion that they've gone through.
特别是SO-2号， 我最喜欢的恒星—— In particular SO-2, which is my favorite star--
每个天文学家 都有自己的最爱—— every astronomer has a favorite one--
那你能看到SO-2号 在做环状运动 so you can see SO-2 goes around
特别的是，你能看到 当它运行到框架中心时 and in particular you can see, as it gets to the center of the frame,
它移动的更加快． it moves much more quickly.
所以那片地方 正发生有趣的事． So something's interesting as it goes through that region.
那么把一切都归纳起来 归纳我们所做的测量 So putting everything together, all the measurements that we've made,
我们能够 做一个动画 we've been able to make an animation
来展示过去巧年来 恒星们运行的轨迹． that shows how the stars have moved over the course of 15 years.
每一颗星在围着 银河系中心绕圈． Each star goes whipping around the center of the galaxy.
最惊奇的是 你会发现 In particular the most striking thing that you'll notice
SO-2号是怎样运行的． is the motion of SO-2.
所以SO-2号是在 一架不可思议的过山车上． So SO-2 goes on an incredible roller coaster ride.
它过来绕一下 然后又退回去． It comes whipping around and then back out.
能有让SO-2 绕着银河系中心 NARRATOR: For an object to have enough gravitational pull
做高速运动的 重心引力的…… to send SO-2 on rapid orbit around the center of the galaxy...
那一定是一颗质量巨大的恒星． it must also have a huge mass.
SO-2号每15年 环绕一圈， GHEZ: SO-2 goes around once every 15 years,
那告诉我们它轨道的引力 是太阳的 and what it tells us is that there is four million times the mass of the sun
400万倍． confined within its orbit.
天文学家 只知道一位竞争者 NARRATOR: Astronomers know of only one contender
可以有如此大的质量 同时体积很小 that has a giant mass but is so small.
不可思议的 巨大的重量 GHEZ: So that's an incredible amount of mass
装在一个很小的体积内， inside a very small volume,
这是证明它是一个黑洞 的关键． and that's the key to proving a black hole.
所以说在我们的 银河系中心 NARRATOR: And so at the center of our galaxy
存在着一个巨大的黑洞． lies a massive black hole,
一个引力巨大 连光都逃不出来的物体． an object whose gravity is so strong not even light can escape it.
这是银河系中心 的真实图像． This is a real image of the center of our galaxy.
我们看不到黑洞― We can't see the black hole--
但是我们能看到发光的尘埃云团 朝着它螺旋向内运动． but we can see bright clouds of dust and gas spiraling toward it.
我们在黑洞的附近． We're nearing the black hole.
它是尘埃和气体流动 的中心…… It's at the center of a stream of dust and gas...
……星球的残骸如果靠的太近 便被粉碎． ...the debris of stars blown apart after straying too close.
黑洞随着时间长大， GHEZ: Black holes grow with time,
随着物质 落入其中， and that happens by material falling onto it,
依附上去， accreting onto it,
这些物质可以是 气体形式 and that material can come in the form of either gas
也可以是被黑洞摧毁 的星球本身． or stars that get torn apart by the black hole itself.
正中间是 看不见的黑洞． NARRATOR: At the center is the invisible black hole.
这是它赖以生存的物质． This is the material it feeds on.
发光的区域 是一个生长的圆盘． The glowing region is the accretion disc.
在这里星球的残骸下坠 Here star debris falls inward
并以令人惊奇的速度 运行着． and whips around at astonishing speed.
摩擦力让这些残骸 达到极高的温度 Friction heats the debris up to such high temperatures
散发出白热的光． that it glows white hot.
所以在银河系中心 是有一个黑洞的． GHEZ: So at the center of our galaxy we do have a black hole.
现在我们知道了， We now know that today,
但是它没有制造 大量的能量． but it's not producing a tremendous amount of energy.
所以也许，我们能说， 这个黑洞在节食中． So it's perhaps, we could say, it's a black hole that's on a diet.
它只是没有足够 的物质供他消耗． It simply doesn't have a lot of material to feast on.
但是如果 SO-2号和其他恒星 NARRATOR: But what would happen if SO-2 and the other stars
被黑洞 吸入会怎么样呢？ were pulled inward by the black hole?
当物质被吸入黑洞 会发生的事是， GHEZ: What happens when that material falls onto the black hole
恩 is that the black hole,
会发生和黑洞 之间的辐射反应 there's radiation associated with the black hole
会产生这些巨大的喷射流 and it can generate these jets,
从银河中心 向外喷射． squirting out from the center of the galaxy.
以接近的光速 喷出次原子微粒， NARRATOR: Spewing out subatomic particles close to the speed of light,
发出的光 像是巨大的宇宙探照灯． the beams are like vast cosmic searchlights.
这是室女A星系， This is Messier 87,
一个在中心有着巨大质量的 黑洞的椭圆形星系． a large elliptical galaxy that has a super massive black hole at its heart.
它在吞噬它自己的星球． It's feasting on its own stars.
从它明亮的核心射出来的是 Shooting out from its bright core
能旅行5000光年的 喷射流． are jets that travel over 5,000 light years.
我愿意称它们为星系 的首席女歌手． GHEZ: I like to call these the prima donnas of the galaxy world.
只有百分之十的星系 有这样的表演． These are the ten percent of galaxies that are showoffs.
天文学家相信 银河系中心的 NARRATOR: Astronomers believe that the massive black hole
巨大的黑洞 at the heart of the Milky Way
从一开始就存在了． has been there from the very start.
但是为了 能回到银河系诞生的地方， But in order to get back to where the galaxy first began,
我们就必须前往星城里 最古老的街坊． we have to travel out to the oldest neighborhood in our star city.
我们继续向上探索， 要远离我们的太阳系． We're traveling upward, away from our solar system,
在银河漩涡臂的外部． out of the spiral arms of our Milky Way.
在前方则存在着巨大的恒星群， 他们绕着星城中心绕行． Up ahead lie vast clusters of stars that orbit the heart of our star city.
大约有150多个这种恒星群． There are over 150 of them.
这些卫星镇，被称为原球状星团， These satellite towns, called globular clusters,
拥有天文学最大奥秘之一的答案． hold the answer to one of the greatest mysteries in astronomy:
那就是银河的真实年龄． the true age of our galaxy.
原球状星团 是非常漂亮迷人的恒星群． BULLOCK: Globular clusters are really fascinating groups of stars.
每一个球状星团由百万恒星组成 They contain about a million stars each,
比较值得一提的是， and the thing that's really cool about them
这些恒星都是非常紧密的聚集 在一起． is the stars are really tightly packed.
如果你有机会 能参观一个原球状星团， KIRSHNER: If you could visit a globular cluster,
你就会发现夜空是蔚为壮观的， the night sky would be spectacular,
许多恒星就会如满月一样光亮． where many of the stars would be as bright as the full moon.
各个方向的夜空都会充斥着 附近明亮的恒星． And the nighttime sky in all directions would be filled with bright nearby stars.
就像总是有烟火似的． There'd be like fireworks all the time.
除了单纯的恒星数量， NARRATOR: Besides the sheer number of stars,
这些恒星群还有更复杂的方面． there's something even more intriguing about these clusters.
原球状星团 很有意思的一个方面 BULLOCK: One of the very interesting aspects of globular clusters
就是没有年轻恒星的迹象． is there's no sign of young stars.
恒星就和人类一样． NARRATOR: Stars are like people.
看看他们，你就能猜出他们的年龄 Look at them, and you can guess their age
以及他们的生活． and the lives they've led.
对人类来说，灰白的头发 满脸的皱纹就是年龄的标志． With people, gray hairs and wrinkles are the telltale signs.
对于恒星来说，我们要看的就是 它们的颜色和尺寸． With stars, it's color and size.
最大的恒星， 超大质量的恒星， BULLOCK: So the biggest stars, the most massive stars,
含有最多大气的恒星， 生命节奏非常快． the ones with the most gas, live life in the fast lane.
生存的时间非常短． They live very short amounts of time.
但是它们燃烧的异常光亮， 并且异常灼热， But they burn very brightly and they're very, very hot,
所以它们应该是蓝色的． and so they tend to be blue.
另一方面，还有红色的恒星 KIRSHNER: On the other hand you have the red stars,
非常谨慎地使用自身的能量 which use their energy very conservatively,
生存时间较长， 发光也并不很明亮． last for a long time, don't glow too brightly.
这些恒星生存的时间很长． And those stars last for a very long time.
所以通过测量球状星团里 BULLOCK: So by measuring the brightnesses
恒星的亮度和颜色， and the colors of the stars in a globular cluster,
我们可以推断出它们的年龄． we can figure out how old they are.
值得一提的是， And here's the remarkable thing.
它们已经很老了． They're very old.
原球状星团， 或者说至少是球状星团里的恒星， Globular clusters, at least the stars in globular clusters,
大多数都是和宇宙本身一样老． in many cases are almost as old as the universe itself.
原球状星团是活化石． NARRATOR: Globular clusters are living fossils.
它们就像是第一批人， They're like discovering a community of people
而这些人从石器时代就已出现． who've been around since the stone age.
有些恒星已经闪耀了120亿年-- Some stars here have been shining for 12 billion years--
比太阳存在时间的两倍还长． more than twice as long as the sun.
这是测出银河年龄的有用工具． And that's a helpful tool in placing an age on the Milky Way.
原球状星团 是银河系的一部分． BULLOCK: Globular clusters are part of our galaxy.
它们沿着银河轨道运行． They orbit our galaxy.
从某种意义上说， 它们的运行轨道就是银河自身． In some sense they're tracers of our galaxy itself.
所以说原球状星团已经很老， And so by the fact that the globular clusters are so old,
也就意味着银河也很老了． it suggests that the galaxy is old.
我们的银河不仅仅是老了一 NARRATOR: And our galaxy isn't just old--
而是相当老． it's very old.
事实上，银河 是宇宙中最古老的物体之一 In fact, the Milky Way is one of the oldest objects in the cosmos.
它几乎是和整个宇宙的起源同步一 It's been around almost since the beginning of the entire universe--
至少存在了120亿年． at least 12 billion years.
原球状星团也表明 那个时候银河里的化学物质 Globular clusters also show that the chemistry of the galaxy back then
和现在有很大不同． was very different from how it is today.
我们可以测出 这些恒星的化学特性． KIRSHNER: We can measure the chemical properties of those stars.
结果表明这些恒星里的 重金属含量极低． Turns out they have very low abundances of the heavy elements.
像铁这样的金属， 在原球状星团里是极少见的， Things like iron are very rare in globular cluster stars,
和太阳相比． compared to a star like the sun.
这就是说早年的银河 并不如现在多姿多彩． NARRATOR: That means the early galaxy was a far less colorful place.
缺少了重金属，我们就无法看到 Without heavy elements there weren't the beautiful hues
现在星云和超新星遗迹里 的美丽色调． we see in nebulas and supernova remnants today.
更重要的是一 这是一个毫无生气的银河． Even more importantly-- it was a galaxy without life.
经过几十亿年， 恒星们形成了足够多的重金属 It took billions of years for stars to form enough heavy elements
使得银河各处的生物开始进化… for the evolution of life to begin anywhere in the Milky Way...
…人们惊讶于 ...leaving many to wonder
银河是如何生存了这么长的时间． how the galaxy has managed to keep going for so long.
银河的谜团之一 BULLOCK: One of the puzzles about our galaxy
就是我们知道在过去的一百亿年里 is that we know that it's had stars forming continuously
恒星在银河不断的形成． for about the last ten billion years.
但是照它消耗大气的速度来看， But at the rate it's eating up its gas now,
形成新的恒星， 已经快要消耗完所有的大气了． it's forming new stars, it should burn out that gas soon.
现在应该缺乏燃料． It should run out of fuel.
所以肯定会有某些新燃料的来源． And so there has to be some source for new fuel.
而这些来源肯定是在银河之外． NARRATOR: That source must be outside the galaxy.
最近，天文学家有了一个惊人的发现 And recently astronomers made a startling discovery:
原球状星团 不是绕银河运行的唯一星团． Globular clusters aren't the only groups of stars orbiting the Milky Way.
还有其他较小的星系绕银河运行． There are other tiny galaxies circling our galaxy
它们被称作超微弱的矮星系 called ultra faint dwarf galaxies.
我们这么久没有发现这些 BULLOCK: The reason why we haven't known
矮星系的原因， about these dwarf galaxies for very long,
是因为这些所谓的超微弱矮行星， these so-called ultra faint dwarf galaxies,
只含有几百个恒星， is that they contain just a few hundred stars,
或者几千个恒星． a thousand stars.
所以你要在几十亿的大量的恒星中 So you try to find a clump of a thousand stars
发现几千个恒星组成的恒星群 while looking through a mass of a billion stars.
确实不容易． It's not easy.
犹如大海捞针． This is a needle in a haystack problem.
多亏我们拥有了精确地图， And it's only because we have the precise maps,
依靠现代天文学的精确度 it's the precision of modern astronomy
才使得我们发现 that's allowed us to discover
这些非常有意思的矮星系． these extremely interesting dwarf galaxies.
这些隐蔽的矮星系也许 会帮助我们解决 NARRATOR: These elusive bodies may help solve the mystery
银河新燃料的秘密． of what's fueling the galaxy.
这些矮星系在绕银河运行， BULLOCK: So these dwarf galaxies are whizzing around our galaxy.
在银河周围的轨道里． They're in orbit around it.
有时候它们离银河太近， Now sometimes they get too close,
如果太近的话，它们就会被扯破． and when they get too close they get ripped apart.
事实上，从某种程度上讲， 它们就会被我们的银河吞掉． In fact they get eaten, in some sense, by our galaxy.
这张电脑模式图 把矮星系做成多彩的圆盘， NARRATOR: This computer model shows dwarf galaxies as colored discs
银河在中间． with our galaxy in the center.
随着时间流逝， 银河会把矮星系拉进来， Over time, our galaxy pulls dwarf galaxies in,
吞噬它们，使用它们的大气和灰尘 devours them, and uses their gas and dust
最终形成新的恒星． to eventually form new stars.
于是同样地 BULLOCK: So in much the same way
大城市可能会整并它的周边城市， that a large city might sort of cannibalize its neighbors,
银河会吞并它周围的矮星系． the Milky Way is cannibalizing its dwarf galaxy population.
原球状星团和矮星系 NARRATOR: Globular clusters and dwarf galaxies
能让我们更深入了解银河的年龄… provide crucial insight to just how old our galaxy is...
以及它使如何存在了这么久． and how it's managed to survive for so long.
这些星系曾经被认为是银河的边界． These bodies were once thought to mark the Milky Way's city limits,
是我们星城的外围． the very outer reaches of our star city.
但是现在， 天文学家们又开始重新思考． But today astronomers are rethinking all that.
我们的银河也许比 我们能看到的要大得多． Our galaxy might be bigger than what we can see,
向外伸展的广度， 是我们无法想象的． spreading out further than we ever imagined.
我们把地球 We're picking up our Earth
从我们安静的郊区移到 and moving from our quiet suburb to a new neighborhood
银河系外旋臂里的一个新的区域． in the outer spiral arm of our galaxy.
在这儿，我们可以解开这一谜团 Here we'll uncover the mystery
到底是什么使得银河里的恒星 都紧密结合在一起的 of what holds all the stars in the Milky Way together.
在新的地点上看，夜空有些不同． From our new address, the night sky looks a little different.
银河更小了，天空也更黑暗了． The Milky Way is smaller and the sky darker.
在这里， 远离银河中心成千上万光年远， Here, tens of thousands of light years away from the center of our galaxy,
我们还是受地心引力的约束． we're still bound by the force of gravity.
地心引力就是 使得任何两件物体 BULLOCK: Gravity is the force that makes any two objects
聚集在一起的力量． want to move towards each other.
在地球上， 铁梁和混凝土梁建成了城市-- NARRATOR: On Earth, cities are built with iron girders and concrete beams--
一种隐形的脚手架对抗着地心引力的 牵引使得建筑物都笔直朝上． an invisible scaffold which holds buildings up against the pull of gravity.
没有这种支架支撑，摩天大楼 会成碎渣，大桥会轰然倒地． Without this scaffolding, skyscrapers would crumble and bridges collapse.
地心引力主宰着地球，以及整个宇宙． Gravity governs Earth and the entire universe.
任何物体只要有质量就会有引力． Anything that has mass has a gravitational pull.
质量越大，引力越大． The more the mass, the stronger the pull.
拥有两千亿的恒星， 银河具有超大的质量一 With 200 billion stars, the Milky Way has a huge mass--
也有极大的万有引力． and a tremendous gravitational attraction to match.
于是，就像一座建筑物一样， 我们的银河也需要一定的力量来支撑 So, like a building, our galaxy also needs propping up
并且对抗地心引力． against the force of gravity.
想象一下银河圆盘． BULLOCK: Imagine the disc of our galaxy.
如果你拿一个群星圆盘 If you just took a disc of stars
把它放在那儿， and put it there,
地心引力就会试图 gravity would tend to make
使圆盘自我崩溃． this disc collapse in on itself,
然后又会马上结合在一起． and it would immediately just fall together.
银河却并非如此． That's not what we see with the galaxy.
事实上是恒星们绕着中心运转 What's actually going on is the stars are orbiting around the center,
这样它们就不会下落． and that's what keeps them from falling in,
就像是地球绕着太阳转． in much the same way that the Earth is orbiting around the sun.
太阳系里面的行星 处于很微妙的平衡中一 NARRATOR: The planets in our solar system are in a delicate balance--
重力牵引着它们围着太阳转 gravity pulls them towards the sun
而它们的轨道速度 却想把它们抛到太空中． while their orbital velocity wants to fling them out into space.
为了保持平衡， In order to stay balanced,
离太阳较远的行星 就要运转的慢一些． planets further from the sun must orbit more slowly.
如果你去太阳系边缘的 BULLOCK: If you go to more distant planets
较远一些的行星， at the edge of the solar system,
它们会比地球绕太阳运行的慢得多 they're going around the sun much more slowly than the Earth is,
这是因为那里的引力比较弱． and that's because the gravity is weaker.
对于银河里面的恒星也应该如此． NARRATOR: The same should hold true for stars in the Milky Way.
它们都绕着银河中心运行， They all orbit the center of the galaxy,
但是离银河中心较远的恒星 but the stars in the outer arm should be traveling more slowly
应该比较近的恒星运转的慢得多． than those closer to the galaxy's heart.
有意思的是， 事实并非如此． BULLOCK: What's interesting is that's not what's going on.
银河较外部的恒星 The stars in the outer parts of the galaxy
和内部的恒星运转的速度几乎一样． are spinning around just as quickly as those in the inner parts.
不只它们如此． NARRATOR: And they're not the only ones.
不只是我们的银河系； 还包括我们观测的其他星系． BULLOCK: It's not just our galaxy; it's every galaxy we look at.
所有星系的外部似乎 都运转的太快了． Every galaxy we look at seems to be spinning too fast in its outer parts.
这些快速运转的恒星 NARRATOR: These speeding stars
应该已经抛出银河系． should be flung out of the galaxy altogether.
但是事实并非如此． But they're not.
这就是困惑所在． BULLOCK: That is a puzzle.
这就意味着那里还有很多质量 This means that there's a lot more mass there
是我们无法观测到的． that we just can't see.
质量产生重力 NARRATOR: Mass that produces the gravity
而重力又使这些恒星在轨道中运行． that holds these stars in their orbits.
但是当天文学家开始调查这些质量 But when astronomers look for the mass,
它们似乎又不复存在… there appears to be nothing there...
于是天文学家乔尔普里马克 得出一个令人震惊的结论． leading cosmologists like Joel Primack to an astounding conclusion.
乔尔所有的星系， JOEL PRIMACK: All of the galaxies,
所有的恒星，大气，灰尘，行星 all of the stars and gas and dust and planets and everything else
和我们用最大的望远镜 可以观测到的事物， that we can see with our greatest telescopes,
只是真实存在事物的0.5%. represent about half of one percent of what's actually out there.
其余的都是隐形不见的． The rest is invisible.
大部分都是我们称为 暗物质的神秘物质． It's mostly some mysterious substance that we call dark matter.
你看不到暗物质． BULLOCK: You can't see dark matter.
你能看到一般物质的原因 The reason why you can see normal matter
是因为灯光照在上面并进行了反射． is because light shines on it and reflects off of it.
你就是这么看到我的． That's how you can see me.
暗物质并不是如此． Dark matter doesn't work that way.
灯光直接穿过暗物质． The light goes right through the dark matter.
我们检测到暗物质是因为它有质量． The way we detect dark matter is because it has mass.
有质量的物体 都会通过重力影响其他事物． Anything with mass affects other things via gravity.
这是质量的黄金法则， 也是质量的功能， That's the golden rule of mass, that's what mass does,
它由于重力可以拉住其他物体． it tugs on other things because of gravity.
没有暗物质，也就没有银河． NARRATOR: Without dark matter, the Milky Way couldn't exist.
银河在不断转动． BULLOCK: So the galaxy is spinning.
而且转动的很快． The galaxy is spinning fairly rapidly.
原因就是它有许多暗物质． The reason why it can spin so rapidly is because it has so much dark matter.
暗物质质量大，于是它重力也大 The dark matter has a lot of mass and therefore it has a lot of gravity,
就可以使恒星不断运转． and that's what keeps the stars whizzing around.
如果可以神奇地把所有的暗物质 If you were to magically take all of the dark matter
从银河里拿开， away from our galaxy,
银河系就是支离破碎． it would fly apart.
恒星会直线运动， The stars would just keep going straight
银河系会在很短的时间内消失不见． and in a very short amount of time the galaxy would just be gone.
各种物体会混乱的往各处飞． PRIMACK: There'd be just a mess of stuff flying every which way.
不仅是我们的银河系是这样， And that's not just true of our galaxy,
所有的星系都会这样， it's true of every galaxy
宇宙中的星系团也会这样． and every cluster of galaxies in the universe.
它们都是因为这种 看不见的物质结合在一起 They're all held together by this invisible stuff
这种物质叫做暗物质． that we call dark matter.
我们需要暗物质． BULLOCK: So we need the dark matter.
是它把星系连接在一起． It's the glue that holds galaxies together.
暗物质的发现 NARRATOR: The discovery of dark matter
已经变革了我们对银河的看法． has revolutionized our picture of the Milky Way.
银河系中的恒星 只是它的质量的一小部分． The stars of the galaxy represent just a fraction of its mass.
其余的部分是由看不见的环圈， 即暗物质组成一 The rest is made up of an invisible halo of dark matter--
它环绕着银河系中所有的恒星 和所有的生物． surrounding every single star and every creature in the galaxy.
恒星只是中间区域． PRIMACK: The stars are just the central region.
而环圈却有它的10倍大． The halo is at least ten times bigger
重量也是 and weighs much more than ten times more
我们所能观测到的恒星，大气 和灰尘的重量的10倍之上． than all the stars and gas and dust that we can see.
这一整体的构造才是真正的银河系． It's that whole structure that's the real Milky Way galaxy.
不只是我们的星系如此， And that's not just true of our galaxy,
我们研究过的其他星系也是这样． it's true of every galaxy we've ever studied.
但是暗物质的功能 不仅仅是把所有星系集中起来． NARRATOR: But dark matter does more than simply hold galaxies together.
天文学家们认为它使得银河 Astronomers now think it binds the Milky Way
形成一个包含数十亿其他星系的 超乎寻常的结构一 into an extraordinary structure with billions of other galaxies--
这一结构可一直延伸到宇宙的边缘． a structure that reaches to the very edge of the universe.
我们把地球从银河系中拿到 We've left our home galaxy to take the earth
数十亿光年外的时空中． across billions of light years of space and time.
望远镜的一大好处就是 BULLOCK: One of the great things about telescopes
它们是时间机器． is they're time machines.
由于光速是有限的， Because light travels at a finite speed,
当我们观察较远的物体时， when we look at distant objects
我们看到的是光离开它们时候的样子 we see them as they were when the light left them.
天文学家回顾几十亿年的历史， NARRATOR: As astronomers look back over billions of years,
他们看到了满是星系的宇宙． they see a universe teeming with galaxies.
但是这些星系在太空中 并非随意的分散． But these galaxies aren't scattered randomly through space.
它们根据微妙的细丝聚集在一起， 交织成一个复杂的结构． They cluster along delicate filaments woven in an intricate structure--
一张硕大的宇宙网络， 它告诉人们 a vast cosmic web that holds the answer
星系的起源． to the birth of galaxies themselves.
这是一个浸在黑暗中的故事． It's a story shrouded in darkness.
我们再往前看， 所有的星系都将消失． Look back far enough and gradually all the galaxies disappear.
我们已经到了一个神秘的时间段． We've reached a mysterious period of time,
125亿年前． 12.5 billion years ago.
有这么一个时间段， 我们是无法观测到事物的． BULLOCK: There's this time period that we can't see
因为神秘物体都未形成． because nothing's formed yet.
这一时代被称作黑暗时代． It's this epoch that's called the dark ages.
黑暗时代时期， 宇宙与我们现如今居住的地方 NARRATOR: During the dark ages, the universe was a very different place
有着很大的不同． than the one we live in today.
当时充满了氢气密云． It's filled with dense clouds of hydrogen gas.
正如大气阻挡了银河中的恒星一样， Just as gas obscures stars in the Milky Way today,
这些氢气密云也会阻挡到 早期宇宙的内部景象． these clouds of hydrogen block the view inside the early universe.
这是非常令人沮丧的， 因为这一区域， BULLOCK: It's extremely frustrating because this region,
这一时间段，在某种程度上， this time period, holds within it, in some sense,
隐秘了星系形成的罗塞塔石碑． the Rosetta Stone of galaxy formation.
但是对于在这些 NARRATOR: But there is one clue to what's happening
氢气密云内部到底发生了什么 我们还是有线索的． inside those dense hydrogen clouds.
往回看到 Look back further in time
宇宙大爆炸之后的38万年． to a moment just 380,000 years after the big bang.
宇宙并非充满黑暗… The universe isn't filled with darkness...
而是充满光亮． but with light.
这种微弱的余光仍然 逃不过现在天文学家的慧眼． Its faint afterglow is still visible to astronomers today.
事实上，这张图片太棒了． BULLOCK: In fact, this picture is amazing.
这是关于早期宇宙的图片． This is a picture of the early universe.
这是反映宇宙大爆炸余光的图片． This is an image of the afterglow of the big bang.
宇宙中充满了炎热的大气， NARRATOR: The universe is filled with a hot atmosphere
大气由物质和辐射构成． of matter and radiation.
但是变革的种子已经播种下了． But already the seeds of change are being sown.
我们看宇宙中的每一个地方 BULLOCK: Everywhere we look around us in the universe
都能看到结构； 我们在哪里都能看到星系． we see structure; we see galaxies all over the place.
那这些星系从何而来？ Where do these galaxies come from?
在这幅图中就藏有重大线索． There's a big clue to this buried in this picture.
如果你靠近仔细看， 你就能看到 If you look closely, you can see
图上有红点和蓝点． that there are red spots and there are blue spots.
红色区域表明这里物质较多． These red regions are regions where there's basically more stuff,
蓝色区域表明这里物质较少． and the blue regions are the regions where there's less stuff.
这幅图片表明了 NARRATOR: This image reveals tiny variations
早期宇宙中气体密度的变更． in the density of the gas that fills the early universe.
细小的波纹会随着时间慢慢生长． Minute ripples that will grow with time.
我们认为这些波纹， 这些原始的波纹， BULLOCK: We think that these ripples, these primordial ripples,
是所有未来结构的种子． are the seeds to all future structure.
这些波纹最终会变为初期的星系． These ripples eventually grew into what became the first galaxies.
从如此小的物体长成如此大的物体． NARRATOR: it takes a powerful force
需要巨大的能量． to grow something so small into something so big.
是重力增强了这些波纹， BULLOCK: It's gravity that amplifies these ripples,
事实上， 我们还需要另一个重力来源 and in fact we need an additional source of gravity
来增强这些波纹以此来形成现如今 我们观察到的星系． to amplify those ripples to form galaxies like we see today,
另一种重力就来自暗物质． and that additional gravity comes in the form of dark matter.
过程是这样的， 开始是暗物质形成结构． PRIMACK: What happens is that first the dark matter forms the structure.
普通物质就会跟随着暗物质． The ordinary matter then follows the dark matter.
在那个时候普通物质就是氢和氮． The ordinary matter is hydrogen and helium at this stage.
氢和氮聚集在 And the hydrogen and helium fall to the center
正在形成的暗物质环圈的中心 of the dark matter halos that are forming,
就会形成星系． and that's going to become the galaxies.
暗物质也许是缺少的一环， NARRATOR: Dark matter may be the missing link
它可以连接早期宇宙中的 这些细小波纹 between these minute ripples in the early universe
和现如今充斥在太空中的 硕大宇宙网络． and the vast cosmic web that now fills space.
但是暗物质是看不到的． But dark matter is invisible.
所以我们没有办法看到 它是如何创造的宇宙网络． So there's no way to actually see it creating the cosmic web.
但是这一过程可以 But the process can be simulated
通过最强大的超级计 算机被模拟出来． in one of the world's most powerful super computers.
乔尔．普麦 加利福尼亚大学 PRIMACK: Here we are at NASA Ames,
这里有昂宿星超级电脑． the research center where we have the Pleiades super computer.
每一机箱都拥有512个处理器． Each one of these cabinets contains 512 processors.
我来展示一下． Let me show you.
所以每一机箱都是5000亿字节． So that's half a terabyte in each one of these cabinets.
这里有110个这样的机箱． There's 110 of these cabinets
来组成昂宿星超级电脑． to make up the entire Pleiades super computer.
这是一个真正的超级电脑． So this is a really big super computer.
这是航天局最大的电脑． This is NASA's biggest.
但挑战也同样巨大一 NARRATOR: The challenge is equally big--
形成一个虚拟宇宙一 to develop a virtual universe--
从它的起源一直到现在-- from its early beginnings all the way to the present day--
去探索暗物质在宇宙形成中 到底起了什么样的作用． to see what role dark matter might have played in shaping the cosmos.
如果你想用家用电脑 完成这一任务的话， If you tried to do this on a home computer,
你将需要680多年． it would take over 680 years.
如果工作顺利， PRIMACK: If we're doing our job right,
我们可以把这些图片做成视频 如果你愿意， we can put the pictures into a video, if you like,
可以展现出宇宙的整体结构． that shows the whole structure of the universe.
这就是最终的结果． NARRATOR: And this is the end result.
叫做波修瓦-- It's called Bolshoi--
是关于 an amazing visualization
现在宇宙中暗物质结构的 of what the structure of dark matter might look like
了不起的视觉盛宴． in the universe today.
我们要看的 PRIMACK: So what we're looking at
就是两亿光年的这个区域， is a region about 200 million light years across,
它还只是我们模拟的一小部分． which is actually just a small part of our really big simulation
我们称之为波修瓦， 在俄语中就是”巨大“的意思． that we call Bolshoi, which is Russian for “big.“
你在这里看到的东西 实际上是看不到的． Everything that you see here is actually completely invisible.
你看到的就是不可见的宇宙． It's not the visible universe that you're seeing.
这里的亮点其实就是暗物质． The bright spots are dark matter.
它们是暗物质环圈， 星系就是在这里产生的． They're the halos of dark matter within which galaxies form.
这样一小团东西就代表着可能是一个， And each one of these little blobs would represent probably one,
或者至少是三两个 和银河差不多大的星系． or at most a couple of Milky Way size galaxies.
你可以看到星系其实是长链形的， And you can see that the galaxies are in long chains,
我们称之为细丝． filaments we call them.
基本上，所有的结构都是由 暗物质的这些细丝构成的． Basically all the structure is forming along these filaments of dark matter.
现在是对检测模拟 是否成功的真正考验： NARRATOR: Now comes the real test of success:
普麦将波修瓦与 Primack compares the Bolshoi predictions
科学家们观测的宇宙中星系 的真实结构方面相比较 with the actual structure of galaxies scientists see in the universe.
就我们所知， PRIMACK: As far as we can tell,
我们用超级电脑做的模拟 these simulated universes that we make in the super computers
与我们实际观测的宇宙是 极为相似的． look just like the observed universe.
几乎没有差异． There don't seem to be any discrepancies at all.
这正是我们观测到的宇宙中 This is exactly the way we see the galaxies distributed
星系的分布方式． in the observed universe.
波修瓦模拟是令人震惊的． NARRATOR: The Bolshoi simulations are astounding.
它们完美的符合 现在宇宙中星系的模式． They match the pattern of galaxies seen in the cosmos today perfectly.
这是极有说服力的证据 It's persuasive evidence
来证明暗物质几十亿年来 一直在塑造着宇宙． that dark matter has been sculpting the universe for billions of years.
这令我印象深刻． PRIMACK: No, I'm really impressed with this
我们在第一次提出这些设想的时候 because we stuck our necks way out
就遇到了瓶颈， when we made these first predictions,
但是最终证明它们是正确的． and they turned out to be right.
并且一直是正确的． And they keep turning out to be right.
这对于一个理论家来说 当然是巨大的快乐． And, you know, this is, of course, great joy for a theorist.
通过回溯到宇宙的起源， NARRATOR: By going back to the beginning of the universe,
天文学家发现了 astronomers have uncovered the origin
整个宇宙底层结构的起源． of the underlying structure of the entire cosmos.
但是我们的时空旅行还远未结束． But our time travel is far from over.
最初的星系是如何点亮最初的恒星 这一问题还未解答． The question of how the first galaxies kindled the very first stars still remains.
我们把地球带进黑暗时代-- We're taking the earth inside the dark age--
125亿年前． a time over 12.5 billion years ago.
当时的景致蔚为壮观． The sight is spectacular.
天空被银河中最初的恒星照亮． Our skies are lit by the first stars of the Milky Way.
这些光亮刺穿了氢雾一 Their light pierces the hydrogen fog--
使地球沐浴在紫外线能量中． bathing the earth in strong ultraviolet energy.
这些最初的恒星会永远改变 我们对宇宙的看法． These first stars will change the way we see the universe forever.
汤姆阿贝尔研究了这些 早期恒星的存在与消亡． Tom Abel studies the life and death of these early stars.
幸运的是 我们现在有电脑了． TOM ABEL: The beautiful thing is that we now have computers.
我们根据物理定律来编程， We program them with the laws of physics,
加入重力，流体力学， put in some gravity, hydrodynamics,
气体如何流动，化学， how gases move around, some of the chemistry,
我们整体来演变， and as we evolve it all together,
我们就会知道恒星是如何形成的， we gain an intuition of how stars come about,
对于早期的恒星，这是至关重要的． and in the case of the very first stars, this is absolutely crucial.
阿贝尔使用黑暗时代 可用的基础的成分 NARRATOR: Abel begins with the basic ingredients
来开始自己的研究： available during the dark ages:
氢气，氦气， 暗物质和重力． hydrogen, helium, dark matter and gravity.
使用电脑模型， Using computer models,
阿贝尔再创造了这些早期的恒星． Abel recreates the lives of these early stars.
我们在这里可以看到 宇宙中的一个早期恒星． ABEL: Here we see one of the first stars in the universe.
是太阳质量的100倍， It's a hundred times as massive as the sun,
亮度的百万倍． a million times as bright.
早期的恒星巨大无比-- NARRATOR: The first stars are huge--
被大量的氢气充斥， swollen by the massive amounts of hydrogen gas
被暗物质的万有引力牵引着． pulled in by the gravitational force of dark matter.
尽管它们拥有燃料来燃烧， ABEL: And so even though they have all this fuel to burn
人们认为它们会存活很长时间． you'd think they could live for a long time.
但燃料会很快挥霍完， They run through it so quickly
所以过了百万年， 它们已经死去了． that even after a few million years they're already dead.
银河中最初的恒星 NARRATOR: The first stars in our Milky Way
是很剧烈、辛烷值高的恒星-- are fierce, high octane stars--
以惊人的速度使用它们的氢气燃料-- burning their hydrogen fuel at tremendous rates--
寿命很短． racing through their life cycle.
它们就像摇滚明星似的． ABEL: They're like the rock stars.
生活节奏快，去世的也早． They live fast and die young.
它们以极快的速度使用自己的燃料， They run through their fuel very quickly
仅仅过了几百万年，它们已经死了． and even after just a few million years they already die.
它们以极为剧烈的爆炸形式死去， NARRATOR: They die in some of the most violent explosions
以此来震动宇宙-- ever to rock the universe--
巨大超新星耀眼地闪烁-- gigantic supernovas that shine brilliantly.
这些大质量恒星 The energy given off
生死之间释放出来的能量 during the life and death of these massive stars
导致了不可思议的转变． leads to a miraculous transformation.
在宇宙史的前十几亿年里， ABEL: In the first billion years of the universe's history,
星系在氢雾中开始形成， galaxies start to form in a dark hydrogen fog,
我们无法看到它们的光亮． their light not being able to get to us.
随着时间飞逝， But as time progresses
最大质量恒星开始释放出紫外线辐射 and their most massive stars put out ultraviolet radiation,
正是这种辐射改变了它们周围的雾气 it's that radiation itself that changes the fog around them,
宇宙在这些地区变得透明了． and the universe becomes transparent in those regions.
这里的星系就把周围的雾气清除掉． These galaxies in here are clearing out the fog around them.
这些蓝色空隙就表明新恒星的能量 NARRATOR: The blue voids are where energy from the new stars
正在清除黑色的氢雾． is clearing the dark hydrogen fog.
宇宙大爆炸之后百万年 ABEL: But towards a billion years after the big bang
所有的雾气都被清除， the entire fog has cleared
我们就能看到所有的星系， and we now see all the galaxies,
黑暗时代宣告结束． and the dark ages end.
随着氢雾消失， NARRATOR: As the hydrogen fog lifts,
我们就第一次看到了新生的星系… we get our first glimpse of newborn galaxies...
包括我们自己的银河． including our very own Milky Way.
这幅非凡的图片 就是哈勃超深场． RICHARD ELLIS: This remarkable image is the Hubble ultra deep field.
是用哈勃太空望远镜拍摄到的 It's the longest exposure that's ever been taken
最长时间之前的影像． with the Hubble Space Telescope.
这真是非凡无比． It's a truly remarkable image,
对于专业天文学家 来说也许是最著名的． probably the most famous to professional astronomers.
11天 哈勃望远镜都对准一小片天空， NARRATOR: For over eleven days Hubble pointed at a tiny patch of sky
只有一角的宽度，75英尺的弧度． about the width of a dime held 75 feet away.
每一个光亮微弱的暗处就是一个星系． Every faint smudge of light is a galaxy.
对理查德埃利斯来说，这就是宝藏． For Richard Ellis, it's a treasure trove.
就像考古学家 ELLIS: So much like an archaeologist would piece together history
要进行深层挖掘才会把历史拼凑起来， by digging into deeper and deeper layers,
作为一名宇宙学家， 我会使用这张图片来 so a cosmologist like myself uses this image
观测宇宙的历史， to look at the history of the universe,
很早之前就存在的遥远星系是如何 how the most distant galaxies, seen as they were a long time ago,
进化和成长为我们身边的更大的系统． evolve and grow to the bigger systems that we see around us today.
这幅图片让我们感觉到了银河的开端． NARRATOR: This image gives us a sense of the dawn of our Milky Way.
我们观察这些早期的星系， ELLIS: When we look at these early galaxies,
它们和我们现如今 观察到的星城是不一样的． they don't resemble the star cities that we see today.
它们凹凸不平，也不整齐， They're lumpy, they're irregular,
它们似乎和周围的星系相互作用， they appear to be interacting with their neighbors,
它们体型上是非常非常小的． they're physically very, very small.
所以早期的宇宙和现在是很不同的． So clearly the universe was very different in those early times.
120亿年前，宇宙比现在要小的多． NARRATOR: 12 billion years ago the universe is a much smaller place.
宇宙还没有膨胀到现在的大小 It hasn't yet expanded to the size it is today.
我们年轻的银河系一路 碰碰撞撞的扩大领地 Our young Milky Way is jostling for room.
因此对这些年轻的 星系来讲 ELLIS: So it's very difficult for these early galaxies
存活下来非常不易 to establish themselves.
那个时候，这些年轻的星系 正努力地想要存活下来 These early galaxies are struggling to survive at this very early time.
适者生存 NARRATOR: It's survival of the fittest--
大的星系通过吞噬小星系 来壮大自身 the largest galaxies grow bigger by devouring the smallest.
因此这些年轻的星系很难壮大 ELLIS: So it's tough for these early systems to form,
但是很明显，它们成功了， 并且它们最终和它们的近邻 融合在了一起 but clearly they do, and they eventually merge with their neighbors
形成了我们现在看见的 更大的星系 and form the bigger systems that we see today.
这些碰撞发生在年轻的宇宙中 NARRATOR: These collisions in the early universe
产生了美丽的螺旋星云， 这正是我们现在生活的地方… created the beautiful spiral galaxy we live in today...
…它们永远不会停止 ...and they've never stopped.
天文学家们相信还有最后的一击 Astronomers believe there's still one final collision
正等着我们的银河系 in store for the Milky Way.
那一击将永远改写历史 One that will change it forever.
我们将地球带到了30亿年后的 未来 We've transported the earth three billion years into the future.
天空由一个巨大的星系主宰，它叫 做安德洛墨达星系 The sky is dominated by a massive galaxy called Andromeda.
它看上去也许很平静 The view may look peaceful,
但是宇宙中最最不幸的灾难之一 but one of the greatest calamities in the universe
正蕴酿着… is about to take place...
…这些神秘的用哈勃望远镜拍摄的 图像提供了蛛丝马迹显示了这场大 灾难即将来临 ...and clues to the impending disaster lie in these mysterious Hubble images.
这些不像是别的那些… Galaxies unlike any other...
扭曲着… distorted...
变形着… deformed.
天文学家借助电脑 Astronomers rely on computers for help
来分析这些神秘的物体到底 代表了什么 in decoding what these mysterious objects represent.
我们所做的就是 在电脑模拟一些星系 PRIMACK: What we do is we make galaxies
看上去跟银河系一样，但 是小一些 that look just like the Milky Way and similar galaxies.
然后我们用电脑模拟它们演化 And we let them evolve in the computer,
它们发展成螺旋型结构 they develop the spiral structure,
他们看起来相当真实 they look quite realistic.
然后我们把它们放在一个 碰撞轨道上 We then put them on a collision path.
定格这些模拟图像 NARRATOR: Freeze frame these simulations
并拿它们和实际图像做比对 and match them with real images
突然间一切变得清晰起来： and suddenly the picture becomes clear:
这是宇宙中最伟大的碰撞一 It's the greatest clash in the cosmos--
星系大碰撞 galaxies in collision.
就像是城市 星系有聚集成团的趋势 Like cities, galaxies tend to cluster.
我们银何系属于其中一个星团 Our Milky Way belongs to a cluster
叫做本星系群 called the local group,
它由至少50个星系组成 made up of at least 50 galaxies.
本星系群中最大的那一个就是 安德洛墨达星系 The largest in the pack is Andromeda--
它是一个螺旋星云，比我们 的银河系还要大 a spiral galaxy that's even bigger than ours.
现在安德洛墨达星系离我们 有250万光年的距离 Today Andromeda lies 2.5 million light years away.
但是天文学家亚伯拉罕·勒布认为 这个距离在缩小 But astronomers like Abraham Loeb believe that distance is closing in.
当我开始研究天体 物理学一个方向时 ABRAHAM LOEB: When I started working in astrophysics
我意识到我的大多数同事 I noticed that most of my colleagues
正研究别的星系间相互作用 are thinking about other galaxies interacting with each other,
互相碰撞 colliding with each other,
然后我就想为什么他们不研究 and I was wondering why aren't they examining
银河系的未来和安德洛墨达星系 the future of the Milky Way and the Andromeda Galaxy
因为终有一天它们会相遇 as they will come together.
一个大麻烦正等着我们 的银河系 NARRATOR: Trouble is brewing for our star city.
我们的星系正冲向宏伟的 安德洛墨达星系 PRIMACK: Our galaxy is rushing toward the great galaxy Andromeda,
它们冲向对方 they're rushing toward each other,
几十亿年后 and they're going to encounter each other
它们就会相遇 in a couple billion years.
罗卜和他的同事们 NARRATOR: Loeb and his colleagues
决定模拟这个巨大的 星系间大碰撞 decide to simulate this intergalactic clash of the titans.
这个是这类碰撞的首次 模拟图 LOEB: This was the first simulation of its kind.
最初，这两个星系相互俯冲 Initially the two galaxies plunge through each other
并通过引力的作用，产生了这些美丽 的由恒星组成的尾巴， producing these beautiful tails of stars, due to the force of gravity.
它们分开后不久又调转 回头，接着相互靠近 They run away, turn around and come back together,
最终形成了椭球状星云 to make one big spheroid of stars,
我们称之为仙女座星系银河系的碰撞 形成的星系 which I called the Milkomeda Galaxy.
当我们的银河系和安德洛墨达星系 相互融合后 NARRATOR: When the Milky Way merges with Andromeda,
大约有近一万亿颗恒星聚到了一起 almost one trillion stars will come together.
我们银何系 KIRSHNER: The beautiful spiral structure
美丽的螺旋结构 of our Milky Way galaxy
并不会持续到永远 is not something that's going to last forever.
它会进入混沌状态一会儿 It's going to be a mess, for a while.
碰撞不会使这两个星系都 The collision will not be one
消亡 in which these two things are destroyed,
但是碰撞会使这两个星系的 but it is one where the gas in each system
气体相互碰撞 will collide with the gas in the other.
这个过程会导致恒星的形成 That it'll have a burst of star formation.
这些新恒星的形成 LOEB: And the formation of these new stars
将标志着一个新的星系的形成 will mark the rebirth of a new galaxy.
这个壮观的哈勃图像 NARRATOR: This spectacular Hubble image
显示了 shows the Antennae Galaxies--
两个螺旋星系间的大碰撞 a grand cosmic collision between two spiral star cities.
星系正经历一场声势浩大的 恒星降生 The galaxies are in a frenzy of star birth--
大量的星云在黑暗中发出 粉红色的光芒 a multitude of nebulas glow pink in the darkness--
星体活动的最后一闪 one final flare of stellar activity
预示着这些星系将融合为一个整体 before the galaxies merge to become one.
当30亿年后 我们的银河系和安德洛墨达星系 This is the fate that awaits our Milky Way
相互融合后，也逃脱不了这一命运 when it merges with Andromeda three billion years from now.
当它们碰撞在了一起 KIRSHNER: When they collide
就会形成许许多多的恒星 there will be a lot of new star formation that takes place,
那时候的银河系会有一小段时间 恢复年轻 there will be a kind of rejuvenation of the Milky Way for a little while
但最终这一合成的星系 and then eventually this combined system
会安定下来形成一个新的星系形式 will settle down to become a new thing,
很有可能是一个更大的星系 probably a bigger galaxy
这个新兴形成的星系可能比 形成它的两个星系更大 than either of the galaxies out of which it was made.
但是真正让人眼前一亮的是这个新兴 星系的形状 NARRATOR: But the real surprise is the shape of this new galaxy.
这个新的星系并不形成在 PRIMACK: A new galaxy is formed
原来的两个星系的圆盘平 面上 where instead of the discs that the original galaxies had,
几乎所有的恒星都差不多在 这个圆盘周围运动 where all the stars are going around more or less on a plane,
事实上，新星系朝着各个方向运动 instead the stars are going every which way,
就和我们看见的椭圆星系一样 just like the elliptical galaxies that we see.
因此我们很肯定这个过程 And so we're pretty sure that this process
大概就是椭圆星系形成的过程 must be a large part of how elliptical galaxies form.
银河系和安德洛墨达星系的碰撞 NARRATOR: The collision of the Milky Way with Andromeda
将会形成一个巨大的椭圆星系 will leave behind a giant elliptical galaxy.
但在那发生以前，我们 还能看见最后的一个景象 But before that happens there'll be one final sight to behold.
安德洛墨达星系 被延伸跨过整个天空的景象 LOEB: The image of Andromeda will be stretched across the sky,
隐隐看上去和银河系一样大 looming as big as the Milky Way itself,
可以想像那儿有可能会有像 人类一样的智能生命的存在 and it's conceivable that there would be human beings like ourselves
正看着天空，见证这一壮观的 景象 looking at the sky and seeing this spectacular image.
我们也许并不是唯一欣赏这一景象 的生命体 NARRATOR: We might not be the only beings enjoying the view.
有没有可能我们的星系也蕴酿 着别的文明呢？ Could our galaxy be home to other civilizations?
是不是在我们银河系还有 别的未知的生命存在？ Unknown life yet to be discovered inside the Milky Way?
在我们银河系里大约有2000亿颗恒星 There are around 200 billion stars in our galaxy.
但是到目前为止我们只敢肯定 一个近邻有生命存在 But there's only one neighborhood we know for sure that sustains life:
地球 Earth.
太阳几乎给 地球上的一切提供能量 GEOFF MARCY: The sun powers almost everything here on the Earth.
这是我们的能量源；它是 It's the energy source; it's the engine
一切生命和别的许多过程的引擎 of life and many other processes.
地球上的生命很大程度上 依靠水 And life here on Earth is based heavily on water.
就我们所知，液态水是一切 生命的基础 And it's liquid water that's the key to life as we know it.
正是因为液态水可以 作一切物体的溶液 And it's because liquid water serves as the solvent,
溶液是混合物，保存了生命 的物理化学特性 the cocktail mixer, for the biochemistry of life.
地球是太阳系是唯一具有 NARRATOR: Earth is the only planet in our solar system
足够液态水的行星 with abundant liquid water.
正如所有原始文明发源地一样 As with any prime real estate,
重中之重就是位置 it's all about location, location, location.
金星更靠近太阳 MARCY: Venus is closer to the sun,
火星离太阳更远些 Mars is farther from the sun,
在炽热的金星表面和 and there's a zone in between the blazing hot furnace of Venus,
寒冷的火星表面之间有一片地方 the frigid Mars,
这片地方我们称作可居住区域 that zone in between we call the habitable zone,
我们的地球正好就落在这 片区域 and the Earth lies smack in that thing,
只有在这里水才能以液态的形式 存在 where water would be in liquid form,
不是以蒸气－一太热 或是冰块一太冷的形式存在 not in steam, too hot, not in ice form, too cold.
而是在一个适宜的温度下，正如 高地洛克斯所说的， But rather a temperature that, as Goldilocks said,
正好适合生命的存在 is just right for life.
适居的绿色区域的地点 NARRATOR: The location of a habitable green zone
取决于这个星体的位置 depends on the star.
炽热的蓝色的恒星，说明它 的绿色区域在更远的地方 With hot blue stars, the green zone is further out.
相较凉一点的红色星体，说明 它更近了一些 With cooler red stars, it's closer in.
银河系的所有恒星都有一个 适居区域 Every star in the Milky Way has a habitable zone.
但并不是所有的恒星都在那 个区域里有行星存在 But not every star has planets within that zone.
1995年，不存常的事件发生了 MARCY: In 1995 something happened that was extraordinary.
我收到了来自我同事的 保罗·巴特勒的电话 I got a call from my collaborator, Paul Butler,
他说的是，乔夫，快来这 and all he said was, Geoff, come over here.
那一刻我永生难忘 And it was a moment that I will never forget.
我沉默着，保罗也沉默着， 我们都惊呆了 I was silent, Paul was silent, and we were just stunned.
那儿，在电脑屏幕上 There on the computer screen
我准确无误地看到了一个 行星的标志 I saw the unmistakable signature of a planet.
马西首次发现了绕着另一颗 恒星旋转的行星 NARRATOR: Marcy had discovered the first planet around another star.
但是事实上他不能明确地看见它 But he couldn't actually see it
因为这个行星太小了也太暗了 because the planet was too small and dim.
任何一个围绕着恒星旋转的行星 都被寄主恒星炽热的光芒掩盖了 MARCY: Any planet orbiting a star is lost in the glare of that host star,
恒星的光芒是它的十亿倍之多 that outshines it by a factor of a billion.
因此，为了要探测行星，我们 往往从恒星入手 And so instead, to detect planets, we watch the stars.
事实上，恒星在太空之中游移 And in fact a star will wobble in space
因为它也受到来自绕着它旋转 because it's yanked on gravitationally by the planet,
的行星或行星群引力的影响 or planets, orbiting that star.
单看恒星自身 And by watching the star alone
我们可以探测到这个恒星是 否有行星 we can determine whether the star has planets
和这些行星离寄主恒星有多远 and how far out those planets are from the host star.
到目前为止，天文学家已经发现了 超过400个行星 NARRATOR: So far astronomers have found over 400 planets
在银河系里绕着恒星旋转 orbiting stars in our galaxy.
但还没有发现任何一个处在 适居区域中 But none of them seem to be in habitable zones.
其中一种非常靠近寄 主恒星旋转的巨型行星 MARCY: One type of giant planet orbits very close to its star.
我们称之为热木星 We ca“ them hot Jupiter's,
因为这些类木星的行星 离恒星非常近 because these Jupiter-like planets are so close
以致于受到来自寄主恒星的烘烤 that they're blow-torched by the intense heat from the star.
发现的另一类行星也很奇怪 The other sort of planet we've found is also bizarre.
我们发现了一类绕长轨道运行的 行星 We've found planets that orbit in elongated orbits,
以椭圆形，拉长的轨道运行 elliptical, stretched out orbits,
但接下来这些行星 会绕离恒星越来越远 but then the planets go very far from the star
它们自身也会变得非常寒冷 where they would be quite cold.
因此到目前为止， 我们所发现的行星 And so the planets that we've found so far
很难使我们能想像 are a little too weird for us to imagine
上面能有生命存在 that life would have a good chance of surviving.
打开电源 MAN: Power on.
外部就位 External.
但所有这一切有可能将会改变 NARRATOR: But all that may be about to change.
最近美国航空航天局发射了一个 强大的新式望远镜叫做开普勒望远镜 Recently NASA launched a powerful new telescope called Kepler,
用来搜寻有可能围绕着恒星在 适居区域绕轨运动的 to hunt for Earth-sized planets
类地球大小的行星 that may orbit habitable zones around nearby stars.
开普勒望远镜以最简单的 形式运作 MARCY: Kepler works in the most simple way.
开普勒所做的仅仅是监控100,000 个恒星的亮度 All Kepler does is monitor the brightness of 100,000 stars
并以相当精确的准度记录下来 with such exquisite precision
然后它根据行星阻挡恒星光线的强弱 that it would detect a planet as small as an Earth-like one
判断出与地球大小相近的行星 as it blocks the starlight.
我们可以从地球上看见当 NARRATOR: We see the same thing from Earth
金星和水星阻挡了太阳时投射的影像 when Venus and Mercury are silhouetted against the sun.
但是开普勒望远镜的任务要艰巨得多 But Kepler's task is far more difficult.
这有点像用一个搜寻光线扫描时 MARCY: It's a little bit like having a searchlight
通过观察搜寻光线上的一个小暗点 in which you're trying to detect any dust on that searchlight
你可以探测到落在 by noticing a dimming of the searchlight
搜寻光线上的任何一粒微尘 when one dust particle falls on this massive searchlight.
从这个微小的暗点 NARRATOR: From this tiny dimming,
我们可以测量出这个行星的大小 the size of the planet can be measured.
结合这个行星导致寄主恒星摇摆 的程度， And together with the way it causes its host star to wobble,
马西可以计算出这个行星的密度 Marcy can work out its density.
当然这是很了不起的 MARCY: And of course this is glorious
因为通过这些手段 because by these measurements
我们能够区分气状行星 we'll be able to distinguish gaseous planets,
很有可能不适合存在生命 probably not suitable for life,
和岩石状行星——星体表面 很有可能有液态水的存在 from the rocky planets that may have a surface covered by liquid water.
天文学家不能肯定 开普勒究竟能发现多少行星 NARRATOR: Astronomers aren't sure how many planets Kepler will find--
但是在浩大的银河系中有 2000亿颗恒星 but with 200 billion stars in the Milky Way,
这个几率还是足以让人振奋的 the odds look promising.
西斯·夏塔已经作出计算了 Seth Shostak has done the math.
你知道，证据表明 SETH SHOSTAK: You know, the indications are
很多恒星都有行星，大概一半的 恒星都有 a lot of those stars have planets, may be half of them do.
而且 行星某种程度上就像是小猫咪 And since planets, you know, being like kittens,
它们常常不是单个出现而是一双 you don't just get one, you get a couple.
银河系大约有数以万亿计的行星 There are probably on the order of a million million planets out there.
一万亿个行星 NARRATOR: A trillion planets.
这是一个无法想像的庞大数字 It's an unimaginably vast number.
但是它们中又有多少有机会 But what are the chances of them being in a location
处在能蕴育生命的区域呢？ where life can flourish?
我们可以想像把一个恒星的 适居区域扩大到 MARCY: We can expand the idea of a habitable zone around a star
整个银河系的适居区域 to a habitable zone within our entire Milky Way galaxy.
搜寻生命之旅 NARRATOR: The search for life begins
开始于搜寻适居区域 with the search for a galactic habitable zone,
这个可以繁荣生命的安全港湾 the safe haven that allows life to flourish.
近距离看，在中心地带有大量的 MARCY: In close, at the hub there is an extraordinary amount
X射线，高频无线电波 甚至伽玛射线 of X-rays, harsh radio waves, even gamma rays
这些射线都能轻易摧毁任何 有希望成为新一轮进化起点的 that would certainly destroy fragile single-celled life
脆弱的单细胞生命 just getting a start toward evolution.
中心地带非常危险 SHOSTAK: Downtown is dangerous.
那儿有一个超大型的黑洞存在 There's a super massive black hole down there.
一旦接近了那玩意， 所有不好的事情都会发生 You get too close to that, all sorts of bad things can happen.
那儿也有的很多恒星 There are also a lot of stars down there
你知道的，许许多多的恒星听起来 是个好事 and, you know, a lot of stars sounds good,
但从另一方面来讲，如果你周围 有过多的恒星 but on the other hand if you have too many nearby stars
这些恒星会逐渐震动我们太阳系的 所有的彗星 they tend to shake up all the comets in your solar system
不断地轰炸你 that are constantly pummeling you
有了这些个轰炸，你只要去问问 恐龙就行了 with these collisions that, just ask the dinosaurs,
对你来讲并不总是好事 are not always good for you.
这个旋臂可以提供 NARRATOR: The spiral arms may offer
星系中最安全的环境 the safest neighborhoods in the galaxy.
但即便是这儿，也有可能危机四伏 But even here, danger may lurk around the corner.
如果你碰巧处在靠近超新星 附近的行星上 SHOSTAK: If you happen to be on a planet near a supernova,
它的爆炸可以把你整个毁了 that explosion could ruin your whole day.
新的一轮生命可能会开始 但是你知道的 Life might get started, and then, you know,
亿万年后，这一轮生命又将灭绝 another couple of hundred million years later it gets wiped out.
所以这些地方有点像禁止入内区域 不会是人类的领地 So these areas are sort of no-go zones, no man's land.
当然，也不会是外星人的领地 如果它们真存在的话 Well, no alien's land, perhaps.
我们银河系外的太空是 一片更加安静的地方 NARRATOR: The outer reaches of our Milky Way are quieter.
但是对命来说还是很难扎下根 But here life would still find it difficult to take root.
在我们银河系的边缘地区 MARCY: At the outskirts of our Milky Way galaxy
那儿没有很多的重金属元素 there aren't very many heavy elements
这些重金属元素构成了我们身体 of which the cells of our bodies and life as we know it
或是一切生命体的细胞 are composed.
因此在我们银河系的边缘地带 And so we may not have the essential building blocks of life
可能不会有构成 生命的关键基石 at the outer edges of our own Milky Way.
因此，我们之所以存在我们 所存在的地方并不是偶然 NARRATOR: So it's not an accident that we are where we are.
我们的地球，处在两个旋臂之间 Our neighborhood, tucked away between two spiral arms,
是个极好的适居位置 is prime real estate.
这儿已有数十亿年没有怎么变动过了 It's remained relatively unchanged for billions of years,
因此生命得以有时间建立与发展演化 giving life time to establish and evolve.
别的高等文明，如果存在的话 Other advanced civilizations, if they exist,
很有可能生活于类似的环境之中 are likely to live in similar neighborhoods,
免于受到来自星系的威胁 cocooned from the dangers of the galaxy.
我们还没有找到他们 We haven't found them yet.
但是，需要强调的是 我们的星系是个很大的地方 But then again, our galaxy's a big place.
我们还没能在别处发现生命的 存在 SHOSTAK: We haven't found any life elsewhere,
我们还没有找到绿藻类层 we haven't found pond scum,
我们还没有在任何地方 发现死了的绿藻类层 we haven't found dead pond scum anywhere else,
虽说不是很有说服力，但是为 什么是那样？ not convincingly, and why is that?
然而，大约有1000颗恒星 已经被仔细的观察过 Well, fewer than a thousand stars have been looked at carefully
是否有能蕴育智能生物的行星 for planets that might have intelligent life.
因此，你知道，这有点像去非洲 So you know, it's sort of like going to Africa
寻找庞大的动物群 你知道，大象拉，长颈鹿拉之类的 looking for mega fauna, you know, elephants, giraffes, something like that,
当你到达非洲时 and you land in Africa
你看着你所探求的第一片土地时 and you look at the first square yard of real estate there
那儿没有任何大象存在 然后你就放弃了 and you say no elephants here, then you give up.
好吧，我们不能放弃 我们这才刚刚开始 Well, we shouldn't give up, we're just beginning.
好吧，如果我们确实找到了生命 MARCY: Well, if we do find life,
这很神奇，如果我们在 宇宙的别的地方找到了生命 it's amazing, if we find life elsewhere in the universe,
我认为股票市场不会仅仅微微一震 I think the stock market won't budge one bit.
但是我们人类将会知道 人类历史上第一次 But we humans will know, for the first time in human history,
表明我们并不孤单 that we're not alone.
在那些星星之中我们还有着 亲缘存在 That we have kindred spirits out among the stars,
我们的使命也许就成为 探索那些个星星 and that our destiny may well be to venture to the stars,
和它们交流 communicate with them
然后成为宇宙之国俱乐部的成员 and become members of a great galactic country club.