眼见不一定为实 Seeing is not believing.
我们的感觉也会欺骗我们 Our senses can deceive us.
即使是恒星也并非它们看起来的样子 Even the stars are not what they appear to be.
被科学展现出来的宇宙 The cosmos, as revealed by science,
可比我们所能想象的要奇怪得多 is stranger than we ever could have imagined.
光 时间 空间 引力 Light and time and space and gravity
共同创造出一个 conspire to create realities
超越人类经验的现实世界 which lie beyond human experience.
那就是我们要去的地方 That's where we're headed.
跟我来 Come with me.
1802年 一个这样的夜晚 Back in 1802, on a night like this,
天文学家威廉·赫歇尔与他的儿子约翰 The astronomer William Herschel strolled the beach
漫步在英国的海滩上 on the English coast, with his son John.
赫歇尔是第一个 Herschel was the first person ever
看到了宇宙之海深处的人 to see into the deeper waters of the cosmic ocean.
在那里 他瞥见了 There he glimpsed the magic trick
光用时间施下的魔法 that light does with time.
父亲 Father...
您相信灵魂吗 do you believe in ghosts?
为什么这么问 我相信孩子 Why, yes, my son!
您真的相信吗 You, you do?
我还以为您不信呢 I would not have thought so.
不 我信的并非人类的灵魂 Oh, no, not in the human kind of ghost.
不 完全不是 No... not at all.
但是抬头看 我的孩子 But look up, my boy,
你可以看见灵魂充满了天空 And see a sky full of them.
您是说恒星吗 父亲 The stars, father?
我不明白 I do not follow.
每一颗恒星都和我们的太阳一样大而明亮 Every star is a sun as big, as bright as our own.
想像一下要把太阳移多远 Just imagine how far away from us you'd have to move the sun
才能让它像恒星一样小而黯淡呢 to make it appear as small and faint as a star.
恒星发出的光速度很快 The light from the stars travels very fast,
比一切东西都要快 faster than anything,
但却不是无穷快 but not infinitely fast.
它们的光到达我们也是需要时间的 It takes time for their light to reach us.
对于最近的一颗也要花好几年时间 For the nearest ones, it takes years.
对别的 则要几个世纪 For others, centuries.
有些恒星离得太远了 Some stars are so far away,
它们的光到达地球甚至需要数十亿年 it takes eons for their light to get to Earth.
有些恒星的光到达这里时 By the time the light from some stars gets here,
它们都已经死了 they are already dead.
对这些恒星 我们看到的是它们的灵魂 For those stars, we see only their ghosts.
我们看到了它们的光 We see their light,
但它们本身在很久以前就已经逝去了 but their bodies perished long, long ago.
约翰 与我之前的人相比 John, I have seen further back in time
我能看到更久之前 than any man before me--
我能看到数百万年前 millions of years into the past.
威廉·赫歇尔第一个理解了 William Herschel was the first person to understand
望远镜其实是一台时间机器 that a telescope is a time machine.
我们只要望向太空 We cannot look out into space
那么看到的一定是过去 without seeing back in time.
光一秒钟能传播三十万千米 In one second, light travels 300,000 kilometers,
或是十八万六千英里 or 186,000 miles.
这几乎是地球到月球的距离 That's nearly the distance from the Earth to the Moon.
所以月球离我们一光秒远 So, the Moon is about one light-second away.
下一次你抬头看月亮 The next time you look at the Moon,
你看到的是一秒前的历史 you'll be seeing one second into the past.
翻译 Foxer 雀儿
校对 OBAFGKM
时间轴 suki
后期 吉吉
总监 OBAFGKM
宇宙
时空之旅
太阳 That Sun...
其实并不在那里 it's not really there.
两分钟后它才真正从地平线升起 It won't actually be above the horizon for another two minutes.
日出其实是幻象 The sunrise is an illusion.
地球的大气像是一个透镜或是一杯水一样 Earth's atmosphere bends the incoming rays of sunlight
弯曲了阳光 like a lens or a glass of water.
所以我们看到的太阳 So we see the image of the Sun
只是在太阳到达那里前 projected above me is a mirage
投射出的幻象 before the physical Sun is actually there.
我身后的太阳就是个幻象 That Sun behind me is a mirage.
和在一个大热天 荒芜的道路上 No more real than the shimmering image
远处出现的蜃楼没有什么不同 that hovers in the distance over a desert road on a hot day.
阳光到达地球需要八分钟时间 Sunlight takes about eight minutes to reach Earth,
所以太阳距离我们八光分 so the sun is eight light-minutes away.
从地球上 我们只能看见 From Earth, we can only ever see the Sun
八分钟前的太阳 as it was eight minutes ago.
还有一件事 And another thing,
太阳其实根本不会"升"起来 the Sun doesn't really "rise" at all.
地球在旋转 而我们也跟着一起转 The Earth turns and we turn with it.
也许看起来并不像 但是现在 It may not look like it, but right at this moment,
我比一架喷气机的速度还快 I'm moving faster than a jet plane
所有在地球上的人都一样 and so are you and everyone on Earth.
当我向那边去时 While I'm at it,
那条地平线 that horizon...
其实并不存在 it's not really there at all.
那边没有边界 There's no edge.
地平线也是另一种幻象 The horizon is just another illusion.
地球和最外侧行星海王星之间的距离 The distance between Earth and the outermost planet Neptune
随着行星绕太阳公转改变 varies as the planets orbit the Sun.
平均而言 需要光走四个小时 On average, the light makes that trip in four hours.
对地球上的我们而言 So for us on Earth,
我们看到的海王星永远是四小时前的 the Neptune we see is always four hours in the past,
距离四光时远 four light-hours away.
但是行星间的距离 But the distances to the planets,
就算最远的一个 even the farthest one...
从恒星和星系的大尺度上看 are mere baby steps on a much grander scale
其实离得很近 of the stars and galaxies.
一旦我们离开太阳附近 As soon as we leave the Sun's immediate neighborhood,
我们就得把距离单位 we need to change the unitive distance
从光时变成光年 from light-hours to light-years.
光年才是宇宙的尺度 A light-year is the yardstick of the cosmos.
一光年就有近百万亿千米 A single one is nearly ten trillion kilometers,
或是60万亿英里 or about six trillion miles.
这是一个距离单位 和米或英里一样 It's a unitive distance, just like a meter or a mile.
光年就是光传播一年的距离 It's the distance light travels in a year.
离太阳最近的恒星 即比邻星 The nearest star to the Sun, Proxima Centauri,
离地球有超过四光年的距离 is a little more than four light-years away from Earth.
四光年有多远呢 How far away is four light-years?
美国宇航局的旅行者号飞船 NASA's Voyager spacecraft moves
速度超过每小时5.6万千米 at more than 56,000 kilometers an hour.
就算在这样惊人的速度下 旅行者号 Even at that astonishing speed, it would take Voyager
也要花八万多年才能到达最近的恒星 more than 80,000 years to reach the nearest star.
而昴宿星团的恒星 And the stars of the Pleiades Cluster,
则有400光年远 400 light-years away.
想象号飞船 The ship of the imagination
拥有极不寻常的能力 is equipped with a highly unusual capability--
实际上是独一无二的 one-of-a-kind, actually.
它让我们可以看到 It makes it possible for us to see what was happening
光从遥远的恒星或是星系 when the light from a distant star or galaxy
踏上去往地球的漫长之旅时 发生的事情 first set out on its long journey to Earth.
当那束光大约400年前离开昴星团时 When that light left the Pleiades, about 400 years ago,
伽利略正第一次通过望远镜观测 Galileo was taking his first look through a telescope.
几年以后 他尝试着测量光的速度 A few years later, he tried to measure the speed of light,
但是他失败了 but he couldn't do it.
他的计划非常精妙 但是那时的技术 He had a very clever plan, but the technology of that era
没有办法测量 just wasn't good enough to measure
像光一样快的运动 the motion of anything that moves as fast as light.
当我们从地球上看蟹状星云 When we look at the Crab Nebula from Earth,
我们看到的是更久之前的样子 we're seeing much farther back in time.
蟹状星云曾是一颗巨星 The Crab Nebula was once a giant star,
质量是太阳的十倍 ten times the mass of the Sun,
直到它发生了超星新爆炸 until it exploded in a supernova.
在它的中心是一颗脉冲星 At its heart is a pulsar,
一颗坍缩到一座城市大小的恒星 A collapsed star the size of a city,
并且每秒自转30周 spinning 30 times a second.
这颗脉冲星旋转着的磁场 This pulsar's whirling magnetic field
疯狂地鞭打附近的电子 whips nearby electrons into a frenzy,
将它们加速到接近光速 accelerating them to almost the speed of light.
它们发出炫目的蓝光 They shine with a blue glow that
照亮了超新星周围的气体 lights up the tendrils of gas
这些气体仍被持续释放出来 still unraveling from the supernova.
蟹状星云 The Crab Nebula
离地球约6500光年 is about 6,500 light-years from Earth.
有些人相信 According to some beliefs,
这就是宇宙的年龄 that's the age of the whole universe.
但是若宇宙只有6500岁 But if the universe were only 6,500 years old,
那我们怎么可能看到蟹状星云 how could we see the light from anything more distant
以外的任何东西呢 than the Crab Nebula?
我们不能 We couldn't.
这个时间不足以让任何方向的光 There wouldn't have been enough time for the light
从任何超过6500光年外的地方 to get to Earth from anywhere farther away
到达地球 than 6,500 light-years in any direction.
这点时间只够光穿过 That's just enough time for light to travel
银河系的很小一部分 through a tiny portion of our Milky Way galaxy.
相信宇宙年轻到 To believe in a universe
只有六千或七千岁 as young as 6,000 or 7,000 years old
就等于隔绝了银河系绝大部分的光 is to extinguish the light from most of the galaxy,
更不用说可观测宇宙中 not to mention the light from all the 100 billion
千亿个星系发出的光了 other galaxies in the observable universe.
银河系的中心 The center of our own galaxy
离地球三万光年 is about 30,000 light-years from Earth.
当我们今天看到的光 The light we see today
从银河系的核心离开时 coming from the core of the Milky Way left there...
我们的祖先正在完善一种征服死亡的方法 When our ancestors were perfecting a way to vanquish death...
那就是通过艺术 by making art
在他们逝去后依旧启发后人 with the power to inspire those who would come long after they were gone,
我们看到的从草帽星系发出的光 the light we see coming from the Sombrero galaxy
已经有三千万年的历史了 is 30 million years old.
当那道光发射出来时 Our ancestors were living in trees
我们的祖先还住在树上 when that light started out.
那时它们也就五千克重 还有长尾巴 They weighed about five kilos and had long tails.
但是就算是三千万光年的距离 But even 30 million light-years away
也不过还是在我们宇宙的后院罢了 is still in our own cosmic backyard.
这些星系是后发星系团的一部分 That galaxy is part of the Coma Cluster,
离我们三亿两千万光年 320 million light-years away.
当你所看到的光开始 What was going on back home
飞往地球时 地球是什么样的呢 when the light you are seeing began its trip to Earth?
没有熟悉的大陆 海洋或河流 No familiar continents, oceans or rivers.
我们的远祖才刚刚 Our distant ancestors were just
离开水登上陆地 leaving the water for the land.
那是很老的光了 That's pretty old light,
但却远不是我们看到的最老的光 but not nearly the oldest light we can see.
最老的光非常微弱 The oldest light is very faint,
是夜空中暗淡的幽灵 a pale ghost in the night.
看见圈中的红点了吗 See that red blob inside the circle?
那是我们见过的最老的星系之一 That's one of the oldest galaxies we've ever seen.
你看到的是被哈勃望远镜捕捉到的 You're looking at 13.4-billion year-old starlight
134亿年前的星光 as captured by the Hubble Space Telescope.
它来自于第一代恒星 It's coming from the very first generation of stars.
那时的地球是什么样子呢 What was happening on Earth back then?
什么也没有 Absolutely nothing.
没有地球 没有太阳 没有银河系 There was no Earth, no Sun, no Milky Way.
数十亿年后它们才会出现 They would not come to be for billions of years.
当我们想要看到更远的宇宙 When we try to look even farther into the universe,
会发现我们到了空间的尽头 we come to what appears to be the end of space...
但是实际上 But actually...
这是时间的起点 it's the beginning of time.
地球拉着我们 Earth pulls on us.
我们无时不刻不在与引力做斗争 Our lives are a relentless struggle with gravity.
那个小女孩正尽全力摆脱 That little girl is trying her best to climb out
引力的束缚 of a gravitational well.
从我们最初想站起来到我们最终屈服 From our first efforts to stand to our final surrender,
我们都在挣扎着克服地球的引力 we are struggling to overcome the Earth's pull.
一个几乎和宇宙同样古老的力场 We are born, live and die in a force field--
我们在其中出生 生活 死亡 one that is almost as old as the universe itself.
宇宙有多老呢 And how old is that?
为了看清138亿年历史的宇宙 To visualize the 13.8 billion year age of the universe,
我们将所有的宇宙时间 we've compressed all of cosmic time
压缩到一年的年历中 into a single year-at-a-glance calendar.
12月31日的午夜就是现在 Midnight on December 31 is this very moment right now.
而1月1日就是时间的开始 And January 1 is the beginning of time.
看见那团炽热的雾了吗 See that glowing fog out there?
那时大爆炸留下的辐射 It's radiation left over from the Big Bang,
也就是138亿年创造了宇宙的 The explosion that made the universe
宇宙大爆炸 13.8 billion years ago.
现在 我们就在已知空间和时间的边缘 Right now, we're at the very edge of known space and time.
那么宇宙大爆炸之前是什么样子呢 So what happened before the big bang?
没人知道 Nobody knows.
没有任何大爆炸之前的证据留下来 No evidence survives from before that moment.
关于宇宙从何而来 We've got some pretty crazy ideas
我们有一些非常疯狂的想法 about where the universe came from,
我们后面会讲到 which we'll get to, in time.
我们在宇宙中的什么位置 Where are we in the universe?
就在宇宙中心 At the very center.
在可观测的宇宙 人人都可以与众不同 In the observed universe, everyone gets to feel special.
无论你生活在哪个星系 No matter which galaxy you happen to live in,
当你抬头望向宇宙时 你都会发现 when you look out to the universe, you'll find yourself
自己身处宇宙的中央 at the center of the cosmic horizon.
但这只是个幻觉 But this is just an illusion.
实际上 宇宙没有中心 In reality, there is no center,
宇宙的地平线和海上的地平线一样 and the cosmic horizon is no more real
都并不存在 than the horizon at sea.
在一个光速有限 时间也有起点的宇宙 It's what you get when you have a finite speed of light
你只能得到这样的结果 in a universe that had a beginning in time.
在宇宙大爆炸的数亿年后 A few hundred million years after the big bang,
巨大的氢气和氦气云收缩成 vast clouds of hydrogen and helium condensed
最初的恒星和星系 into the first stars and galaxies.
出现了这些新光源 With these new sources of light,
宇宙漫长的黑暗时代结束了 the long dark ages of the universe ended.
随着空间继续膨胀 As space continued to expand,
宇宙在更大尺度上演化 cosmic evolution unfolded on grander scales.
当第一代恒星死去后 As the first generation of stars died,
它们向宇宙播撒了更重元素的种子 they seeded space with heavier elements,
为行星的形成创造了可能 making possible the formation of planets,
最后 是生命 and ultimately, life.
大爆炸创造了物质和能量 Matter and energy were formed in the big bang.
但还不仅于此 But that's not all.
空间和时间也被创造了 Space and time were created, too,
以及所有将物质约束到一起的力 and all the forces that bind matter together,
其中就有引力 including gravity.
艾萨克·牛顿发现了一条数学法则 Isaac Newton discovered a mathematical law
用于描述引力的作用方式 that describes how gravity works.
有那条法则 就可以解释行星的运动了 With that law, he could explain the motions of the planets.
100多年后 More than 100 years later,
威廉·赫歇尔发现引力能做的远不止这些 William Herschel realized gravity could do much more.
约翰 你能保守一个秘密吗 John, can you keep a secret?
可以 父亲 Yes, father.
我有一个发现 但是从没告诉过别人 I've made a discovery and have yet to tell another soul.
将我们束缚在地球上的引力 The gravity that holds us to the Earth--
也就是牛顿发现的 the same gravity that Newton showed
将行星约束在轨道上的引力 keeps the planets in their orbits--
我发现 I've discovered
它对遥远的恒星一样有效 that it also rules the distant stars.
父亲 但是您是怎么发现的呢 Father... but how can you know this?
你能不能找到狮子座 Can you find the constellation of the Lion?
在那里 There.
很好 Well done.
那你能不能找到 Can you now find the star
狮子脖子处的恒星 that joins the lion's head to his body?
是那个 That one.
那颗恒星其实是两颗恒星 That star is really two stars
它们彼此很近所以看起来像是一颗 so close together that they appear to be one.
我自你出生前很久就开始 I've been watching them through my telescope
用望远镜观察它们了 since long before you were born.
它们非常缓慢地围绕着彼此起舞 They dance around each other very slowly.
比一般行星公转的速度慢得多 More slowly than any planet moves around the Sun.
很多我们今晚看到的恒星 Many of the stars we see tonight,
也许是大多数 perhaps most of them,
都在与它们看不见的舞伴舞蹈 dance with invisible partners.
引力帝国统治着一切天上的世界 Gravity's empire governs all the heavens.
一个世纪前 A century earlier,
艾萨克·牛顿也因 Isaac Newton had been haunted
不了解产生引力的机制而困扰 by the same absence of a mechanism for gravity.
相隔甚远的天体 How could distant bodies affect each other
如何跨越真空 不接触彼此而相互影响呢 across empty space without actually touching?
他所称的"远距离作用"使他困惑 This "action at a distance," as he called it, baffled him.
在19世纪 迈克尔·法拉第发现了 In the 19th century, Michael Faraday discovered
我们正被不可见的力场包围 that we were surrounded by invisible fields of force
这解释了引力的原理 that explained how gravity works.
苹果和地球并没有直接接触 The apple and the Earth don't touch each other,
但是它们间的场却可以 but the fields between them do.
他想象这些引力线 He imagined those lines of gravitational force
从所有大质量天体向四周发射 radiating out into space from every massive body--
包括地球 月球 太阳 所有物体 the Earth, the Moon, the Sun, everything.
把牛顿难住的问题 Here was the answer to that question
得到了答案 that had stumped Newton.
1865年 詹姆斯·克拉克·麦克斯韦 In 1865, James Clerk Maxwell translated Faraday's idea
为法拉第关于电场和磁场的想法 about fields of electricity and magnetism
建立了数学方程 into mathematical laws.
他发现这些场以波的形式传递 He discovered that these fields move through space in waves.
当他计算它们能传多快时 When he calculated how fast they move,
竟发现它们的速度是光速 it turned out to be the speed of light.
我们发现了宇宙的壁毯上交织的线 We were beginning to discover the threads of the cosmic tapestry,
但是我们还没法领悟出上面丰富的图案 but we were not yet able to discern the rich pattern
如时间 光 空间 引力的编织方法 that time, light, space and gravity weave.
当阿尔伯特·爱因斯坦在柏林 As Albert Einstein worked in Berlin
研究他的引力理论时 on his theory of gravity,
他将前三者的画像都放到了面前 he kept the portraits of these three men before him.
他知道自己是站在他们的肩膀上 He knew he was standing on their shoulders.
数年前 还是青少年的他 Years before, as a teenager, he had an insight
就展现出和他们一样惊人的洞察力 that was as Earth-shaking as any idea of theirs.
一个夏天 当他在意大利 And it happened one summer
做着白日梦时发生了 while he was daydreaming in Italy.
在1895年的夏天 In the summer of 1895,
爱因斯坦父亲在德国的生意失败了 Einstein's father's business in Germany had failed,
他们家就搬到了北意大利 and the family had moved here to northern Italy.
年轻的爱因斯坦喜欢在这些路上漫步 Young Einstein loved wandering these roads and
让他的思绪自由地探索 giving his mind free rein to explore.
这里有些东西是永恒的 There's something timeless about this place.
自爱因斯坦早年的白日梦 Nothing here has really changed
到现在这里几乎没有什么变化 since the time of Einstein's early daydreams.
有一天 他开始思考光 One day, he began to think about light
以及光的速度 and how fast it travels.
每天我们都要测量 In everyday life, we always measure the speed
某个移动物体相对于其他物体的速度 of a moving object with respect to something else,
某样假设静止的东西 something that's presumably not moving,
某样在宇宙中静止的东西的速度 something in the cosmos that's not in motion.
比如 我以每小时十千米的速度 For example, I'm moving about ten kilometers per hour
相对于大地移动 relative to the ground.
但就像我之前提到的 大地也在运动 But as I mentioned earlier, the ground is moving.
地球正以超过每小时1600千米的速度自转 Earth is turning at more than 1,600 kilometers per hour.
当它围绕太阳公转时 While it orbits the Sun,
速度就超过了每小时10万千米 at more than 100,000 kilometers per hour.
而太阳又以每小时80万千米的速度 And the Sun is moving through the galaxy
在银河系中运动 at a half a million miles per hour.
而银河系又在宇宙中 And the Milky Way is moving through the universe
以每小时240万千米的速度运动 at nearly one and a half million miles an hour.
宇宙中没有静止 There is no fixed place in the cosmos.
万物皆是运动的 All of nature is in motion.
对于年轻的爱因斯坦来说 It was hard even for the young Einstein
都很难去想象某个绝对的标准 to imagine some absolute standard
来测量所有这些相对运动 to measure all those relative motions against.
就是这本书 This is the very book
这激励了少年时代的爱因斯坦 That inspired Einstein as a young boy.
给孩童的一本书 改变了整个世界 Give a kid a book and you change the world.
甚至可以说 是整个宇宙 In a way, even the universe.
看这里 第一页上 Look at this-- the very first page,
记录了电流通过电线 it describes the astonishing speed
和光穿过空间时 of electricity through wires
惊人的速度 and light through space.
爱因斯坦回忆起少年时代 Einstein remembered what he'd learned as a child
从书里学到的知识 from this book,
也是 此时此刻是他第一次 and perhaps, for the first time, right here,
思考人在达到光速时 wondered what the world would look like
看到的世界将会是怎样 if you could travel at the speed of light.
爱因斯坦越深入思考这个问题 The more Einstein thought about it,
他就越发困惑 the more troubled he became.
单是想象人以光速运行 If you imagine traveling at the speed of light,
就会发现矛盾重重 paradoxes seem to pop up everywhere.
爱因斯坦惊奇地发现 Einstein was shocked to realize
许多被人理所应当地认定 that so much of what had been uncritically accepted as truth
甚至连最权威的人物也同意的事情 by even the greatest authorities on the subject
其实大错特错 was just plain wrong.
当以高速运行时 When traveling at high speeds,
有一些公理是不可违背的 there are certain rules which must be obeyed.
爱因斯坦称之为 相对论 Einstein called these rules "the principles of relativity."
试想一个妙龄少女骑着摩托车 Imagine that young woman who just blew past us
从我们身边呼啸而过 on the motorbike,
再试想她骑着车穿过整个宇宙 imagine she was riding her bike through the cosmos.
运动物体发出的光线以同样的速度传播 Light from a moving object travels at the same speed,
与该物体是静止还是运动状态无关 no matter whether the object is at rest or in motion.
这个女孩的速度不算入光的传播速度 Her speed is not added to the speed of light.
她的摩托车发出的光 The light from her motorbike
依然会以光速传播 still travels at the speed of light.
自然之律 Nature commands,
汝不可将我之速 加诸光之速 "thou shalt not add my speed to the speed of light."
并且 没有实体物质 Also, no material object
能以等于或超过光速的速度运行 can travel at or faster than the speed of light.
物理学不会阻止你 There's nothing in physics that prevents you
无限接近于光速地运行 from traveling as close to the speed of light as you like.
甚至是光速的百分之九十九点九都可以 99.9% of the speed of light is just fine,
但是无论如何 but no matter how hard you try,
你都无法达到光速 you never gain that last decimal point.
为了现实世界在逻辑上自洽 For reality to be logically consistent,
这要求有一个宇宙临界速度 there must be a cosmic speed limit.
这条鞭子发出的声音 是因为它的尖端 The crack of that whip is due to its tip
运动的速度大于声音传播的速度 moving faster than the speed of sound.
这产生了冲击波 It makes a shockwave,
在意大利的郊外 造成了微型音波爆炸 a mini sonic boom, in the Italian countryside.
打雷也是同样的道理 A thunderclap works the same way,
同样的还有超音速飞机发出的轰鸣声 and so does the sound of a passing supersonic jet.
为什么可以超越声速 So why is the speed of light
却不能超过光速 any more a barrier than the speed of sound?
这不仅是因为光的传播速度 The answer is not just that light travels
比音速快将近一百万倍 about a million times faster than sound.
这也不像建造第一台超音速飞机一样 And it's not merely an engineering problem,
是一个简单的工程问题 like building the first supersonic jet.
反之 光的速度上限 Instead, the light barrier
是最基本的自然定律 is a fundamental law of nature,
和重力一样基础 as basic as gravity.
爱因斯坦找到了他所认为的世界的绝对框架 Einstein found his absolute framework for the world,
在所有物质都在相对运动的宇宙中 this sturdy pillar among all the relative motions
不变的基石 within the motions of the cosmos.
所有光以同样速度传播 Light travels just as fast,
不管它的光源运行速度是多少 no matter how fast or slow its source is moving.
光速是恒定不变的 相对一切事物都是如此 Speed of light is constant, relative to everything else.
没有东西可以追上光 Nothing can ever catch up with light.
自然规律最重要的一点 The thing about the laws of nature
就是它是不可违背的 is that they're unbreakable.
物理学家的工作就是去找到这些规律 The job of physicists is to discover these commandments,
那些不为文化差异和时过境迁所动 the ones that do not vary from culture to culture
永恒的定律 or time to time
在浩瀚宇宙里掌握真理 and hold true throughout the cosmos.
爱因斯坦认为 这也是为什么 That's why, as Einstein showed,
在接近光速时会发生奇妙的现象 funny things happen close to the speed of light.
以接近光速运行 Traveling close to the speed of light
可以让生命永恒 is kind of an elixir of life
因为你的生物钟和相对于你甩下的一切 because your biological clock slows down
变得慢下来 relative to those you leave behind.
这个现象可能能为我们这些 This phenomenon may provide us humans,
只能活一个世纪的人类 who only live for a century or so,
一个去到其他恒星的可行方法 a practical means to travel to the stars,
去另一个由第四维度时空带来的 where the magic show of spacetime
奇妙世界 really gets crazy.
十九世纪的天文学家威廉·赫歇尔 The 19th-century astronomer William Herschel
喜欢和他的儿子约翰 loved to share the wonders of the universe
分享宇宙的神秘 with his son John.
我曾经有个朋友 一个很聪明的人 I once had a friend, very clever fellow,
来自利兹[英国城市]的天文学家和牧师 an astronomer and a parson at Leeds,
名字叫作约翰·米歇尔 by the name of John Michell.
他在你还是个婴儿时就凄惨死去 Poor man died when you were a babe,
愿上帝让他安息 God rest his soul.
他认为有些恒星是隐形的 He held that some stars are invisible.
它们是存在的 但是我们看不到它们 They really exist, but we shall never see them.
米歇尔叫它们暗星 "Dark Stars," Michell called them.
爸爸 恕我直言 With all due respect, father,
你的朋友肯定是错了 surely your friend was mistaken.
如果没有人能看到它们 If no one can see them,
那人们怎么可能知道它们存在呢 then how can we possibly know they exist?
你看到了留下这些脚印的人吗 约翰 Did you see the man who left those footprints, John?
没有 怎么了 爸爸 Why, no, father.
我没看到 I did not.
但你知道他们一定来过这里对吗 But do you know that he exists?
约翰·米歇尔可能是你没听说过的 John Michell is one of the greatest scientists
最伟大的科学家之一 you've probably never heard of.
他十八世纪时在英国工作 He lived and worked in England in the 18th century.
就算他曾经有过画像 那也不可能还在了 If he ever sat for a portrait, it no longer exists.
一个相识的人曾这样形容他 He was once described by an acquaintance
一个小矮子 as "a short little man,
肤色黝黑 大腹便便 of black complexion, and fat."
米歇尔设想过有一颗巨大的恒星 Michell imagined a star so big,
巨大到没有物体 甚至光 so massive, that nothing, not even light,
可以逃脱它的重力场 could escape its gravitational grip.
你能找到那颗暗星吗 Can you find the dark star?
你不能直接通过肉眼看到它 You can't see it with your eyes, not directly,
但是它也会在宇宙里留下它的足迹 but it may leave a kind of footprint on the cosmic shore.
米歇尔意识到我们也许可以 Michell realized that we might be able to detect
借助暗星巨大的重力探测到它们 some of these dark stars because of their extreme gravity.
如果它恰好靠近 If one happened to be near
一颗更小 更明亮的伴星 a smaller, luminous companion star,
那这颗恒星可能会看似被巨大引力束缚 that star would appear to travel in a tight orbit
绕着虚空运行 around nothing.
即使我们看不到 Even though we can't see it,
我们也会知道有一个大质量天体 we know something with a lot of mass
存在于这里 has to be right there.
那就是暗星 A dark star,
或者在今天我们称之为 黑洞 or what today we call a black hole.
黑洞到底长什么样子 What does a black hole look like
它的内部又会是如何 and what would it be like inside?
我们会提到的 但是首先 We'll get there, but first,
我们先在我的故乡稍作停留 let's make a pit stop in my hometown,
纽约 New York City,
这里在我的眼里 where it's always seemed to me
一切事物总是永不停歇 that everything is in constant motion.
我大部分时间都生活在这里 I've lived here most of my life.
总有新鲜的事物出现 There's always something new to see.
但是有一个事永远不变 重力 But one thing never changes-- gravity.
地球上的重力在过去的 Gravity on Earth has been the same
四十五亿年里都不曾改变 for the past four and a half billion years.
那么万一 如今我们可以改变它呢 But what if, today, we could alter it?
根据爱因斯坦所说 重力源自于 Gravity is a distortion in the shape of spacetime
四维时空的扭曲 as Einstein showed.
空间可以无限地膨胀 收缩和扭曲 Space can expand and contract and warp without limit.
如果地球的大小和密度改变了哪怕一点点 If the Earth's size or density were even a little different,
它的重力场也会随之改变 its gravity would be, too.
可能性是无穷无尽的 There's an infinite range of possibilities.
纽约客们在家里 New Yorkers feel right at home
受到地球的重力吸引 in the gravitational pull of the Earth,
称之为 一个G called "one g."
假设我们关闭一条街的重力 Suppose we turn off the gravity on one of its streets.
所有在运动的人和物体 People and objects that were already in motion
都会离开地面开始飞行 are launched into flight.
或者我把重力提高到 Now what if I turn the gravity up
比如说 八或九个G to, say, eight or nine g's?
出于人道主义 Out of compassion,
我们疏散一下现场 let's evacuate the area.
这大概是一个战斗飞行员 This is about the same g-force
在高速转弯时感到的重力值 that a fighter pilot in a high-speed turn would feel.
只经历几分钟不会对你造成伤害 A few minutes of this wouldn't hurt you,
但是绝对不好受 but it wouldn't be comfortable.
在十万个G时 At 100,000 g's,
即使是消防栓 even fire hydrants become crushed
也会被自身重量所压碎 by their own enormous weight.
但是当一百万个G时 But at millions of g's,
甚至连光也会向重力屈服 even light bows to gravity.
光还是按照它的既定速度传播 The light still moves at its constant speed,
但是它无法逃脱 but it cannot escape
米歇尔所说的暗星 Michell's dark star...
我们所说的黑洞 Our black hole.
最近的黑洞可能比你想的近许多 And the nearest one may be closer than you think.
不是所有恒星都会变成黑洞 Not every star can become a black hole.
一千颗中只有一颗能有足够的质量 Only about one in a thousand is massive enough.
最近的一处离地球可能不超过一百光年 The nearest one could be within 100 light years of Earth.
黑洞不像科幻小说所说 Black holes aren't the mythic cosmic
是神秘宇宙中的吸尘器 vacuum cleaners of science fiction
它们不会到处蚕食没有防备的世界 they don't go around gobbling up unsuspecting worlds.
只能是你靠近它 You've got to come to them.
但如果你这么做了 But if you do,
它可能会成为你最后见到的东西 it might be the last thing you ever see.
那就是我们和几百万G的重力做抵抗 That was us resisting a few million g's of gravity.
不要忘记 它甚至会吞噬光 Don't forget, that thing swallows light.
我们要和它保持距离 We'll keep our distance.
当巨大的恒星耗尽了自身的核燃料 When giant stars exhaust their nuclear fuel,
就无法保持自己温度 they can no longer stay hot enough
来抵抗自身向内的引力作用 to fend off the inward pull of their own gravity.
质量最大的恒星坍缩成黑暗 The most massive stars collapse into darkness,
只剩下自己的重力场 leaving only their gravity behind.
这个黑洞吞噬了一颗超大质量恒星 This black hole enshrouds the shrunken corpse
坍缩的残骸 of a supergiant star.
恒星自身已经萎缩成 The star itself has shriveled into something
比这片黑暗更小的物体 even smaller than this darkness,
直径只有六十四千米 only 64 kilometers wide.
这是有史以来发现的第一个黑洞 This is the first black hole ever discovered--
天鹅座X-1 Cygnus X-1.
我们究竟是如何发现 How did we on Earth ever find something
如此渺小 黑暗和遥远的物体呢 so small and dark and far away?
我们通过另一种光线看到它 X射线 We looked at it in another kind of light. X-rays.
在X射线中 我们无法看到这颗蓝色的恒星 In X-ray light, we lost sight of the blue star
因为它的表面温度只有三万度 because its surface is a tepid 30,000 degrees.
但是黑洞周围围绕的盘状气体 But the disk of gas around the black hole
由于一亿度的温度 放出耀眼的X射线 glowed brilliantly in X-rays at 100 million degrees.
威廉·赫歇尔的研究指出 As William Herschel discovered,
许多恒星和相距不远的伴星 many stars have close companions
组成一个双星系统 forming a binary star system
但如果其中一颗恒星非常巨大 but if one member of such a pair is enormous
而另一颗是致密星 and the other is compact,
较小的一颗会吸收和耗尽 the smaller star can drain and consume the atmosphere
较大恒星的大气 of its larger sibling.
这种不公平的关系可以延续百万年 This neurotic relationship can last for millions of years.
较大恒星的大气会因虹吸效应 The atmosphere of the larger star was being siphoned onto
形成一个发光的炽热吸积盘 围绕着黑洞 a glowing hot accretion disk that revolves around
并螺旋着进入其中 and spirals into a black hole.
不可抗拒的引力加速了蓝色恒星的气体 The overwhelming gravity was accelerating the blue star's gas
进入死亡漩涡 into a death spiral,
穿越时空的边界 crossing the spacetime boundary,
从此消失不见 never to be seen again.
分离开黑洞 The fateful boundary
和宇宙中其他一切的关键边界 that separates a black hole from the rest of the universe
叫做事件视界 is called an event horizon.
在我们看来 盘上的物质 From our point of view, the substance in the disk
在靠近事件视界时会减速 slows down as it approaches the event horizon,
不会真正到达视界 never quite reaching it.
但是如果你乘着旋转的气体 But if you were riding on that spiraling gas--
我不推荐你这么做 and i don't advise it--
你就能在几秒钟内穿越事件视界 you would sail past the event horizon in a matter of seconds
到达一个有去无回 into the undiscovered country
无法被探索的国度 from which no traveller returns.
我们所有探索过许多星系的中心地带 We have searched the hearts of dozens of galaxies,
每一个星系 我们都找到了一个超大质量黑洞 and in every case, we have found a super-massive black hole.
银河系也不例外 Our own galaxy is no exception.
离银河系中心最近的恒星 The stars nearest the center of our galaxy
以超过每小时四千万千米的速度公转 whip around at more than 40 million kilometers an hour.
什么让它们运行得这么快 What could make them move so fast?
唯一符合逻辑的解释 The only logical explanation
就是一个四百万倍太阳质量的天体 is that something with the mass of four million suns
存在于银河系中心 lies at the center.
这个有太阳四百万倍质量的天体发出的光在哪 So where's the blazing light of four million suns?
既然我们无法看到 Since we can't see it,
就说明它被黑洞吞噬了 it must be imprisoned inside a black hole.
地球是远处在安全距离之外的 Earth is far enough away to be perfectly safe.
但其他星球可能不这么走运了 Other worlds might not be so lucky.
如果你能通过危险的旅途 If you somehow survived the perilous journey
成功穿越视界 across the event horizon,
你就能够溯古追今 you'd be able to look back out
看着整个宇宙的未来历史 and see the entire future history of the universe
在你眼前徐徐展开 unfold before your eyes.
怎么做到的 How?
因为当四维时空被黑洞的巨大引力 Because when spacetime is warped
所扭曲的时候 by the extreme gravity of a black hole,
时间也被伸展到了极限 time is stretched to the limit.
那你面前将出现怎样的光景 But what would be in front of you?
当我们到达那里 我要提前警告你 Before we go there, i should warn you
我们正在进入一个未知的科学领域 that we're entering uncharted scientific territory.
我们只知道 将会有还未被发现的物理定律 For all we know, there may be undiscovered laws of physics
在黑洞的中心控制一切 that govern events at the center of a black hole.
但是在下一个爱因斯坦出现之前 But until the next Einstein comes along,
我们来假想一个思维实验 let's perform a thought experiment.
这就是约翰·米歇尔在十八世纪 That's how John Michell first imagined dark stars
第一次想象暗星 in the 18th century,
和爱因斯坦开始构思相对 and how Einstein conceived of his theory of rela...
父亲 您相信灵魂吗 Father, do you believe in ghosts?
不 我信的并非人类的灵魂 Oh, no, not in the human kind of ghosts.
不 完全不是 No, not at all.
但是抬头看 我的孩子 But look up, my boy,
你可以看见灵魂充满了天空 and see a sky full of them.
如果你能在通向黑洞的旅程中幸存下来 If you could survive the trip into a black hole,
你可能会在宇宙中的另一处时空出现 you might emerge in another place and time in our own universe,
不受相对论的基本规律控制 circumventing the first commandment of relativity...
汝不可超越光速行之 Thou shalt not travel faster than light.
没有东西可以超越光速穿过空间 Nothing can move through space faster than light.
但是空间不仅仅是虚无 But space is not mere emptiness.
它可以被伸展 收缩和变形 Its properties can stretch and shrink and can be deformed.
当这发生的时候 时间也变形了 And when that happens, time is deformed, too.
爱因斯坦发现空间和时间 Einstein discovered that space and time
只是同一物体的两个方面 即四维时空 are just two aspects of the same thing, spacetime.
四维时空本身可以变形 Spacetime itself can deform enough
足够以任何速度带着你去任何地方 to carry you anywhere at any speed.
黑洞可能同样也是穿梭宇宙的隧道 Black holes may very well be tunnels through the universe.
在这样的星际交通系统上 On this intergalactic subway system,
你能去到宇宙时空最遥远的地方 you could travel to the farthest reaches of spacetime,
甚至也可以达到更为奇妙的地方 or you might arrive in someplace even more amazing.
我们可能发现自己处于一个完全不同的宇宙 We might find ourselves in an altogether different universe.
但是浩大的宇宙是怎样浓缩进一个黑洞里 But how can a whole universe fit inside of a black hole,
而它只是我们宇宙小小的一部分呢 which is only a small part of our universe?
这是时空带给我们的另一个小把戏 It's another magic trick of spacetime.
黑洞巨大的引力 The phenomenal gravity of a black hole
可以扭曲整个宇宙的时空塞入黑洞 can warp the space of an entire universe inside it.
地球上的重力可能足够拽住我们 Our local gravity might be a drag to us,
但是和一个坍缩恒星内部相比 but it's really feeble compared
实在是太过微弱了 with what goes on inside a collapsed star.
据我们所知 As far as we know,
当一个巨型恒星坍缩成一个黑洞 when a giant star collapses to make a black hole,
中心地带超大的密度和压强接近大爆炸 the extreme density and pressure at the center mimic the big bang,
而大爆炸开创了我们的宇宙 which gave rise to our universe.
在黑洞内部的宇宙 And a universe inside a black hole
可能产生属于自己的黑洞 might give rise to its own black holes.
那些黑洞又可以创造其他宇宙 And those could lead to other universes.
这可能就是我们宇宙的真正形态 Maybe that's how our cosmos came to be.
我们只知道 For all we know,
如果你想知道黑洞内部真实的样子 if you want to see what it's like inside a black hole,
看看周围就可以了 just look around you.
威廉·赫歇尔继续探索太阳 William Herschel went on to discover that the Sun
和它的行星在银河中的运行 and its planets are moving through the milky way.
那他的儿子约翰呢 And whatever became of his son John?
他成长为一名出色的科学家 He grew up to become a great scientist.
他继续了父亲的深空观测 His deep-space observations built on those of his father
他建立了我们今天所用的标准星系表 to become the basis for the standard catalog of galaxies we use today.
当威廉的身体每况愈下时 When William was in failing health,
约翰彻夜陪着他 John stayed with him through the long nights at his telescope
用望远镜观测恒星 to help him sweep the stars.
当他父亲去世时 约翰写了他的墓志铭 And when his father died, John wrote his epitaph...
"他打破了天堂之墙" "he broke through the walls of heaven."
约翰总是追忆起 John often reminisced
那个和他父亲在一起的夏夜 about those summer nights with his father.
这可能就是他寻找如何保存过去的原因 Maybe that's why he sought a way to preserve the past.
约翰·赫歇尔作为奠基者之一 John Herschel was one of the founders
找到了一种新形式的时间旅行 of a new form of time travel,
捕捉画面和回忆的新方法 a means to capture light and memories.
他也为此创造了一个新词 He actually coined a word for it,
摄影 Photography.
仔细想想 When you think about it,
摄影也是一种时间旅行 photography is a form of time travel.
这个人穿越世纪 凝视着我们 This man is staring at us from across the centuries...
一个被光影定格的灵魂 A ghost preserved by light.
不难想象 在不久的将来 It's not hard to imagine that in the near future,
我们就可以从三维空间 we'll be able to capture the past
留住过去 in all three dimensions.
我们可以跨入我们的回忆 We'll be able to step inside a memory.
人们也许不可能回到过去 It may not be possible to travel backward in time,
但也许某一天 我们可以把过去带到当下 but perhaps, one day, we can bring the past to us.
这是我过去的某一时刻 Here's a moment from my past.
就像约翰·赫歇尔所做的 Like John Herschel,
我可以记起我的少年时代 I'm remembering a younger version of myself.
1975年 12月20日 December 20, 1975.
在下着雪的纽约洲伊萨卡 A snowy day in Ithaca, New York.
道路上的一个分叉点将我 A branchpoint on the road that brought me
带到了此时此刻和你在一起 to this moment with you.
那是我碰到卡尔·萨根的日子 It was the day I met Carl Sagan.
让我想起天上的幽灵星星 Reminds me of those ghost stars in the sky...
你知道 它们的光依然照射着我们 You know, the ones that still shine their light upon us
即使它们早已离去 long after they're gone.