我们为何在此 Why are we here?
我们又来自何方 Where do we come from?
这些问题源远流长 These are the most enduring of questions.
而人类天性就爱探索答案 And it's an essential part of human nature to want to find the answers.
追根溯源 And we can trace that ancestry back
时间定格在几十万年前 人类文明出现之刻 hundreds of thousands of years to the dawn of humankind.
实际上 我们的故事将延伸至更早的年代 But in reality, our story extends far further back in time.
从宇宙起源说起 Our story starts with the beginning of the universe.
宇宙起源于一百三十七亿年前 It began 13.7 billion years ago.
而今 宇宙中已形成逾千个星系 And today it's filled with over 100 billion galaxies,
每个星系拥有数以千亿的星球 each containing hundreds of billions of stars.
在本节目中 我将向大家讲述这个故事 In this series, I want to tell that story
因为说到底 我们是宇宙的一部分 because ultimately we are part of the universe.
宇宙的故事 便是我们的故事 So its story is our story.
要讲述这个故事就不能忽略一个最基本的东西 It's a story that you couldn't tell without something so fundamental
没有它 宇宙便无从说起 that it's impossible to imagine the universe without it.
它在宇宙中无所不在 It's woven into the very fabric of the cosmos.
这便是时间 Time.
在时间长河的浸润下 The relentless flow of time
宇宙不断演化 has driven the evolution of the universe
并创造出无数令人叹为观止的奇迹 and created many extraordinary wonders.
这些奇迹将引领我们 These wonders take us from the very first moments
见证宇宙生命的始与末 in the life of the universe to its eventual end.
宇宙的奇迹
命运
这里是秘鲁西北海岸的长基罗 This is Chankillo on the north-western coast of Peru.
它在南美的考古遗址中算不上引人注意 And it's one of South America's lesser known archaeological sites.
但对我来说 它绝对是最迷人的地方 But, for me, it is surely one of the most fascinating.
约两千五百年前 Around 2,500 years ago,
一个几乎不为我们所知的文明 a civilisation we know almost nothing about
在荒漠中筑起了这固若金汤的庙宇 built this fortified temple in the desert.
它的外墙曾经一片炽白 Its walls were once brilliant white
上面喷绘着各种图案 and covered with painted figures.
如今 就算再小的绘饰碎片都已灰飞湮灭 Today, all but the smallest fragments of the decorations are gone.
这个文明的所有信息 The details of this culture
及其文字记载的踪迹也已消失殆尽 and all traces of its language are lost.
不过 如果你站在合适的地方 And yet, if you stand in the right place,
依然能感受长基罗的真谛 you can still experience the true purpose of Chankillo,
就如同你亲眼见证它拔地而起的瞬间 in just the same way as you could the day that it was built.
但前提是 必须在日出前赶到这 But, to do that, you have to be here before the sun rises.
这些塔楼构成了古代阳历 These towers form an ancient solar calendar.
在每年的不同时期 Now, at different times of year,
地平线上的日出点也会有所不同 the sunrise point is at a different place on the horizon.
对于南半球来说 12月21日为夏至 21st December, which here in the southern hemisphere
是一年中日照最长的一天 is the summer solstice, the longest day,
因而太阳会从最右边的塔楼升起 and the sun rises just to the right of the right-most tower.
在随后的一年里 Then, as the year passes,
太阳会穿过一座座塔楼 the sun moves through the towers
到了6月21日 until on 21st June,
也就是冬至 一年中日照最短的那天 which is the winter solstice, the shortest day,
它会从最左边的塔楼升起 it rises just to left of the left-most tower.
就在远处那座山 Actually just in between that mountain you can see in the distance
与最左边的塔楼之间 and the left-most tower.
因而在一年的任何时候 只要你观察日出 So, at any time of year, if you watch the sun rise,
就能通过太阳的位置 you can measure its position and you can tell,
准确说出日期 误差最多两三天 within an accuracy of two or three days, the date.
今天是9月15号 Today's date is September the 15th.
这也就意味着 So that means the sun will rise
太阳将在第五和第六座塔间升起 between the fifth and the sixth towers.
长基罗依然可以行使其太阳历的职责 Chankillo still works as a calendar
因为正如同这些巨石当初坐落之时 because the sun still rises in the same place today
太阳依旧在同一位置升起 as it did when these stones were first laid down.
真是太壮观了 That's a magnificent sight,
太阳从塔尖冉冉升起 as the sun burns through the towers.
在这里 你几乎能嗅到古代的气息 You can almost feel the presence of the past here.
想象一下当时的场景 Imagine what it must have been like.
数千市民伫立在这 恭候日出 Thousands of citizens stood here to greet the sun,
太阳即是他们的神明 which was almost certainly a deity. Almost certainly their god.
这是多么伟大的成就啊 What a magnificent achievement.
也许这是人类第一次尝试度量神的国度 Probably one of our earliest attempts to begin to measure the heavens.
千年之后 Over the millennia,
这股探知天空的渴望 that desire to measure what's going on in the sky
造就了现代天文学 has led to modern astronomy
也成为了现代文明的基石 and the foundations of our modern civilisation.
也许我会在自己的花园里建一个 I might build one in my garden.
真想建一个 I want one!
耸立在山脊上的十三座塔楼 The 13 towers that line this ridge
应证了人类对天地时间的无限迷恋 stand testament to our enduring fascination with the clockwork of the heavens.
也见证了芸芸众生与宇宙的直接联系 And to the direct connection between our lives and the cosmos.
日出日落 这史诗般的脉搏 The rising and setting of the sun provides an epic heartbeat
教会人类标记时间的痕迹 that allows us to mark the passage of time.
一日为二十四个小时 A day on Earth is the 24 hours
即地球绕轴自转一周 it takes our planet to rotate once on its axis.
一月为二十九天半 Our months are based on the 29-and-a-half days
即月亮在夜空完成盈亏圆缺 it takes the moon to wax and wane in the night sky.
一年为三百六十五又四分之一天 And a year is the 365-and-a-quarter days
即地球绕太阳公转一周 it takes us to orbit once around the sun.
人类的生命便消逝在这些熟悉的时间量程之间 These familiar timescales mark the passing of our lives.
然而宇宙的时间量程远比年月日浩大 But the life of the universe plays out on a much grander scale.
仰望夜空 映入眼帘的不仅仅是一颗颗星星 When you look up into the night sky, you don't just see stars.
那点点星光更是悬在夜空中的百万支时钟 Those tiny points of light are a million different clocks,
它们的存在记载了 whose lifespans mark out the passage of time
数十亿 甚至数万亿年时间的流逝 over billions, or even trillions, of years.
本片将向您介绍跨度无垠的时间 This film is about the greatest expanses of time.
那塑造了宇宙的深邃时间 The deep time that shapes the universe.
宇宙从大爆炸开始 From its fiery beginnings,
经历无数代恒星 行星 星系的演变 through countless generations of stars, planets and galaxies,
最终走向灭亡 to its eventual demise,
随着时间的推移 宇宙的命运也已注定 the fate of the universe is determined by the passage of time.
宇宙的时间量程大到无法想象 Timescales in the cosmos seem so unimaginably vast,
它几乎在我们的认知范围之外 it's almost impossible to relate to them.
然而 在地球上的某些角落 Yet there are places on Earth where
我们能接触到宇宙量程下的时间 we can begin to encounter time on these universal scales.
这里是哥斯达黎加北太平洋海岸的奥斯蒂奥纳尔 This is Ostional on the northern Pacific coast of Costa Rica.
我到这来是为了 And I've come here to
亲眼目睹一场在人类踏入此地时 witness a natural event that's been happening
就一直出现的自然现象 long before there were any humans here to see it.
我猜一定能 And I suppose it really is a
通过这扇窗口 了解地球生命的历史 window into the distant past of life on our planet.
当太阳沉落地平线 Once the sun has dipped below the horizon
月亮助兴 引起潮汐之时 and the moon conspired to make the tides just right,
一群史前生物便会造访这片海滩 this beach is visited by prehistoric creatures.
它们在黑夜的掩护下 浮出了海面 Under the cover of darkness, they emerge from the ocean.
普拉亚·奥斯蒂奥纳尔是地球上少数几个 Playa Ostional is one of the few beaches in the world
有大量海龟产卵的海滩 where large numbers of sea turtles make their nests.
但真正与众不同的 是这个场景 But what makes this truly remarkable is the sheer length of time
在历史上年复一年地不断上演 scenes like this have been playing out.
这大概是地球最古老的生命循环之一 This is part of one of the oldest life-cycles on Earth.
在过去的一亿年里 On nights like these,
每到这样的夜晚 for the last 100 million years,
这些海龟 turtles like this have been
就会爬上海滩产卵 hauling themselves out of the ocean to lay their eggs.
这几乎是段近乎无限的时间 It's an almost incomprehensible timespan.
一亿年前 恐龙还在地球上横行 100 million years ago, there were dinosaurs roaming the Earth,
地球也是另一番面貌 but the Earth itself looked very different.
那时南美洲不与北美洲毗邻 South America was not connected to North America.
北美大陆在靠近欧洲的某处 North America was somewhere over close to Europe.
澳大利亚则连接着南极 Australia was connected to Antarctica.
这真是 It really is quite...
太棒了 能如此近距离接触这古老的生命循环 wonderful to be so close to such an ancient cycle of life.
我能听到它的呼吸 I can hear breathing, actually.
令人难忘的经历 So, a remarkable experience.
这场景真令人陶醉 I mean, it really is beautiful to see that.
就如同穿越 On one night of many hundreds of
回到了过去一亿年的某个夜晚 millions of nights stretching back into the past.
她回去了 And she's gone.
捕捉这样一个瞬间 To witness a moment like this
开启了通往遥远过去的道路 is to open up a connection to the deep past.
亲历那已远远超越了人类历史的时间旅程 To experience timespans far longer than the history of our own species.
然而即使是这有着一亿年历史的海龟故事 Yet even the 100-million-year story of the turtles
也仅仅为我们探寻浩瀚的宇宙史开了个头 only begins to connect us with the vast sweep of cosmic time.
整个太阳系 Our entire solar system
正绕着银河系的中心 is travelling on an unimaginably vast orbit,
在一个无比庞大的轨道上行进 spinning around the centre of our galaxy.
要花上两亿五千万年 It takes 250 million years
才能绕银河转一圈 to make just one circuit of the Milky Way.
自人类出现以来 In the entire history of the human race,
我们还未绕过这个轨道的千分之一 we've travelled less than a tenth of 1% of that orbit.
这些循环看似永恒不变 These cycles seem eternal and unchanging,
但随着时间之书徐徐展开 but as the story of time unfolds,
一条真理跃然眼前 a fundamental truth is revealed.
没有什么能够永恒 Nothing lasts forever.
这是时间带给我们最宝贵的财富 This is the most profound property of time.
在宇宙深处频繁上演的一幕 And it plays out just as vividly here on Earth
也正在地球上生动地上演着 as it does in the depths of space.
这里是阿根廷南部巴塔哥尼亚地区的莫雷诺冰川 Well, this is the Perito Moreno Glacier in Patagonia in southern Argentina.
它是正向南美大陆推进 And it's one of the hundreds of glaciers
源自巴塔哥尼亚南部地区冰原的数百条冰川之一 that sweep down the continent from the southern Patagonian ice fields.
如果你继续朝这个方向行进 And, you know, if you carry on that way,
往南大概一千千米 south about 1,000 kilometres,
就将抵达南美洲的末端 you get to the end of South America.
从那开始 通往南极洲的道路将畅通无阻 From then on, there's nothing to the Antarctic.
放佛就近在眼前 And it feels like that today.
川上之冰一望无际 The glacier is such a massive expanse of ice,
乍一看 that at first sight,
它就如同宇宙中的那些循环 just like the cycles of the heavens,
稳固不变 it appears fixed and unchanging.
但近距离观察便发现 它无时不刻不在运动 Yet, seen close-up, it's continually on the move.
且已持续了数万年 As it has been for tens of thousands of years.
整个冰川的表层一直在向湖中脱落 The whole face of the glacier is moving into the lake
每天脱落大概这么多 something like that much every day.
这意味着 每年都有2.5亿公吨的冰 That means that well over a quarter of a billion tonnes of ice
从冰川表面脱落 融入湖中 drop off the face of the glacier into the lake every year.
一天差不多就有一百万公吨 That's about a million tonnes a day.
你能用耳朵捕捉到这一过程 And you can hear it happening.
时不时地 Just every now and again,
听到雷鸣般的断裂声 you hear this tremendous cracking sound.
好像这个地方是活的一样 It really is like the place is alive.
这些巨大的冰块 You know, it's quite disturbing
掉进湖中着实令人不安 when these enormous chunks of ice fall into the lake.
虽然冰川看上去很稳定 Although this thing seems stable
运动也十分缓慢 and the movement seems glacially slow,
事实上 有可能发生非常剧烈的塌陷 actually there can be really violent collapses.
这是个生机勃勃的地方 It's an incredibly dynamic place to be.
冰川的运动 The movements of the glacier
让我们理解了时间的本质 provide an insight into the nature of time.
时间便是将事件按顺序简单排好 It is simply the ordering of events into sequences.
一步接一步 One step after another.
随着时间流逝 雪花落地 冰块形成 As time passes, snow falls, ice forms,
冰川慢慢地沉入深谷 the glacier gradually inches down the valley
巨大的冰块逐渐掉进湖中 and huge chunks of ice fall into the lake below.
但即使如此简单的顺序也包含着深刻的内涵 But even this simple sequence contains a profound idea.
事件发生的顺序总是相同的 Events always happen in the same order.
它们从不混乱 也不会逆向发生 They're never jumbled up and they never go backwards.
你永远也不会见到这种景象逆向发生 Now that's something that you would never see in reverse.
但有趣的是 没有任何一条物理定律 But, interestingly, there's nothing in the laws of physics
能描述这些水分子如何运动 that describe how all those water molecules are moving around
为何这种运动不能使它们在湖面凝聚 that prevent them from all getting together on the surface of the lake,
再跃出水面 进而凝结成冰块 jumping out of the water, sticking together into a block of ice
重新粘合回冰川的表面 and then gluing themselves back on to the surface of the glacier again.
但有趣的是 But, interestingly,
我们却理解世界为什么不会逆向发展 we do understand why the world doesn't run in reverse.
这是有原因的 There is a reason.
我们有科学的解释 We have a scientific explanation.
被称为"时间箭头" And it's called the arrow of time.
我们从没见过浪花离开湖面 We never see waves travelling across lakes,
聚集在一起 组成巨大的冰块重回冰川 coming together and bouncing chunks of ice back onto glaciers.
我们被迫前往将来 We are compelled to travel into the future.
那是因为 And that's because
时间箭头规定 随着时间流逝 the arrow of time dictates that as each moment passes,
万物也在发生变化 things change.
变化一旦发生 就无法更改 And once these changes have happened, they are never undone.
永恒的变化是人类生命中最基本的部分 Permanent change is a fundamental part of what it means to be human.
随着时间流逝 我们都会变老 We all age as the years pass by.
人们出生 成长 死亡 People are born, they live, they die.
我想这只是生命中悲悲喜喜的一部分 I suppose it's part of the joy and tragedy of our lives.
但纵观宇宙 But out there in the universe,
那些宏伟的如史诗般的循环好像永恒不变 those grand and epic cycles appear eternal and unchanging.
然而这只是错觉 But that's an illusion.
宇宙长河就如同我们的生命一样 You see, in the life of the universe, just as in our lives,
一切都在不可逆转地变化 everything is irreversibly changing.
通过在变化中变化 By building change upon change,
时间箭头带动了整个宇宙的演变 the arrow of time drives the evolution of the entire universe.
若我们留意那深邃的宇宙 And as we look out deep into the cosmos,
便可以慢慢将故事展开 we can see that story unfold.
这是狮子座一部分的缩小图 This is an image of a tiny piece of night sky in the constellation of Leo.
其实就是狮子嘴所在的位置 It's actually where the mouth of the Lion would be.
尽管表面平淡无奇 And, despite appearances,
但它却是近些年来天文史上最有趣的图像之一 it is one of the most interesting images taken in recent astronomical history.
有趣之处就在于这个红斑 The interesting thing is this little red blob here,
看起来很普通 which looks very unremarkable.
但那红斑却是一次巨型宇宙大爆炸的余辉 But what that red blob is is the afterglow of an enormous cosmic explosion.
象征着恒星的死亡 It's the death of a star.
大约是 That was about...
太阳质量的四十到五十倍 40 or even 50 times the mass of our sun.
它被诗意地命名为GRB 090423 Poetically named GRB 090423,
曾是一颗沃尔夫-拉叶星 it was once a Wolf-Rayet star.
它被快速旋转的气体云覆盖 Shrouded by rapidly swirling clouds of gas,
其亮度是太阳的一万倍 it burned 10,000 times more brightly than our sun.
但正是因为它如此明亮 其寿命异常短暂 But because it burned so brightly, it was extremely short-lived.
这种巨星衰竭时自身也会塌缩 As it died, the giant star collapsed in on itself.
导致大质量的光线和星体物质 That caused massive jets of light and stellar material
从磁极喷射而出 to be ejected from its poles,
爆炸中放射出的光芒是太阳的一万亿倍 in an explosion that shone with the light of 10 million billion suns.
这便是此次灾难性爆炸的余辉 And it's the afterglow of this catastrophic explosion
从地球上看 它只是一个暗淡的红点 that is just visible from our planet as a faint red dot.
这还不是GRB 090423的最有趣之处 But that's not what's so interesting about GRB 090423.
当我们仰望天空 You see, when we look up into the sky,
望向遥远的恒星和星系时 at distant stars and galaxies,
我们其实是在仰望过去 then we're looking back in time
因为光从那些遥远天体到达地球需要时间 because the light takes time to journey from them to us.
而光从那个红点处传播到我们这里 And the light from that red dot has been travelling to us
差不多历经了整个宇宙史 for almost the entire history of the universe.
我们看到的是一百三十亿年前 You see, what we're looking at here is an event that happened
发生的事件 13 billion years ago.
大约只是大爆炸宇宙形成之后的六亿年 That's only about 600 million years after the Big Bang, after the universe began.
所以这是宇宙历史中非常早的一个时期的产物 So this is something incredibly early in the universe's history.
事实上 这便是我们观察到的最古老的天体 In fact, this is the oldest single object that we've ever seen.
我们看到的是宇宙初期的一颗恒星 What we're looking at here is the explosive death
爆炸灭亡的景象 of one of the first stars in the universe.
在不断进化中 宇宙经历了不同的纪元 As it evolves, the universe passes through distinct eras.
在这漫长的岁月中 每一段起始和终结 Vast ages, whose beginnings and endings
都伴随着独一无二的里程碑 are marked by unique milestones.
奇迹一个个诞生 一个个消亡 The births and deaths of its wonders.
第一颗恒星的诞生 The moment the first stars were born
是宇宙进化中最重要的变化之一 is one of the most important changes in the evolution of the cosmos.
它标志着"原初时代"的结束 It signals the end of the Primordial Era
也标志着宇宙第二个重要时期的开始 and marks the beginning of the second great age of the universe.
也就是我们现今生活的时期 The time in which we live.
"生星时代" The Stelliferous Era -
恒星漫天的时代 the age of the stars.
星光照亮了夜空 Starlight illuminates the night sky
也照亮了我们的生活 and starlight illuminates our days.
我们的太阳只是银河系两千亿颗恒星中的一颗 Our sun is just one of 200 billion stars in our galaxy.
我们的星系也只是可观察的宇宙范围内的 Our galaxy is one of 100 billion
一百亿个星系中的一个 in the observable universe.
数不尽的星球上有数不胜数的岛屿 And countless islands of countless stars.
尽管宇宙的年龄超过了一百三十亿岁 Although the universe is over 13 billion years old,
我们周围的恒星还是处于"生星时代" we still live close to the stars of the Stelliferous Era.
这是宇宙中壮美而复杂的一个时期 It's an age of astonishing beauty and complexity in the universe.
宇宙中到处都是 The cosmos is absolutely awash with stars
被星云和行星系统包围的恒星 surrounded by nebulae and systems of planets.
我们未曾探索的世界不计其数 Countless billions of worlds that we've yet to explore.
然而宇宙并不是一成不变的 But the cosmos isn't static and unchanging.
它不会永远保持这样 It won't always be this way.
因为 由于时间箭头的作用 Because, as the arrow of time plays out,
它产生出一个动态与美丽并存的宇宙 it produces a universe that is as dynamic as it's beautiful.
我们观测到了无数恒星诞生 灭亡 We've seen stars born and we've seen stars die.
我们也知道明天不会与今天一样 And we know that tomorrow won't be the same as today
因为时间箭头告诉我们 because the arrow of time says
未来总是与过去有所不同 the future will always be different from the past.
但是什么促使宇宙进化呢 But what drives this evolution?
为什么过去和未来会存在不同 Why is there a difference between the past and the future?
又为什么会存在时间箭头呢 Why is there an arrow of time at all?
我们都对时间箭头有种直观的理解 We all have an intuitive understanding of the arrow of time.
显然万物都在变化 It seems obvious to us that things change
未来将与过去不同 and the future will be different to the past.
我们知道这一点 We know that
因为我们目睹了年复一年的变化 because we see the effects of the passing years all around us.
这里是卡曼斯科 This is Kolmanskop,
纳米比亚南部一座废弃的钻石矿城 an abandoned diamond mining town in southern Namibia.
整座小城建立于1908年 This entire town was founded in 1908,
当时 从吕德里茨港口 when a worker who was building the railway
到纳米比亚中部的铁路正在兴建之中 from the port of Luderitz inland into the centre of Namibia
一位修路工在这片沙漠里找到了一颗钻石 found a single diamond here in this desert.
在之后的四十年里 For 40 years,
这里曾经是一个多达千人的繁荣社区 this was a thriving community of up to 1,000 people.
从沙里淘到钻石 A place where you could become a millionaire,
你就能成为百万富翁 picking diamonds out of the sand.
随着金钱涌入 他们在沙漠之中建起了豪宅 While the money rolled in, they built grand houses
过上了灯红酒绿的生活 and lived a champagne lifestyle in the desert.
但当钻石枯竭时 这座城镇被废弃了 But when the diamonds dried up, the town was abandoned.
半个世纪后 随着黄沙慢慢侵蚀 And for half a century it's fallen
它变成了如今的断壁残垣 into disrepair as it's slowly reclaimed by the sands.
宇宙中无时无刻都在上演着 The processes at play here at Kolmanskop
卡曼斯科闹剧 are happening everywhere in the universe.
因为这并不仅是时间箭头的核心思想 Because it isn't simply permanent change
所阐述的永恒变化 that's central to the arrow of time.
更是一种衰退 It's decay.
但对此作出的科学解释 But the scientific explanation for why that is
并非源于试图去了解宇宙中时间的影响 didn't come from attempting to understand the effects of time in the universe.
而是源于试图建造更快的火车 It came from trying to build a faster train.
早在十九世纪 Back in the 19th century,
工程师们就很关注蒸汽机的效率问题 engineers were concerned with the efficiency of steam engines.
火要达到多热 How hot should the fire be?
蒸汽机引擎中要加入何种沸腾物质 What substance should you boil in the steam engine?
是水还是其他东西 Should it be water or something else?
这都是些深奥的问题 These were profound questions.
为解答这些问题 热力学诞生了 And out of those questions arose the science of thermodynamics.
与此同时 热量 温度 能量等概念 It's when concepts like heat and temperature and energy
首次进入科学词典 entered the scientific vocabulary for the first time.
现在 随着我们了解的深入 Now, along with that deeper understanding
为理解宇宙进化和时间流逝 emerged what is probably the most important law of physics
一条可能是最重要的物理定律应运而生 for understanding the evolution of the universe and the passage of time.
这便是"热力学第二定律" It's called the Second Law of Thermodynamics.
"热力学第二定律"之所以深奥 The reason the Second Law of Thermodynamics was so profound
是因为其核心内容包括了一个完全新鲜的概念 was because, at its heart, it contained a radically new concept.
即物理学家们所说的"熵" Something physicists call "entropy".
熵在元素的角度解释了 Entropy explains why, left to the mercy of the elements,
砂浆粉碎 玻璃破碎以及房屋倒塌的原因 mortar crumbles, glass shatters and buildings collapse.
也合理解释了 And a good way to understand
为何不将物体看作单一的个体 how is to think of objects not as single things,
而是看作许多成分的组合体 but as being made up of many constituent parts.
就像一颗颗沙粒堆成了这个沙堆 Like the individual grains that make up this pile of sand.
熵可以测量出在保持沙堆不变的情况下 Now, entropy is a measure of how many ways I can rearrange those grains
我能有多少种方式重新排列沙粒 and still keep the sand pile the same.
结果发现 And there are trillions and
有数万亿种方式 trillions and trillions of ways of doing that.
我可以把沙堆堆成许多东西 I mean, pretty much anything I do to this sand pile,
就算我把沙子弄乱 混到四周 if I mess the sand around and move it around,
也完全不会改变它的形状或结构 then it doesn't change the shape or the structure at all.
因而 从熵的意义上说 So, in the language of entropy,
这块沙堆的熵值很高 this sand pile has high entropy
我们可以随意重列它的成分 because there are many, many ways that I can rearrange its constituents
但不引起变化 and not change it.
现在我来创造些宇宙的规则吧 Now let me create some order in the universe.
这个沙堡里的沙粒 Now, there are approximately
应该跟沙桩里的一样多 as many sand grains in this sandcastle as there are in the sand pile.
但你看 我随便弄就能把它弄乱 But now, virtually anything I do to it will mess it up,
都能让它失去井然有序的外表结构 will remove the beautiful order from this structure.
因此 这个沙堡的熵值很低 And because of that, the sandcastle has a low entropy.
它是一个更为有序的状态 It's a much more ordered state.
因此 能随意排列沙粒 So many ways of rearranging the sand grains
而结构不会改变的 高熵值 without changing the structure, high entropy.
而不改变结构 Very few ways of rearranging the sand grains
不改变它的有序状态 without changing the structure,
重列方式很少的 低熵值 without disordering it, low entropy.
想象下如果我把沙堡丢在沙漠里一天 Imagine I was to leave this castle in the desert all day.
会发生的事显而易见 Then it's obvious what's going to happen.
沙漠的风会吹得狂沙乱舞 The desert winds are going to blow the sand around
这个小城堡也将瓦解 and this castle is going to disintegrate.
它会变得更无序 继而坍塌 Is going to become less ordered. Is going to fall to bits.
但从基本原理上想想究竟发生了什么 But think about what's happening on the fundamental level.
风把沙粒从城堡上吹走 I mean, the wind is taking the sand off the castle
吹向四处 落到别处形成沙堆 and blowing it over there somewhere and making a sand pile.
物理定律里没有哪条原理显示 There's nothing fundamental in the laws of physics that says
风不能从某处带走沙粒 that the wind couldn't pick up some sand from over here,
再放到另一处 deposit it here
再精确地按照沙堡的形状摆放 and deposit it in precisely the shape of a sandcastle.
原则上来说 In principle, the wind could
风可以用一堆沙建起一座沙堡 spontaneously build a sandcastle out of a pile of sand.
没有理由解释为什么不能发生 There's no reason why that couldn't happen.
但它就是绝对绝对不可能发生 It's just extremely, extremely unlikely
因为只有几种排列方式 because there are very few ways of organising this sand
能让这些沙看起来像一座城堡 so that it looks like a castle.
然而另一种可能性却不可避免 It's overwhelmingly more likely
风吹起沙粒时 that when the wind blows the sand around
能改变城堡这种低熵值的结构 it will take the low entropy structure of the castle
把它变成一种高熵值的结构 沙堆 and turn it into a high entropy structure, the sand pile.
熵值总是在增大 这是为什么 So, entropy always increases. Why is that?
因为一种不可抗的可能性促使的 Because it's overwhelmingly more likely that it will.
迎着风不能自发形成沙堡 It seems incredible that a law that says
这条定律能解释物理学中最深奥的理论之一 that sandcastles don't spontaneously form on the wind
这看来有些不可思议 could solve one of the deepest mysteries in physics.
但正是利用熵增加原理 But by saying entropy always increases,
热力学第二定律解释了 the Second Law of Thermodynamics is able to explain
为何时间具有单方向性 why time only runs in one direction.
对我而言 热力学第二定律 The Second Law of Thermodynamics, for me,
揭示了物理学中一切有力量的 demonstrates everything that's powerful
美好的 深刻的事物 and beautiful and profound about physics.
这个科学定律最初出现 You see, here's a law that entered science
是解释热量如何流动 as a way of talking about how heat moves around
以及蒸汽机的效能的 and the efficiency of steam engines.
但到最后 它却能解释 But it ended up being able to explain
科学史上最伟大的奥秘之一 one of the great mysteries in the history of science.
为何过去与未来存在区别 Why is there a difference between the past and the future?
按照第二定律 You see, the second law says
一切事物都是从有序趋向无序 that everything tends from order to disorder.
这也意味着 That means that there is
过去和未来是有差异的 a difference between the past and future.
过去 宇宙更加有序 In the past, the universe was more ordered.
而未来 宇宙会更加无序 In the future, the universe will be less ordered.
这也说明时间是按照一定的方向流逝 And that means there's a direction to the passage of time.
热力学第二定律把"时间箭头"这一概念 So the Second Law of Thermodynamics has introduced the concept
引入了科学领域 of an arrow of time into science.
自从这些采矿设备于1954年被废弃以来 The arrow of time has been playing out in
时间箭头一直在卡曼斯科上演 Kolmanskop since the mining facility was abandoned in 1954.
然而在宇宙中 But in the universe,
时间箭头已演绎了近十四亿年 it's been playing out for almost 14 billion years.
并将产生深远影响 And it will have profound consequences.
因为这意味着恒星不会一直闪耀 Because it means stars cannot shine forever.
甚至包括太阳系的核心星球 Including the star at the centre of our Solar system.
即使在生命终结之际 At the end of its life,
太阳也不会消失不在 the sun won't simply fade away to nothing.
燃烧殆尽后 它的核心将会坍塌 As it begins to run out of fuel, its core will collapse
由此产生的额外热量 and the extra heat this generates
将引起外层膨胀 will cause its outer layers to expand.
在此后约一亿年的时间里 In around a billion years' time,
这将对我们脆弱的世界造成灾难性的影响 this will have a catastrophic effect on our fragile world.
渐渐地 地球将越来越热 Gradually, the Earth will become hotter and hotter.
那样 地球只剩下一天完美日子 So there will be one last perfect day on Earth.
最终 地球上所有生命 But eventually the existence of all life on this planet
都将不复存在 will become impossible.
很久很久以后 最后一个生命消失 Long after a life has disappeared,
太阳将会变得无比巨大 the sun will have grown so much
甚至大到足以填满整个地平线 it will fill the entire horizon.
它将变成一个红巨星 It will become a red giant.
这将是太阳生命的最后阶段 The last phase of its life.
如此一来 我们的星球不太可能幸存下来 Our planet might not survive to this point.
但倘若能幸存 But, if it does,
也会被烤得只剩下一块焦糊的小秃石 little more than a scorched and barren rock will remain
见证我们的星球做最后的垂死挣扎 to witness the final death throes of our star.
随后六亿年之内 太阳将会爆炸 In six billion years, our sun will explode.
向太空中抛出大量的气体和粉尘 Throwing vast amounts of gas and dust out into space,
从而形成一个巨大的星云 to form a gigantic nebula.
而它的"心脏"则变成一块散发着微光的灰烬 And at its heart will beat a faintly glowing ember.
那便是曾经巨大壮丽的太阳所残留的 All that remains of our once magnificent sun.
将比地球还要小 It will be smaller than the size of the Earth.
体积和亮度 Less than a millionth of its
都不及现今的百万分之一 current volume and a fraction of its brightness.
太阳将变成一个白矮星 Our sun will have become a white dwarf.
白矮星没有可供燃烧的能源 With no fuel left to burn,
它那微弱的光芒源自于 a white dwarf's faint glow comes from
已熄灭的大熔炉里的最后一点余热 the last residual heat from its extinguished furnace.
太阳也便灭亡 The sun is now dead.
它的残留物 Its remains slowly cooling
将在广袤极寒太空中逐渐冷却 in the freezing temperatures of deep space.
从现在地球所在位置看 Looking at it from where the Earth is now,
它发出的光芒 it would only generate the same
只相当于晴夜里的满月的光亮 amount of light as the full moon on a clear night.
太阳的命运也是所有恒星的命运 The fate of the sun is the same as for all stars.
终有一天 它们都会消亡 One day, they must all eventually die
宇宙将会陷入永无止境的黑暗之中 and the cosmos will be plunged into eternal night.
这便是时间箭头最深远的影响 And this is the most profound consequence of the arrow of time.
因为我们居住的这个结构化宇宙 Because this structured universe that we inhabit,
及宇宙中所有的奇迹 恒星 行星和星系 and all its wonders - the stars, the planets and the galaxies -
都不可能永远存在 cannot last forever.
宇宙最终将逐渐消亡 The cosmos will eventually fade and die.
首先将迎来生星时代的终结 First will come the end of the Stelliferous Era.
星光岁月的终结 The end of the age of starlight.
最大的恒星将会最先消亡 The largest stars are the first to disappear,
剧烈坍塌后 变成黑洞 violently collapsing into black holes.
仅仅只存活了几百万年 Just a few million years after their formation.
它们消亡很久后 却有一种星体能存留下来 But long after they're gone, just one type of star will remain.
这是与太阳系最近的一颗恒星 This is a picture of the nearest star to our solar system,
比邻星 Proxima Centauri.
离我们只有4.2光年 It's only 4.2 lightyears away.
与照片中其他更远距离的恒星相比 But the reason it doesn't stand out against the much more distant stars
它没有那么显眼 in this photograph
因为比邻星非常非常小 is that Proxima Centauri is incredibly tiny.
比邻星是一种红矮星 It's a kind of star known as a red dwarf star.
它的质量相当于太阳的百分之十一到十二左右 It's only about 11-12% the mass of our sun.
但我们能看到的它所发出的光亮 But to our eyes it would appear to shine
比太阳小了一万八千倍 18,000 times less brightly.
但红矮星有一个优势 But red dwarfs do have one advantage over
是其它那些更明亮更壮丽的恒星所没有的 their much more luminous and magnificent stellar brethren.
正因为它们非常小 And that's because they're so small,
以致它们的核燃料燃烧得异常缓慢 they burn their nuclear fuel incredibly slowly,
因而它们有数亿万年的寿命 so they have lifespans of trillions of years.
也就是说 像比邻星一类的恒星 And that means that stars like Proxima Centauri
将会是宇宙中最后存留的恒星 will be the last living stars in the universe.
如果人类能活到很久以后的未来宇宙 If we survive into the far future of the universe,
可以想象人类的后代 then it's possible to imagine our distant descendants
将围绕红矮星建设他们的文明 building their civilisation around red dwarfs
以便从这些最后消亡的恒星的余火中获取能源 to capture the energy from those last fading embers of stars,
就如同我们的祖先在寒冷冬夜 just as our ancestors crowded around campfires
围着篝火取暖一样 for warmth on cold winter's nights.
比邻星之所以燃烧如此缓慢 The reason why Proxima Centauri burns so slowly
是因为它体积很小 低重力 is because its small size and low gravity
比起大恒星 它的核心承受着较低的压力 mean its core is under much lower pressure than larger stars.
也因如此 它的内部持续翻涌 This also means that its interior is constantly churning,
在表面会煽动起一场火热的风暴 whipping up the surface into a fiery turmoil.
即使它燃烧得如此缓慢 Explosive solar flares occur almost continually,
爆炸性的耀斑活动仍旧持续发生 even though it burns so dimly.
但比邻星最终还是会消亡 But Proxima Centauri will eventually die.
如同太阳 它也会变成白矮星 And like our sun, it too will become a white dwarf.
随着生星时代终结 As the Age of Starlight ends,
哪怕再昏暗的一道微光 都将消失于宇宙中 all but the dimmest flicker of light in the universe will go out.
白矮星这微弱的光芒 The faint glow of white dwarfs
将是黑暗的空洞中唯一的光芒 will provide the only illumination in a dark and empty void,
零星散落在死星和黑洞中 littered with dead stars and black holes.
到那时 宇宙将有一百兆年历史 By this point, the universe will be 100 trillion years old.
然而即使到现在 And yet, even now,
也才是这漫长生命周期的开始阶段 the vast majority of its lifespan still lies ahead of it.
地球上有些地方 能够找到一点细微的迹象 There are few places on Earth where you can get an inkling
知晓遥远的未来将会发生什么 of what the far future has in store.
这里是纳米比亚的骷髅海岸 This is Namibia's Skeleton Coast,
流经南大西洋的寒流 汇入纳米布沙漠 where the cold water to the South Atlantic meet the Namib Desert.
这是地球上最荒凉的地方之一 And it is one of the most inhospitable places on Earth.
早在十七世纪 Back in the 17th century,
葡萄牙水手就称此地为"地狱之门" Portuguese sailors used to call this place the Gates to Hell
因为你每天早上都能看见的沿岸的巨大浓雾 because this dense fog that you see pretty much every morning along this coast,
会与形状不断变化的沙丘融合 coupled with the constantly shifting shape of the sandbanks,
据文字记载 多年以来 meant that over the years,
无数船只在这个海岸附近失事 literally thousands of ships were wrecked along this coastline.
然而就算你靠了岸 And even if you made it to shore,
问题也还没解决 that wasn't the end of your problems
因为这里的浪潮非常猛烈 because the currents are so strong here
根本无法将船驶回大海 that there is no way of rowing back out to sea.
你看那边 If you look that way,
方圆几百英里尽是一片荒漠 there's just hundreds of miles of inhospitable desert.
这就是个有来无回的地方 So, it genuinely was a place of no return.
如果在这里搁浅 那就是你的末日了 If you were shipwrecked here, this was the end of your universe.
这是爱德华·博伦号 This is the Eduard Bohlen.
她曾是一艘远洋轮 She was once an ocean-going steamer,
运送乘客及货物往返欧洲 ferrying passengers and cargo between here and Europe.
1909年9月5日 她在浓雾中搁浅了 On 5th September, 1909 she ran aground in thick fog.
然而 与所有在沿岸失事的船只一样 Yet, like all the vessels wrecked along this shoreline,
她在这里腐朽殆尽所耗的时间 the time it takes her to decay to nothing
远远多于她在海上航行的时间 will be far longer than her time at sea.
在宇宙遥远的未来里 In the far future of the cosmos,
残余的白矮星也将面临相似的命运 a similar destiny awaits the remaining white dwarfs.
那些残存到最后的恒星最终将变成黑矮星 A black dwarf will be the final fate of those last stars.
白矮星的温度会降至非常低 White dwarfs that have become so cold
几乎不放出任何光或热 that they barely emit any more heat or light.
黑矮星是简并物质中一种黑暗的 Black dwarfs are dark,
密集性消散的球体 dense decaying balls of degenerate matter,
只比星尘略大一点 little more than the ashes of stars.
构成它们的原子被严重压缩 Their constituent atoms are so severely crushed
因此黑矮星比太阳密度大一百万倍 that black dwarfs are a million times denser than our sun.
要达到这个点需要很长时间 Stars take so long to reach this point,
乃至一百四十亿年后的今天 that after nearly 14 billion years
我们也相信 目前宇宙中还没有黑矮星 we believe there are currently no black dwarfs in the universe.
尽管没见过黑矮星 But despite never seeing one,
但我们仍旧可预见它们的结局 we can still predict how they will end their days.
如同制成这艘船的钢铁 Just as the iron that makes up this ship
终将锈腐 被风沙吹散一样 will eventually rust and be carried away by the desert winds,
我们认为黑矮星内部的物质 so we think that the matter inside black dwarfs,
即宇宙最后的物质 the last matter in the universe,
终将消失 will eventually evaporate away
变成放射物进入虚无的空间里 and be carried off into the void as radiation,
什么都不会残留 leaving absolutely nothing behind.
黑矮星消失后 With the black dwarfs gone,
不会残留哪怕一粒原子 there won't be a single atom of matter left.
我们曾经繁荣的宇宙 All that will remain of our once rich cosmos
将只剩下光的微粒 以及黑洞 will be particles of light and black holes.
再经过一段长得无法想象的时间后 After an unimaginable length of time,
甚至连黑洞都将消失 even the black holes will have evaporated
宇宙将变成一片纯粹的光海 and the universe will be nothing but a sea of photons,
温度渐渐趋于一致 gradually tending towards the same temperature,
随宇宙膨胀将温度降至绝对零度 as the expansion of the universe cools them towards absolute zero.
我说"长得无法想象的时间" And when I say "Unimaginable period of time,"
是真的长得无法想象 I really mean it.
一万亿亿亿亿 It's 10,000 trillion trillion trillion
亿亿亿亿亿亿亿亿年 trillion trillion trillion trillion trillion years.
这是多大的数字啊 How big's that number?
如果我用一个原子代表一年开始计算 If I were to start counting with a single atom representing one year
那么整个宇宙中所有的原子加起来 then there wouldn't be enough atoms in the entire universe
都无法接近那个数字 to get anywhere near that number.
当最后一刻恒星残留的最后一点物质 Once the very last remnants of the very last stars
完全消失殆尽 have finally decayed away to nothing,
当所有物质都达到同一温度 and everything reaches the same temperature,
宇宙的故事就彻底完结了 the story of the universe finally comes to an end.
在整个宇宙历史中 For the first time in its life,
宇宙将第一次成为永恒不变的 the universe will be permanent and unchanging.
最终 熵值将不能再增大 Entropy finally stops increasing
因为宇宙再也无法变得更加无序 because the cosmos cannot get any more disordered.
什么也不会发生 永远都不会发生什么 Nothing happens and it keeps not happening.
永远 Forever.
这便是众所周知的"宇宙热寂" It's what's known as the Heat Death of the Universe,
在那之后 宇宙将变得 an era when the cosmos will remain
广阔无垠 寒冷无比 荒芜而凄凉 vast and cold and desolate for the rest of time.
因为到那时 But that's because there is no
过去 现在和将来已经没有什么不同 difference between the past, the present and the future.
无法计算时光的流逝 There's no way of measuring the passage of time
因为宇宙已没有任何变化 because nothing in the cosmos changes.
时间箭头由此不复存在 The arrow of time has simply ceased to exist.
这是宇宙无法避免的真相 It's an inescapable fact of the universe,
也被写入了物理学基本定律 written into the fundamental laws of physics.
整个宇宙将消亡 The entire cosmos will die.
银河系中的两千亿恒星将全部消亡 Every single one of the 200 billion stars in our galaxy will go out.
如同太阳末日 便是地球末日 And just as the death of the sun means the end of life on our planet,
每一颗恒星的灭亡 so the death of every star
都可能预示着宇宙中其他某种生命的灭亡 will extinguish any possibility of life in the universe.
太阳将会灭亡 会把地球烧成灰烬 The fact that the sun will die and it will incinerate the Earth
会消灭地球上所有的生命 and obliterate all life on our planet in the process,
也许这让人有点沮丧 might sound a bit depressing to you.
当然你也许会问 You might legitimately ask,
"肯定能用另一种方式构建宇宙吧" "Well, surely you could build a universe in a different way?"
"肯定能构建一个不必从有序走向无序的宇宙吧" "Surely you could build it so it didn't have to descend from order into chaos?"
答案是"不能" Well, the answer is "No, you couldn't,"
除非你想让宇宙中的生命都灭绝 if you wanted life to exist in it.
时间箭头和不断发生的变化 The arrow of time, the sequence of changes
将宇宙慢慢推向死亡 that slowly leads the universe to its death,
这与最初生命起源的条件几乎相同 is the very same thing that creates the conditions for life in the first place.
物质形成需要时间 Because it takes time for matter to form
重力将物质集中成恒星和行星也需要时间 and it takes time for gravity to pull it together into stars and planets.
在宇宙的青春期 The arrow of time creates a
时间箭头创造了一扇明亮的窗口 bright window in the universe's adolescence.
在这个时期 生命成为可能 During which, life is possible.
但那不是一扇永远敞开的窗口 But it's a window that doesn't stay open for long.
作为宇宙生命过程中的一小部分 As a fraction of the lifespan of the universe,
从宇宙起源到最后一个黑洞消失的这个过程中 as measured from its beginning to the evaporation of the last black hole,
生命 正如我们所知 life, as we know it, is only possible
只有百分之千亿分之 for one thousandth of a billion billion billionth
千亿分之千分之一的可能性 billion billion billionth billion billion billionth of a per cent.
所以对于我来说 And that's why, for me,
宇宙中最惊人的奇迹不是恒星 the most astonishing wonder of the universe isn't a star
不是行星 也不是星系 or a planet or a galaxy.
甚至根本就不是一个物质 It isn't a thing at all.
而是时间里的一瞬间 It's an instant in time.
那个瞬间 就是现在 And that time is now.
人类存在于地球的这段时期 Humans have walked the earth
只是这时间长河中简短的片刻中最小的一部分 for just the smallest fraction of that briefest of moments in deep time.
但我们在地球上的短短二十万年里 But in our 200,000 years on this planet,
取得了非凡的进步 we've made remarkable progress.
仅仅在两千五百年前 It was only 2,500 years ago
我们还坚信太阳是个神 that we believed that the sun was a god
还在山顶上建造石塔 测量它的轨道 and measured its orbit with stone towers, built on the top of a hill.
如今 我们好奇的不是太阳神 而是科学 Today, the language of curiosity is not sun gods, but science.
我们有了天文台 And we have observatories
它们比这十三座塔楼复杂精细得多 that are almost infinitely more sophisticated than the 13 towers,
可以通过它们瞭望宇宙深处 that can gaze out deep into the universe.
更值得一提的是 And, perhaps even more remarkably,
通过物理和数学理论 through theoretical physics and mathematics,
我们能预测出宇宙在遥远的未来会是什么样子 we can calculate what the universe will look like in the distant future.
甚至可以具体预测它的结局 And we can even make concrete predictions about its end.
我相信 And I believe
只要我们继续探索宇宙 it's only by continuing our explanation of the cosmos
解开其运行的自然规律 and the laws of nature that govern it,
我们就能真正理解 that we can truly understand
在这个充满奇迹的宇宙中存在的人类和地球 ourselves and our place in this universe of wonders.
而这些正是我们在地球上短暂的时间里所做的 And that's what we've done in our brief moment on Planet Earth.
1977年 一艘叫旅行者一号的探测器 In 1977, a space probe called Voyager 1
发射入太阳系进行太空旅行 was launched on a grand tour of the solar system.
它造访了一些大气体巨行星 And it visited the great gas giant planets -
木星和土星 在转向宇宙空间之前 Jupiter and Saturn - and made some wonderful discoveries
发现了一些惊奇的现象 before heading off towards interstellar space.
十三年后 它的使命差不多结束之后 13 years later, after its mission was almost over,
它转过身 it turned around
为它的家乡 太阳系 拍下最后一张照片 and took one last picture of its home solar system.
这就是那张照片 This is that picture.
照片中最迷人的地方 And the beautiful thing about this picture
就是这个单像素的光 is this single pixel of light
悬浮在漆黑的太空中 suspended against the blackness of space.
因为这个像素 这个点 就是地球 Because that pixel, that point, is Planet Earth.
这是离地球最远距离拍的照片 The most distant picture of our planet ever taken.
六十亿公里远 6 billion kilometres away.
虽然我知道它的科学价值非常有限 And whilst I suppose it has very limited scientific value.
但对于我来说 这个小光点 For me, this tiny point of light
这也许是对人类素质的 is the most powerful and profound demonstration
最强大最深远的见证 of perhaps the most human of qualities.
也是人类思考宇宙及地球存在的 Our unique ability to reflect on the universe's existence
最强有力和意义深远的证明 and our place within it.
人类及地球上所有的生命 Just as we, and all life on Earth,
都生活在这个漂泊在浩瀚宇宙中的小斑点上 stand on this tiny speck adrift in infinite space,
宇宙中的生命也只能在时间长河中存活一瞬间 so life in the universe will only exist for a fleeting bright instance in time.
因为生命 Because life,
如恒星 行星及星系一样 just like the stars and the planets and the galaxies,
只是宇宙从有序到无序暂时经历的一个过程 is just a temporary structure on the long road from order to disorder.
但这并不是说人类显得无关紧要 But that doesn't make us insignificant
因为人类是宇宙所创造的有意识的物种 because we are the cosmos made conscious.
生命就是宇宙理解自己的方法 Life is the means by which the universe understands itself.
在我看来 人类的真正重要性在于 And, for me, our true significance lies in
有能力 有欲望理解和探索这个美丽的宇宙 our ability and our desire to understand and explore this beautiful universe.
我们拥有世界上所有的时间 We have all the time in the world
有足够的时间 Time enough for life
尽情生活 to unfold
所有珍贵的事物都准备好了 All the precious things love has in store...
只有现在 only now.