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Upload by APTXvn 一趟去地心的旅行 温度高达华氏1万3千度 A journey to the center of the earth, where temperature are 待定 thirteen thousands degrees Fahrenheit
比太阳表面的温度还要高 Hotter than the surface of the sun.
地球上最强大的力量 移动整个大陆 The most powerful force on the face of the planet.Moving whole continents
可以造山 也可以摧毁它 Creating mountains, exploding them apart.
还有持续10万年的难以想象的冰天雪地 And unimaginable winter of ice lasting a hundred thousand years.
科学史上几个最伟大的发现 Some of the greatest discovery in the history of science, 透露出我们居住的星球极端复杂而且动力十足 have revealed what an incredibly complex and dynamic planet we live on.
这些都是我们令我们大开眼界的发现 改变我们看待天地的世界 Discoveries that opened our eyes, changing how we see the sky above and earth blow.
翻译:TIV 特大碗牛肉面 制作校对:特大碗牛肉面@CHD
世界百大发现 地球科学
1980年3月,地质学家在这里探测到一连串小型地震 In March 1980, geologists detected a serious of small earthquakes here, 就在华盛顿州圣海伦火山底下 beneath mountain St. Helens in Washington State.
这代表沉寂已久的火山正在苏醒 It was a signal that the long dormant volcano was waking up. 它终于在5月18日清晨醒来了 Finally on the morning of May eighteenth, it did.
圣海伦火山的爆发威力是广岛原子弹的500倍 Mountain St. Helens had erupted with the force five hundred times the atomic bomb that was dropped on Hiroshima
炽热的火山灰冲向大气层 高达15英里 A cloud of hot ash roared fifteen miles into the atmosphere
230平方英里的森林被完全摧毁 230 square mile of forests were wiped out.
总共600万棵树,可以盖30万栋2层楼房 Six million trees, enough wood to build three hundred thousand two storey houses
自有历史记录以来 文明就面临地震和火山的威胁 Throughout recorded history, civilization has lived with the threat of earthquakes and volcanoes
但这种破坏的起因一直是个谜 让人百思不解 But the cause of their destructed power remained elusive, shrouded in mystery.
直到第一个伟大发现的到来 地球内部的动静才开始浮现在眼前 It wasn’t until our first great discovery that a picture of what was happening inside the earth began to emerge.
外核
几个世纪以来 我们对地球内部的认识 For centuries, most of what we knew the earth’s interior
大多来自这一类的采矿活动 came from mining operation like this one.
直到科学家开始使用地震仪研究地震后 It wasn’t until scientists began using seismograph to study earthquakes.
他们才对地球内部有了更精确的了解 That they gained more accurate understanding of the insight of the earth.
地震发生时 地震仪测量地底地震波震动的速度和强度 When an earthquake occurred, seismograph measured the speed and intensity of the seismic waves that vibrated underground.
科学家利用此种方法 辨识出地球内部不同的地层 Using this method, scientists identified different layers inside the earth.
按照岩石密度的改变 区分不同的地区 Each one characterized by changes and rock density.
例如,第一层是地壳,即覆盖地球的薄石层 For example, the first layer was the crust, a skin of rock covering the planet.
其深度从3英里到30英里不等 Its depths very from three to thirty miles.
地壳之下是地幔 大约1800英里厚 Blow that was the mantle with a depth of about eighteen hundred miles
地幔之下呢? As for what was blow that?
最早的线索来自一次突破性的发现 A breakthrough discovery provided the first clue.
1906年,英国地质学家理查德欧汉在分析一场大地震的地震仪记录时 In 1906, British geologist Richard Altman was analyzing seismographic reading caused by a large earthquake.
他看到某些奇怪的东西 When he saw something odd.
地震的震动在反射时并没有如预期般抵达地心 As the vibration from earthquake reverberated, they didn’t arrive at the center of the earth as expected. 就像有障碍物挡住了地震波一样 It was as if they hit an obstacle.
欧汉明白该障碍物一定是地球最深处的部分 Altman realized the obstacle must be the inner most part of the earth.
那是一块很厚的坚硬物质 地震波无法穿透 A dense mass hard enough to reflected seismic waves from going all the way through.
欧汉发现了地球的核心 Altman had discovered the earth’s core.
这是一个划时代的发现 因为它为另一个科学家的研究铺平道路 It was a landmark discovery because it set the stage for the work of another scientist
她正要帮助我们推翻对地球内部的理解 Who is about to help revolutionized our understanding of what was happening inside the earth.
内核
随着欧汉的发现 许多人相信地球核心的面貌已经完整了 With Altman’s discovery, many believed that picture of the earth’s core was complete.
但1930年代早期 英格-莱曼并不赞同这个理论 But in the early 1930, Inge Lehmann wasn’t so sure.
丹麦地震学家莱曼在丹麦和格陵兰岛展开大规模工作 Lehmann was a Danish seismologist, who worked extensively in Denmark and Greenland.
她在那里研究地震波的速率 Studding the velocity seismic waves from earthquakes
1936年,她正在分析几年前发生的地震的地震波规模 In 1936, she was analyzing the seismic waves from an earthquake that had occurred several years earlier.
世界各地的地震监测站也记录了那一次的地震 Seismological stations around the world had made recording of the same quake.
对比这些记录莱曼计算出地震波穿越地核时速率有了改变 By comparing their readings, Lehmann calculated that the seismic waves had passed through the earth’s core. There was a change in their velocity.
它们好像碰到了某种分界线 As if they had encountered another boundary of some kind.
然后她突然意识到 众所周知的地球内部结构其实不够完整 Then it occurred to her. Something was missing from accepted structure of the earth’s interior.
地球不是只有1个核心 而是2个 The earth didn’t just have one core. It had two.
莱曼发现的核心是地球的内核 The core that Lehman had found was the earth’s inner core.
据我们所知,它是一个主要成分为铁的固态核心 Today, through precise seismic measurements, we know that it is made of solid iron.
它之所以成为实心是因为地心引力在此创造出的压力 Solid because gravity at center of the earth created a pressure 是地球表面的300万倍 three million times the pressure exert on surface.
之前理查德欧汉发现的核心是地球的外核 The core that Richard Altman had discovered turned out to be the earth’s outer core. 由液态铁和其他元素组成 It’s made of liquid iron and other elements.
这块炽热搅动的物质产生电流 A hot churning mass that generates electric currents, 接着创造出磁场 保护地球免受危险的宇宙射线辐射 which in turn created the magnet field that, protects the earth from dangerous cosmic radiation.
欧汉和莱曼发现的2个核心加起来形成直径超过4000英里的巨型结构 Together, the two core that Altman and Lehman discovered form a massive structure over four thousand miles diameter.
比行星火星稍微大一点 Slightly larger than the planet mars.
地核的温度可达华氏1万3千度 At the center of the core, the temperature can be as high as thirteen thousands degree Fahrenheit, 比太阳表面温度还要高2000度 which is two thousand degrees hotter than the surface of the sun
为了对地球2个核心的发现有进一步的了解 To get a better understanding of what we’ve learned from the discoveries of the earth’s two cores,
我来拜访地球物理学教授凯瑟琳约翰逊博士 I caught up with Doc. Catherin Johnson,
她正在加利福尼亚南部的一个矿场上做野外研究 a professor of geophysics doing field research at a mine location in southern California.
一开始是什么造成地球的高温? What made the earth hotter at the first place?
地球原先的热来自地球的形成 The earth’s original heat actually came from how the earth formed. 它是在所谓的小行星体撞击后形成的 It formed through collisions of small bodies we call then planetesimals
这些星体撞击后释放出大量的热能 The collisions of these bodies released huge amounts of heat.
-来自非常远的距离之外 That came from astronomical distance. -没错 它们相互撞击 It’s right, just crashing to each other.
然后将所有的动能转变成热能 And turning all that kinetic energy into heat.
那个热能仍在这里? So, the heat is still here?
是的,其实地球成型时也释放热能 Yeah, and the heat is still here and there is also the heat with released actually during the formation of the earth’s cores. 这些星体撞击在一起 So all these bodies came together
它们是岩石,还夹杂一些金属 They are rocky. They have bit of metals in them.
-金属沉淀在地球内部,就形成… That metals settled within the earth to from. -重力 Gravity.
重力,只有自身的重力。 Gravity, yes, just by gravity.
从地球表面附近掉到地心的落差产生的能量 But the change in this gravitational energy going from near the surface of the earth to falling to the center, 事实上也释放了大量热能 actually also released a lot of heat.
为什么地球还没冷却下来? Why wasn’t the earth cool off?
它还没冷却 是因为它冷却的很慢 It hasn’t cooled off because it actually cools very slowly.
考虑到它现在的温度,那似乎就很惊人了 That’s seems perhaps surprising given hot
它原先的温度非常高 But its original temperature was very very hot. 但地球的体积庞大 所以冷却下来要花很长时间 So it takes the earth’s massive, so it takes a long time for it to cool.
因此体积小一点的行星 比如火星 It’s why small planets like mars
再小一点的比如月亮 都已经冷却许多了 Even small like planetesimal bodies like moon have pretty much cooled off.
地球的冷却可能已经持续了数十亿年 But here on earth, the cooling off the planet is perhaps billions of years away.
因为地心的巨大热能 扮演了像是天然火炉的角色 Thanks to the intense heat of the core, which acts as a kind of natural furnace.
欧汉和莱曼并不知道这个火炉还有什么能耐 What Altman and Lehmann didn’t know was what else was this furnace was capable of.
那就是我们下一个伟大发现 And that’s our next great discovery.
大陆漂移
1911年的德国 Germany 1911.
气象学家阿尔弗雷德魏格纳在浏览几本书时注意到某个东西 A meteorologist named Alfred Wegener was browsing through some books when something caught his eye.
他发现大西洋两岸的动植物化石列表一模一样 A list of Atlantic plants and animal fossils that had been found on opposite sides of the Atlantic Ocean.
魏格纳百思不解 相同的生物如何从世界的一端到另一端? Wegener was intrigued. How could the same species have gotten from one part of the world to another?
他仔细研究南美的东海岸和非洲的西海岸 He examined the eastern coast of South America and the western coast of Africa.
惊讶的发现 这两大洲的海岸线也可以拼的起来 And was struck out the shape of the two coastlines might fit together.
他研究越多 发现的关联越多 The more he looked the more links he found.
东非的陆地哺乳动物也栖息在马达加斯加岛 Species of land mammals and east Africa also inhabited in the island of Madagascar
那是如何发生的? 难道动物同时在两个地方进化吗? How did that happen?Did the animals evolve at both places at once?
-安静! quiet please
或者它们从这个地方游了几百里 横跨印度洋来到另一个地方? Or did they somehow cross from one land to the other, swimming hundreds of miles across the Indian Ocean.
然后魏格纳完全明白了 And then Wegener saw all clearly
他认识到世上所有大陆曾经是一整块大陆 He realized that all the continents in the world had once formed
他称之为盘古大陆 取自希腊语,意思为“全地球” A giant single landmass that he called Pangaea from the Greek pangea meaning all earth.
在南美和非洲两岸发现的动植物在盘古大陆时期曾是一家人 It was in Pangaea that the plants and animals found on opposite sides of world had once shared the same home.
然后在几亿年后 盘古大陆分裂了 Then, over hundreds of millions of years, Pangaea had split apart
它一片片的裂块就漂移到目前所在的位置 And its jigsaw pieces had drifted to their present locations
魏格纳将他的理论称为“大陆漂移” Wegener called his theory continental drift.
魏格纳并非是第一个认为地球是一块超级大陆的科学家 Wegener wasn’t the first scientist to speculate that the earth had once been dominated by a super continent.
不过他是第一个收集到大量证据并提出有力证明的人 But he was the first to pore together all the evidence and make a strong case for it.
可惜的是他的同行并不太能接受 Unfortunately, his peers weren’t very accept it.
没有任何机制能解释大陆是如何穿越海洋的 There was no mechanism to explain how the continents might plow through the oceans
大陆漂移的理论在当时实在是难以相信 Continental drift was just too incredible to believe.
结果就是他的发现并未被多数人采纳 As a result, his discovery was largely ignored.
-安静!不然就出去! Quiet down or get out of here.
海底扩张 111 00:10:49,469 --> 00:10:53,139 二战时,德国潜艇四处潜行 World war two, German U-boat ran the proud
为了追踪他们,盟军研发出新的水底探测方法 To track them, the allied forced developed new sonar methods.
科学家也被召集来探测海底 And scientists were enlisted to help survey the ocean floor.
美国宣战时 哈里赫斯是普林斯顿大学的地质学教授 When the United States entered the war, Harry Hess was a geology professor in Princeton University.
他刚好也是个海军预备役士兵 But he also happened to be a navy reservers.
所以不久后,他就在太平洋上指挥一艘进攻运输两用舰船 So it wasn’t long before he found himself command a tank transport ship in the pacific.
为了抢滩登陆时方便登陆 赫斯的船上配备一台测深仪 To help maneuver when coming in for a beach landing, Hass’ ship was equipped with a depth sounder.
他仍然念念不忘地质学家的身份 Still being a geologist at heart.
每次出航时他都用测深仪测量海底的深度 He used the sounder to measure the depth of the ocean floor whenever the ship was out to sea.
他的发现令他惊讶不已 And what he discovered startled him
二战时,大部分的科学家认识中的海底还是这个样子 Until the second would war, most scientists imagined the bottom of ocean look like this
平坦宽阔 Flat 除了沉积物 没什么东西 wide with nothing but settlement.
但在太平洋的波涛下2英里处 What about two miles beneath the ways of the Pacific Ocean
赫斯发现了完全不同的东西 Harry Hass discovered something else entirely.
像这里的加州山脉 有峡谷和沟渠 Mountains, like these here in California with deep canyons and tranches
还有数百座高峰,我们现在相信这些曾是活火山 Hundreds of high peeks that we now believe are once active volcanoes
以上这些统统在太平洋海底 而且令人吃惊的是 And all of these, at bottom of Pacific Ocean, surprisingly though,
太平洋山脉并不是让哈里赫斯名列百大的发现 The discovery of the pacific mountain range was not made Harry Hass part of our great one hundred. 我们等等就谈到那部分 We will get to that in a minute.
为了了解这一切导向何处 To understand where all this headed.
我要向前跳跃到另一个事件 它让地质界引起了骚动 Like to skip a height to another event that set the geology world buzzing
多年来,探测大西洋的海洋学家 For years, oceanographers surveyed the Atlantic Ocean.
从取得的声纳记录指出下面有某个巨大的东西 And taken sonar readings that indicating there was something down there, something big.
1953年 他们发现它就是长达1万2千英里的山脉 In 1953, they found out what it was, a twelve thousand mile long mountain range.
他们称之为中大西洋脊 They called it the Mid-Atlantic Ridge
-它之所以如此巨大… The reason it’s so great
为了帮助我们加深认识 我拜访了尼尔奇思科 To fills in, a paved a visit to Neal Driscoll.
他是斯克利普斯海洋研究所的地质学家 A geologist at the Scripps institution of oceanography.
重大发现之一就是高高耸立在海底之上的海底火山脊 One of the big discoveries that was made was that there was this ridge of underwater volcanoes that stood high above the sea floor.
大西洋中间的山有多高? How high is the mountain in the mid-Atlantic?
平均深度约4000-5000米 中洋脊约有2500米高 The average sea floor depth around the order of about 4000-5000meters, mid-ocean ridge seize up about 2500 meters
所以它们平均比周围海底高出约2.5公里 So, they 待定about two half kilometers on average higher than the surrounding see floor 海底就是这里显现的深兰色部分 that charly不确定 here in blue colors.
-那么就是超过1英里高 So, that’s over a mile high. -没错 Yes.
哈里赫斯此时又要回到我们的故事里了 And that’s where Harry Hass comes back into the story.
分析从中大西洋脊取得的样本和声纳记录 Analyzing course samples in sonar reading around mid-Atlantic ridge, 赫斯有了惊人发现 Hass made an astonishing discovery.
几乎是令人费解的现象 A phenomena almost beyond comprehension.
他判断出距离洋脊越远 大西洋海底的历史就越古老 The age of the Atlantic Ocean floor he determined was progressively older, the further moved away from the ridge
哈里赫斯发现海底在不断扩张 Harry Hass has discovered that the sea floor was spreading.
他推断岩浆在洋脊处的地球内部被往上挤 He concluded that molten rock was being forced up from inside the earth.
接着在洋脊部形成新的地壳 And the ridge were then formed into new crust on the ocean floor.
随着更多的岩浆冒出来 之前的逐渐被推挤到两旁 Gradually was pushed away on either side as more molten rock continued pushing up from behind it.
赫斯把这个伟大发现称为“海底扩张” Hass called his great discovery sea floor spreading.
哈里赫斯刚好能把这一切整合起来 Harry Hass was in a position that he could bring it altogether
岩浆不断喷出向两旁扩张 不断出现新的地面 Things were spreading apart. New earth was being generated
但经过这些后 地球应该变大 But if you did this for long enough, the earth should grow
但是地球并没有变大 And it doesn’t.
-地球没有变的更大? Erath doesn’t get any bigger. -没有 No.
哈里认识到如果某处不断出现新的陆地 Harry appreciated the fact that if new earth was being generated in one area,
就必须有另外一处不断消耗或者再循环 There have to be consumed or recycled in another area
把海底扩张的地壳循环到地底的过程 叫做“隐没” The process that recycle the crust of the spreading ocean floor back inside the earth is called subduction.
但正如我们下一个伟大发现显示的 But is our next great discovery revealed
它只是一个规模更大的过程的一部分 Is all part of a much larger process
那或许是地球上最强大的力量 Perhaps most powerful forces on the face of the earth.
板块构造学说 赫斯发现了海底扩张 Hass’s discovery that the sea floor was spreading
让阿尔弗雷德魏格纳的盘古大陆想法免于默默无闻 Rescued Alfred Wegener’s idea of Pangaea from obscurity.
现在能解释大陆漂移的地质机制就此出现 Now there was the geological mechanism to explain continental drift.
-那很简单 That’s simple. -你一听到,就会觉得很棒 once you hear it, it does sound great.
到了1960年代,2个想法综合成一套理论 即板块构造的科学 By the nineteen sixties, both ideas were synthesized into a single theory, the science of plate tectonics
这个伟大发现显示地球相当复杂且动力十足 A great discovery that revealed just how complex and dynamic our planet it is.
许多科学家推断不只是地壳在移动中 Several groups of scientists had concluded that not only is the earth’s crust moving, 地表也分裂为互相连接的大板块 but the surface of the planet is broken into large interconnected plates
这些板块持续移动 漂流在地幔的岩浆之上 These plates are constantly in motion floating on the layer of molten rock in the earth’s mantle.
听起来很不可思议,我是说,似乎太疯狂了 This seems fantastic; I mean this seems just too crazy.
-整个世界怎么可能在滑动? 我知道人们在怀疑什么… How could the whole world be sliding around. -没错 I can see where people were suspecting. Yes.
但那只是速度的问题,就像你的指甲一直在长 But it’s the rates like your fingernail grow.
-速度不是太快,我完全没有感觉 Not very fast. I don’t feel a thing. -没错 That’s right.
但逐渐累积下来就很惊人了 所以重点就在这里 Accumulately, it’s huge. That here the thing is
就地质年代而言 这些变迁就相当重要 Geological time scales, it’s what makes it so important 因为一年后,它就移动几厘米 because if you think of it over a year, you moved a few centimeters.
想象一下数百万年后,那就是好几公里 And think of millions of years, that you moving kilometers.
大约2亿5千万年前 所有板块组成一个盘古大陆 And about twenty-five million years ago, all the plates were together in Pangaea,
-但它们一直向外移动 而且还会再度移动回来 And they moving apart and they’ll come back together. -它们为什么会移动回来? Why they come back together?
因为现在太平洋四周都有隐没的现象 Because the Pacific Ocean right now had subduction all around it. 板块持续被消耗,循环 And the plates is actually being consumed and recycled
而在大西洋扩张的地方则没有什么隐没的现象 With the Atlantic ocean is spreading without much subduction.
所以大西洋在扩张,太平洋在缩小 So the Atlantic Ocean is kind of grow, the Pacific Ocean is kind of close
然后我们会离亚洲越来越近,并且向太平洋靠拢 And then will start getting closer, Asian and closing up the Pacific Ocean.
-真疯狂 It’s crazy. . -的确,非常了不起 It’s pretty good
一旦你听说,就不难想象地质学家… One you hear it, it’s hard to imagine geologist.
-也不相信这回事,对 not believing it. -不相信 yes
所以这个理论和机制是很重要的贡献 So once the theory and mechanism that was important contribution.
-因为我们不会相信,直到…. We can’t believe it until -没错 yes
所以板块是在扩张,而不是移动 So the plates are spreading. They are not plowing不确定
理解板块构造学说,让科学家们对地球变动的面貌有了新的认识 The understanding of the plate tectonics has given scientists new insights into the changing face of our planet.
这里就可以看到一个强有力的证据 就在加利福尼亚的海岸线上 A dynamic example of some of those changes can be seen here on the California coastline.
地球上最大的两个板块 太平洋板块和北美板块在此相撞 Where two of the earth’s largest plates, the pacific and the North America, collide.
有好几个结果 There are numbers of results.
其中之一就是板块隐没地球之处出现了火山 But one we get volcanoes with the plates that subducted back into the earth.
这些火山的出现是因为 隐没的板块释放出水 These volcanoes happened because the plates get subducted, releases water
而这些水降低了上面那个板块熔化的温度 And the water lowers the molten temperature of the overriding plates and
简单点说,就是火山作用 Make it easier. And we get volcanism,
-所以我们就有了惠特尼山和沙斯塔山 So that’s really get to know Whitney, Mount Shasta, Mount. -就是这样的,没错 Things like these, absolutely.
安第斯山脉就是这类火山的绝佳例子 So the Andes are perfect example of this type of volcanoes.
其他地方有中洋脊 以及比周围高出1-2公里的海底 Other places that you get the mid-ocean ridges, you get pieced of sea floor that were one to two kilometers higher than the surrounding sea floor.
这些就是海底火山链 延伸到所有海洋盆地 These are underwater volcano chains that stretch the link of these ocean basins
其他地方则有大型的平移断层 Other places you get large strike-slip fault
什么是平移断层? So what’s the strike-slip fault
平移就是板块相互移动 而它们一定会扭曲变形 The strike-slip is when the plates move by one and another, and they don’t do it without kinks and twists.
所以如果有扭曲变形 那些地方就会卡住 So, when the kinks and twists are, there can be places that lock
然后就迅速释放出许多能量和动力 地震 And then they release and then they release quickly with a lot of energy and momentum
-会弄垮建筑物等等 Tipping不确定 over buildings and so on, -会造成许多震动,没错 causing a lot of shakings yes
但如果没有地震,就永远不会发现这些理论吧? So, without earthquake, we’ll never found all the stuff right?
地震真的很重要 因为它使我们得以解释板块几何学 Earthquakes are really important because they’ve allowed us to define the plate geometries.
它让我们可以确定板块边界 They’ve allowed us to define the boundaries
那么火山呢? So, what about volcanoes? 火山爆发前 大多时候会先有地震活动 Before volcanoes laid off, a lot of times there is a pre-eruptions seismic activities
震动?没错 Shaking, yes
岩浆流到表面时会造成压力 然后压力就会释放出来 And the magma access不确定 to the surface and causes stress and stresses released.
在这里可以看到板块构造学的证据吗? Do you see ever a plate tectonic right here?
可以,我们看到的这些悬崖 Yes, we are looking at the sea cliffs
这些都是沉淀下来的 这些沉积物,在海平面下约500米处沉淀 These were the depositive. This settlement was deposited about 500 meters blow the sea level.
然后它们往上隆起 And they’ve been uplifted.
因此我们才可以就近亲眼目睹板块构造学 So here, we are looking at the plate tectonic on its own backyard.
目前为止我们已经探索了几项显示地球内部情况的伟大发现 So far, we’ve explored the several great discoveries have revealed what’s happening inside the earth.
接下来的发现 要让我们对天上的情况大开眼界 The next discoveries opened our eyes to what’s happening above.
当我们掌握这么多科学技术后 With so much technology on our fingertips, 预测天气似乎应该是一门精确的科学 it seems like predicting the weather should be more of an exact science.
但全球天气形态如此复杂多变 But global weather patterns are so complex, so volatile
要在2个星期前正确预测今天的天气是不可能的 It’s impossible to accurately forecast conditions more than about two weeks in advance.
天气的变数很多 可能在一瞬间就改变 Weather assumne待定variables, it can change quickly.
不预期地带来狂风暴雨 Bring unexpected feral
大雷雨的能量可以超过1颗原子弹包含的破坏力 The energy in a large thunderstorm can be greater than the destructive power contained in one atomic bomb.
足够提供一个大城市数月的电力 Enough energy to generate electricity for a major city for month
打一次闪电可以产生1亿瓦特的电力 One lightning bomb can strike with the power of one hundred million watts.
将附近的空气烧到5万度 是太阳表面温度的5倍 Scorching the air around to a scolding fifty thousand degrees, five times hotter than the surface of the sun.
但一直在1890年以前 But at late of the eighteen nineties, 人们对于头顶上的天空几乎一无所知 更别说预测天气了 surprisingly little was known of the sky above, little known how to predict the weather.
直到下一个伟大发现才有所改观 Until our next great discovery.
对流层和平流层
法国气象学家里昂泰斯朗-德波尔进行过数百次无人热气球飞行 A French meteorologist named Lyons Tessler de Boer conducted hundreds of unmanned balloon flights
德波尔在每个飞行器上配置一批电钟驱动的科学仪器 De Boer equipped each flight with a range of clock driven scientific instruments 持续记录高空环境 that continuously record the high altitude conditions.
里面有温度计 气压计和测量湿度的湿度计 There were thermometer, barometer and hygrometer to measure humidity.
根据这些仪器收集到的资料 From the information gathered by these instruments, 德波尔成为第一个发现大气层分为数层的人 De Boer was the first to discover that the atmosphere divided into layers.
每一层都有独特的气象状态 Each characterized by distinctive meteorological conditions.
他发现的第一个层的范围是从地表到约10英里高的地方 The first layer he found rises from the surface of the earth to an altitude about ten miles.
他将这一层命名为“对流层” 意思是:变动的范围 He named this layer the troposphere meaning sphere of change
这里是云形成以及天气发生的地方 This is where clouds form and all our weather happens.
大多数的气候经由时速达200英里的高速气流传到地球 Much of deliver to us curt to see at giant不确定 streams which can hit speed up to 200 miles an hour.
对流层之上,德波尔发现了第二个层 Above that, De Boer found the second layer, 他称为“平流层” which he called the stratosphere meaning sphere of layers.
距离地表30英里 It reaches 30 miles above the surface of the earth.
德波尔的发现 让我们对大气层的了解彻底改变 De Boer’s discovery revolutionized our understanding of the atmosphere
并引领大家进入天气与气候研究的现代科学 And help ushered the modern science of weather and climate studies.
现在有17颗国际气象卫星绕地球运行,记录天气 Right now, there are 17 international satellites orbiting the earth, tracking the weather.
每天有1千个以上的气象观测气球 Over thousands weather balloons are lunched every day.
还有1万多个观测站监控着每个大陆上的气候状况 And more than ten thousands observation stations monitor climate conditions on every continent,
为什么我们要如此关注天气? Why are these attentions to the weather?
显然及时的风暴警报能帮助拯救生命 Obviously a timely storm could save lives
但这也关乎经济 But it’s also about the economy.
光是美国1/3的经济就是2.7万亿美元 仰赖于我们对天气的分析 In united states alone, one third of the economy about two point seven trillion dollars depend on our now analysis what’s happening with the weather.
而德波尔的热气球为我们开出一条道路 And De Boer’s hot air balloons helped to lead the way
正如我们下一个伟大发现 Just like our next great discovery.
宇宙辐射
20世纪早期 科学家发现一种神秘的辐射方式会破坏他们的实验 In the early days of the twentieth century, scientists found that a mysterious form of radiation was spoiling their experiments.
他们找不出这个辐射从何而来 They couldn’t figure out what this radiation was coming from
直到物理学家维克多赫斯做出了一个重大发现 Until a physicist name Victor Hess made an important discovery.
赫斯相信辐射可能来自太空 他便搭乘热气球展开一连串的飞行 Believing the radiation might be coming from the sky, Hess made a series of flight in the hot air balloon.
用各种仪器收集资料 包括测量放射电荷的验电器 Collecting data with a variety instruments, including an electroscope which measures radioactive charge
在一次他的热气球航行中 During one of the balloon flights, 他遇到日全食 当时的放射量仍维持不变 there was a total solar eclipse, when radiation level stayed the same,
赫斯就明白辐射不可能来自太阳 而是来自宇宙 Hess knew that the radiation couldn’t becoming from the sun, it had becoming form the cosmos.
有了这样的认识 维克多赫斯发现了宇宙辐射 With that insight, Victor has discovered cosmic radiation.
外太空的辐射蕴含带电的核分子 大多是质子 Electrically charged atomic particles, protons mostly.
来自太空深处的辐射其能量足够穿透大气层 Radiation form deep space, powerful enough to penetrate the earth’s atmosphere
而且也潜藏着危险 And potentially dangerous too.
宇宙辐射能造成基因突变和癌症 Capable of causing genetic mutations and cancer
据估计每年有10多万人死于天然的太空辐射引发的癌症 It’s estimated that each year, more than one hundred thousand people die from cancer caused by the small natural dose of radiation from space.
由于发现了宇宙辐射 奥地利的赫斯于1936年获得诺贝尔奖 For his discovery of cosmic radiation, Hess, a native of Austria, was awarded a share of 1936’s Nobel Prize.
但这个奖无法保护他免受纳粹的迫害 赫斯的妻子是犹太人 But the prize didn’t shield him from the Nazis. Hess’s wife was Jewish
而他们被列入即将送到集中营被埋葬的名单 And they were marked for entering不确定 the concentration camp
好在一位盖世太保官员警告他们 他们就在被逮捕前逃离奥地利 Finally, a Gestapo officer warned them and they fled Austria before they could be arrested.
1946年,他们成为美国公民 By 1946, they were American citizens.
赫斯的热气球飞行改成在帝国大厦顶楼一连串的科学实验 And Hess treated his balloon flights for series of scientific tests atop the Empire State Building
赫斯不再做宇宙辐射的实验 目前担任福特大学的教授 Instead of testing for cosmic rays, Hess now a professor in Ford university
他到帝国大厦测量另一种辐射 Went to the empire state building to measure another kind of radiation.
赫斯在纽约的上空工作 Working high above the New York sky land, 分析他在顶楼收集到的雨水样本里的辐射量 Hess analyzed the radiation level in rain samples that collected at the of the top of the building.
因为不到1年前 原子弹空投到日本的广岛市 The reason that less than a year before, the atomic bomb had been dropped in Hiroshima
维克多赫斯就是第一位在美国测试这次爆炸产生的辐射尘埃的科学家 Victor Hess was the first scientist test for radioactive follow-up from that blast in the United States.
宇宙射线的来源仍然未知 The origin of cosmic rays is still not clear.
它们可能来自超新星 也就是在外太空爆炸的星星 They probably come from supernova, exploding stars in deep space
或者在宇宙大爆炸那个时候就有了 They may be left over the big ***, were the mass of all the stars that universe exploded at once.
不管来自何处 我们很幸运有地球磁场的保护 Wherever it origin, we are fortunately that the magnetic field that surrounds our planet protects us
从而免于多数宇宙辐射中的负面影响 From the most damaging effects of the radiation
但我们的下一个发现要披露地球磁场是在不断变化的 But is our next discovery reveals its magnetic field that is continually in flex,
磁场倒转
我们已经知道 地球的磁场就是一层防护罩 As we’ve already seen, the earth’s magnetic fields access a shield, protecting our planet ’s dangerous radiation.
保护我们的星球免受大部分的危险辐射 from much of the sun
1906年,法国地质学家伯纳布容对于磁场有了惊人的发现 But in 1906, a French geologist named Bernard Brundes made a startling discovery about the field.
布容当时在考察法国中部司马夫中央山脉地区熔岩 Brundes was examining newly formed volcanic rocks near a lava flow in central France.
火山岩浆蕴含地球深处的矿物质 Lava from a volcano contains minerals from the deep earth.
岩浆内部的铁分子可以自由移动 Inside the molten lava, iron particles are freed to move
但当岩浆冷却,形成岩石后 铁分子会根据地球磁场排成直线 But its flow began to cool and formed into rocks, the iron particles allied themselves according to the earth’s magnetic field
就像指南针 like a compass.
它们变成运转中的地球磁场的化石记录 They become a fossilize snapshot of the earth’s magnetic field in action.
但布容在研究时发现,有一些岩石含有完全反方向排列的铁分子 But during his research, Brunhes found some of his research contained iron particles that were magnetized in the opposite direction.
指南针的指针被翻转过来 Their compass niddle had flipped
南变北,被变南 Pointing south instead of north.
这是相当重大的发现 This was the moment of discovery.
布容认识到过去某个时刻 Brunhes realized that some point in the path 地球的磁场改变方向 旋转了180度 that the earth’s magnetic field had changed direction and reversed itself
这是个意义重大的发现 It was a significant discovery.
证明地球是个动力十足的行星 超乎许多人的想象 It meant that the earth was a far more dynamic planet than many had imagined.
不断在变化着 Constantly changing.
我们已经知道在过去的2000万年中地球磁场已旋转约60次 We can see that the earth’s magnetic field has reversed about sixty times in last twenty million years
大约是几十万年就变换一次 As every couple of thousands years or so.
我们现在就可能在经历旋转的过程 And we may be going through a reversal right now.
因为过去的150年间,地球的磁场已经减弱百分之十的力量 Because the earth’s magnetic field has decreased in shrinks about ten percent in only the last century and a half.
没人知道为什么会这样 不过布容的发现的确引起争议: No one exactly sure what happens, but brunhes’s discovery does raise a provocative question.
当地球的磁场为0时,会发生什么事情? What happens when the earth’s magnetic field goes to zero?
答案或许就在火星上 The answer may lie on mars
科学家已经侦测出这颗红色星球可能一度拥有磁场 Scientists had detected that the red planet once may had a magnetic field
由一颗类似的火炉般的核心供给动力 如同地球的地核 Powered by a furnace like a core, just like the one on earth.
但在过去某个时候 火星核的热源消失了 But at some point in its past, the heat source of the mars core was extinguished.
失去内部的火炉 这颗星球也就完蛋了 Without its internal furnace, the planet died.
磁场消失了 有害的宇宙和太阳射线不断攻击这颗星球 Its magnetic field disappeared and dangerous cosmic and solar rays bombarded the planet.
如我们所知,会歼灭任何生命 Wiping out any chances of life as we know it
那有可能发生在地球吗? Could that happened here?
地核的组成分子和体积大概能保持内部发热达数十亿年 Well, the composition and size of the earth’s core such that the earth will probably stay hot inside for billions of years.
但如果地球的磁场旋转归零 又会发生什么事情呢? But what happens when the earth’s magnetic field reverses and goes to zero
如果在接下来的一千年内发生 What will happen in the next thousands years or so 届时大概又会出现很多人类科学家 there probably be humans’ round scientists
他们会测量宇宙射线 然后研究它们对生物的影响 And they can measure cosmic rays and study their effects on living things.
我们下一个伟大发现源于一个谜题 Our next great discovery began with a puzzle.
19世纪初期,欧洲的科学家发现低洼地区的某些岩石形态 Early in the nineteenth century, European scientists found that certain rock formations in low line areas
与远在北方地势很高的地方所发现的一般石头十分相似 Born striking resembles with rock normally found at much higher elevation further north.
它们是怎么移动到那里的? How did they get there?
有一个想法是石头被巨大的冰河移动过去 One idea put forth was that the rock has been moved by giant glaciers.
它们一度从山脉开始扩张 然后再退回到目前的位置上 That once expanded out of the mountains then retreated to their present locations.
冰河期的理论于是诞生了 The theory of the ice age was born.
周期性冰河时期
是什么导致冰河时期的产生? What could cased the ice age happened.
这个问题直到一战前都还是个谜 The question remained a mystery until around the First World War.
有位南斯拉夫科学家 米留廷米兰科维奇发展出一套理论 A Yugoslavia scientist named Milutin Milankovic developed a theory
当时已经发展出几个数学模式 At the time, several mathematical models had been developed 用来解释地球绕太阳轨道的某些细微却重要的变化 to explain subtle but significant variations in the earth’s orbit around the sun
天文学家计算出两者的距离和地球轨道的形状 The astronomers had calculated that the distance between the two and 每隔10万年就会逐渐改变 the shape of the orbit gradually changing every one hundred thousand years
每隔4万年左右 地轴的角度会稍微倾斜 And every forty thousand years or so, the angles of the earth access tilted slightly,
这会影响太阳照射地球的位置 This effect was the sun’s energy reaches the earth
米兰科维奇利用这些和其他方式用相当准确的数字计算出来 Using these and other measurements, Milankovic calculated with great mathematical precision
轨道变化如何在地球的历史上造成重大的气候变动 How the orbital variations has caused major climate changes over the history of the earth.
这些变动始于地球轨道的细微改变 The changes began when the subtle shift of the earth’s orbit
产生凉爽的夏天和更严寒的冬天 Produced cooler summers and colder winters.
这个改变产生了多米诺效应 This change created a domino effect. 年复一年,几个世纪下来 That, year after year, century after century,
让冰河扩张,冰原变大 Allowed the glaciers to expand and ice sheet to grow.
当地球的轨道终于又改变时 冰就消退了 When the orbit of the earth eventually changed again, the ice retreated.
米兰科维奇发现了一个机制 能解释周期性冰河时期的发生 Milankovic had discovered a mechanism to explain the creation of the periodic ice ages.
今日,米兰科维奇的多数理论都已经被证实 也被人所接受 Today, most of Milankovic’s theories had been confirmed and accepted.
据估计,过去几百万年间 地球可能经历过17次的冰河时期 It’s estimated that the earth may have experienced as many as 17 ice ages over the last several millions years.
巨大的冰原覆盖了三分之一的地球 With giant ice sheet covering as much as the third of the planet.
周期性的冰河时期要10多万年才发生一次 Well periodic ice age happened over hundreds of thousands years
而才不到100年,下一个伟大发现就呈现在我们眼前 Our next great discovery has unfolded just a hundred years
从地质学的时间来看,可以称这个发现为一场“灾难性事件” Which in geological terms makes it a catastrophic event.
比冰河时期更值得注意 而且它正发生在你我身旁 More significant than the ice age and it’s happening right now.
全球变暖
这是北卡罗来那州艾许维尔的国家气象资料中心 This is the national climatic data center in Asheville North Carolina.
世界各地的天气资料都储存于此 Weather records from around the world were stored here.
有一些资料甚至可以追溯到1700年 Some data back as far as the seventeenth hundreds.
但象中心主任托马斯卡尔这种专家却对上一个世纪的气候特别感兴趣 But the weather of the last century that was particular interested to expert like Thomas Karl, director of the center.
记录指出,过去100年来 The record indicate that over the past one hundred years, 地球表面温度增加了1华氏度(1华氏度=5/9摄氏度) the surface temperature of the planet has increased about one degree Fahrenheit
听起来好像不多 That may not sound like much. 但许多人相信这代表短时间内一段显著的暖化趋势 But many believed that represents a significant warming trend in a relative short period of time
暖化的影响的确很大 这是很严重的全球议题 The impacts of that warming are indeed substantial. This is a major global problem
关于造成地球温度升高的猜测 Speculation about what causing the earth to heat up 长久以来都聚焦在燃料的使用上 has long centered on the burning of fossil fuels.
虽然二氧化碳和其他气体都是在地球大气层中自然形成 While carbon dioxide and other gases occurred naturally in the earth’s atmosphere.
科学家怀疑,工业制造出的二氧化碳是否就是气候改变的主因 Scientists wonder if a buildup of industrial CO2 could be responsible for the climate change.
终于有位美国地球化学家大卫基林 Finally, American geochemist David Keeling 开始测量大气中到底有多少二氧化碳 set out to measure just how much carbon dioxide might be up there.
1958年,基林从地球上方2英里处取得了空气样本 In 1958, keeling took air samples 2 miles above the earth.
就在夏威夷的毛纳罗峰上空 High atop among the Mauna Loa Hawaii.
之所以选择这个位置 是因为那里的空气几乎未受污染 Location was chosen because the air was mostly unpolluted.
基林将样本收集到烧瓶里 用红外线气体分析器测量二氧化碳的量 Keeling collected the samples in flask and measured the CO2 levels of infra-red gas analyzer
结果十分惊人 The results were astonishing.
基林发现大气中的二氧化碳含量 Keeling found that the level of the carbon dioxide of the atmosphere 正在以每年33亿吨的速度增加 was increasing at the rate of 3.3 billion tons a year.
那是划时代的一刻 It was a landmark moment. 一夜之间,全球变暖和二氧化碳含量过高联系了起来 Suddenly, the bateover待定connection between global warming and rising CO2 levels became more than academic issue.
我们取得了重要的数据 Here were measurable data.
今天大气层中的二氧化碳含量持续增加 Today, the level of CO2 in the atmosphere continues to rise.
专家相信,今天的二氧化碳含量比工业革命之前还要多30% It’s now the level some 30 percent greater than what experts believed was prior to the industrial revolution.
许多科学家相信,这种增长正在对世界各地气候造成重大影响 An increasing that many scientists believed is having a significant impact on climate around the world.
全球变暖的气候变动中 最显著的例子之一就在这里 One of the most visible examples of climate change from global warming is here.
华盛顿州的南瀑布冰河正在逐渐融化 At the south cascade glacier in Washington states where the ice is melting.
1928年冰河的面貌就如照片所见 This is how the glacier appeared in 1928,
这是1975年 1975,
2003年 2003
调查显示,南瀑布冰河在上个世纪中已经后退了1.2英里 According to surveys, the south cascade glacier has retreated by one point two miles over the last century.
它的表面已经流失掉相当于72英尺深的水 It has lost equivalent of 72 feet of water from the phycnise待定 of the surface.
全世界的冰河都在消退 And glaciers are shrinking worldwide.
一份针对16万座高山冰河和冰帽的地质调查显示 One geological survey of one hundred sixty thousand mountain glaciers icecaps,
冰的数量正在以极快的速度减少 reported that the volume of the ice decreasing at a significant rate.
虽然科学家之间已经有共识 但地球的气候仍逐渐在变暖 While there is a general consensus among scientists that the earth climate is becoming warmer
大家还在辩论着 到底多少的二氧化碳才能引起全球变暖 There is still some debate over how much carbon dioxide is to blame不确定
尽管闹的不可开交 Regardless of the debate, 研究人员还是追踪到比以往更多的全球变暖现象 researchers are tracking global warming more than ever
已经有电脑模型 预测目前的变暖趋势可能导致的后果 Computer models have been developed to anticipate what may happen if the current warming trend continues.
从大规模的水灾 到世界各地生态系统的破坏 From wide-spread flooding to the devastation of ecosystem around the world.
火山学家估计1980年圣海伦火山的爆发 Volcanologists estimated that the 1980’s eruption of Mount St Helens 释放大约1000万吨二氧化碳到大气层 released about ten million tons of carbon dioxide into the atmosphere.
听起来好像很多 That’s sounds like a lot 却无法和人类每年排放到大气中的260亿吨二氧化碳相比 until you compare the 26 billion tons of CO2 that humans popping待定 into the atmosphere every year.
大多来自石化燃料的燃烧 Mostly from burning fossil fuels.
这样想好了 7座圣海伦大小的火山要连续喷发整整一年 Think of this way, it would take seven volcanoes the size of Mount St Helens erupting everyday of the year,
才追的上我们制造出的二氧化碳排放量 To equal the amount of CO2 emission that we produce
从冰河时期的形成到全球变暖的影响 From the creation of the ice ages to the effects of global warming
地球的气候在不断的改变 The earth’s climate is roller coast不确定 of changes
而我们下一个伟大发现 能帮助我们整合所有的观点 And our next great discovery helped put it all in perspectives
地质变动
好几个世纪以来 For centuries, 人们都相信地球是由大灾难塑造出来 比如圣经中的洪水 people believed that the earth was shaped by catastrophes, like the biblical flood
但19世纪初期 But in the early eighteenth hundreds, 牛津大学毕业的律师,查尔斯莱尔,颠覆了这种观念 an oxford educated lawyer named Charles Lyell shattered that belief
并彻底改革了地质学 and revolutionized geology.
莱尔花了数年到世界各地 研究数不清的岩石构造和化石标本 Lyell spent years traveling the world, studying overwhelming number of rock formations and fossil samples
他观察细致入微 He had a brilliant eye for detail and piece by piece, 他开始看出每一块岩石都在诉说着不同的故事 he began to see the rock told different story.
虽然各种灾难 While catastrophe 比如火山爆发 地震 洪水都偶尔会对地球造成影响 such as volcanoes, earthquakes and floods occasionally affected the planet
但最大的变动还是极度缓慢且天然的地质过程所造成的结果 The greatest changes were the result of the incredibly slow and natural geological process.
驱动此过程的元素包括风,水 A process driven by wind, water, 侵蚀与地球的变暖和冷却 erosion and the heating and cooling of the earth.
这些变动的记录都保存在岩石中 但莱尔的最根本见解是: A record of those changes was contained in the layers of rock. But here was Lyell’s most radical insight.
地质变动的缓慢过程的机制是时间 很长的时间 The mechanism for that slow process of geological change was time, lots of time.
莱尔相信 地球比一般人相信的要古老的多 The earth Lyell argued was far older than was generally accepted
在他的划时代著作《地质学原理》中,他提出所有的发现 And he presented proof of his finding and the landmark book called principles of geology.
现在,他的著作被认为标志着现代地质学的诞生 Today, the publication is considered the birth of the modern geology.
萨缪尔保令 是麻省理工学院的地质学教授 Samuel Bowring is a professor of geology at MIT.
我认为莱尔的思想发展中很重要的一点 I think a very important in Lyell’s development of far待定 就是他去勘查意大利的火山,特别是威苏维火山时 was a trip to see the volcanoes of Italy Vesuvius
他在那里亲眼看到 那座山是由连续的火山流构建起来的 And set belief particular where he actually saw that the mountain was built up of successive flows
一部分的山还留下比较完整的爆发痕迹 And they had some of these, and he has good ideas one they were erupted, 因为它们都是有历史意义的 because here is historical
他能够据此推断 这座火山本身必定有几十万年历史 And he was able to use that to extrapolate that the volcano itself must be hundreds of thousands years old.
当时谈论几十万年是革命性的事情 And at that time, talking about hundreds of thousands years was revolutionary.
其他人主张演化有定向性 地球诞生那天和今天的地球已经不同了 Others argued for a directionality in evolution that the earth on day one is not the same earth as today.
已经发生某个累积许久的变动了 Some secular change has occurred.
这也是今天地质学家们的争议之处 This is the debate geologists have today.
板块构造在45亿年前就上演了吗? Where plate tectonic operate for half billion years ago. 还是在地球历史上是后来发生的事情? Is this something developed later on in earth’s history.
今天许多人认为查尔斯莱尔是地质学界的达尔文 Today, many considered Charles Lyell to be the Charles Darwin in geology.
现实生活中,这两个人之间的关系也相当密切 In real life, the connection between the two men was significant.
达尔文带了莱尔论文集的第一集第一版 随着小猎犬号出航 Darwin took the first edition copy of the volume one of Lyell’s treaties on his cruise with the Beagle
他阅读这本著作 同时潜心研究演化的理论领悟出进化论 And what he realized from reading this as he was also simultaneously worrying about revolution was here, was the solution to revolution
我们的时间是无穷无尽的 We have limitless time.
莱尔的发现引起各方一窝蜂的勘查地球的真正年龄 Lyell’s discovery set off a fire storming interest in determining the true age of the earth.
原本大家相信地球还很年轻 但莱尔的关键性著作推出后 Until then, most everyone believed the planet was young. But the publications of Lyell’s seminal book
地质学家都想知道地球有多年轻 Geologists want to know how young.
我们的下一个发现提供了答案 Our next great discovery provided an answer
放射性同位素测年法
地球到底有多老? Exactly how old was the earth?
这个谜题直到1907年才解开 The question persisted until 1907,
美国化学家波特兰伯尔伍德找到一种方法 When an American chemist Bertram Boltwood discovered a way 让地球的岩石和矿物质自己提供答案 to make the rocks and minerals of the earth, provided an answer.
科学家已经知道岩石含有自然发生的放射性元素 比如铀 Scientists already knew that rocks contained naturally occurring radioactive elements such as uranium
每种元素会依据自己的速率或时钟衰变成另一种元素 They also knew that each element decayed into other elements 而且速率几乎不会改变 according to its own rates or clocks and that rate almost never changed.
伯尔伍德在研究这些衰变率时 While studying these rates of decay, 发现铀的矿物质样本都含有铅的成分 Boltwood found that mineral samples of uranium always contain traces of lead
他相信这表示铀缓慢衰变的过程中残留的最后一个元素就是铅 It was indicationly不确定 believed that lead was the last element remaining from uranium slow process of decay.
伯尔伍德据此将一切整合起来 测量铀样本里的铅含量 Form this observation, Boltwood put all together. If he measured the amount of lead contained in the uranium sample.
再用已知的铀衰变率计算 就可以判断岩石大致的年龄 And calculated it by the m待定 which uranium decays, he could determine the approximate age of the rock
这是个突破性的发现 It was a breakthrough discovery.
科学家突然有特殊的精准的新工具来断定地球的地质历史 Suddenly, scientists had an extraordinary and accurate new tool for calibrating the geological history of the earth.
称作“放射性测年法” It was called radiometric dating.
放射性测年法的好处 The great thing about radiometric dating is 就是我们能相当精准的测定大峡谷里岩石的年龄 it allows us to determine the age of the rocks in great canyon with quiet bit of precision.
所以我们能了解在大峡谷形成之前整个岩石沉积的历史 So we can understand the whole history of deposition of this rock before the canyon was carved.
我们现在知道大峡谷最底层的岩石有17亿到18亿年的历史 We know that the rocks in the very deep part of the canyon are one point seven to one point eight billion years old.
但它们的上方却覆盖着只有5亿3千万年历史的沙岩 And they overlay by a flex surfaces of sandstones only five hundred and thirty million years.
所以如果没有地质年代学 我们根本无从得知 So, without geochronology we would never know that we are missing
越过整层表面后 已经遗失了10多亿年的历史 More than of a billion years of history across that surface
这段历史却出现在世上的某个地方 那段历史并未出现在这里 Now, other places in the world have that history. Here, we don’t have that history.
这是必须要记住的要点 地质记录是极度不完整的 It’s important to remember geological record is remarkably incomplete
那么一个世纪前的地质年代就是地球上的时间 So century ago, geochronology, time in the earth,
100年前的正确率是多少?百分之十还是百分之五十? Century ago, the accuracy of ten percent? Fifty percent?
100年前 我们甚至不知道什么是定年 所以有更多的不确定性 Hundreds ago, we even didn’t know what was dating so uncertainty was much much larger
他们能测定约20亿年的东西 They were getting dates of around two billion.
当然,这对于我们了解地球的年龄是个大突破 Which, of course, was a huge breakthrough.
不过,那只是地球真正年龄的一半 In terms of understanding how old the earth was but was only half of two ages of the earth.
直到1950年代 人们才开始对陨石定年 It wasn’t until the nineteen fifties, that people began to date meteorolite
我们才开始明白 地球大概有45亿到46亿年的历史 That we began to realize the earth is probably four point five, six billion years
为了体会那是多么长的时间 我们来举个例子 To appreciate how much time that is, consider this.
如果我们将整个地球的历史比喻为24小时 If we compare the entire history of the earth to aspend 24 hours.
100万年在30分钟内就会流逝 A million year would go by about 30 minutes, 也就是说,整个人类文明史不到1秒的时间就结束了 which means that the entire epic story of human civilization would be over in less than one second.
时钟还没滴答一声呢 Not even a tick of a clock.
为什么这么重要? So why is this so important?
纵观整个演化历史 充满了惊人的绝种事件 when we look at the history of revolution. History of revolution is punctuated by incredible extinction events.
2亿5千1百万年前 The Permian Trias extinction to fifty one million years ago 二叠纪与三叠纪时的大灭绝,灭绝了90%的海底生物 killed ninety percent of everything that lived in the oceans
问题是这会是渐进式的过程吗? So, the question is, was this sort of a gradual process
我们是否会看到越来越多的生物灭绝 最后幸存者终于发出欢呼 or we saw an increasing amount of extinction and finally the last herald
或者这是铺天盖地的瞬间灭绝? or was that catastrophic.
二叠纪时的地球生活是否美好? 然后一夜之间,万物就绝灭了? Was life wonderful on the Permian earth And suddenly everything went extinct.
想回答这些问题 就要透过精准的地质年代学 The way to answer that question is through high precision geochronology
越来越多的资料显示 那个事件发生在一瞬间 And the date of the accumulation right now suggest that was a extremely rapid event
说到一瞬间发生的事件 So as to say rapid event, 我们有个相当符合的模式 那就是小行星撞击 one model that we have works for well impact of the asteroid.
近来有些证据显示 And recently, there has been some evidence put forth suggests 可能有颗小行星在二 三叠纪之间撞击地球 there may have been an asteroid at that boundary impact the earth,
灭绝的另一面也很重要 The other aspect of the extinctions is really important, 对某些人来说,这个部分甚至比了解灭绝更有意思 some people even more exciting than understanding the extinction itself.
那就是生态系统会怎样?要多长时间才能复原? Is, what happens to the ecosystem. How long did it take to recover
万物被灭绝后,就像重新设定整个进化的时钟 When you wipe everything out is like resetting the whole evolutionary clock.
而先前完全被消灭的生态系统由新的生物填满 And then you allowed new things to fill the ecosystem that was completely bleadered待定
是否有了这次灭绝 It could be that if that extinction, 才有恐龙的兴起,接着哺乳类的出现? we wouldn’t see the rise of the dinosaurs and then mammals
我们才会住在一个如此不同的星球上? 我们才能住在这里? We could live on a very different planet. We wouldn’t live here.
-看这片风景,你会觉得自己很渺小。 You look at this view and if you can insignificant inspect, -没错 right
它的壮观让人赞叹 但接着你想到能从它那里学到什么 And the grandeurs of this astonishing
-那又是另一种… And when you think about , What you can learn from it? -的确,它就像本书 in another whole level. And it’s like a book.
那里有许多信息等着我们去挖掘 There is lots of information, waiting for us to extraculate,
那些我们从不知道 The information that we haven’t even thought about. 但可以由岩石来记录的讯息 能做的事情可多了 Asking the record to produce for there’s a lot to do.
-搞科学的不会没饭吃 That’s job security for science. -是的 Yes
地球是个复杂且动力十足的星球 The earth as a complex and dynamic planet
地壳在变动 地幔在移动 The Crust is shifting
大气层一直捉摸不定 The mantle is moving
生活在地球上的所有物种都随之改变 The atmosphere is constantly in flex
我们的祖先也改变了,否则我们无法生存至今 All the species that live on the earth are changing along with it. Our ancestors did we wouldn’t be here.
地球挑战所有的生物,而生命迄今一直勇于接受挑战 The earth is challenging all living things. And so far, life has been apt to the challenge. Upload by APTXv�