I'm really glad to be here. I'm glad you're here, because that would be a little weird. I'm glad we're all here. And by "here," I don't mean here. Or here. But here. I mean Earth. And by "we," I don't mean those of us in this auditorium, but life, all life on Earth --
我真的很高興能來這裡。 我也很高興你們能來這裡, 要不然會有點奇怪。 我很高興我們都在這裡。 我說的「這裡」,不是現場這裡。 或這裡。 卻是這裡。 我指的是地球。 而且我說的「我們」, 不是這座大禮堂裡的各位, 而是生命, 地球上所有的生命──
(Laughter)
(笑聲)
from complex to single-celled, from mold to mushrooms to flying bears.
從複合體到單細胞, 從黴菌到蘑菇, 到飛天熊都是。
(Laughter)
(笑聲)
The interesting thing is, Earth is the only place we know of that has life -- 8.7 million species. We've looked other places, maybe not as hard as we should or we could, but we've looked and haven't found any; Earth is the only place we know of with life. Is Earth special? This is a question I've wanted to know the answer to since I was a small child, and I suspect 80 percent of this auditorium has thought the same thing and also wanted to know the answer. To understand whether there are any planets -- out there in our solar system or beyond -- that can support life, the first step is to understand what life here requires.
有趣的是, 地球是我們知道 唯一有生命的地方── 八百七十萬種生物。 我們找過其它地方, 可能找得還不夠勤快, 但是我們找過, 沒有發現任何生物。 地球是我們所知唯一有生命的地方。 地球得天獨厚嗎? 這個問題的答案 我從小時候就想知道, 而且我猜禮堂裡八成的人 都想過同樣的事,也想知道答案。 要知道是否有別的行星── 無論是在我們的太陽系 還是其它地方── 能支持生命, 第一步要了解在這裡 生命的要素是什麼。
It turns out, of all of those 8.7 million species, life only needs three things. On one side, all life on Earth needs energy. Complex life like us derives our energy from the sun, but life deep underground can get its energy from things like chemical reactions. There are a number of different energy sources available on all planets. On the other side, all life needs food or nourishment. And this seems like a tall order, especially if you want a succulent tomato.
事實證明, 這八百七十萬種物種 只需要三件事就能維持生命。 那邊那張照片, 地球上所有的生命都要能量, 像我們這樣的複合生物體 要從太陽取得能量, 地下深處的生物 則從化學反應取得能量。 地球上有很多種能量來源 可供大家使用。 另外那一邊照片, 所有的生命都需要食物或營養。 這聽起來像是無理的要求, 尤其在你想要一顆多汁的番茄時。
(Laughter)
(笑聲) (譯註:一般超市的番茄都很乾)
However, all life on Earth derives its nourishment from only six chemical elements, and these elements can be found on any planetary body in our solar system. So that leaves the thing in the middle as the tall pole, the thing that's hardest to achieve. Not moose, but water.
然而,地球上所有的生命 只要六種化學元素就能取得營養, 而這些元素可在 我們的太陽系中 每一個行星體上找到。 所以這讓中間這項成了高不可及、 很難拿到的東西。 不是麋鹿,是水。
(Laughter)
(笑聲)
Although moose would be pretty cool.
雖然麋鹿也滿酷的。
(Laughter)
(笑聲)
And not frozen water, and not water in a gaseous state, but liquid water. This is what life needs to survive, all life. And many solar system bodies don't have liquid water, and so we don't look there. Other solar system bodies might have abundant liquid water, even more than Earth, but it's trapped beneath an icy shell, and so it's hard to access, it's hard to get to, it's hard to even find out if there's any life there.
不是冰凍的水,也不是氣狀的水, 而是液態水。 這是生命要生存都需要的東西。 所有的生命。 許多太陽系沒有液態水, 所以我們不去那裡找。 有些太陽系可能有大量液態水, 甚至可能多過地球, 但是都困在冰層底下, 所以很難拿到,很難接近, 甚至很難發現那裡到底有沒有生命。
So that leaves a few bodies that we should think about. So let's make the problem simpler for ourselves. Let's think only about liquid water on the surface of a planet. There are only three bodies to think about in our solar system, with regard to liquid water on the surface of a planet, and in order of distance from the sun, it's: Venus, Earth and Mars. You want to have an atmosphere for water to be liquid. You have to be very careful with that atmosphere. You can't have too much atmosphere, too thick or too warm an atmosphere, because then you end up too hot like Venus, and you can't have liquid water. But if you have too little atmosphere and it's too thin and too cold, you end up like Mars, too cold. So Venus is too hot, Mars is too cold, and Earth is just right. You can look at these images behind me and you can see automatically where life can survive in our solar system. It's a Goldilocks-type problem, and it's so simple that a child could understand it.
這樣只剩下幾座星體我們應該考慮。 所以我們來為自己簡化一下問題。 我們只要想想 在星球表面的液態水就好。 這樣我們的太陽系裡 只剩三座星體可想, 考慮行星表面是否有液態水, 與太陽的距離依次是 金星、地球及火星。 你要有大氣層使水能維持液態。 你必須非常小心考慮大氣層。 你不能有太大的大氣層, 太厚或太溫暖都不行, 因為這樣會像金星一樣太熱, 而且沒有液態水。 但是如果你的大氣層太少, 而且太薄太冷, 結果就會像火星一樣太冷。 所以金星太熱,火星太冷, 地球則是剛剛好。 看看我後面的照片,你自然會看到 我們的太陽系 哪裡有生命可以存活。 這是典型的 《金髮女孩與三隻熊》問題, 而且這太簡單了,小孩都能理解。
However, I'd like to remind you of two things from the Goldilocks story that we may not think about so often but that I think are really relevant here. Number one: if Mama Bear's bowl is too cold when Goldilocks walks into the room, does that mean it's always been too cold? Or could it have been just right at some other time? When Goldilocks walks into the room determines the answer that we get in the story. And the same is true with planets. They're not static things. They change. They vary. They evolve. And atmospheres do the same. So let me give you an example.
然而, 我要提醒各位兩件事, 是《金髮女孩與三隻熊》故事中, 常常被我們忽略 但我認為非常切題的事。 第一: 金髮女孩走進屋時, 如果熊媽媽碗裡的粥太冷, 那是指粥早就冷了? 還是曾有剛剛好的時間? 金髮女孩走進屋的時間決定了 故事的答案。 行星也一樣。 行星不是靜態的東西。 它們一直在改變。 它們變化,它們演化。 大氣層也一樣。 我舉一個例子。
Here's one of my favorite pictures of Mars. It's not the highest resolution image, it's not the sexiest image, it's not the most recent image, but it's an image that shows riverbeds cut into the surface of the planet; riverbeds carved by flowing, liquid water; riverbeds that take hundreds or thousands or tens of thousands of years to form. This can't happen on Mars today. The atmosphere of Mars today is too thin and too cold for water to be stable as a liquid. This one image tells you that the atmosphere of Mars changed, and it changed in big ways. And it changed from a state that we would define as habitable, because the three requirements for life were present long ago. Where did that atmosphere go that allowed water to be liquid at the surface?
這是我很愛的一張火星照片。 這既非最高解析度,也並非最美, 更不是最新的照片, 但這張照片顯示河床切過行星表面; 被流動、液態水切割出的河床; 河床要上百、上千 甚至上萬年才能形成。 現在的火星不可能發生這件事。 現在的火星大氣層太薄太冷, 水因而不能維持液態。 這一張照片告訴我們 火星的大氣改變了, 而且改變很大。 它從我們定義的適居狀態 變成現在的樣子, 因為生命三大要素 在很久以前曾經出現過。 本來能讓水在地表 維持液態的大氣去了哪裡?
Well, one idea is it escaped away to space. Atmospheric particles got enough energy to break free from the gravity of the planet, escaping away to space, never to return. And this happens with all bodies with atmospheres. Comets have tails that are incredibly visible reminders of atmospheric escape. But Venus also has an atmosphere that escapes with time, and Mars and Earth as well. It's just a matter of degree and a matter of scale. So we'd like to figure out how much escaped over time so we can explain this transition.
嗯,有人說它逃逸到宇宙。 大氣粒子有足夠的能量 逃脫此行星的重力, 散逸到太空,一去不返。 這種現象在有大氣的 星體上都會發生。 彗星的尾巴 正是大氣逃逸絕佳的視覺提醒。 但是金星的大氣也會隨時間逃逸, 火星及地球也一樣。 這只是程度及規模的問題。 所以我們要找出逃逸的速率, 才能解釋這種轉變。
How do atmospheres get their energy for escape? How do particles get enough energy to escape? There are two ways, if we're going to reduce things a little bit. Number one, sunlight. Light emitted from the sun can be absorbed by atmospheric particles and warm the particles. Yes, I'm dancing, but they --
大氣怎麼得到逃逸所需的能量? 粒子怎麼得到足以逃逸的能量? 如果我們簡化一下來看, 有兩種方式。 第一,陽光。 從太陽射出的光被大氣粒子吸收, 使粒子增溫。 是,我是在跳舞,不過它們──
(Laughter)
(笑聲)
Oh my God, not even at my wedding.
天啊,我在自己的婚禮上都沒跳。
(Laughter)
(笑聲)
They get enough energy to escape and break free from the gravity of the planet just by warming. A second way they can get energy is from the solar wind. These are particles, mass, material, spit out from the surface of the sun, and they go screaming through the solar system at 400 kilometers per second, sometimes faster during solar storms, and they go hurtling through interplanetary space towards planets and their atmospheres, and they may provide energy for atmospheric particles to escape as well.
它們得到足夠的能量逃逸 並掙脫重力, 這一切只要增溫就夠了。 得到能量的第二種方法是太陽風。 這些是從太陽表面噴出的 粒子、團塊及物質, 而且它們在太陽系裡 以每秒 400 公里的速率呼嘯而過, 在太陽風暴期間有時候還更快, 而且它們飛馳通過行星際空間, 朝著行星及其大氣飛去, 因而它們也可以提供能量 讓大氣粒子逃逸。
This is something that I'm interested in, because it relates to habitability. I mentioned that there were two things about the Goldilocks story that I wanted to bring to your attention and remind you about, and the second one is a little bit more subtle. If Papa Bear's bowl is too hot, and Mama Bear's bowl is too cold, shouldn't Baby Bear's bowl be even colder if we're following the trend? This thing that you've accepted your entire life, when you think about it a little bit more, may not be so simple. And of course, distance of a planet from the sun determines its temperature. This has to play into habitability. But maybe there are other things we should be thinking about. Maybe it's the bowls themselves that are also helping to determine the outcome in the story, what is just right.
這就是我感興趣的東西, 因為這跟適居性有關。 我曾說過金髮女孩的故事中有兩件事 我要你們注意並提醒你們一下, 第二件事更微妙一點。 如果熊爸爸碗裡的粥太燙了, 而熊媽媽的粥太冷了, 那熊寶寶的粥不就應該更冷了, 如果我們順著趨勢想? 你一輩子都沒懷疑過的這件事, 仔細一想後可能沒那麼簡單。 當然,行星的溫度取決於 它與太陽的距離。 這就與適居性有關。 但是我們可能還必須考慮其它事。 可能碗本身 也會決定這個故事的結局, 也就是「剛剛好」的問題。
I could talk to you about a lot of different characteristics of these three planets that may influence habitability, but for selfish reasons related to my own research and the fact that I'm standing up here holding the clicker and you're not --
我可以跟大家講很多 這三個行星不同的特性, 這些特性可能也會影響適居性, 但是我有私心, 因為那跟我的研究有關係, 而且站在這裡拿著遙控器的是我, 不是你們──
(Laughter)
(笑聲)
I would like to talk for just a minute or two about magnetic fields. Earth has one; Venus and Mars do not. Magnetic fields are generated in the deep interior of a planet by electrically conducting churning fluid material that creates this big old magnetic field that surrounds Earth. If you have a compass, you know which way north is. Venus and Mars don't have that. If you have a compass on Venus and Mars, congratulations, you're lost.
所以我只跟你們講一兩分鐘就好, 來談一下磁場。 地球有磁場;金星及火星沒有。 磁場在行星內部深處產生, 由導電的液態物質環繞流動 而產生這個環繞地球的 巨大古老磁場。 如果你有羅盤, 你會知道哪邊是北邊。 金星與火星沒有這個。 如果你在金星及火星上用羅盤, 恭喜喔!你迷路了。
(Laughter)
(笑聲)
Does this influence habitability? Well, how might it? Many scientists think that a magnetic field of a planet serves as a shield for the atmosphere, deflecting solar wind particles around the planet in a bit of a force field-type effect having to do with electric charge of those particles. I like to think of it instead as a salad bar sneeze guard for planets.
這會影響適居性嗎? 又怎麼影響? 許多科學家認為行星的磁場 就像大氣層的防護罩, 使在行星四周的太陽風粒子偏轉, 有點像(星際爭霸戰) 力場防護罩效應, 因為跟這些粒子的電荷有關。 我喜歡把它比喻為沙拉吧上面 擋噴嚏的防護罩。
(Laughter)
(笑聲)
And yes, my colleagues who watch this later will realize this is the first time in the history of our community that the solar wind has been equated with mucus.
是的,以後看這片的同僚會發現, 這是史上頭一遭有人在我們這行 把太陽風等同為黏液。
(Laughter)
(笑聲)
OK, so the effect, then, is that Earth may have been protected for billions of years, because we've had a magnetic field. Atmosphere hasn't been able to escape. Mars, on the other hand, has been unprotected because of its lack of magnetic field, and over billions of years, maybe enough atmosphere has been stripped away to account for a transition from a habitable planet to the planet that we see today.
好吧,所以這個效應, 就是地球可以受到保護 幾十億年, 因為我們有磁場。 大氣至今無法逃脫。 另一方面,火星沒有受到保護, 因為它沒有磁場, 所以幾十億年來, 可能已經揭掉了夠多的大氣, 使這個原本適居的行星轉變為 今天我們看到的樣子。
Other scientists think that magnetic fields may act more like the sails on a ship, enabling the planet to interact with more energy from the solar wind than the planet would have been able to interact with by itself. The sails may gather energy from the solar wind. The magnetic field may gather energy from the solar wind that allows even more atmospheric escape to happen. It's an idea that has to be tested, but the effect and how it works seems apparent. That's because we know energy from the solar wind is being deposited into our atmosphere here on Earth. That energy is conducted along magnetic field lines down into the polar regions, resulting in incredibly beautiful aurora. If you've ever experienced them, it's magnificent. We know the energy is getting in. We're trying to measure how many particles are getting out and if the magnetic field is influencing this in any way.
其他科學家認為磁場的 作用可能更像船上的帆, 讓行星能與太陽風的能量 產生更多交互作用, 比自身的交互作用還要更多。 帆可以聚集風的能量。 磁場可以聚集太陽風的能量, 讓更多大氣逃逸。 這個理論還需要證明, 但是其影響及作用方式 看起來很明顯。 那是因為我們知道 太陽風的能量會注入 地球上的大氣層。 那股能量順著磁力線傳導, 向下導入兩極, 產生炫麗無比的極光。 如果你曾看過極光,那真是壯麗! 我們知道能量進來了。 我們試著測量有多少粒子跑出去, 還有磁場是否 以任何方式影響這一點。
So I've posed a problem for you here, but I don't have a solution yet. We don't have a solution. But we're working on it. How are we working on it? Well, we've sent spacecraft to all three planets. Some of them are orbiting now, including the MAVEN spacecraft which is currently orbiting Mars, which I'm involved with and which is led here, out of the University of Colorado. It's designed to measure atmospheric escape. We have similar measurements from Venus and Earth. Once we have all our measurements, we can combine all these together, and we can understand how all three planets interact with their space environment, with the surroundings. And we can decide whether magnetic fields are important for habitability or not.
所以我丟了一個問題給各位, 但是我還沒有答案。 我們沒有解答。 但是我們正在找。 怎麼找呢? 嗯,我們送了幾艘太空船 到這三個行星上。 有些已經在軌道上環繞了, 包括目前正在環繞火星的 MAVEN (火星大氣與揮發物演化任務)太空船, 我有參與這項計畫, 而且由此地的科羅拉多大學領導。 我們用它測量大氣逃逸。 我們對金星及地球也做了 類似的測量。 一旦我們收及到所有的測量數據, 我們就能把這些綜合起來, 我們就能了解 這三個行星如何與太空環境, 與它們周邊的環境交互作用, 我們就能決定磁場 對適居性的重要與否。
Once we have that answer, why should you care? I mean, I care deeply ... And financially as well, but deeply.
一旦我們有了答案, 我們為什麼要在意? 我是說,我很在意── 財務上我也很在意啦! 不過真的很在意。
(Laughter)
(笑聲)
First of all, an answer to this question will teach us more about these three planets, Venus, Earth and Mars, not only about how they interact with their environment today, but how they were billions of years ago, whether they were habitable long ago or not. It will teach us about atmospheres that surround us and that are close. But moreover, what we learn from these planets can be applied to atmospheres everywhere, including planets that we're now observing around other stars. For example, the Kepler spacecraft, which is built and controlled here in Boulder, has been observing a postage stamp-sized region of the sky for a couple years now, and it's found thousands of planets -- in one postage stamp-sized region of the sky that we don't think is any different from any other part of the sky.
首先,這個問題的答案 會教我們更多這三個行星的事, 金星、地球及火星, 不只是它們如何 與現今的環境交互作用, 還有幾十億以前的交互作用, 很久以前的適居性如何。 它會教我們很多 環繞及靠近我們的大氣層的事。 此外,我們從這幾個行星學到的, 可以應用到別處的大氣層, 包括我們正在觀察的幾個行星, 它們環繞著其它恆星。 舉個例子,克卜勒太空望遠鏡, 就在波德這裡建造並控制, 已經觀察了郵票大小的天空 好幾年了, 它發現了數千個行星── 就在郵票大小的一小片天空中, 這片天跟其它部分的天空 沒什麼不同。
We've gone, in 20 years, from knowing of zero planets outside of our solar system, to now having so many, that we don't know which ones to investigate first. Any lever will help. In fact, based on observations that Kepler's taken and other similar observations, we now believe that, of the 200 billion stars in the Milky Way galaxy alone, on average, every star has at least one planet. In addition to that, estimates suggest there are somewhere between 40 billion and 100 billion of those planets that we would define as habitable in just our galaxy.
在 20 年內,我們從以為 太陽系以外沒有行星, 到現在我們知道有這麼多, 甚至不知道該從哪一個 開始調查起。 任何方法都有幫助。 其實,從克卜勒太空望遠鏡 及其它類似的觀測所發現的來看, 我們現在相信 光是在我們銀河系的 二千億顆星星裡, 每顆星平均都至少有一個行星。 除此之外, 估計這些行星中 還有約四百億到一千億顆, 我們可以定義為適居, 僅僅在我們的銀河!
We have the observations of those planets, but we just don't know which ones are habitable yet. It's a little bit like being trapped on a red spot --
我們有這些行星的觀測, 但是我們還不知道 哪一個是適合居住的。 這就跟困在 TED 這塊紅地毯上一樣,
(Laughter)
(笑聲)
on a stage and knowing that there are other worlds out there and desperately wanting to know more about them, wanting to interrogate them and find out if maybe just one or two of them are a little bit like you. You can't do that. You can't go there, not yet. And so you have to use the tools that you've developed around you for Venus, Earth and Mars, and you have to apply them to these other situations, and hope that you're making reasonable inferences from the data, and that you're going to be able to determine the best candidates for habitable planets, and those that are not.
在舞台上, 你知道還有其它的世界存在, 極度想要更了解他們, 想調查並找出是不是有一兩個 和自己有點像。 你做不了這件事, 你去不了那裡,還不行。 所以你必須使用你手邊 為了金星、地球及火星 而發展的工具, 還必須將它們應用在 這些不同的狀況下, 希望自己能從數據做出合理的推斷, 希望自己能選出最好的 適居行星,還要找出不合適的。
In the end, and for now, at least, this is our red spot, right here. This is the only planet that we know of that's habitable, although very soon we may come to know of more. But for now, this is the only habitable planet, and this is our red spot. I'm really glad we're here.
最終,至少目前, 這是我們的紅地毯,就在這裡。 這是目前我們所知唯一適居的行星, 雖然我們可能很快就會發現 還有其它的。 但是目前,這是唯一適居的行星, 這就是我們的紅地毯。 我真的很高興我們都在這裡。
Thanks.
謝謝。
(Applause)
(掌聲)