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  • I'm here to tell you about the real search for alien life.

    在這裡我要告訴各位一個有關 探尋外星生命的真實故事。

  • Not little green humanoids arriving in shiny UFOs,

    我所說不是長得像人的綠色小個子 乘坐發光飛碟抵達地球,

  • although that would be nice.

    儘管那個主題也很好。

  • But it's the search for planets orbiting stars far away.

    我們在找尋的是 繞行恆星的遠方行星。

  • Every star in our sky is a sun.

    天空中每一顆恆星都是一個太陽。

  • And if our sun has planets --

    如果我們的太陽有行星

  • Mercury, Venus, Earth, Mars, etc.,

    如水星、金星、地球、火星等等,

  • surely those other stars should have planets also,

    當然那些其他恆星也應該有行星,

  • and they do.

    它們確實有行星。

  • And in the last two decades,

    在過去的二十年,

  • astronomers have found thousands of exoplanets.

    天文學家已發現數千顆系外行星。

  • Our night sky is literally teeming with exoplanets.

    夜晚的天空幾乎佈滿系外行星。

  • We know, statistically speaking,

    依據統計,我們知道,

  • that every star has at least one planet.

    每顆恆星至少有一顆行星。

  • And in the search for planets,

    在探尋行星中,

  • and in the future, planets that might be like Earth,

    未來,行星或許像地球一樣,

  • we're able to help address

    我們能夠提出

  • some of the most amazing and mysterious questions

    一些令人訝異且神秘的問題

  • that have faced humankind for centuries.

    這問題已經圍繞人類數百年之久。

  • Why are we here?

    我們為什麼在這裡?

  • Why does our universe exist?

    我們的宇宙為什麼存在?

  • How did Earth form and evolve?

    地球是如何形成與演變而來的?

  • How and why did life originate and populate our planet?

    生命的起源是什麼 我們為何生活在這顆星球上?

  • The second question that we often think about is:

    我們經常思考的第二個問題是:

  • Are we alone?

    我們獨立存在宇宙中嗎?

  • Is there life out there?

    有其他的生物存在嗎?

  • Who is out there?

    他們是誰?

  • You know, this question has been around for thousands of years,

    你知道, 這個問題已經圍繞人類數千年了,

  • since at least the time of the Greek philosophers.

    至少從古希臘哲學家那時候起 就已經有這個問題。

  • But I'm here to tell you just how close we're getting

    但此時我要告訴你 我們有多接近

  • to finding out the answer to this question.

    取得這個問題的答案。

  • It's the first time in human history that this really is within reach for us.

    這是人類史上的第一次

  • Now when I think about the possibilities for life out there,

    當我思索其他生物存在的可能性,

  • I think of the fact that our sun is but one of many stars.

    事實上太陽是眾多恆星之一。

  • This is a photograph of a real galaxy,

    這是一張真實銀河星系的照片,

  • we think our Milky Way looks like this galaxy.

    我們認為銀河就像這張照片。

  • It's a collection of bound stars.

    是由眾多恆星組成。

  • But our [sun] is one of hundreds of billions of stars

    太陽是千億恆星中的一員

  • and our galaxy is one of upwards of hundreds of billions of galaxies.

    我們的銀河是千億銀河中的一員。

  • Knowing that small planets are very common,

    我們知道小行星是非常普遍的,

  • you can just do the math.

    可以算得出來。

  • And there are just so many stars and so many planets out there,

    那裡有好多的恆星行星,

  • that surely, there must be life somewhere out there.

    必然一定有生物存在。

  • Well, the biologists get furious with me for saying that,

    生物學家 對我這樣的說法會非常生氣,

  • because we have absolutely no evidence for life beyond Earth yet.

    因為我們的確無法證明 地球之外有生物存在。

  • Well, if we were able to look at our galaxy from the outside

    如果我們能夠從外部觀察銀河系

  • and zoom in to where our sun is,

    將太陽的位置放大觀察,

  • we see a real map of the stars.

    我們看到一張真實的恆星地圖。

  • And the highlighted stars are those with known exoplanets.

    高亮度的恆星 是那些為大家所知的系外行星。

  • This is really just the tip of the iceberg.

    這只是冰山的一角。

  • Here, this animation is zooming in onto our solar system.

    這個動畫放大太陽系的位置。

  • And you'll see here the planets

    你會看到這些行星

  • as well as some spacecraft that are also orbiting our sun.

    和一些太空船一樣繞著太陽轉。

  • Now if we can imagine going to the West Coast of North America,

    想像我們到北美的西岸,

  • and looking out at the night sky,

    看著那裡的夜空,

  • here's what we'd see on a spring night.

    這就是當地春天的夜晚。

  • And you can see the constellations overlaid

    你可以看到佈滿星群

  • and again, so many stars with planets.

    同樣的,很多的恆星和行星。

  • There's a special patch of the sky where we have thousands of planets.

    天空有一特殊區塊 那裡有數千顆行星。

  • This is where the Kepler Space Telescope focused for many years.

    這是克卜勒太空望遠鏡 多年來關注的地方。

  • Let's zoom in and look at one of the favorite exoplanets.

    我們放大畫面 觀察其中一顆我們喜愛的系外行星。

  • This star is called Kepler-186f.

    這恆星被稱為克卜勒-186f。

  • It's a system of about five planets.

    是一個由五個行星組成的系統。

  • And by the way, most of these exoplanets, we don't know too much about.

    順道一提,大部分的系外行星 我們並不太了解。

  • We know their size, and their orbit and things like that.

    我們知道它們的大小, 運行軌道之類的。

  • But there's a very special planet here called Kepler-186f.

    有一個非常特別的行星 被稱為克卜勒-186f。

  • This planet is in a zone that is not too far from the star,

    這顆行星所在區域 距離恆星不遠,

  • so that the temperature may be just right for life.

    其溫度可能適合生物生存。

  • Here, the artist's conception is just zooming in

    這是藝術家的觀念,將畫面放大

  • and showing you what that planet might be like.

    向你們展示那顆行星的樣子。

  • So, many people have this romantic notion of astronomers

    因此, 很多人對天文學家有浪漫的想法

  • going to the telescope on a lonely mountaintop

    在一個孤寂的山頂 對著望遠鏡

  • and looking at the spectacular night sky through a big telescope.

    透過大的望遠鏡 觀察壯觀的夜空。

  • But actually, we just work on our computers like everyone else,

    但事實上,我們只是 和其他人一樣在電腦前忙碌,

  • and we get our data by email or downloading from a database.

    透過郵件或從資料庫下載 以取得資料。

  • So instead of coming here to tell you

    我不是跑到這裡來告訴你

  • about the somewhat tedious nature of the data and data analysis

    有點冗長乏味的資料和資料分析

  • and the complex computer models we make,

    以及我們做的複雜電腦程式,

  • I have a different way to try to explain to you

    我要以不同的方式向你們解說

  • some of the things that we're thinking about exoplanets.

    我們對系外行星的一些想法。

  • Here's a travel poster:

    這是一張旅行海報:

  • "Kepler-186f:

    「克卜勒-186f:

  • Where the grass is always redder on the other side."

    這草的顏色 總是比另一邊的草還要紅。」

  • That's because Kepler-186f orbits a red star,

    那是因為克卜勒-186f 繞著紅恆星運轉,

  • and we're just speculating that perhaps the plants there,

    我們只是推測那裡的行星,

  • if there is vegetation that does photosynthesis,

    如果有進行光合作用的植物,

  • it has different pigments and looks red.

    會有不同的色素 看起來是紅色。

  • "Enjoy the gravity on HD 40307g,

    「盡情享受 HD 40307g 的重力,

  • a Super-Earth."

    一顆超級地球。」

  • This planet is more massive than Earth

    這顆行星遠大於地球

  • and has a higher surface gravity.

    而且有較大地表引力。

  • "Relax on Kepler-16b,

    「在克卜勒-16b上放輕鬆

  • where your shadow always has company."

    影子在那裡成雙成對。」

  • (Laughter)

    (笑聲)

  • We know of a dozen planets that orbit two stars,

    我們知道繞著二顆恆星 運轉的十二顆行星,

  • and there's likely many more out there.

    那裡可能有更多的行星。

  • If we could visit one of those planets,

    如果我們能夠參觀其中一顆行星,

  • you literally would see two sunsets

    你幾乎可以看到二個日落

  • and have two shadows.

    和二個自己的影子。

  • So actually, science fiction got some things right.

    事實上, 科幻小說的故事有些是正確的。

  • Tatooine from Star Wars.

    星際大戰裡的塔圖因星

  • And I have a couple of other favorite exoplanets

    我還有我喜歡的外行星

  • to tell you about.

    要告訴你。

  • This one is Kepler-10b,

    這顆是克卜勒-10b,

  • it's a hot, hot planet.

    是一顆很熱的行星,

  • It orbits over 50 times closer to its star

    繞行就近的恆星超過五十次

  • than our Earth does to our sun.

    超過地球繞太陽的次數。

  • And actually, it's so hot,

    事實上,它的溫度很高

  • we can't visit any of these planets, but if we could,

    我們無法參觀任何這類的行星 如果可以的話,

  • we would melt long before we got there.

    在我們到達之前就已經融化。

  • We think the surface is hot enough to melt rock

    我們認為其表面溫度很高 足以融化岩石

  • and has liquid lava lakes.

    有液體熔岩湖。

  • Gliese 1214b.

    格利澤 1214b。

  • This planet, we know the mass and the size

    這顆行星,我們知道它的質量和體積

  • and it has a fairly low density.

    其密度極低。

  • It's somewhat warm.

    有溫暖的氣候。

  • We actually don't know really anything about this planet,

    事實上我們對這星球一無所知,

  • but one possibility is that it's a water world,

    但有一個可能性是 這顆行星是個水世界,

  • like a scaled-up version of one of Jupiter's icy moons

    像一顆放大版的木星冰冷衛星之一

  • that might be 50 percent water by mass.

    或許水就佔了質量的一半。

  • And in this case, it would have a thick steam atmosphere

    在這種情況下, 它有厚厚的大氣流,

  • overlaying an ocean,

    覆蓋著一片海洋,

  • not of liquid water,

    但不是液體形態的水,

  • but of an exotic form of water, a superfluid --

    而是異質形態的水,一種超級液體,

  • not quite a gas, not quite a liquid.

    不完全是氣態,不完全是液態。

  • And under that wouldn't be rock,

    在海洋下面並非岩石,

  • but a form of high-pressure ice,

    而是一種高壓冰的形態,

  • like ice IX.

    如同冰 IX。

  • So out of all these planets out there,

    在那些行星範圍之外的地方,

  • and the variety is just simply astonishing,

    其多樣性也令人驚訝,

  • we mostly want to find the planets that are Goldilocks planets, we call them.

    我們大部分想找的行星 是金髮星球行星。

  • Not too big, not too small,

    體積不太大,也不太小,

  • not too hot, not too cold --

    溫度不太熱,也不太冷,

  • but just right for life.

    剛好適合生物生存。

  • But to do that, we'd have to be able to look

    不過要做到這一點, 我們必須能夠

  • at the planet's atmosphere,

    觀察到這顆行星的大氣,

  • because the atmosphere acts like a blanket trapping heat --

    因為大氣就像一塊保溫地毯

  • the greenhouse effect.

    溫室效應。

  • We have to be able to assess the greenhouse gases

    我們必須能夠偵測到其他行星的

  • on other planets.

    溫室氣體。

  • Well, science fiction got some things wrong.

    這方面,科幻小說的描述有誤。

  • The Star Trek Enterprise

    「星艦迷航-企業號」

  • had to travel vast distances at incredible speeds

    必須以高速繞行其他行星

  • to orbit other planets

    做長距離旅行

  • so that First Officer Spock could analyze the atmosphere

    因此副艦長斯波克才能分析大氣

  • to see if the planet was habitable

    以看出該行星是否適合生物定居

  • or if there were lifeforms there.

    或者是否有生物存在。

  • Well, we don't need to travel at warp speeds

    我們不需要以極高速度行駛

  • to see other planet atmospheres,

    以取得其他其他行星的大氣資料,

  • although I don't want to dissuade any budding engineers

    雖然我不想去勸阻 新進工程師

  • from figuring out how to do that.

    去找到實踐這項工作的方法。

  • We actually can and do study planet atmospheres

    實際上我們可以 由地球軌道

  • from here, from Earth orbit.

    去研究那些行星的大氣。

  • This is a picture, a photograph of the Hubble Space Telescope

    這是哈柏望遠鏡的照片

  • taken by the shuttle Atlantis as it was departing

    由太空梭亞特蘭蒂斯號 返航時所拍攝的照片

  • after the last human space flight to Hubble.

    最後一次載人太空船到哈柏之後。

  • They installed a new camera, actually,

    他們在太空船上安裝新的照相機,

  • that we use for exoplanet atmospheres.

    可以用來收集外行星大氣資料。

  • And so far, we've been able to study dozens of exoplanet atmospheres,

    目前,我們已經能夠 研究數十個外行星大氣資料,

  • about six of them in great detail.

    其中六個有非常詳細的資料。

  • But those are not small planets like Earth.

    這些行星不像地球是個小行星。

  • They're big, hot planets that are easy to see.

    它們體積大且溫度高, 是容易觀察到的行星。

  • We're not ready,

    我們還沒準備好,

  • we don't have the right technology yet to study small exoplanets.

    我們沒有相當的技術 以研究小行星。

  • But nevertheless,

    儘管如此,

  • I wanted to try to explain to you how we study exoplanet atmospheres.

    我仍然想要向大家解釋 我們是如何研究外行星大氣。

  • I want you to imagine, for a moment, a rainbow.

    大家可以想像一下彩虹。

  • And if we could look at this rainbow closely,

    如果我們可近距離觀察彩虹,

  • we would see that some dark lines are missing.

    可以看到一些暗色線消失了。

  • And here's our sun,

    這是我們的太陽。

  • the white light of our sun split up,

    白色光分解了。

  • not by raindrops, but by a spectrograph.

    不是被雨滴,而是被光譜儀分解了。

  • And you can see all these dark, vertical lines.

    你可以看到這暗色垂直的線。

  • Some are very narrow, some are wide,

    有些非常窄,有些寬,

  • some are shaded at the edges.

    有些邊緣被遮住了。

  • And this is actually how astronomers have studied objects in the heavens,

    這就是天文學家 如何研究太空物質的方式,

  • literally, for over a century.

    這是過去一百年的研究方式。

  • So here, each different atom and molecule

    這張圖,每一原子和分子

  • has a special set of lines,

    各有特殊的頻譜線,

  • a fingerprint, if you will.

    你可以把它當作指紋,

  • And that's how we study exoplanet atmospheres.

    那就是我們利用這訊息 來研究外行星的大氣成份

  • And I'll just never forget when I started working

    我永遠忘不了 二十年前

  • on exoplanet atmospheres 20 years ago,

    剛開起研究外行星大氣的時候,

  • how many people told me,

    多少人告訴我,

  • "This will never happen.

    「這行不通。

  • We'll never be able to study them. Why are you bothering?"

    我們永遠無法做到。 為何費心在這種事上?」

  • And that's why I'm pleased to tell you about all the atmospheres studied now,

    那就是為什麼我很高興要告訴你們 目前所有有關的大氣研究,

  • and this is really a field of its own.

    它已成形了。

  • So when it comes to other planets, other Earths,

    當談及到其他行星, 其他類似地球行星,

  • in the future when we can observe them,

    將來我們可以觀察到,

  • what kind of gases would we be looking for?

    什麼是我們要尋找的氣體?

  • Well, you know, our own Earth has oxygen in the atmosphere

    你知道,地球的大氣

  • to 20 percent by volume.

    含有百分之二十的氧氣。

  • That's a lot of oxygen.

    含量很高。

  • But without plants and photosynthetic life,

    但若沒有植物及其光合作用。

  • there would be no oxygen,

    大氣中不會有氧氣。

  • virtually no oxygen in our atmosphere.

    事實上我們的大氣中沒有氧氣。

  • So oxygen is here because of life.

    因為生物的存在才有氧氣。

  • And our goal then is to look for gases in other planet atmospheres,

    我們目標就是尋找 其他行星大氣中的氣體,

  • gases that don't belong,

    氣體原本不存在,

  • that we might be able to attribute to life.

    或許我們可以歸功於生物。

  • But which molecules should we search for?

    我們在尋找哪些分子呢?

  • I actually told you how diverse exoplanets are.

    我告訴過各位外行星的種類很多。

  • We expect that to continue in the future

    未來會陸續發現更多

  • when we find other Earths.

    當我們發現其他類似地球的行星。

  • And that's one of the main things I'm working on now,

    這是我目前正在從事的最主要工作,

  • I have a theory about this.

    我有個自己的理論。

  • It reminds me that nearly every day,

    它幾乎每天提醒我,

  • I receive an email or emails

    我收到一封或多封郵件

  • from someone with a crazy theory about physics of gravity

    是對重力物理學理論

  • or cosmology or some such.

    或是宇宙論 提出瘋狂想法的人所寄來的。

  • So, please don't email me one of your crazy theories.

    所以請不要再給我發這種郵件了。

  • (Laughter)

    (笑聲)

  • Well, I had my own crazy theory.

    我有自己瘋狂的理論。

  • But, who does the MIT professor go to?

    麻省理工學院的教授要跟誰探討呢?

  • Well, I emailed a Nobel Laureate in Physiology or Medicine

    我向諾貝爾生理及醫學獎得主發信

  • and he said, "Sure, come and talk to me."

    他說,「好,我們討論一下。」

  • So I brought my two biochemistry friends

    我帶了二個 我的生物化學領域的朋友

  • and we went to talk to him about our crazy theory.

    要和他討論我們的瘋狂理論。

  • And that theory was that life produces all small molecules,

    那理論是,生命製造了所有小分子,

  • so many molecules.

    許許多多的分子。

  • Like, everything I could think of, but not being a chemist.

    所有我可以想得到的事情, 雖然我不是個化學領域專家。

  • Think about it:

    想想看:

  • carbon dioxide, carbon monoxide,

    二氧化碳,一氧化碳,

  • molecular hydrogen, molecular nitrogen,

    氫分子,氮分子,

  • methane, methyl chloride --

    甲烷,氯甲烷,

  • so many gases.

    等諸多氣體。

  • They also exist for other reasons,

    它們的存在也有其原因,

  • but just life even produces ozone.

    生物即可產生臭氧。

  • So we go to talk to him about this,

    所以我們和他談論這個主題,

  • and immediately, he shot down the theory.

    結果立刻被他否決。

  • He found an example that didn't exist.

    他找到一個不存在的氣體的例子。

  • So, we went back to the drawing board

    所以我們回去從頭做起

  • and we think we have found something very interesting in another field.

    我們發現在其他領域 非常有趣的東西。

  • But back to exoplanets,

    回到外行星這個話題,

  • the point is that life produces so many different types of gases,

    重點是生物製造各種不同的氣體,

  • literally thousands of gases.

    差不多有幾千種。

  • And so what we're doing now is just trying to figure out

    我們現在要做的是試著找出

  • on which types of exoplanets,

    外行星上有那些氣體,

  • which gases could be attributed to life.

    那些氣體是由生物產生。

  • And so when it comes time when we find gases

    當我們在外行星大氣中

  • in exoplanet atmospheres

    所找到的氣體

  • that we won't know if they're being produced

    不知道這些氣體是由

  • by intelligent aliens or by trees,

    外星人製造,或是樹木所產生,

  • or a swamp,

    或是由沼澤產生。

  • or even just by simple, single-celled microbial life.

    或是來自單細胞生物。

  • So working on the models

    所以有了一些模型