I saw a UFO once. I was eight or nine, playing in the street with a friend who was a couple of years older, and we saw a featureless silver disc hovering over the houses. We watched it for a few seconds, and then it shot away incredibly quickly. Even as a kid, I got angry it was ignoring the laws of physics. We ran inside to tell the grown-ups, and they were skeptical -- you'd be skeptical too, right? I got my own back a few years later: one of those grown-ups told me, "Last night I saw a flying saucer. I was coming out of the pub after a few drinks." I stopped him there. I said, "I can explain that sighting."
我曾經看過一次幽浮。 我當時約八、九歲, 和一位朋友在街上玩耍, 他比我大幾歲, 我們看到了一個毫無特色的 銀色碟形物在房子上方盤旋。 我們看了幾秒鐘, 接著,它以非常快的 速度瞬間飛走。 即使當時只是孩子, 我很氣它竟然可以不遵守物理定律。 我們跑進屋內告訴大人, 大人充滿懷疑—— 換成是你們也會懷疑,對吧? 幾年後我也找回了我的懷疑: 其中一位大人告訴我: 「昨晚我看到了飛碟。 我在酒吧喝了幾杯, 當時正要離開。」 我在那時打斷他。我說: 「我能解釋你的目擊。」
(Laughter)
(笑聲)
Psychologists have shown we can't trust our brains to tell the truth. It's easy to fool ourselves. I saw something, but what's more likely -- that I saw an alien spacecraft, or that my brain misinterpreted the data my eyes were giving it? Ever since though I've wondered: Why don't we see flying saucers flitting around? At the very least, why don't we see life out there in the cosmos? It's a puzzle, and I've discussed it with dozens of experts from different disciplines over the past three decades. And there's no consensus. Frank Drake began searching for alien signals back in 1960 -- so far, nothing. And with each passing year, this nonobservation, this lack of evidence for any alien activity gets more puzzling because we should see them, shouldn't we?
心理學家已經證明了 我們不能相信我們的大腦 會告訴我們真相。 要愚弄自己是很容易的。 我看到某種東西, 但哪種情況比較有可能—— 是我看到了外星人的太空船? 或是我的大腦錯誤詮釋了 我的眼睛給它的資料? 從那之後,我就一直納悶: 為什麼我們不會到處看到飛碟? 至少, 為什麼我們不會看到 在宇宙中有生命? 這是個謎, 在過去三十年,我已經 和數十位不同領域的專家討論過。 沒有達成任何共識。 1960 年,法蘭克德雷克 就開始尋找外星人的線索—— 目前,一無所獲。 隨著每一年過去, 都沒人觀察到, 且缺乏外星人活動的證據, 讓這一切更令人迷惑不解, 因為我們應該會看見他們,對吧?
The universe is 13.8 billion years old, give or take. If we represent the age of the universe by one year, then our species came into being about 12 minutes before midnight, 31st December. Western civilization has existed for a few seconds. Extraterrestrial civilizations could have started in the summer months. Imagine a summer civilization developing a level of technology more advanced than ours, but tech based on accepted physics though, I'm not talking wormholes or warp drives -- whatever -- just an extrapolation of the sort of tech that TED celebrates. That civilization could program self-replicating probes to visit every planetary system in the galaxy. If they launched the first probes just after midnight one August day, then before breakfast same day, they could have colonized the galaxy. Intergalactic colonization isn't much more difficult, it just takes longer. A civilization from any one of millions of galaxies could have colonized our galaxy.
宇宙已經 138 億歲了, 這是概略數字。 若我們把宇宙的年齡比喻為一年, 那麼我們這個物種大約是在 午夜前 12 分鐘才出現的, 12 月 31 日。 西方文明才幾秒鐘而已。 外星文明可能在夏季就已經出現。 想像一個夏季文明, 發展出了比我們更先進的科技水平, 不過,我是指以已經 被接受的物理為基礎, 不是指蟲洞或曲速引擎—— 諸如此類—— 只是 TED 所頌掦的 那種科技的推斷而已。 該文明有可能可以設計出 會自我複製的探測飛船, 去探訪銀河系中的每一個星系。 如果他們在八月某一天的午夜之後 發射了第一艘探測飛船, 那麼在同一天的早餐時間之前, 他們就已經殖民了整個銀河系。 跨銀河系的殖民並不會困難太多, 只是比較花時間。 數百萬銀河系中的任何一個文明 都有可能在我們的銀河殖民。
Seems far-fetched? Maybe it is, but wouldn't aliens engage in some recognizable activity -- put worldlets around a star to capture free sunlight, collaborate on a Wikipedia Galactica, or just shout out to the universe, "We're here"?
似乎很牽強? 也許是吧, 但外星人不會從事一些 可辨識的活動嗎?—— 比如在一顆恆星的周圍建立 小世界來捕捉免費的陽光、 合作撰寫銀河維基百科, 或是對著宇宙大叫: 「我們在這裡!」
So where is everybody? It's a puzzle because we do expect these civilizations to exist, don't we? After all, there could be a trillion planets in the galaxy -- maybe more.
所以,他們在哪裡? 這是個謎,因為我們確實預期 會有這類文明存在,對吧? 畢竟,銀河系中 可能有一兆個星球—— 甚至更多。
You don't need any special knowledge to consider this question, and I've explored it with lots of people over the years. And I've found they often frame their thinking in terms of the barriers that would need to be cleared if a planet is to host a communicative civilization. And they usually identify four key barriers.
不需要任何特殊知識, 你也會去思考這個問題, 這些年來,我已經和許多人 一起探索了這個問題。 我發現,他們通常 在表述他們的想法時, 會用需要被清除的四個障礙 來思考一個星球是否會有 能夠溝通的文明存在。 他們通常會去確認四項關鍵障礙。
Habitability -- that's the first barrier. We need a terrestrial planet in that just right "Goldilocks zone," where water flows as a liquid. They're out there. In 2016, astronomers confirmed there's a planet in the habitable zone of the closest star, Proxima Centauri -- so close that Breakthrough Starshot project plans to send probes there. We'd become a starfaring species. But not all worlds are habitable. Some will be too close to a star and they'll fry, some will be too far away and they'll freeze.
可居住性—— 那是第一個障礙。 我們需要有一個剛好屬於 「適居帶」的外星星球, 也就是說,水要以液體形式流動。 外面有這種星球存在。 2016 年,太空人確認了 在最近的恆星適居帶上 有一個星球, 這個恆星是比鄰星—— 它非常近,近到「突破攝星」 計畫打算要送探測飛船過去。 我們成了在星際旅行的物種。 但並非所有世界都可居住。 有些會太靠近恆星,會被烤熟, 有些則太遙遠,會被冰凍。
Abiogenesis -- the creation of life from nonlife -- that's the second barrier. The basic building blocks of life aren't unique to Earth: amino acids have been found in comets, complex organic molecules in interstellar dust clouds, water in exoplanetary systems. The ingredients are there, we just don't know how they combine to create life, and presumably there will be worlds on which life doesn't start.
無生源論—— 從無生命到創造生命—— 那是第二個障礙。 生命的基礎建材並非地球獨有: 已經發現慧星上有氨基酸, 行星際塵雲中有複雜的有機分子, 行星系統中有水。 原料已經存在, 我們只是不知道它們 要如何結合起來創造生命, 很有可能,這些世界的 生命跡象尚未開始。
The development of technological civilization is a third barrier. Some say we already share our planet with alien intelligences. A 2011 study showed that elephants can cooperate to solve problems. A 2010 study showed that an octopus in captivity can recognize different humans. 2017 studies show that ravens can plan for future events -- wonderful, clever creatures -- but they can't contemplate the Breakthrough Starshot project, and if we vanished today, they wouldn't go on to implement Breakthrough Starshot -- why should they? Evolution doesn't have space travel as an end goal. There will be worlds where life doesn't give rise to advanced technology.
第三個障礙是科技文明的發展。 有些人說,我們已經在 和外星智慧共享我們的星球。 一篇 2011 年的研究指出, 大象能夠合作來解決問題。 一篇 2010 年的研究指出, 被囚禁的章魚能夠認出不同的人類。 2017 年的研究則指出, 渡鴉會規劃未來事件—— 很美好、聰明的生物—— 但牠們無法去思考 「突破攝星」計畫, 如果今天我們都消失了, 牠們也不會去執行 「突破攝星」計劃—— 為什麼牠們要去執行? 演化的最終目標並不是太空旅行。 有一些世界中的生命 不會去發展先進科技。
Communication across space -- that's a fourth barrier. Maybe advanced civilizations choose to explore inner space rather than outer space, or engineer at small distances rather than large. Or maybe they just don't want to risk an encounter with a potentially more advanced and hostile neighbor. There'll be worlds where, for whatever reason, civilizations either stay silent or don't spend long trying to communicate.
跨越太空的溝通—— 那是第四個障礙。 也許先進文明會選擇探索內太空, 而不是外太空, 或做短距離的工程建設, 而非長距離的。 或許,他們只是單純 不想冒險,以免遇到 可能更先進且有敵意的鄰居。 在某些世界,不論是什麼理由, 文明可能會保持沉默,或不會 花費心力去試圖與遠方溝通。
As for the height of the barriers, your guess is as good as anyone's. In my experience, when people sit down and do the math, they typically conclude there are thousands of civilizations in the galaxy. But then we're back to the puzzle: Where is everybody? By definition, UFOs -- including the one I saw -- are unidentified. We can't simply infer they're spacecraft. You can still have some fun playing with the idea aliens are here. Some say a summer civilization did colonize the galaxy and seeded Earth with life ... others, that we're living in a cosmic wilderness preserve -- a zoo. Yet others -- that we're living in a simulation. Programmers just haven't revealed the aliens yet. Most of my colleagues though argue that E.T. is out there, we just need to keep looking, and this makes sense. Space is vast. Identifying a signal is hard, and we haven't been looking that long. Without doubt, we should spend more on the search. It's about understanding our place in the universe. It's too important a question to ignore.
至於障礙有多高, 大家都只能猜測。 依我的經驗, 當大家坐下來算數學時, 他們的結論通常是, 在銀河系中有數千個文明存在。 但,我們又回到 原本的謎:他們在哪裡? 就定義來說, 幽浮(不明飛行物)—— 包括我看見的那一個—— 是「不明」的。 我們不能很簡單地說 它們是太空船。 你仍然可以為了好玩 而想像有外星人來到這裡。 有人說,夏季文明 的確已經殖民了銀河系, 且在地球播下生命的種子…… 其他人說,我們是住在 宇宙的荒野保護區—— 一個動物園。 還有其他人—— 說我們住在模擬世界中。 只是程式設計師尚未 讓外星人現身而已。 不過,我大部分的同事 主張有 E.T. 存在, 只是我們得要繼續尋找, 這是合理的。 太空很大。 找到一個訊號是很困難的, 且我們才開始找沒有很久。 無疑的,我們應該 投入更多心力去搜尋。 重點在於了解我們 在宇宙中的定位。 這個問題太重要了,不能無視它。
But there's an obvious answer: we're alone. It's just us. There could be a trillion planets in the galaxy. Is it plausible we're the only creatures capable of contemplating this question? Well, yes, because in this context, we don't know whether a trillion is a big number. In 2000, Peter Ward and Don Brownlee proposed the Rare Earth idea. Remember those four barriers that people use to estimate the number of civilizations? Ward and Brownlee said there might be more.
但,有一個很明顯的答案: 我們是孤單的。 只有我們。 在銀河系可能有一兆個星球。 若說我們是唯一會思忖 這個問題的生物,聽起來合理嗎? 是的,因為在這個情況中, 我們不知道一兆是否 算是很大的數目。 2000 年時,彼得沃德和唐布朗利 提出了「地球殊異」的想法。 還記得人們用來 估計文明數目的那四個障礙嗎? 沃德和布朗利說,可能還有更多。
Let's look at one possible barrier. It's a recent suggestion by David Waltham, a geophysicist. This is my very simplified version of Dave's much more sophisticated argument. We are able to be here now because Earth's previous inhabitants enjoyed four billion years of good weather -- ups and downs but more or less clement. But long-term climate stability is strange, if only because astronomical influences can push a planet towards freezing or frying. There's a hint our moon has helped, and that's interesting because the prevailing theory is that the moon came into being when Theia, a body the size of Mars, crashed into a newly formed Earth. The outcome of that crash could have been a quite different Earth-Moon system. We ended up with a large moon and that permitted Earth to have both a stable axial tilt and a slow rotation rate. Both factors influence climate and the suggestion is that they've helped moderate climate change. Great for us, right? But Waltham showed that if the moon were just a few miles bigger, things would be different. Earth's spin axis would now wander chaotically. There'd be episodes of rapid climate change -- not good for complex life. The moon is just the right size: big but not too big. A "Goldilocks" moon around a "Goldilocks" planet -- a barrier perhaps.
咱們來看看一個可能的障礙。 這是地球物理學家大衛沃爾瑟姆 在近期提出來的。 這是我的極簡化版, 大衛的原版是更精密許多的主張。 我們現在能夠在這裡, 是因為地球先前的居民享受了 40 億年的好天氣—— 雖然起起落落, 但總的來說仍然是溫和的。 但長期的穩定氣候是很奇特的, 因為天文氣候的影響是有可能 將一個星球推向結冰或烤熟狀況的。 我們的月球似乎是有幫上忙, 那很有趣, 因為普遍流行的理論是 月球會出現是因為忒伊亞, 和火星一樣大的天體, 撞上了剛形成的地球。 撞擊的結果本來有可能 是個很不同的地球—月球系統。 我們最後得到的是一個大月球, 那讓地球有一個穩定的 軸向傾斜角度, 和緩慢的轉速。 這兩個因子影響了氣候, 意味著它們協助調節了氣候改變。 對我們很好,對吧? 但沃爾瑟姆指出, 如果月球再大個幾英哩, 一切就會不同。 地球的轉軸現在就會 混亂地偏離正軌。 就會發生快速氣候變遷的情形—— 對複雜的生命來說不是好事。 月球的大小剛剛好: 夠大但不會太大。 在一個「適居」的星球周圍 有個「適居」的月球—— 也許也是個障礙。
You can imagine more barriers. For instance, simple cells came into being billions of years ago ... but perhaps the development of complex life needed a series of unlikely events. Once life on Earth had access to multicellularity and sophisticated genetic structures, and sex, new opportunities opened up: animals became possible. But maybe it's the fate of many planets for life to settle at the level of simple cells.
你們可以想像出更多障礙。 比如, 數十億年前, 簡單細胞就出現了…… 但也許要發展出複雜的生命, 還需要一連串 不太可能發生的事件。 一旦地球上的生命能夠有多細胞 以及精密的基因結構, 還有性, 就會有新的機會產生: 可能會出現動物。 但,也許,許多星球的命運就是 只會有簡單細胞等級的生命存在。
Purely for the purposes of illustration, let me suggest four more barriers to add to the four that people said blocked the path to communicative civilization. Again, purely for the purposes of illustration, suppose there's a one-in-a-thousand chance of making it across each of the barriers. Of course there might be different ways of navigating the barriers, and some chances will be better than one in a thousand. Equally, there might be more barriers and some chances might be one in a million. Let's just see what happens in this picture.
純粹只是為了說明清楚, 讓我再提出四個 可能的障礙,來補充 前面已提到大家認為會阻擋 與外星文明溝通的四個障礙。 我再說一遍,純粹只是為了 補充說明清楚, 假設跨越每一個障礙的 機會是千分之一。 當然,可能會有不同的 方式來通過障礙, 有些機會可能會高於千分之一。 同樣的,可能會有更多障礙 且當中某些的機會 只有百萬分之一。 咱們來看看,在這狀況下 會發生什麼事。
If the galaxy contains a trillion planets, how many will host a civilization capable of contemplating like us projects such as Breakthrough Starshot? Habitability -- right sort of planet around the right sort of star -- the trillion becomes a billion. Stability -- a climate that stays benign for eons -- the billion becomes a million. Life must start -- the million becomes a thousand. Complex life forms must arise -- the thousand becomes one. Sophisticated tool use must develop -- that's one planet in a thousand galaxies. To understand the universe, they'll have to develop the techniques of science and mathematics -- that's one planet in a million galaxies. To reach the stars, they'll have to be social creatures, capable of discussing abstract concepts with each other using complex grammar -- one planet in a billion galaxies. And they have to avoid disaster -- not just self-inflicted but from the skies, too. That planet around Proxima Centauri, last year it got blasted by a flare. One planet in a trillion galaxies, just as in the visible universe.
如果銀河系有一兆個星球, 有多少個星球上會有文明存在, 且像我們一樣能夠去思忖 像「突破攝星」這樣的計畫? 可居住性—— 在對的恆星周圍有對的星球—— 一兆剩下了十億。 穩定性—— 氣候要長久都能很宜人—— 十億剩下了一百萬。 生命必須要能開始—— 一百萬剩下了一千。 必須要有複雜的生命形式出現—— 一千剩下了一個。 必須要能夠去使用精密的工具—— 一千個銀河中只有 一個星球能符合。 要了解宇宙, 他們就得要發展出 科學和數學的技術—— 一百萬個銀河中只有 一個星球能符合。 要去接觸其他恆星, 他們必須要是社交型的生物, 有能力和彼此討論抽象的概念, 使用複雜的文法—— 十億個銀河中只有 一個星球能符合。 他們還得要避開災難—— 不只是自己造成的災難, 還有來自天空的災難。 繞著比鄰星的那個星球, 在去年被太陽耀斑給轟擊了。 一兆個銀河中只有 一個星球能符合。 這是在可見宇宙中的假設。
I think we're alone. Those colleagues of mine who agree we're alone often see a barrier ahead -- bioterror, global warming, war. A universe that's silent because technology itself forms the barrier to the development of a truly advanced civilization. Depressing, right?
我想我們是孤單的。 我那些認同我們是孤單的同事 通常能夠先看到障礙—— 生物災難、 全球暖化、戰爭。 一個沉默的宇宙, 因為科技本身就會形成障礙, 讓一個真正先進的文明很難發展。 讓人沮喪,是吧?
I'm arguing the exact opposite. I grew up watching "Star Trek" and "Forbidden Planet," and I saw a UFO once, so this idea of cosmic loneliness I certainly find slightly wistful. But for me, the silence of the universe is shouting, "We're the creatures who got lucky." All barriers are behind us. We're the only species that's cleared them -- the only species capable of determining its own destiny. And if we learn to appreciate how special our planet is, how important it is to look after our home and to find others, how incredibly fortunate we all are simply to be aware of the universe, humanity might survive for a while. And all those amazing things we dreamed aliens might have done in the past, that could be our future.
我的主張正好相反。 我是看《星艦迷航記》 與《禁忌星球》長大的, 且我見過一次幽浮, 所以我肯定對這個宇宙孤獨的 想法感到有點愁悶。 但,對我來說, 宇宙的沉默正在吶喊: 「我們是走運的生物。」 我們越過了所有的障礙。 我們是唯一清除了 所有障礙的物種—— 唯一能夠決定自身命運的物種。 如果我們學會帶著感激 欣賞我們的星球有多特別、 照顧我們的家園並尋找其他的 是多麼重要的事、 單單知道宇宙的存在 我們就有多麼幸運, 那麼人類也許還能生存一陣子。 所有那些不可思議的事, 我們幻想外星人 在過去可能做過的事, 都可能成為我們的未來。
Thank you very much.
非常謝謝各位。
(Applause)
(掌聲)