Well, you know, sometimes the most important things come in the smallest packages. I am going to try to convince you, in the 15 minutes I have, that microbes have a lot to say about questions such as, "Are we alone?" and they can tell us more about not only life in our solar system but also maybe beyond, and this is why I am tracking them down in the most impossible places on Earth, in extreme environments where conditions are really pushing them to the brink of survival. Actually, sometimes me too, when I'm trying to follow them too close. But here's the thing: We are the only advanced civilization in the solar system, but that doesn't mean that there is no microbial life nearby. In fact, the planets and moons you see here could host life -- all of them -- and we know that, and it's a strong possibility. And if we were going to find life on those moons and planets, then we would answer questions such as, are we alone in the solar system? Where are we coming from? Do we have family in the neighborhood? Is there life beyond our solar system?
你们知道吗, 有时最重要的信息 会通过最细微的事物传达。 在接下来15分钟里, 我将很确定的告诉你们: 微生物可以从很大程度上 解释这样的问题,比如, “我们是独一无二生命的吗?” 微生物能告诉我们的还有很多, 不仅是关于我们太阳系以内的生物, 可能还包括以外的, 这就是为什么我正在地球上 最恶劣的环境中寻找它们的踪迹, 那些极端的环境会 把微生物推向生存危机的边缘。 有时候试图追踪得太紧, 连我自己也会面临生命危险。 然而重点是: 我们是太阳系里唯一的高级文明物种, 但这并不意味着附近没有微生物生命。 事实上,大家看到的这些行星和卫星 我们确信,都可能孕育着生命, 而且可能性还很高。 如果我们能够在 那些行星和卫星上找到生命, 那么我们就能回答这样的问题,比如, 在太阳系里我们是唯一生物吗? 我们是从哪里来的呢? 我们的邻居中有我们的同类吗? 太阳系以外有没有生命呢?
And we can ask all those questions because there has been a revolution in our understanding of what a habitable planet is, and today, a habitable planet is a planet that has a zone where water can stay stable, but to me this is a horizontal definition of habitability, because it involves a distance to a star, but there is another dimension to habitability, and this is a vertical dimension. Think of it as conditions in the subsurface of a planet where you are very far away from a sun, but you still have water, energy, nutrients, which for some of them means food, and a protection. And when you look at the Earth, very far away from any sunlight, deep in the ocean, you have life thriving and it uses only chemistry for life processes.
我们之所以能够提出这些问题 是因为我们对于“可居住星球”的理解 有了革命性的发展, “适居行星”如今的定义是 一个具有可储存稳定状态水地域的行星, 但是对我来说,这是 可居住性的横向定义, 因为这可以涉及到另一个星球, 其实可居住性 还有另一个维度的定义, 一个纵向的维度。 把它想成 某个行星次地表的环境, 在那里你离恒星很远, 但你仍旧有水、能量、营养, 对于其中一些生物来说, 这意味着食物和保护。 当我们再观察地球, 在远离阳光的深海里, 你会找到欣欣向荣的生命, 它们的生命过程只涉及到化学反应。
So when you think of it at that point, all walls collapse. You have no limitations, basically. And if you have been looking at the headlines lately, then you will see that we have discovered a subsurface ocean on Europa, on Ganymede, on Enceladus, on Titan, and now we are finding a geyser and hot springs on Enceladus, Our solar system is turning into a giant spa. For anybody who has gone to a spa knows how much microbes like that, right? (Laughter)
因此当你这样考虑, 所有的围墙都坍塌了。 你基本上不受任何限制了。 如果你最近有看新闻头条, 你就会了解到 我们在木卫二、木卫三、土卫二 和土卫六上发现了冰下海洋, 现在我们又在土卫二上 发现了间歇泉和温泉。 我们的太阳系正在变成 一个巨大的温泉浴场。 去泡过温泉的人应该知道 里边能有多少微生物,对吧? (笑声)
So at that point, think also about Mars. There is no life possible at the surface of Mars today, but it might still be hiding underground.
在这个前提下,再来想想火星。 现在的火星表面不可能有生命, 但地下仍可能潜藏着生命。
So, we have been making progress in our understanding of habitability, but we also have been making progress in our understanding of what the signatures of life are on Earth. And you can have what we call organic molecules, and these are the bricks of life, and you can have fossils, and you can minerals, biominerals, which is due to the reaction between bacteria and rocks, and of course you can have gases in the atmosphere. And when you look at those tiny green algae on the right of the slide here, they are the direct descendants of those who have been pumping oxygen a billion years ago in the atmosphere of the Earth. When they did that, they poisoned 90 percent of the life at the surface of the Earth, but they are the reason why you are breathing this air today.
我们不仅在进一步理解宜居性, 我们也在进一步了解 地球上有哪些生命的印记。 我们有所谓的"有机分子", 这些是生命大厦的建筑材料, 我们有化石, 还有矿物质、生物矿物质, 生物矿物质是由细菌和 岩石发生反应所产生的, 当然,我们还有大气中的气体。 看看幻灯片右边 那些微小的绿藻, 它们是十亿年前往地球大气中 输送氧气的生物的直系后裔。 当时它们制造的氧气, 毒害了地球表面百分之九十的生命, 但却造就了现如今你们呼吸的这种空气。
But as much as our understanding grows of all of these things, there is one question we still cannot answer, and this is, where are we coming from? And you know, it's getting worse, because we won't be able to find the physical evidence of where we are coming from on this planet, and the reason being is that anything that is older than four billion years is gone. All record is gone, erased by plate tectonics and erosion. This is what I call the Earth's biological horizon. Beyond this horizon we don't know where we are coming from.
但是随着我们对所有这些事情的 认知不断增长, 我们仍然有一个问题无法回答, 那就是:我们是从哪里来的? 事实上情况正在变糟, 因为我们永远无法找到实物证据 证明我们起源于这个星球上的何处, 原因是四十亿年前的所有事物都不在了。 所有记录都消失了, 被板块运动和侵蚀抹得一干二净。 我把这个称为“地球的生物视野”。 超出了这个视界范围, 我们看不到我们的起源。
So is everything lost? Well, maybe not. And we might be able to find evidence of our own origin in the most unlikely place, and this place in Mars.
那么是否所有证据都丢失了呢? 也许并没有。 我们也许会在最不可能的地方 找到我们的起源, 这个地方就是火星。
How is this possible? Well clearly at the beginning of the solar system, Mars and the Earth were bombarded by giant asteroids and comets, and there were ejecta from these impacts all over the place. Earth and Mars kept throwing rocks at each other for a very long time. Pieces of rocks landed on the Earth. Pieces of the Earth landed on Mars. So clearly, those two planets may have been seeded by the same material. So yeah, maybe Granddady is sitting there on the surface and waiting for us. But that also means that we can go to Mars and try to find traces of our own origin. Mars may hold that secret for us. This is why Mars is so special to us.
这是如何做到的呢? 我们知道,太阳系刚诞生的时候, 火星和地球被巨大的 小行星和彗星撞击过, 这些强力撞击形成的 喷出物到处都是。 地球和火星曾经很长一段时间 一直向对方丢岩石。 一片片岩石落到地球上。 一片片地球碎片落在火星上。 很明显,这两个行星有可能 是由同种物质孕育形成的。 所以是的,有可能老祖宗 正坐在火星表面等着我们呢。 但这也意味着,我们可以在火星上 试试寻找人类起源的蛛丝马迹。 火星有可能为我们保存了这个秘密。 这就是为什么火星对我们如此重要。
But for that to happen, Mars needed to be habitable at the time when conditions were right. So was Mars habitable? We have a number of missions telling us exactly the same thing today. At the time when life appeared on the Earth, Mars did have an ocean, it had volcanoes, it had lakes, and it had deltas like the beautiful picture you see here. This picture was sent by the Curiosity rover only a few weeks ago. It shows the remnants of a delta, and this picture tells us something: water was abundant and stayed founting at the surface for a very long time. This is good news for life. Life chemistry takes a long time to actually happen.
但是寻找的前提是: 火星在曾经条件适宜的时候 必须具备可居住性。 那么,火星曾经具有宜居性吗? 如今,一系列的研究行动 正告诉着我们同一个答案。 当地球上出现生命的时候, 火星确实有过海、火山、湖泊, 还拥有过图中那样的美丽三角洲。 这张照片是仅仅几周前 由好奇号发送回来的。 照片显示一个三角洲的残骸, 而且告诉我们: 水资源曾经很丰富, 并且很长一段时间 在地表保持喷涌状态。 这对于生命是个好消息。 生命化学要用很长时间才能真正发生。
So this is extremely good news, but does that mean that if we go there, life will be easy to find on Mars? Not necessarily.
所以这是非常好的消息, 但是这是否表示如果我们去火星, 就能轻松找到生命呢? 并不见得。
Here's what happened: At the time when life exploded at the surface of the Earth, then everything went south for Mars, literally. The atmosphere was stripped away by solar winds, Mars lost its magnetosphere, and then cosmic rays and U.V. bombarded the surface and water escaped to space and went underground. So if we want to be able to understand, if we want to be able to find those traces of the signatures of life at the surface of Mars, if they are there, we need to understand what was the impact of each of these events on the preservation of its record. Only then will we be able to know where those signatures are hiding, and only then will we be able to send our rover to the right places where we can sample those rocks that may be telling us something really important about who we are, or, if not, maybe telling us that somewhere, independently, life has appeared on another planet.
事情是这样的: 当生命在地球表面爆发时, 火星上的一切是背道而驰的, 真的是完全相反。 大气被太阳风一揭而散, 火星失去了它的磁层, 接着宇宙射线和紫外线冲击了地表 然后水资源逃离到了空间中和地层下。 所以如果我们想要了解, 如果我们想要在火星表面 找到那些生命印记的蛛丝马迹, 如果它们在那里的话, 我们需要了解这每一个事件 对于火星保存的记录有过怎样的影响。 只有这样我们才能知道 那些生命的印记藏在哪里了, 只有到那时我们才能 将火星车发送到正确的地点, 在那里提取那些 可能蕴含重要信息的岩石, 并借此解开关于我们是谁的秘密, 不然,或许它能告诉我们在某个地方 生命曾在另一个星球上独立地出现过。
So to do that, it's easy. You only need to go back 3.5 billion years ago in the past of a planet. We just need a time machine.
那么为了做到这件事,其实很简单。 你仅需要回到35亿年前 回到一个行星的过去。 我们只需要一个时光机。
Easy, right? Well, actually, it is. Look around you -- that's planet Earth. This is our time machine. Geologists are using it to go back in the past of our own planet. I am using it a little bit differently. I use planet Earth to go in very extreme environments where conditions were similar to those of Mars at the time when the climate changed, and there I'm trying to understand what happened. What are the signatures of life? What is left? How are we going to find it? So for one moment now I'm going to take you with me on a trip into that time machine.
很简单,对吧? 事实上的确很简单。 看看你的周围——答案是地球。 这就是我们的时光机。 地质学家正在利用这个时光机 返回我们星球的过去。 我所使用的方式稍有不同。 我用地球去到非常极端的环境, 过去在气候变化的时候 那里的环境条件和火星上的非常相似, 在那里,我正试图理解 曾经发生过什么。 有什么生命的印记? 留下了什么?我们要如何找到它? 那么现在暂且由我带领你们和我一起 进行一次时光机旅行。
And now, what you see here, we are at 4,500 meters in the Andes, but in fact we are less than a billion years after the Earth and Mars formed. The Earth and Mars will have looked pretty much exactly like that -- volcanoes everywhere, evaporating lakes everywhere, minerals, hot springs, and then you see those mounds on the shore of those lakes? Those are built by the descendants of the first organisms that gave us the first fossil on Earth.
现在大家看到的是, 我们在4500米的安第斯山脉上, 但事实上我们处在地球和火星 形成后不到十亿年的时间。 地球和火星应该看起来 差不多就是这个样子: 到处都是火山, 到处都是热气腾腾的湖泊, 矿物质,温泉, 你们看到那些湖边的土丘了吗? 那些是由首个微生物的后代建造的, 它们给了我们地球上的第一枚化石。
But if we want to understand what's going on, we need to go a little further. And the other thing about those sites is that exactly like on Mars three and a half billion years ago, the climate is changing very fast, and water and ice are disappearing. But we need to go back to that time when everything changed on Mars, and to do that, we need to go higher. Why is that? Because when you go higher, the atmosphere is getting thinner, it's getting more unstable, the temperature is getting cooler, and you have a lot more U.V. radiation. Basically, you are getting to those conditions on Mars when everything changed.
但是如果我们要了解正在发生什么, 我们需要前进得更远一些。 和火星三十五亿年前很像的一点是, 那些地方的气候正迅速变化, 水和冰正在消融。 但是我们需要回到 火星上一切都已变迁的时候, 为此,我们需要向更高处前进。 为什么呢? 因为当你到了更高处, 大气会变得更稀薄,更不稳定, 温度会降得更低, 你会得到更多的紫外线辐射。 基本上, 你会更接近火星上 一切都改变时的环境条件。
So I was not promising anything about a leisurely trip on the time machine. You are not going to be sitting in that time machine. You have to haul 1,000 pounds of equipment to the summit of this 20,000-foot volcano in the Andes here. That's about 6,000 meters. And you also have to sleep on 42-degree slopes and really hope that there won't be any earthquake that night. But when we get to the summit, we actually find the lake we came for. At this altitude, this lake is experiencing exactly the same conditions as those on Mars three and a half billion years ago. And now we have to change our voyage into an inner voyage inside that lake, and to do that, we have to remove our mountain gear and actually don suits and go for it. But at the time we enter that lake, at the very moment we enter that lake, we are stepping back three and a half billion years in the past of another planet, and then we are going to get the answer came for. Life is everywhere, absolutely everywhere. Everything you see in this picture is a living organism. Maybe not so the diver, but everything else. But this picture is very deceiving. Life is abundant in those lakes, but like in many places on Earth right now and due to climate change, there is a huge loss in biodiversity. In the samples that we took back home, 36 percent of the bacteria in those lakes were composed of three species, and those three species are the ones that have survived so far.
我没有保证这次时光旅行 会是一个安逸的旅行。 在这个时光机里,你不会光坐着。 你要把1000磅的设备 拖到安第斯山脉上 20000英尺高的火山山顶。 差不多有6000米。 而且你要在42度的斜坡上睡觉, 并且希望那晚不要发生任何地震。 但是当我们到达峰顶, 我们找到了我们此行想要寻找的湖泊。 在这个高度上,这一湖泊正经历着 跟三十五亿年前火星上 一模一样的环境条件。 现在我们要改变路线, 开始一段湖内的旅程, 为此,我们要脱掉登山用具, 穿上潜水服,然后就下水吧。 但是,当我们进入湖中的时候, 就在我们踏入湖里的那一刻, 我们正在返回到 三十五亿年前的另一个星球上, 接着我们就要找到 我们此行要找的答案。 到处都是生命,完完全全到处都是。 你们在这个照片里看到的一切 都是活生生的微生物。 也许这个潜水员并不是, 但所有其他都是。 但这个照片很有欺骗性。 生命在那些湖泊里十分丰富, 但是正如现在地球上很多地方, 由于气候变化 生物多样性遭受了巨大损失。 在我们带回去的那些样本里, 那些湖里36%的细菌 都是由三种物种组成的, 并且它们是迄今为止 存活下来的仅有的物种。
Here's another lake, right next to the first one. The red color you see here is not due to minerals. It's actually due to the presence of a tiny algae. In this region, the U.V. radiation is really nasty. Anywhere on Earth, 11 is considered to be extreme. During U.V. storms there, the U.V. Index reaches 43. SPF 30 is not going to do anything to you over there, and the water is so transparent in those lakes that the algae has nowhere to hide, really, and so they are developing their own sunscreen, and this is the red color you see. But they can adapt only so far, and then when all the water is gone from the surface, microbes have only one solution left: They go underground. And those microbes, the rocks you see in that slide here, well, they are actually living inside rocks and they are using the protection of the translucence of the rocks to get the good part of the U.V. and discard the part that could actually damage their DNA. And this is why we are taking our rover to train them to search for life on Mars in these areas, because if there was life on Mars three and a half billion years ago, it had to use the same strategy to actually protect itself. Now, it is pretty obvious that going to extreme environments is helping us very much for the exploration of Mars and to prepare missions. So far, it has helped us to understand the geology of Mars. It has helped to understand the past climate of Mars and its evolution, but also its habitability potential. Our most recent rover on Mars has discovered traces of organics. Yeah, there are organics at the surface of Mars. And it also discovered traces of methane. And we don't know yet if the methane in question is really from geology or biology. Regardless, what we know is that because of the discovery, the hypothesis that there is still life present on Mars today remains a viable one.
这是另一个湖,就在第一个的旁边。 大家所看到的这个红色 并不是由矿物质产生的, 而是由里面的某种微小藻类而产生。 在这个区域,紫外线放射非常严重。 地球上的任何地方, 紫外线指数达到11都意味着极端数值。 在那里的紫外线风暴中, 紫外线指数达到了43。 防晒指数30在那里 起不到任何作用, 并且那些湖泊里的水清澈到 水藻完全没有地方藏身, 所以它们形成了自己的防晒层, 也就是你所看到的这个红色。 但它们只能适应到这个程度, 当所有的水都从地表消失了之后, 微生物就只能通过一种 途径继续生存下去: 到地下去。 你们在图上里看到的这些岩石, 其实那些微生物正生活在岩石里, 而且它们正利用着 岩石的半透明性对它们的保护 来合理的利用紫外线, 并摒弃紫外线可能会 破坏它们DNA的部分。 这就是为什么我们训练火星车 在这些地方探索火星生命, 因为如果三十五亿年前 火星上曾经有生命, 它们必然要用同样的方法来保护自己。 现在,非常明显地, 去极端环境可以很大程度上帮助我们 进行火星的探测和任务准备。 到目前为止,这帮助我们 了解了火星的地质情况。 帮助我们了解到 火星过去的气候和气候变迁, 也帮助我们了解了 火星的宜居性潜能。 我们最近的一个火星探测车 发现了有机物的痕迹。 是的,火星地表有有机物。 它还发现了甲烷的印记。 我们还不知道那里的甲烷 是在地质过程中生成的 还是通过生物过程产生的。 不论如何,我们知道因为这个发现, 现如今火星上还有生命存在的假设 仍然是有望能被证实。
So by now, I think I have convinced you that Mars is very special to us, but it would be a mistake to think that Mars is the only place in the solar system that is interesting to find potential microbial life. And the reason is because Mars and the Earth could have a common root to their tree of life, but when you go beyond Mars, it's not that easy. Celestial mechanics is not making it so easy for an exchange of material between planets, and so if we were to discover life on those planets, it would be different from us. It would be a different type of life. But in the end, it might be just us, it might be us and Mars, or it can be many trees of life in the solar system. I don't know the answer yet, but I can tell you something: No matter what the result is, no matter what that magic number is, it is going to give us a standard by which we are going to be able to measure the life potential, abundance and diversity beyond our own solar system. And this can be achieved by our generation. This can be our legacy, but only if we dare to explore.
所以现在,我想我已经让你们相信了 火星对我们有很特殊的意义, 但是把火星看成太阳系中 唯一可能找到潜在微生物生命的地方 是一个错误的想法。 原因是虽然火星和地球 在生命树上可能拥有相同的根基, 但是谈到火星以外的星球, 就并不是那么简单了。 天体力学上星球间物质的交换 并非那样容易, 所以如果我们能 在那些星球上找到生命, 那里的生命将和我们不同。 它们会是不同种类的生命。 但是到最后,也有可能就只有我们, 或者只有我们和火星, 或者也可能太阳系里有很多生命树。 我还不知道答案, 但是我能告诉大家的是: 不论答案如何, 不论那个神奇的数字是几, 这将会给我们带来一个标准, 我们将可以利用这个标准 衡量我们太阳系以外的 生命的潜能、丰富性和多样性。 这是可以在我们这一代实现的。 这可以成为我们的遗赠, 但前提是我们敢于探索。
Now, finally, if somebody tells you that looking for alien microbes is not cool because you cannot have a philosophical conversation with them, let me show you why and how you can tell them they're wrong. Well, organic material is going to tell you about environment, about complexity and about diversity. DNA, or any information carrier, is going to tell you about adaptation, about evolution, about survival, about planetary changes and about the transfer of information. All together, they are telling us what started as a microbial pathway, and why what started as a microbial pathway sometimes ends up as a civilization or sometimes ends up as a dead end.
现在,最后, 如果有人告诉你 寻找外星微生物不是那么酷, 因为你不能和它们 进行一场有意义的对话, 我来告诉你,为什么你能 以及如何能告诉他们,这是错的。 有机物质会告诉你 有关环境,复杂度 以及多样性的信息。 DNA,或者任何其他信息载体, 会告诉你有关适应性, 进化,生存,行星变迁, 以及信息传递的内容。 所有的加在一起,它们能告诉我们 什么是微生物途径的开端, 以及为什么有时候一些 微生物途径的开端 会最终形成一个文明, 另一些时候则会最终走到尽头。
Look at the solar system, and look at the Earth. On Earth, there are many intelligent species, but only one has achieved technology. Right here in the journey of our own solar system, there is a very, very powerful message that says here's how we should look for alien life, small and big. So yeah, microbes are talking and we are listening, and they are taking us, one planet at a time and one moon at a time, towards their big brothers out there. And they are telling us about diversity, they are telling us about abundance of life, and they are telling us how this life has survived thus far to reach civilization, intelligence, technology and, indeed, philosophy.
看看太阳系,再看看地球。 地球上有很多智慧的物种, 但只有一个物种实现了科技发展。 就在我们自己太阳系的旅程里, 有一个非常、非常强有力的信息: 这就是我们应当如何 寻找外星生命,无论生命大小。 微生物在叙述,我们在聆听, 并且它们正把我们带领到 一个个行星,一个个卫星, 带到它们外面的那些大哥哥那里。 它们在告诉我们多样性的信息, 它们在告诉我们生命的丰富性, 它们在告诉我们 生命是如何存活至今 来取得文明、 智能、科技,甚至是,哲学。
Thank you.
谢谢大家。
(Applause)
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