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I want to find aliens. Finding life on another planet is not just going to be a little hard, it's going to be very hard.
我想找到外星人。在另一颗行星上寻找生命不是有点儿困难，是非常困难。
But for the first time in human history, we have a chance to detect signs of life on another planet. Or maybe we've already detected it on Venus. Or maybe not.
但这是人类历史上第一次有机会在另一个星球上发现生命迹象。也许我们已经在金星上探测到外星生命了，也许没有。
There are still two big hurdles when it comes to confirming life on another world.
我们在确认另一个世界是否存在生命时仍面临两大障碍。
The first is building a telescope big enough to do this, and the second is interpreting what we will find.
一是造一个足够大的望远镜进行探测，二是对我们的发现进行解释。
When we think of extraterrestrial life, we tend to think of aliens like funny little green men, not aliens as single-celled microbes.
我们对外星生命的刻板印象就是“有趣的小绿人”，而不是说什么单细胞微生物。
But it's actually detecting signs of microbial life on another planet that I'm most optimistic about, and what I focus my research on.
但其实在另一个星球上发现微生物生命的迹象是我最为乐观的，同时也是我研究的重点。
I model how a star's high-energy radiation can make gases from microbes harder or easier to see with future telescopes.
我模拟了恒星的高能辐射如何使微生物中的气体更难或更容易用未来的望远镜观测到。
Microbes have dominated our planet's biosphere for most of Earth's history.
在地球历史的大部分时间里，微生物一直主宰着地球的生物圈。
They've been emitting gases that can be seen in our atmosphere -- even light years away -- for billions of years.
数十亿年来，它们一直在排放可以在大气中看到的气体——甚至在光年之外。
Now, if an alien astronomer were looking at Earth, they would probably detect gases like oxygen, methane and nitrous oxide before detecting signs of us.
此时，如果一个外星天文学家在观察地球，他们可能会在发现我们的迹象之前先探测到氧气、甲烷和一氧化二氮等气体。
Even with an active biosphere like Earth's, most of the gases that indicate life are coming from single-celled microbes, not from animals.
即便在像地球这样活跃的生物圈中，大多表明生命存在的气体都来自单细胞微生物，而不是动物。
This is what we'll try to do in the next decade of astronomy -- try to find signs of microbial life on planets orbiting other stars.
这就是我们天文学未来十年里要做的事情——在围绕其他恒星运行的行星上寻找微生物生命的迹象。
But the technology to detect the atmosphere of a planet the size of Earth around another sun is incredibly difficult.
但想要探测到地球大小的行星围绕另一个太阳的大气层，技术是极其困难的。
It's like trying to determine the size of a firefly in front of a spotlight while looking from another continent.
就像我站在另一个大陆上想要确定聚光灯前的一只萤火虫的大小一样。
What's amazing is that with telescopes in the 2020s, we're overcoming this technological barrier.
令人兴奋的是，21世纪20年代出现了望远镜，所以我们正在克服这一技术障碍。
The second issue defining alien life will be to interpret what these biosignature gases actually mean.
定义外星生命的第二个问题是解释这些具有生物特征的气体到底意味着什么。
Twenty-one percent of our atmosphere is oxygen, and nearly all of that oxygen comes from life.
大气的21%是氧气，而几乎所有的氧气都来自生命。
So here's the tricky question: Would detecting oxygen on another planet mean life?
所以这里有个棘手的问题：在另一个星球上探测到氧气是否就意味着该星球上有生命？
No, not necessarily, because we know of ways to get oxygen without biology.
不，不一定，因为我们知道无需生物就能获得氧气的方法。
I try to understand a planet's geology and its star's radiation so that we can better identify a true life signal.
我想要了解一颗行星的地质以及它的恒星的辐射，以便我们能更好地识别真正的生命信号。
And this is what makes the preliminary detection on Venus of phosphine, a potential biosignature gas, so compelling but also so confusing.
这就是为什么在金星上初步探测到磷化氢——一种潜在的生物特征气体——会如此引人注目但也如此令人困惑的原因。
Venus is not where we expected to find life.
金星并不是我们期望发现生命的地方。
It is a hellish world, with a surface temperature of nearly 900 degrees Fahrenheit.
那是一个地狱般的世界，表面温度接近900华氏度。
Could life be floating in the more temperate upper atmosphere? But then how would such life eat and reproduce?
生命能够漂浮在更温和的高层大气中吗？那么这些生命是如何进食和繁殖的呢？
This discovery will have to be vetted over the coming decade.
这一发现将在未来十年中接受审查。
First, we must verify the detection of phosphine itself, and then later, we would have to confirm that this gas is coming from life and not from some unexpected geological or photochemical process.
首先，我们必须确认发现了磷化氢本身，然后，我们必须确认这种气体来自生命而不是来自某些意想不到的地质或光化学过程。
If true, this would be one of the most profound discoveries of our generation.
如果这是真的，这将是我们这一代最深刻的发现之一。
If it turns out that we were fooled, that we mistook this gas for biology when it's from some other process, we will have a sobering lesson to apply to planets orbiting distant stars.
如果事实证明我们被愚弄了，我们误以为这种气体就是生物，而实际上它则来自于其他过程，那么我们将得到一个发人深醒的教训，这一教训可以应用到围绕遥远恒星运行的行星上。
Venus is close -- literally, our next-door neighbor -- and yet we still have trouble understanding it.
金星离我们很近——确切地说，是我们的邻居——但我们仍难以理解它。
The planets we're finding orbiting other stars are weird and unexpected.
我们发现的围绕其他恒星运行的行星都很奇怪，出乎意料。
Some have the density of cotton candy, and others rain molten iron.
有些有着棉花糖的密度，还有一些会下铁水。
And most stars are different from our sun, with high-energy flares that can make it difficult for life.
而且大多数恒星和我们的太阳不同，它们有高能耀斑，使生命难以生存。
So the more we're looking at different biosignature gases, the more we realize that there's no single gas that's enough to understand a planet and to claim alien life.
所以，我们对不同生物特征气体的研究越多，我们就越意识到没有一种单一的气体足以了解一颗行星并宣告外星生命的存在。
It is just really difficult to distinguish life from nonlife from light years away. And here's where the ambiguity lies.
我们很难区分光年之外的生命和非生命，这就是不明确的地方所在。
How will we know if a clue is a sign of life or is not?
我们怎么知道一个线索是不是生命的迹象呢？
Well, first, we'll need to understand as much as we can about a planet's geology and the star it orbits.
首先，我们需要尽可能多地了解一颗行星的地质和它围绕的恒星。
We'll learn vital lessons by exploring our own solar system in places such as Venus and Mars.
我们通过在金星和火星等地探索太阳系将学到重要的经验。
We're getting closer to answering one of humanity's biggest questions: Are we alone in the universe?
我们越来越接近回答人类最大的问题之一：人类在宇宙中是孤独存在的吗？
Any claim will be hotly debated. So basically, I'm stretched between two desires.
任何主张都将引起激烈辩论，所以基本上，我在两种欲望之间进退两难。
I want to find alien life, but likely will not have a clear answer.
我想找到外星生命，但很可能不会有明确的答案。
And that's OK; science is nuanced and self-correcting. It's what I love about it.
没关系，科学是细致入微的，是可以自我修正的，这就是我喜欢科学的原因。
Science is about balancing this duality of skepticism and of hope.
科学就是要平衡怀疑和希望的二元性。
We won't be able to teleport ourselves to another planet and take pictures of alien kangaroos jumping around.
我们无法将自己瞬移到另一个星球，也无法拍摄外星袋鼠跳来跳去的照片。
And without an intelligent "Hello, Earthlings!" signal, we might still feel lonely, even if we find out we're not alone in the universe.
如果没有“你好，地球人！”的智能信号，我们可能仍会感到孤独，即便我们发现我们在宇宙中并不孤单。
Despite these challenges, I'm super excited about alien microbes and what they could teach us.
尽管有这些挑战，我还是对外星微生物以及它们能教给我们的东西感到非常兴奋。
Even if we find just one other sign of life, then likely the universe is teeming with it, from single-celled to complex.
即使我们只发现了一种生命迹象，那么很可能宇宙中到处都是从单细胞生命到复杂生命等各种生命。
If we search for decades and find nothing, then that is equally humbling. But we must try.
如果我们找了几十年却一无所获，那也同样受挫，但我们必须尝试。
We must do this search even when it means sitting with uncertainty along the way. Thank you.
我们必须进行这项研究，即便这意味着我们一路上都要面对不确定性。谢谢！
