Extraordinary claims require extraordinary evidence, and it is my job, my responsibility,
非同寻常的结论需要非同寻常的证据。这是我的职责和责任
as an astronomer to remind people that alien hypotheses should always be a last resort.
作为天文学家，去提醒人们外星人假说一直都该是最后一根救命稻草。
Now, I want to tell you a story about that.
现在，我要给你们讲这么一个故事。
It involves data from a NASA mission, ordinary people and one of the most extraordinary stars in our galaxy.
故事中有来自NASA项目中的数据，有普通人，还有一颗银河系里最非同寻常的星星。
It began in 2009 with the launch of NASA's Kepler mission.
故事开始于2009年，NASA启动了开普勒计划。
Kepler's main scientific objective was to find planets outside of our solar system.
开普勒计划的首要科学目标是寻找太阳系以外的行星。
It did this by staring at a single field in the sky, this one, with all the tiny boxes.
它持续观测一小块天区，就这块，所有这些小方块。
And in this one field, it monitored the brightness of over 150,000 stars continuously for four years, taking a data point every 30 minutes.
在这小块区域中，它持续观测超过15万颗恒星的亮度，整整四年，每30分钟就采集一次数据。
It was looking for what astronomers call a transit.
它在搜寻天文学家叫做掩食的东西。
This is when the planet's orbit is aligned in our line of sight, just so that the planet crosses in front of a star.
它发生在行星轨道和我们的观测视线重合情况。这样，行星就会从恒星前面经过。
And when this happens, it blocks out a tiny bit of starlight, which you can see as a dip in this curve.
这种情况下，行星就会挡住一点点的星光。你可以在光度曲线上看到小小的负峰。
And so the team at NASA had developed very sophisticated computers to search for transits in all the Kepler data.
于是NASA团队开发出非常复杂的电脑程序，来搜寻开普勒数据中的掩食事件。
At the same time of the first data release, astronomers at Yale were wondering an interesting thing: What if computers missed something?
在首次数据发布的同时，耶鲁大学的天文学家在考虑一个有趣的问题：万一电脑错过了什么怎么办？
And so we launched the citizen science project called Planet Hunters to have people look at the same data.
于是，我们又发起了一项名为“行星猎人”的公民科学项目。这个项目依靠大众来分析同样的数据。
The human brain has an amazing ability for pattern recognition, sometimes even better than a computer.
人脑有着惊人的模式识别能力，有时候甚至比电脑都厉害。
However, there was a lot of skepticism around this.
然而，这个项目遭到了很多质疑。
My colleague, Debra Fischer, founder of the Planet Hunters project, said that people at the time were saying,
我的同行，黛布拉·费舍尔，行星猎人项目的发起人，说那时候人们议论道：
"You're crazy. There's no way that a computer will miss a signal."
“你们疯了。电脑绝不可能错过信号。”
And so it was on, the classic human versus machine gamble. And if we found one planet, we would be thrilled.
所以这又是人和机器赌哪个的老段子。如果我们发现了一颗行星，那我们就会特别高兴。
When I joined the team four years ago, we had already found a couple.
四年前，在我加入这个团队的时候，我们已经有了发现。
And today, with the help of over 300,000 science enthusiasts, we have found dozens,
而今天，通过超过30万科学爱好者的努力，我们已经发现了数十颗行星，
and we've also found one of the most mysterious stars in our galaxy.
而且我们发现了这一颗银河系中最最奇异的恒星。
So to understand this, let me show you what a normal transit in Kepler data looks like.
为了说清楚，请看一下开普勒数据中一次正常的掩食是什么样子。
On this graph on the left-hand side you have the amount of light, and on the bottom is time.
这幅图中，左边轴是光强度，底下的横轴是时间。
The white line is light just from the star, what astronomers call a light curve.
这条白线是单纯来自恒星的光，天文学家称为光度曲线。
Now, when a planet transits a star, it blocks out a little bit of this light,
现在，当一颗行星掩过恒星，它阻挡了一点点星光，
and the depth of this transit reflects the size of the object itself.
而这个掩食的深度反映了行星体自身的大小。
And so, for example, let's take Jupiter. Planets don't get much bigger than Jupiter.
所以，例如木星。行星通常不太会比木星还要大。
Jupiter will make a one percent drop in a star's brightness.
木星会减弱百分之一的星光。
Earth, on the other hand, is 11 times smaller than Jupiter, and the signal is barely visible in the data.
换做地球，地球只有木星的1/11大，它的信号在数据中几乎看不见。
So back to our mystery. A few years ago, Planet Hunters were sifting through data looking for transits,
回到我们的谜题。几年前，行星猎人正在筛选数据寻找掩食，
and they spotted a mysterious signal coming from the star KIC 8462852.
他们发现了一个诡异的信号来自恒星KIC 8462852。
The observations in May of 2009 were the first they spotted, and they started talking about this in the discussion forums.
2009年五月是他们首次发现这个信号，他们开始在论坛中讨论这个发现。
They said and object like Jupiter would make a drop like this in the star's light, but they were also saying it was giant.
他们说一个类似木星的星体可以造成这样的星光削弱，但他们也说这家伙太大了。
You see, transits normally only last for a few hours, and this one lasted for almost a week.
你看，掩食通常只持续几个小时，而这一个持续了将近一周。
They were also saying that it looks asymmetric, meaning that instead of the clean,
他们也在说谱线看起来不对称，这是说，不像木星那样有一个干净、
U-shaped dip that we saw with Jupiter, it had this strange slope that you can see on the left side.
U型的负峰，大家看，这条数据左侧的倾斜度很奇怪。
This seemed to indicate that whatever was getting in the way and blocking the starlight was not circular like a planet.
这似乎意味着，无论闯进来挡住星光的是什么东西，它不会像行星那样是个球形。
There are few more dips that happened, but for a couple of years, it was pretty quiet.
后来陆续还有少量的负峰，但这颗星在之后的一两年一直都没什么动静。
And then in March of 2011, we see this. The star's light drops by a whole 15 percent,
然后在2011年三月，我们观察到了这个。这颗恒星的光度掉了整整15%，
and this is huge compared to a planet, which would only make a one percent drop.
这比一颗行星能造成的大太多了，行星只能造成1%的光度下降。
We described this feature as both smooth and clean.
我们把这条谱线特征描述为光滑和干净。
It also is asymmetric, having a gradual dimming that lasts almost a week, and then it snaps right back up to normal in just a matter of days.
它也是不对称的，在持续近一周的时间内逐步减弱，然后在一两天内立马反弹回正常的光度。
And again, after this, not much happens until February of 2013. Things start to get really crazy.
在此之后，又是什么都没发生，直到2013年二月。事情的发展完全出乎意料。
There is a huge complex of dips in the light curve that appear,
光度曲线上出现了一大群复杂的负峰，
and they last for like a hundred days, all the way up into the Kepler mission's end.
而且它们持续了差不多一百天，一直延续到开普勒计划结束。
These dips have variable shapes. Some are very sharp, and some are broad, and they also have variable durations.
这些负峰有着各种形状。有一些很尖锐，有一些很宽，以及有不同的持续时间。
Some last just for a day or two, and some for more than a week.
有一些只持续一两天，有的则超过一周。

And there's also up and down trends within some of these dips, almost like several independent events were superimposed on top of each other.
而且在一些光度负峰中，还出现上上下下的起伏，感觉好像是几个独立事件重叠在一起。
And at this time, this star drops in its brightness over 20 percent.
而且这次，这颗恒星的亮度下降了超过20%。
This means that whatever is blocking its light has an area of over 1,000 times the area of our planet Earth.
这说明，不管是什么东西挡住了光，这家伙有着超过地球1000倍的面积。
This is truly remarkable. And so the citizen scientists, when they saw this,
这真心是非同寻常。当公民科学家发现这个时，
they notified the science team that they found something weird enough that it might be worth following up.
他们通知了科学家团队，称他们发现了足够奇怪的东西可能值得后续跟进研究。
And so when the science team looked at it, we're like, "Yeah, there's probably just something wrong with the data."
于是当科学家团队看过数据之后，我们觉得：“好吧，会不会只是数据有点问题。”
But we looked really, really, really hard, and the data were good.
不过经过我们非常、非常、非常仔细的调查，数据没有问题。
And so what was happening had to be astrophysical, meaning that something in space was getting in the way and blocking starlight.
因此，出现这些负峰一定有天体物理学的原因，说明太空中有什么东西经过了我们和恒星之间，挡住了它的光。
And so at this point, we set out to learn everything we could about the star to see if we could find any clues to what was going on.
这个时候，我们竭力研究关于这颗恒星的一切，希望能找到任何可以解释这些现象的线索。
And the citizen scientists who helped us in this discovery, they joined along for the ride watching science in action firsthand.
帮助我们发现这颗星的公民科学家也加入了讨论，见证科学第一线的行动。
First, somebody said, you know, what if this star was very young and it still had the cloud of material it was born from surrounding it.
首先，有人提出，是不是这颗星非常年轻，它仍旧保有它诞生之时周围的星际云物质。
And then somebody else said, well, what if the star had already formed planets,
另外有人说，好吧，是不是这颗星已经形成了行星系统，
and two of these planets had collided, similar to the Earth-Moon forming event.
而两颗行星相撞了，就像地球--月球的形成过程。
Well, both of these theories could explain part of the data, but the difficulties were that the star showed no signs of being young,
好吧，这两种假说都可以解释部分数据，但是困难在于，这颗恒星没有显示任何年轻的特征，
and there was no glow from any of the material that was heated up by the star's light,
而且也没有来自任何物质被星光加热发出的光晕。
and you would expect this if the star was young or if there was a collision and a lot of dust was produced.
如果恒星年轻，或者碰撞产生大量尘埃，通常会出现这种现象。
And so somebody else said, well, how about a huge swarm of comets that are passing by this star in a very elliptical orbit?
又有人说，好吧，会不会是一大群彗星呢在一个非常椭圆的轨道上一连串地穿过这颗恒星？
Well, it ends up that this is actually consistent with our observations.
好吧，这个假说倒是和我们的观测相吻合。
But I agree, it does feel a little contrived. You see, it would take hundreds of comets to reproduce what we're observing.
但是我同意，这感觉有点牵强。你看，需要数百颗彗星，才能重现我们的观测。
And these are only the comets that happen to pass between us and the star.
而这些只是恰好从我们和恒星中间穿过的彗星。
And so in reality, we're talking thousands to tens of thousands of comets.
所以实际情况下，将会有成千上万颗彗星。
But of all the bad ideas we had, this one was the best. And so we went ahead and published our findings.
但是在我们所有的烂解释中，这个算是最好的了。于是我们发表了我们的发现。
Now, let me tell you, this was one of the hardest papers I ever wrote.
要我说，这是我写过的最困难的论文之一。
Scientists are meant to publish results, and this situation was far from that.
科学家理应发表明确的结果，而这次我们离结果还有十万八千里呢。
And so we decided to give it a catchy title, and we called it: "Where's The Flux?" I will let you work out the acronym.
所以我们决定起一个抓眼球的标题，我们的题目是：《光去了哪里》。麻烦大家自行意会这个梗。
So this isn't the end of the story.
不过这故事还没完呢。
Around the same time I was writing this paper, I met with a colleague of mine, Jason Wright, and he was also writing a paper on Kepler data.
在我写这篇论文的同时，我见了一位同行，贾森·莱特，他也在写一篇有关开普勒数据的论文。
And he was saying that with Kepler's extreme precision, it could actually detect alien megastructures around stars, but it didn't.
他说道，从开普勒无与伦比的精度来看，它其实可以探测到恒星周围的外星人建筑，但是并没有发现。
And then I showed him this weird data that our citizen scientists had found, and he said to me, "Aw crap, Tabby. Now I have to rewrite my paper."
然后我给他看了这个由我们公民科学家发现的奇怪数据，然后他对我说，“见鬼，塔碧。这下我论文得重写了。”
So yes, the natural explanations were weak, and we were curious now. So we had to find a way to rule out aliens.
所以，没错，自然解释很牵强，我们很好奇。我们必须找到一个排除外星人的方法。
So together, we convinced a colleague of ours who works on SETI,
于是我俩一起说服了我们在SETI（寻找地外文明计划）工作的一位同行，
the Search for Extraterrestrial Intelligence, that this would be an extraordinary target to pursue.
说这是一个非常出色的追逐目标。
We wrote a proposal to observe the star with the world's largest radio telescope at the Green Bank Observatory.
我们起草了一份观测这颗恒星的项目书，请求使用绿岸天文台的世界上最大的射电天文望远镜。
A couple months later, news of this proposal got leaked to the press and now there are thousands of articles, over 10,000 articles, on this star alone.
两三个月后，这份项目书的消息被媒体刺探到了。好吧，现在有几千篇报道，可能超过一万篇，单单关于这颗恒星。
And if you search Google Images, this is what you'll find.
如果你用谷歌图片搜索，你会找到这些。
Now, you may be wondering, OK, Tabby, well, how do aliens actually explain this light curve?
现在，观众可能会问，好吧，塔碧，究竟怎么用外星人去解释这光度曲线？
OK, well, imagine a civilization that's much more advanced than our own.
好吧，想象一个远比我们发达的文明。
In this hypothetical circumstance, this civilization would have exhausted the energy supply of their home planet, so where could they get more energy?
在这个假设条件下，这个文明肯定耗尽了他们母星的能源。所以他们从哪里获取更多的能量？
Well, they have a host star just like we have a sun, and so if they were able to capture more energy from this star,
你看，他们有一颗宿主恒星，就像我们有太阳一样，那如果他们能够从恒星中抓取更多能量，
then that would solve their energy needs. So they would go and build huge structures.
那就可以解决他们的能源需求。所以他们可能会去建造这些巨型建筑。
These giant megastructures, like ginormous solar panels, are called Dyson spheres.
这些巨大的超级建筑，比如巨大的太阳能电池板，叫做“戴森球”。
This image above are lots of artists' impressions of Dyson spheres.
上面这些图片是许多艺术家想象中的戴森球。
It's really hard to provide perspective on the vastness of these things, but you can think of it this way.
很难去想象这些东西究竟有多庞大，但你可以这么想。
The Earth-Moon distance is a quarter of a million miles.
地球--月球间的距离是四十万公里。
The simplest element on one of these structures is 100 times that size. They're enormous.
这些巨型结构中的最简单的单元，是100倍地月距离。它们是庞然大物。
And now imagine one of these structures in motion around a star.
再想象这样一个建筑围绕着一颗恒星运动。
You can see how it would produce anomalies in the data such as uneven, unnatural looking dips.
你可以看到这为什么可以造成数据中异常如此不对称，不自然的负峰。
But it remains that even alien megastructures cannot defy the laws of physics.
但是即使是外星人的超级建筑，也不能违反物理定律。
You see, anything that uses a lot of energy is going to produce heat, and we don't observe this.
任何使用大量能量的东西将会产生热量，但是我们没有观测到。
But it could be something as simple as they're just reradiating it away in another direction, just not at Earth.
但这有可能只是非常简单的，他们把热量释放到了另一个方向，没有对着地球。
Another idea that's one of my personal favorites is that we had just witnessed an interplanetary space battle
我个人最喜欢的另一种可能性是我们恰好目睹了一场星球大战，
and the catastrophic destruction of a planet.
一颗行星被灾难性地彻底摧毁了。
Now, I admit that this would produce a lot of dust that we don't observe.
我承认，这会产生很多尘埃，然而我们没有观测到。
But if we're already invoking aliens in this explanation,
但是如果我们已经在用外星人来解释，
then who is to say they didn't efficiently clean up all this mess for recycling purposes?
那谁说他们不会秋风扫落叶一般清理干净尘埃，回收利用？
You can see how this quickly captures your imagination. Well, there you have it.
你看，这很快就激发想象力啦。好啦，故事就是这样。
We're in a situation that could unfold to be a natural phenomenon we don't understand or an alien technology we don't understand.
我们的处境是，既可以解释成我们没搞清楚的自然现象，又可以解释成我们没搞清楚的外星人科技。
Personally, as a scientist, my money is on the natural explanation.
作为科学家，我个人还是会赌这是个自然现象。
But don't get me wrong, I do think it would be awesome to find aliens.
但是别误解了，我绝对认同能找到外星人非常棒。
Either way, there is something new and really interesting to discover.
不管怎样，有新东西，非常有趣的东西等待发现。
So what happens next? We need to continue to observe this star to learn more about what's happening.
那么，接下来呢？我们需要继续观测这颗恒星，去更详细地了解发生了什么。
But professional astronomers, like me, we have limited resources for this kind of thing, and Kepler is on to a different mission.
然而，像我这样的职业天文学家，我们在这方面的资源有限。而开普勒望远镜已经在执行另一项计划了。
And I'm happy to say that once again, citizen scientists have come in and saved the day.
所以我很高兴地说，又一次，公民科学家加入进来救场。
You see, this time, amateur astronomers with their backyard telescopes stepped up immediately
你看，这次，业余天文爱好者拿着他们的业余望远镜立刻加入进来，
and started observing this star nightly at their own facilities, and I am so excited to see what they find.
开始在自己的观测点夜观此星。我非常期待他们的发现。
What's amazing to me is that this star would have never been found by computers because we just weren't looking for something like this.
对我来说，激动人心的是这颗恒星可能根本不会被电脑发现，因为我们单纯没有把这样的恒星当成目标。
And what's more exciting is that there's more data to come.
更激动人心的是，将来还有更多的数据。
There are new missions that are coming up that are observing millions more stars all over the sky.
有新的观测项目要上马，准备观测百万颗恒星，布满全天。
And just think: What will it mean when we find another star like this?
思考一下：如果我们又找到一颗这样的恒星，意味着什么？
And what will it mean if we don't find another star like this? Thank you.
而如果我们一颗都没找到，那又意味着什么？谢谢。