The most mysterious star in the universe | Tabetha Boyajian

翻译人员: Luyao Zou 校对人员: Bighead Ge

Extraordinary claims require extraordinary evidence,

非同寻常的结论 需要非同寻常的证据。

and it is my job, my responsibility, as an astronomer

作为天文学家， 这是我的职责和责任

to remind people that alien hypotheses should always be a last resort.

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,

故事中有来自 NASA 项目中的数据，

ordinary people and one of the most extraordinary stars in our galaxy.

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

开普勒计划的 首要科学目标

was to find planets outside of our solar system.

是寻找太阳系以外的行星。

It did this by staring at a single field in the sky,

它持续观测一小块天区，

this one, with all the tiny boxes.

就这块，所有这些小方块。

And in this one field,

在这小块区域中，

it monitored the brightness of over 150,000 stars

它持续观测超过 15 万颗恒星的亮度，

continuously for four years,

整整四年，

taking a data point every 30 minutes.

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,

它发生在行星轨道和 我们的观测视线重合情况。

just so that the planet crosses in front of a star.

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,

这种情况下，行星 就会挡住一点点的星光。

which you can see as a dip in this curve.

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

于是 NASA 团队开发出 非常复杂的电脑程序，

to search for transits in all the Kepler data.

来搜寻开普勒 数据中的掩食事件。

At the same time of the first data release,

在首次数据发布的同时，

astronomers at Yale were wondering an interesting thing:

耶鲁大学的天文学家 在考虑一个有趣的问题：

What if computers missed something?

万一电脑错过了什么怎么办？

And so we launched the citizen science project called Planet Hunters

于是，我们又发起了一项 名为“行星猎人”的公民科学项目。

to have people look at the same data.

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,

人脑有着惊人的模式识别能力，

sometimes even better than a computer.

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,

我的同行，黛布拉·费舍尔， 行星猎人项目的发起人，

said that people at the time were saying,

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.

所以这又是人和机器 赌哪个的老段子。

And if we found one planet, we would be thrilled.

如果我们发现了一颗行星， 那我们就会特别高兴。

四年前， 在我加入这个团队的时候，

When I joined the team four years ago,

we had already found a couple.

我们已经有了发现。

And today, with the help of over 300,000 science enthusiasts,

而今天，通过超过 30 万 科学爱好者的努力，

we have found dozens,

我们已经发现了数十颗行星，

and we've also found one of the most mysterious stars

而且我们发现了 这一颗银河系中

in our galaxy.

最最奇异的恒星。

So to understand this,

为了说清楚，

let me show you what a normal transit in Kepler data looks like.

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,

这幅图中，左边轴是光强度，

and on the bottom is time.

底下的横轴是时间。

The white line is light just from the star,

这条白线是单纯来自恒星的光，

what astronomers call a light curve.

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.

所以，例如木星。

Planets don't get much bigger than Jupiter.

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,

换做地球， 地球只有木星的 1/11 大，

and the signal is barely visible in the data.

它的信号在数据中几乎看不见。

So back to our mystery.

回到我们的谜题。

A few years ago, Planet Hunters were sifting through data looking for transits,

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,

2009 年五月是他们 首次发现这个信号，

and they started talking about this in the discussion forums.

他们开始在论坛中 讨论这个发现。

They said and object like Jupiter

他们说一个类似木星的星体

would make a drop like this in the star's light,

可以造成这样的星光削弱，

but they were also saying it was giant.

但他们也说这家伙太大了。

You see, transits normally only last for a few hours,

你看，掩食通常只持续几个小时，

and this one lasted for almost a week.

而这一个持续了将近一周。

They were also saying that it looks asymmetric,

他们也在说谱线看起来不对称，

meaning that instead of the clean, U-shaped dip that we saw with Jupiter,

这是说，不像木星那样 有一个干净、U 型的负峰，

it had this strange slope that you can see on the left side.

大家看，这条数据左侧 的倾斜度很奇怪。

This seemed to indicate

这似乎意味着，

that whatever was getting in the way and blocking the starlight

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。

was not circular like a planet.

There are few more dips that happened,

后来陆续还有少量的负峰，

but for a couple of years, it was pretty quiet.

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.

然后在 2011 年三月， 我们观察到了这个。

The star's light drops by a whole 15 percent,

这颗恒星的光度 掉了整整 15%，

and this is huge compared to a planet,

这比一颗行星能造成的大太多了，

which would only make a one percent drop.

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,

它也是不对称的，

having a gradual dimming that lasts almost a week,

在持续近一周的时间内 逐步减弱，

and then it snaps right back up to normal in just a matter of days.

然后在一两天内 立马反弹回正常的光度。

And again, after this, not much happens

在此之后，又是什么都没发生，

until February of 2013.

直到 2013 年二月。

Things start to get really crazy.

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,

而且它们持续了 差不多一百天，

all the way up into the Kepler mission's end.

一直延续到 开普勒计划结束。

These dips have variable shapes.

这些负峰有着各种形状。

Some are very sharp, and some are broad,

有一些很尖锐， 有一些很宽，

and they also have variable durations.

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,

而且在一些光度负峰中， 还出现上上下下的起伏，

almost like several independent events were superimposed on top of each other.

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

这说明不管是什么东西 挡住了光，

has an area of over 1,000 times the area of our planet Earth.

这家伙有着超过地球 1000 倍的面积。

This is truly remarkable.

这真心是非同寻常。

And so the citizen scientists, when they saw this,

当公民科学家发现这个时，

they notified the science team that they found something weird enough

他们通知了科学家团队， 称他们发现了足够奇怪的东西

that it might be worth following up.

可能值得后续跟进研究。

And so when the science team looked at it,

于是当科学家团队看过数据之后，

we're like, "Yeah, there's probably just something wrong with the data."

我们觉得：“好吧，会不会 只是数据有点问题。”

But we looked really, really, really hard,

不过经过我们非常、 非常、非常仔细的调查，

and the data were good.

数据没有问题。

And so what was happening had to be astrophysical,

因此，出现这些负峰一定有 天体物理学的原因，

meaning that something in space was getting in the way

说明太空中有什么东西 经过了我们和恒星之间，

and blocking starlight.

挡住了它的光。

And so at this point,

这个时候，

we set out to learn everything we could about the star

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。

to see if we could find any clues to what was going on.

And the citizen scientists who helped us in this discovery,

帮助我们发现这颗星的 公民科学家，

they joined along for the ride

也加入了讨论，

watching science in action firsthand.

见证科学第一线的行动。

First, somebody said, you know, what if this star was very young

首先，有人提出， 是不是这颗星非常年轻，

and it still had the cloud of material it was born from surrounding it.

它仍旧保有它诞生之时 周围的星际云物质。

And then somebody else said,

另外有人说，

well, what if the star had already formed planets,

好吧，是不是这颗星 已经形成了行星系统，

and two of these planets had collided,

而两颗行星相撞了，

similar to the Earth-Moon forming event.

就像地球——月球的形成过程。

Well, both of these theories could explain part of the data,

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，

but the difficulties were that the star showed no signs of being young,

and there was no glow from any of the material

而且也没有来自任何物质

that was heated up by the star's light,

被星光加热发出的光晕。

and you would expect this if the star was young

如果恒星年轻，

or if there was a collision and a lot of dust was produced.

或者碰撞产生大量尘埃， 通常会出现这种现象。

And so somebody else said,

又有人说，

well, how about a huge swarm of comets

好吧，会不会是一大群彗星呢

that are passing by this star in a very elliptical orbit?

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.

但是我同意， 这感觉有点牵强。

You see, it would take hundreds of comets

你看，需要数百颗彗星，

to reproduce what we're observing.

才能重现我们的观测。

And these are only the comets

而这些只是

that happen to pass between us and the star.

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,

但是在我们所有的烂解释中，

this one was the best.

这个算是最好的了。

And so we went ahead and published our findings.

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,

科学家理应发表明确的结果，

and this situation was far from that.

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,

所以我们决定 起一个抓眼球的标题，

and we called it: "Where's The Flux?"

我们的题目是： 《光去了哪里》

I will let you work out the acronym.

麻烦大家自行意会这个梗

(Laughter)

（笑声。标题的英文缩写为 WTF，即“什么鬼”）

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,

在我写这篇论文的同时，

I met with a colleague of mine, Jason Wright,

我见了一位同行， 贾森·莱特

and he was also writing a paper on Kepler data.

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,

他说道，从开普勒 无与伦比的精度来看，

it could actually detect alien megastructures around stars,

它其实可以探测到 恒星周围的外星人建筑，

but it didn't.

但是并没有发现。

And then I showed him this weird data that our citizen scientists had found,

然后我给他看了这个由我们 公民科学家发现的奇怪数据，

and he said to me,

然后他对我说，

"Aw crap, Tabby.

“见鬼，塔碧。

Now I have to rewrite my paper."

这下我论文得重写了。”

So yes, the natural explanations were weak,

所以，没错， 自然解释很牵强，

and we were curious now.

我们很好奇。

So we had to find a way to rule out aliens.

我们必须找到一个 排除外星人的方法。

So together, we convinced a colleague of ours

于是我俩一起说服了

who works on SETI, the Search for Extraterrestrial Intelligence,

我们在 SETI（寻找地外 文明计划）工作的一位同行，

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

我们起草了一份 观测这颗恒星的项目书

with the world's largest radio telescope at the Green Bank Observatory.

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,

两三个月后，

news of this proposal got leaked to the press

这份项目书的消息 被媒体刺探到了

and now there are thousands of articles,

好吧，现在有几千篇报道

over 10,000 articles, on this star alone.

可能超过一万篇， 单单关于这颗恒星。

And if you search Google Images,

如果你用谷歌图片搜索，

this is what you'll find.

你会找到这些。

Now, you may be wondering, OK, Tabby, well,

现在，观众可能会问， 好吧塔碧，

how do aliens actually explain this light curve?

究竟怎么用外星人 去解释这光度曲线？

好吧，想象一个 远比我们发达的文明，

OK, well, imagine a civilization that's much more advanced than our own.

In this hypothetical circumstance,

在这个假设条件下，

this civilization would have exhausted the energy supply of their home planet,

这个文明肯定耗尽了 他们母星的能源。

so where could they get more energy?

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,

你看，他们有一颗宿主恒星， 就像我们有太阳一样，

and so if they were able to capture more energy from this star,

那如果他们能够 从恒星中抓取更多能量，

then that would solve their energy needs.

那就可以解决 他们的能源需求。

So they would go and build huge structures.

所以他们可能会去 建造这些巨型建筑。

These giant megastructures,

这些巨大的超级建筑，

like ginormous solar panels, are called Dyson spheres.

比如巨大的太阳能电池板， 叫做“戴森球”。

This image above

上面这些图片

are lots of artists' impressions of Dyson spheres.

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,

很难去想象这些东西 究竟有多庞大，

但你可以这么想。

but you can think of it this way.

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

这些巨型结构中的 最简单的单元，

is 100 times that size.

是 100 倍地月距离。

They're enormous.

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

你可以看到这为什么 可以造成数据中异常

such as uneven, unnatural looking dips.

如此不对称，不自然的负峰。

But it remains that even alien megastructures

但是即使是 外星人的超级建筑，

cannot defy the laws of physics.

也不能违反物理定律。

You see, anything that uses a lot of energy

任何使用大量能量的东西

is going to produce heat,

将会产生热量，

and we don't observe this.

但是我们没有观测到。

But it could be something as simple

但这有可能只是非常简单的，

as they're just reradiating it away in another direction,

他们把热量释放到了另一个方向，

just not at Earth.

没有对着地球。

Another idea that's one of my personal favorites

我个人最喜欢的 另一种可能性是

is that we had just witnessed an interplanetary space battle

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

我承认， 这会产生很多尘埃，

that we don't observe.

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

那谁说他们不会秋风扫落叶 一般清理干净尘埃，

for recycling purposes?

回收利用？

(Laughter)

（笑声）

You can see how this quickly captures your imagination.

你看，这很快 就激发想象力啦。

Well, there you have it.

好啦，故事就是这样。

We're in a situation that could unfold

我们的处境是，

既可以解释成 我们没搞清楚的自然现象，

to be a natural phenomenon we don't understand

or an alien technology we don't understand.

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?

那么，接下来呢？

We need to continue to observe this star

我们需要继续观测这颗恒星

to learn more about what's happening.

去更详细地了解发生了什么。

But professional astronomers, like me,

然而，像我这样的职业天文学家，

we have limited resources for this kind of thing,

我们在这方面的资源有限。

and Kepler is on to a different mission.

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,

所以我很高兴地说，又一次，

citizen scientists have come in and saved the day.

公民科学家加入进来救场。

You see, this time,

你看，这次，

amateur astronomers with their backyard telescopes

业余天文爱好者 拿着他们的业余望远镜

stepped up immediately and started observing this star nightly

立刻加入进来， 开始在自己的观测点

夜观此星。

at their own facilities,

and I am so excited to see what they find.

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

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，

because we just weren't looking for something like this.

因为我们单纯没有把 这样的恒星当成目标。

And what's more exciting

更激动人心的是，

is that there's more data to come.

将来还有更多的数据。

There are new missions that are coming up

有新的观测项目要上马，

that are observing millions more stars

准备观测百万颗恒星，

all over the sky.

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?

而如果我们一颗都没找到， 那又意味着什么？

Thank you.

谢谢。

(Applause)

（掌声）