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On April 10th, 2019 the world saw, for the first time ever, visual confirmation that black holes actually exist.
2019年4月10日，全球首次见到了黑洞实际存在的图像。
Technically, up until now they only existed in theory.
从技术角度来讲，在此之前，黑洞只存在于理论中。
We were pretty sure they were there based on stuff like stars with weird orbits at the center of our galaxy,
我们很确信黑洞之所以存在是有原因的，比如太阳系中心存在一些轨道奇异的恒星、
and really strong radio and other electromagnetic signals coming from really small points in space.
强大的无线电等电磁信号（由宇宙中极小的点发射而出）。
But we never actually saw one. Which is why it made such a big splash when researchers released this image of M87*,
但以前的我们实际上并未看到过这样的景象。所以，当科学家公布M87*的图像时，会激起如此的轩然大波。
the supermassive black hole at the center of the galaxy M87, 55 million light years away from Earth.
M87*是M87星系中心的一个特大质量黑洞，距离地球5500万光年远。
It's all thanks to the Event Horizon Telescope, or EHT, a collaboration of over 200 individuals spanning 13 institutions and the globe.
捕捉到这样的图像要感谢视界望远镜（EHT），这个项目有200多人参与，他们来自世界上的13个研究所。
Last week, they published their findings in six papers in The Astrophysical Journal Letters.
上周，他们在《天体物理学杂志通讯》的6篇论文中发表了自己的发现成果。
In this now famous fuzzy photo, we can't actually see the black hole of course.
这张著名的图像有些模糊，所以我们通过它并不能看到黑洞。
Or, rather, its event horizon, the final point of no return for light and matter.
也就无法看到视界，即光和物质航线临界点。
The black shadowy blob at the center is actually about 2.5 times bigger than the event horizon.
那个中央的黑色朦胧斑点大概是视界的2.5倍。
That's as close as the laws of physics will let us get.
这已经接近于物理学定律能让我们抵达的极限了。
Turns out it's hard to take a picture of something that light cannot escape from.
我们发现，如果一个物体无法反射出光，那么我们很难捕捉到它的图像。
Now to snap this picture, we needed a telescope with a resolution of 2,500 times better than the Hubble Space Telescope.
所以，为了给它拍摄图像，我们需要一个望远镜，其分辨率得达到哈勃望远镜的2500倍。
In astronomy, angular resolution refers to the ability to see two objects that appear close together in space as their own distinct sources.
在天文学上，角坐标分辨率是指看分辨两个距离很近的物体的能力。
But it really just comes down to how much detail you get in to an image.
其实这个指标看的是对一张图像细节的分辨能力。
And there are really only two ways to improve it.
其实只有2种方法能提高这种能力。
One is to study light that has a shorter wavelength.
一是研究波长较短的光。
The other is to make your telescope bigger, specifically, increase its collection area, or the size of whatever it uses to collect light.
二是扩大望远镜规模，即增加望远镜的收集区，即收集光的区域的大小。
Radio waves are really the best waves to use for studying supermassive black holes, because that's where they, or rather, the material around them, emit most of their light.
无线电波是研究特大质量黑洞最好的波，因为这是它们或者说它们附近的物质放出大部分光的地方。
Also, longer wavelength light does better at penetrating all that gas and dust between us and what we're trying to look at.
此外，波长越长的光穿透气体和灰尘的能力越强，就能帮助我们观测事物。
So to study a black hole like this, astronomers are interested in radio wavelengths of about 1 millimeter.
所以，要研究这样一个黑洞，天文学家对大概1毫米左右波长的无线电波感兴趣。
But there's a catch. At those wavelengths, the telescope you need to resolve a black hole would have to be, like, as big as a planet.
但有一个问题：如果是这样的波长，那么能解析黑洞的望远镜就被必须跟行星一样大。
So the EHT collaboration came up with one.
于是，EHT项目组就想到了一个主意。
They turned the entire Earth into a telescope.
他们将地球作为这个望远镜。
Now, just cause you didn't notice any construction in your particular backyard, that doesn't mean it didn't happen.
虽然大家在自家后院并未发现任何动静，但这并不意味这件事没发生。
Here's a weird thing about telescopes: you can take a bunch of small ones, spread them out, and get computers to link them all up, and pretend to have a telescope that's as big as the distance between them.
关于望远镜，有个奇异之处：你可以把很多小的望远镜分布在不同的地方，然后通过多台计算机连接，做成一个超大望远镜的感觉，可以与观测者与被观测物之间的距离相抗衡。
And this actually works. You get gaps in the images, but the same amount of resolution.
而这种方法也真地奏效。图像和图像之间虽有差距，但分辨率是相同的。
This technique is called interferometry. Say you have two telescope dishes spaced a kilometer apart.
这种技术名为干扰量度法。假设有两个望远镜相隔1000米。
They're both pointed at the same target in the sky.
它们所观测的目标是天空中的同一个物体。
Light coming from that source is going to hit the two at slightly different times, but if you have super accurate clocks to keep track of that, you can combine the two signals.
被观测物散发出的光打在这两个望远镜上的次数会略有不同，但如果有两个极为精确的时钟可以记录这种细微差别的话，那么我们可以合并这两个信号。
The light waves from the two telescopes will interfere with one another, like ripples from two different sources in a pond.
来自两个望远镜的光波会彼此干扰，就像池子里2个不同的物体所发出的涟漪。
But with some sophisticated computer programs, you can use that interference to generate an image.
但有了精密的计算机程序后，这种干扰可以为我所用，从而生成一张图像。
And suddenly, it's like you had one dish a kilometer across.
这样子，就仿佛每隔1000米就有一架望远镜一样。
The more telescopes you have, the more complex it gets, but the better your image will be.
所布置的望远镜越多，就会越精密，图像也会越清晰。
To create the EHT, astronomers had to upgrade, link, and synchronize eight pre-existing telescopes around the world, from Hawai'i to Spain to Antarctica.
为了创建EHT项目，天文学家们必须对8个现有的望远镜进行升级、互联和同步，这8架望远镜分布于世界各地，从夏威夷到西班牙再到南极洲不一而足。
They collected petabytes worth of data, which was flown on hard drives to supercomputers in the US and Germany to be processed into a picture.
他们收集了大量数据，这些数据通过硬盘驱动器传输到美国和德国的超级电脑上，进而加工成图像。
Which requires the programs not to just stitch together separate images, but eliminate all the noise coming from stuff that's not the black hole,
这不仅需要各个程序将不同的图像连接在一起，还需要将不属于黑洞的杂音消去。
and then to fill in all the gaps due to us not having a single telescope dish the size of a planet.
然后还要将非单一望远镜拍摄所造成的空白填补上。
Filling in those gaps is kind of like inferring the melody of a well-known song when you can only hear some of the notes.
填补这些空白有点像推测一首知名歌曲的旋律，但只给你几个音符让去你推测。
But it might be difficult to narrow it down to just one song.
但很难缩减到一首歌里。
Like, maybe it's Under Pressure or maybe it's Ice Ice Baby.
比如，这首歌可能是《面临压力》，也可能是《冰冰宝贝》。
That's why EHT didn't produce just one image.
因此，EHT项目组生成的图像不止一张。
Initially, there were actually four. Four separate teams worked independently from one another to produce the first images to avoid potential bias.
一开始，有4个单独的项目组独立运作，他们生成了第一批图像。这样做是为了避免先入为主。
They used two different classes of algorithms, but in the end they all came out relatively the same.
他们用了2组不同的算法，但最后得到了结果基本上是一致的。
Most importantly, you can see the shadow in the middle of all of them.
最重要的是：在图像中央都可以看到阴影。
That proved their techniques were working.
这样就证明这种方法是有效的。
After some more refinement, the now-famous final image was made by averaging three different processing methods.
在进行了进一步修近后，现在世人皆知的那幅图像终于通过将3种处理方法取均值而得到。
And the Internet, rightly, went wild. We are, like, way late to this party. Sorry.
于是，网络上疯传这幅图。我们本期节目播出之时，这张图已经传疯了。
Now in the future, there are several ways to improve images like these.
今后，还有多种方法可以精进图像的精准度。
One is to simply look at the object for longer.
一种方法是单纯地观测物体，但是观测时间要更久些。
The collaboration observed M87* over 4 nights, between 7 and 25 times each night, collecting data for just three to seven minutes apiece.
EHT项目用时4晚观测到了M87*，每晚观测次数在7-25次之间。每条收集的数据大概只有3-7分钟。
Another is to collect data at other wavelengths of light, which will require upgraded technology with faster processing speeds.
还有一种方法是在其他光的波长段收集数据，这种方法需要进行技术升级，加快处理速率。
We could also add in more telescopes, as well as add ones that have larger collecting dishes.
我们也可以增加更多的望远镜，或者纳入收集数据量更大的望远镜。
Which EHT is working on. Naturally, astronomers want to apply this method to study other supermassive black holes.
这也是EHT正在做的事情。天文学家当然也希望能将这个方法用于研究其他的特大质量黑洞。
Like Sagittarius A*, the strong radio source at the center of our galaxy, the Milky Way.
比如人马座A*，这是银河系中央的一个强大无线射电源。
It's also about a thousand times less massive than M87*, but way, way closer.
它的质量大概是M87*的1/1000，只是离我们更近了。
But it's hiding behind a lot of stuff that will interfere with the signal we receive, which future observations will need to account for.
但在它与我们之间有许多可以干扰信号的物质存在，这是今后的观测所要考虑的问题。
The first ever black hole picture took the internet by storm.
黑洞的第一幅图像引起了网络热议。
But when you understand how much work went into making it, and how many talented scientists were involved, and how they turned our planet into a telescope?
但大家是否了解这背后所付出的努力、期间有多少位杰出科学家的加入以及他们是如何将行星变为望远镜的呢？
It only gets cooler. Thanks for watching this episode of SciShow Space News, which we couldn't make without the support of our patrons.
如果知道这些，你就会觉得这张图像更酷了。感谢收看本期的《太空科学秀》以及大家的支持。
If you like what we do here, and you're interested in being a part of it, check out patreon.com/scishow.
如果您喜欢我们的节目并想参与其中的话，可以登录patreon.com/scishow看看。
