黑洞什么样？有图有真相！
人类史上首张黑洞“证件照”今天终于“冲洗”出来了！
首先让我们来看一看黑洞的“真面目”
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The first-ever image of a black hole was unveiled on Wednesday, marking a historic breakthrough in astrophysics research.
The moment was announced concurrently at press conferences held in the six cities of Shanghai, Taipei, Tokyo, Washington, Brussels, and Santiago.
The image was extracted from data collected by the Event Horizon Telescope (EHT), a global program in 2017 that cost scientists a little over two years to build.
看完了黑洞的首张“证件照”，和你想象中的样子是不是有很大的差别？
在等待黑洞照片“官宣”的过程中，“脑洞”大开的网友们Po出了他们心中的“黑洞照”
比如
也有人觉得电影《星际穿越》给出了“黑洞长什么样”的标准答案
当然还有这样的搞笑版“黑洞照”
什么是黑洞？
也许很多人是通过科幻电影对于黑洞的瑰丽想象认识黑洞的。
那么黑洞究竟是什么呢？
理论上，黑洞是爱因斯坦广义相对论预言存在的一种天体，它具有的超强引力使得光也无法逃脱它的势力范围，该势力范围称作黑洞的半径或事件视界。
A black hole is a region in space where the pulling force of gravity is so strong that even the light cannot escape.
Albert Einstein's theory of general relativity predicts that a sufficiently compact mass can deform space-time to form a black hole. The boundary of the region from which no escape is possible is called the event horizon.
根据质量，天文学家们将宇宙中的黑洞大致分成三类：原始黑洞、恒星黑洞以及星系黑洞。
Black holes can come in a range of sizes, but there are three main types of black holes.
The smallest ones are known as primordial black holes or miniature black holes. Scientists believe this type of black hole is as small as a single atom but with the mass of a large mountain.
The most common type of medium-sized black holes is called "stellar." Dozens of stellar black holes may exist within the Milky Way galaxy.
Supermassive black holes are the largest ones, which can have a mass equivalent to billions of suns.
黑洞研究史概览
十八世纪
数学家拉普拉斯等人基于牛顿万有引力，提出了“暗星”的存在，可以算是黑洞概念的雏形。
1915年
爱因斯坦提出广义相对论，给出了爱因斯坦场方程。
1916年
德国天文学家卡尔•史瓦西通过计算得到了爱因斯坦引力场方程的一个真空解，表明如果将大量物质集中于空间一点，其周围会产生奇异的现象，即在质点周围存在一个界面——事件视界面，一旦进入界面，即使光也无法逃脱。
1967年
美国科学家约翰•惠勒首次使用了“黑洞”一词，来描述引力坍缩体。
1971年
基于X射线探测卫星乌呼鲁获取的数据，一个非典型射电源——天鹅座X-1，被暂定为黑洞，这是宇宙中发现的第一个黑洞。
如何“拍”到黑洞？
2017年，全球200多名科学家组成一个研究团队，成立“事件视界望远镜”项目（Event Horizon Telescope，简称EHT）。
该项目通过位于全球的八个天文望远镜，构建一个口径等同于地球直径的“虚拟”望远镜，从而收集海量数据，勾勒出黑洞的模样。
EHT的“照相镜头”对准了两个黑洞：位于银河系中心的人马座 A*黑洞以及位于星系M87中的黑洞。
Sagittarius A* is the black hole at the center of the Milky Way galaxy. / Photo via NASA
In 2017, a project named "Event Horizon Telescope" (EHT) was set up. Scientists from the EHT team combined the power of eight radio observatories around the world to create a "virtual" radio telescope that's about the size of our earth.
This large "virtual" radio telescope helps researchers make out the details of two nearby supermassive black holes. The first, called Sagittarius A*, is at the center of Milky Way galaxy. It's about 26,000 light-years from the earth. The second supermassive black hole resides inside an extremely large galaxy called Messier 87 (M87), which is about 53.5 million light-years away from our planet.
第一张黑洞“证件照”有何意义？
此前，科学家们往往通过测量黑洞对周围天体的作用和影响，间接推测黑洞的存在：比如通过观测恒星的运动轨迹来探究它是否正在围绕黑洞运动；使用精密的科学仪器探测黑洞“吸食”周围的天体物质时喷射出高能粒子。
许多科学家认为，此次公布的照片，为证明黑洞的存在提供了直接证据。
A black hole is invisible as the strong gravity that is pulling all of the light into its center. So how can we find black holes in the universe?
Scientists previously depended on exploring the black holes' effects on other stars to speculate their existence. For example, when a star is orbiting a certain point in space, scientists can study the star's motion to find out if it is orbiting a black hole. Some scientific instruments can also see the high-energy particle which is produced when a black hole and a star are orbiting close together.
Over the past years, images of black holes have been limited to pictures of the stuff surrounding them, or to computer models. Scientists believe that this groundbreaking image provides direct visual evidence to confirm years of scientific speculation of black holes.
“蜗牛角上争何事，石火光中寄此生”
面对浩瀚的宇宙，人类不过是最渺小的存在
今天我们掀起了黑洞的“神秘面纱”
未来还有更多的宇宙未知等待探索
部分英文综合自NASA
部分中文综合自央视新闻、瞭望周刊