人类首次“看到”引力波 终于找到金子的源头了
On Monday, scientists who won a Nobel Prize for their discovery of gravitational waves announced the first detection of the collision of two neutron stars. Astronomers detected the merger from 130 million light-years away, in the galaxy NGC 4993, on the morning of August 17. The team alerted astronomers all over the world to the event right after it happened, helping them point telescopes directly at the scene of the crash. 此次引力波事件具有极为重要的意义,天文学家使用了大量地面和空间望远镜进行观测,形成了一场天文学历史上极为罕见的全球规模的联合观测。不过,在引力波事件发生时,仅有4台X射线和伽马射线望远镜成功监测到爆发天区,中国的“慧眼”望远镜便是其中之一。 根据探测记录,科学家复原出整个事件发生的过程:在距离地球1.3亿光年的长蛇座星系NGC4993中,两颗中子星互相绕转。在并合前约100秒时,它们相距400公里,每秒钟互相绕转12圈,并向外辐射引力波。它们越转越近,直至最终碰撞在一起,形成新的天体,并发出电磁辐射。 The collision created the first observed instance of a single source emitting ripples in space-time, known as gravitational waves, as well as light, which was released in the form of a two-second gamma ray burst. It is being hailed as the first known instance of multi-messenger astrophysics: one source in the universe emitting two kinds of waves, gravitational and electromagnetic. 你戴的金戒指来自中子星碰撞? 中国紫金山天文台副研究员金志平参与的国际团队,通过对此次引力波光学信号的观测和光谱分析,首次提供确凿证据证实,中子星合并是宇宙中金银等元素的主要起源。金志平说:“这就是宇宙中的‘巨型黄金制造厂’。” These images revealed a radioactive soup giving birth to unfathomable amounts of platinum, gold, and silver — not to mention elements like the iodine found in our bodies, the uranium in nuclear weapons, and the bismuth in Pepto-Bismol — while shooting those materials deep into space. The two neutron stars most likely merged to form a black hole, though the tiny bit of neutron star that escaped — and formed new elements — could get recycled into planets like Earth where aliens may eventually dig up the metals as we have. 什么是“引力波”? 引力波是由黑洞、中子星等碰撞产生的一种时空涟漪,宛如石头丢进水里产生的波纹。百年前,爱因斯坦广义相对论预言了引力波的存在,但直到2015年人类才首次探测到引力波,3名美国科学家因此获得今年的诺贝尔物理学奖。 Gravitational waves were first directly detected two years ago, proving Albert Einstein's theory of general relativity, and recently, three scientists were awarded the Nobel Prize in Physics for their work on that first detection. Those gravitational waves were the result of two black holes colliding, and the signal lasted for only a fraction of a second. Because black holes don't emit light, these waves were invisible and only "heard" as thumps.
这是人类第五次探测到引力波,然而科学界的兴奋之情甚至不亚于第一次探测到引力波时。因为与之前被探测到的四个引力波信号不同,这次探测到的引力波信号GW170817来自1.3亿光年外两颗并合的中子星,而且科学家第一次同时观测到了引力波及其电磁对应体,以及科学家预言的巨新星现象。
2. This is the first time gravitational waves from the merger of binary neutron stars have been observed. 3. This observation is the first to definitively identify binary neutron star collisions as a source of short gamma-ray bursts. Theorized for many years, this is the first direct link between those phenomena. 4. This discovery is the first verification of a "kilonova" explosion, confirming binary neutron star collisions as one source for the universe's heaviest elements, such as gold and uranium. 5. This is the first binary neutron star pair confirmed outside of our own Milky Way galaxy, and this is the closest to Earth that astronomers have seen a gamma ray burst. 6. The gravitational wave signals from GW170817 have enabled scientists to measure the expansion rate of the universe in a completely new way. 7. The partnership between LIGO and Italy-based Virgo allowed telescopes to rapidly turn their attention towards the area of sky where the neutron stars collided. 8. This event presents the strongest evidence to date for the detection of a gamma-ray burst off-axis, which means the cone emission from the explosion is not pointed directly at Earth. 9. The gravitational waves and light waves arrived within seconds of each other, suggesting they may travel at the same speed and confirming a prediction of Albert Einstein. The difference in detection time is likely a reflection of what happens during the explosion process. 10. Only gravitational wave observatories can directly detect unexploded binary neutron stars outside of our local galactic neighborhood, or directly observe the stars pre-collison, albeit only briefly before impact. |