top
第259期
(2017/10/26出刊)
人類首度見證 中子星重力波 解黃金之謎

 Two months ago, scientists found something for the first time: the signals from two neutron stars crashing into each other. The discovery would soon reveal secrets of the cosmos, including how gold was created.
 The crash happened 130 million years ago, while dinosaurs still roamed on Earth, but the signal didn't arrive on Earth until August 17 after traveling 130 million lightyears. A light-year is 9.46 trillion km.
 The crash created a fierce burst of gamma rays and a gravitational wave, a faint ripple in the fabric of space and time first theorized by Albert Einstein a century ago. Neutron stars, made when massive stars explode in supernovas, are the smallest, densest stars known to exist. A teaspoon of a neutron star has a mass of about a billion tons.
 Before August, the only other gravity waves detected by LIGO were created by colliding black holes. Black holes don't let any light escape, so astronomers couldn't see anything. This spectacular crash is what scientists have been waiting for.
 Measurements of the light and other energy coming out from the crash have helped explain how fast the universe is expanding, and where heavy elements like platinum and gold come from.

 兩個月前,科學家首次偵測到兩顆中 子星互相碰撞後產生的訊號,這個發現 可望解開宇宙之謎,包括黃金的成因。
 這次碰撞發生在1.3 億年前,當時恐龍 仍生活在地球上,但是碰撞產生的訊號 直到今年8 月17 日才抵達地球,亦即旅 行了1.3 億光年。一個光年約為9.46 兆 公里。
 這次的中子星碰撞釋出強烈的伽瑪射 線與重力波,在時空織布上掀起微弱的 漣漪,這也是愛因斯坦在一個世紀前率 先提出的理論。中子星是大質量超新星 爆炸後形成的星體,也是宇宙中已知最 小、密度最大的星體。一茶匙的中子星重 量就高達10 億噸左右。
 在今年8 月之前,美國干涉重力波偵 測站(LIGO)觀測到的重力波都是出於 黑洞碰撞,但黑洞碰撞不會釋出光,所以 天文學家什麼也看不到。這次的天文奇 觀是科學家期待已久的現象。
 藉由測量這次碰撞釋出的光與其他能 量,有助於解開一些謎團,包括宇宙的擴 大速度、白金與黃金等重金屬的來源等。