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(Probably Not a) Giant Alien Antenna¹ 强大的“外星人”光束

The Earth is studded with telescopes, listening for electromagnetic radiation from the great beyond. And a decade ago, astronomers² stumbled upon a mysterious signal: a powerful pulse of radio waves just a few thousandths of a second long. Mysterious because:

地球上星罗棋布到处都是望远镜，监听来自广袤的宇宙中的电磁辐射。十年前，天文学家们偶然发现了一个神秘的信号：强大的无线电脉冲信号。这信号非常神奇，因为：

"What is the nature of the sources?" Avi Loeb, a theoretical astrophysicist at Harvard. Whatever the sources are, he says, "they seem to be brighter by 10 of billions of times more than the brightest radio sources we know about."

“这些信号来源的实质是什么?”艾维·罗卜是哈佛大学的天体物理学家。他表示，无论这些信号的来源是什么，“似乎都比我们知道的最亮的无线电来源还要亮数十亿倍。”

The radio pulses are known as "fast radio bursts"—and Loeb says you'd need something tens of billions of times brighter than a pulsar to produce them. So he and his colleague Manasvi Lingam investigated another possibility: "We know of one simple way to produce very powerful radio waves, and that's using a radio antenna."

这些无线电脉冲被称为“快速无线电脉冲”—— 罗卜表示产生这种脉冲信号，是由比脉冲星要亮数百亿倍的脉冲星。所以，罗卜和同事Manasvi Lingam调查了其他的可能性：“我们知道其他的办法可产生非常强的无线电波，那就是利用无线电天线。”

A radio antenna built and controlled by extraterrestrials, to be more precise. Loeb and Lingam did the math on how big that stellar-powered radio antenna would have to be, to transmit signals like fast radio bursts. And whether it would even hold up from an engineering standpoint—like would it melt under its own heat?

更加准确的说，是由外星人建立并控制的无线天线。罗卜和Lingam通过数学计算由星体提供动力的无线电天线传送快速无线电信号有多强大。并且从工程学角度而言，可以站得住脚吗，由于自身的热度，是否会融化?

Using those energy and engineering constraints³, they found that the radio beam emitter would have to be twice the diameter of Earth. Pretty big—for us. But at least theoretically possible, he says, for more advanced civilizations. The study is in The Astrophysical Journal Letters.

利用能源以及工程约束，他们发现无线电光束发射器必须是地球直径的两倍。对于我们来说，这是太大了。但是，罗卜表示，至少从理论层面来讲，可以推进更为先进的文明。该研究结果发表在《天体物理学》杂志上。

To be clear: this is definitely not proof that intelligent aliens exist. It's just proof of concept, that someone, smarter than us, could in theory build such a thing. And why you might build it?

需要明确的是：这绝对不是智慧外星人存在的证据。这只是一种概念的证明，比我们更加聪明的人，可以在理论上构建这种快速无线电脉冲。可是为什么要构建呢?

"The idea is that an advanced technological⁴ civilization could produce a beam of radio waves focused on a sail that is pushing on the sail, such that eventually the sail will reach a fraction of the speed of light." We'll just have to see what arrives first: alien sailors, pushed by radio waves? Or the technological advances to allow us humans to build such a thing ourselves.

“先进的技术文明可以产生一种推动发展的无线电光束，最终将会达到一小部分的光速。”我们只需要观看是什么首先到达:由无线电推动的外星人舵手?还是由于技术进步，我们人类首先自己创造了这种光束。