PTE考生目前最大的问题之一就是练习题缺乏。除了有限的基本官方书（PLUS，Testbuilder, OG）之外就没有题了。很多英语基础不是很扎实的同学很难找到练习材料。悉尼文波雅思PTE培训学校专门为澳洲，尤其是悉尼、墨尔本的PTE考生准备了适合PTE听力阅读练习的科学60秒。各位PTE同学可以练习PTE听力中的summarise spoken text和PTE口语中的retell lecture，练习记笔记技巧和复述。
60秒科学节目（SSS）是科学美国人网站的一套广播栏目，英文名称：Scientific American – 60 Second Science,节目内容以科学报道为主，节目仅一分钟的时间，主要对当今的科学技术新发展作以简明、通俗的介绍，对于科学的发展如何影响人们的生活环境、健康状况及科学技术，提供了大量简明易懂的阐释。
This is Scientific American — 60-Second Science. I’m Christopher Intagliata.
The Earth is studded with telescopes, listening for electromagnetic radiation from the great beyond. And a decade ago,
astronomers stumbled upon a mysterious signal: a powerful pulse of radio waves just a few thousandths of a second long. Mysterious because:
“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.”
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 ManasviLingam investigated another possibility: “We know of one simple way to generate very powerful radio waves, and that’s using a radio antenna.”
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?
Using those energy and engineering constraints, 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.
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? “The idea is that an advanced technological 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.
Thanks for listening for Scientific American — 60-Second Science Science. I’m Christopher Intagliata.