英语听力文摘电视“雪花”

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Better Than Barney

某天夜里，你一觉醒来发现电视机忘了关，节目却已播完，电视屏幕上“嘶嘶”地闪着雪花，也许你不会想到，再普通不过的雪花噪音竟包含来自137亿年前宇宙大爆炸的遗物——微波背景辐射。宇宙微波背景辐射是一种低噪音的电磁波辐射。目前科学界普遍接受的宇宙起源理论认为，宇宙诞生于距今约137亿年前的一次大爆炸。微波背景辐射作为大爆炸的“余烬”，均匀地分布于宇宙空间。随着宇宙不断膨胀，其背景辐射的温度也逐渐降低，现在的温度只有约2.725℃，它是宇宙中最完美的黑体辐射。“微波背景辐射其实就在我们身边。当然肉眼是看不到的。电视机通过天线接收的电磁波中，有1%来自微波背景辐射。这种电磁波对人体健康没有影响，而且随着宇宙的膨胀，力量越来越弱，温度越来越低，但它不会消失。

What is better than (1)Barney? Really? Learn about the Big Bang on this Moment of Science.

We’ve heard it a hundred times before. There’s never anything to watch on television. Fifty channels and not one worth sitting down to. Well, (2)PBS is nice. But you get the idea.

If you feel bored by TV, why not try a little experiment? All you have to do is turn to a station where nothing is currently being broadcast. What do you see?… That blank screen isn’t really blank. Rather it’s full of random-seeming flashes of light, sometimes called “snow.” Now, what if we told you that you have just discovered evidence of the Big Bang?

It’s true. Around three percent of the little sparkles of light you see on an unused channel are caused by (3)photons (4)left over from the Big Bang, the explosion that (5)started off our entire universe. Here’s how it works.

For about 300,000 years after the Bang, the universe was so dense that photons couldn’t go anywhere without (6)bumping into electrons and being (7)annihilated. At that 300,000 year mark, however, things (8)cooled off enough to allow atoms to form. That gave electrons something to do instead of always (9)intercepting photons. The photons were set free, to cruise endlessly through space, right up to the present day — about 15 billion years later.

These photons fill all of space, trillions passing through your body every second. They are so weak by this point, though, that you can’t see them or sense them. Unless you open up an (10)antenna to a similar wavelength and listen. Your television set is just the machine to do this.

So take another look at that (11)fuzz. It’s brought to you by the origin of the cosmos.

译文：

我们已经听过很多次了，没有什么好看的电视节目。50个频道却没有一个值得看。嗯，公共广播是一个不错的选择。但是你知道的...

如果你觉得电视节目很无聊，为什么不尝试一个小实验呢?你所要做的就是调到一个没有任何节目的频道。你看到了什么?...黑色的屏幕并不真正是黑的。相反屏幕上似乎是充满了随机排列的小光点，有时叫做“雪花”。现在如果我告诉你你发现了宇宙大爆炸的证据，你相信吗?

这是真的。在你看到的这些未使用频道上出现的小光点中，有三分之一是由宇宙大爆炸遗留下来的光子引起的。这些爆炸形成了我们整个宇宙。现在，让我们看看它们是怎样工作的吧!

宇宙大爆炸30万年后，密度很大，光子走到哪都会碰到电子相互结合而湮没，但是这时候温度下降，原子得以形成。这就让电子有事可做，而不总是拦截光子。光子自由后，不断地穿梭于太空中，直到今天-大概150亿年以后。

这些光子占满了所有的空间。每一秒就有几万亿个光子穿过你们的身体。这一刻它们是如此微弱，你既不能看见也不能感受到。除非你打开一个有类似波长的天线的设备听听看，你的电视就是这样的机器。

再看看绒毛，这是从宇宙起源时就带来的。

Notes:

(1)barney ['bɑ:ni] n.[口]大吵大闹;拉曳器

(2)PBS abbr. (美)公共广播公司(Public Broadcasting Service)

(3)photons ['f?u,t?ns] n.光子;光量子(photon的复数)