距地球6500万光年外的外星人能看到活着的恐龙吗？：英语精读讲义

We don't usually think about aliens when we think about dinosaurs,

当我们想到恐龙时，通常不会想到外星人，

but someone by the name of Dr. Matt Caplan 短語搭配

但是一位名叫马特·卡普兰博士的人

recently asked a very fascinating question about these two subjects.

最近问了一个关于这两个主题的非常有趣的问题。

In his search for an answer,

在寻找答案的过程中，

he was forced to delve into topics such as light speed, black holes, and telescopes. 講解

他不得不深入研究光速、黑洞和望远镜等主题。

Join him in his exploration in this episode of The Infographics Show,

和他一起在这个视频系列 The Infographics Show 中探索，

Could Aliens 65 Million Light Years Away From Earth See Dinosaurs Alive?

6500万光年外的外星人能看到活着的恐龙吗？

Don't forget to subscribe and click the bell button so that you can be part of our notification squad.

别忘了订阅并点击小铃铛，这样你就能成为我们通知小队的一员。

In theory, the answer is yes.

理论上，答案是肯定的。

Light that left Earth 65 million years ago

6500万年前离开地球的光

is now 65 million light years away.

现在距离我们6500万光年。

So if aliens knew where to point their telescope, they could see dinosaurs. 語法

所以，如果外星人知道该把望远镜指向哪里，他们就能看到恐龙。

But is it possible for anyone, even a super technologically advanced alien, 語法

但是，任何人，即使是技术超发达的外星人，

to build a telescope powerful enough?

有可能造出足够强大的望远镜吗？

Light takes time to travel. 短語搭配

光传播需要时间。

So looking at anything is equivalent to looking back in time. 短語搭配

所以，看着任何东西都等同于回顾过去。

And the farther away it is,

离得越远，

the farther back in time you see.

你能看到的时光就越久远。

For example, if your eyes are about 2 ft away from the screen you're watching this video on,

例如，如果你的眼睛距离你观看这个视频的屏幕大约两英尺，

then you're seeing this video as it was about 2 nanoseconds earlier.

那么你看到的这个视频大约是2纳秒前的画面。

That's basically instantaneous and way faster than the human reaction time. 用詞

这基本上是瞬间的，并且比人类的反应时间快得多。

So the light speed delay doesn't muck up our daily lives. 短語動詞

所以光速延迟不会打乱我们的日常生活。

But if you look at the moon,

但如果你看月亮，

the light left it about a second ago,

光大约在一秒钟前离开了它，

long enough for there to be noticeable pauses in communication with Apollo astronauts. 語法

这个时间足以导致在与阿波罗宇航员通讯时出现明显的停顿。

For the sun,

对于太阳来说，

it's closer to 8 minutes.

接近8分钟。

So if for some crazy reason the sun disappeared,

所以，如果出于某种疯狂的原因，太阳消失了，

then no one on Earth would know it for about 8 minutes.

那么地球上的人大约在8分钟内都不会知道。

When astronomers look through their telescopes at distant stars,

当天文学家通过望远镜观察遥远的恒星时，

they're seeing them as they were many years ago.

他们看到的是许多年前的恒星。

Coincidentally, this is one way astronomers measure distance.

巧合的是，这也是天文学家测量距离的一种方法。

A light year is just the distance it takes light to travel in a year,

光年仅仅是光在一年内传播的距离，

conveniently tying distance and age into one number. 語法

方便地将距离和年龄结合成一个数字。

So again,

所以，再次强调，

in theory,

理论上，

the light that left the Earth millions of years ago

数百万年前离开地球的光

is now millions of light years away.

现在已经在数百万光年之外。

And in that light is a glimpse of dinosaurs.

而在这束光中，就隐藏着恐龙的一瞥。

Since the dinosaurs went extinct 65 million years ago,

既然恐龙在6500万年前灭绝了，

then the closest alien that could see dinosaurs,

那么能够看到恐龙的最近的外星人，

if he knew where to point his telescope,

如果他知道该把望远镜指向哪里，

is 65 million light years away.

是在6500万光年之外。

But in practice, 表達脈絡

但在实际操作中，

it's much harder because the Earth is small

这要困难得多，因为地球很小，

and 65 million light years is a long distance.

而且6500万光年是一段很长的距离。

For perspective, 表達脈絡

为了让你有个直观的了解，

the vast majority of the visible stars in the night sky

夜空中绝大多数肉眼可见的恒星，

are within about 1,000 light years of us.

都在距离我们大约1000光年以内。

The Milky Way is about 100,000 light years across.

银河系的直径大约为10万光年。

The nearest galaxy,

最近的星系，

Andromeda,

仙女座星系，

is about 2.5 million light years away.

距离我们约250万光年。

At 65 million light years,

在6500万光年的距离上，

our alien astronomers would be in the far-off Virgo cluster of galaxies.

我们的外星天文学家将处于遥远的室女座星系团中。

So,

所以，

if these aliens want to see dinosaurs,

如果这些外星人想看恐龙，

they're going to need a big telescope.

他们需要一台很大的望远镜。

Human astronomers can only barely resolve nearby planets in our own galaxy, 表達脈絡

人类天文学家目前几乎只能勉强分辨出我们银河系内的近邻行星，

let alone extragalactic planets.

更不用说银河系外的行星了。

In fact,

事实上，

only a handful of observations have been reported of extragalactic exoplanets. 短語搭配

关于银河系外系外行星的观测报告寥寥无几。

One is the Andromeda and the other is cheating.

一个是在仙女座星系，另一个则有点“作弊”。

It's only 2,000 light years away from Earth

它距离地球只有2000光年，

because it was acquired by the Milky Way in a galactic merger. 用詞

因为它是由于一次星系合并而被银河系捕获的。

So how do telescopes allow us or aliens to see across the universe?

那么，望远镜是如何让我们或外星人看穿宇宙的呢？

Consider an analogy. 表達脈絡

让我们打个比方。

Imagine the sun is constantly casting an enormous barrage 習語

想象太阳不断向四面八方发射出密密麻麻的

of little tiny bouncy balls in all directions.

小弹力球。

These balls are photons or individual particles of light.

这些球就是光子，或者说是单个的光粒子。

On Earth,

在地球上，

some will bounce off of a T-Rex and then get caught in your eye,

一些球会从霸王龙身上弹开，然后进入你的眼睛，

so your brain will be able to register, 用詞

因此你的大脑就能够察觉：

"Oh, that's a T-Rex. I'm going to die."

“哦，那是霸王龙。我要死了。”

The farther you are from the T-Rex, 語法

你离霸王龙越远，

the fewer balls make it to your eye and so the harder it is to see the T-Rex.

进入你眼睛的球就越少，因此也就越难看到霸王龙。

Some other balls will hit the T-Rex and bounce up and off into space to travel the universe.

还有些球会击中霸王龙，然后反弹到太空中，在宇宙中穿梭。

Telescopes are lenses and mirrors to refocus a bunch of those space balls

望远镜是由透镜和面镜组成的，用于将大量这类太空球

over a wide area to a small collector

从广阔的区域重新聚焦到一个小收集器上，

so that we can get the benefit of a really big eye. 短語搭配

这样我们就能获得如同拥有一只超级大眼睛般的好处。

And the farther you want to see,

你想看得越远，

the bigger an eye you need.

你需要的眼睛就越大。

So how big does an alien telescope need to be?

那么外星人的望远镜需要多大呢？

Fundamentally,

从根本上说，

a given lens can only focus light so well due to quantum properties of light. 語法

由于光的量子特性，给定的透镜聚焦光线的能力是有限的。

No matter how super intelligent these aliens are, 語法

无论这些外星人有多么超级智能，

they can't cheat fundamental physics. 習語

他们也无法违背基础物理学。

Using what we know about the resolution limits of man-made lenses,

利用我们已知的人造透镜的分辨率极限，

physicists can calculate that a lens would need to be over 36 million miles across,

物理学家可以计算出，一块透镜的直径需要超过3600万英里，

which is about a third of the distance to the sun.

也就是大约地球到太阳距离的三分之一。

This lens would fill up about half of Mercury's orbit

这个透镜会填满水星大约一半的轨道，

and it would only give the aliens a view of the Earth as one pixel.

而它只能够让外星人将地球看作一个像素点。

And if that wasn't impossibly huge enough already,

如果这还不够大得离谱的话，

these aliens wanted to see dinosaurs,

别忘了这些外星人想看的是恐龙，

not just the Earth.

而不仅仅是地球。

If you want to resolve a dinosaur, 用詞

如果你想分辨出一只恐龙，

even as just a dot,

哪怕只是一个小点，

then the telescope lens needs to be much bigger,

望远镜的透镜需要大得多，

4.4 light years across.

直径达到4.4光年。

Such a telescope would fit comfortably between our sun and the nearest star system, 用詞

这样一个望远镜可以轻松地塞进我们的太阳与最近的恒星系统

Alpha Centauri.

半人马座阿尔法星之间。

Human astronomers often give their telescopes hilarious names like The Very Large Array

人类天文学家常常给他们的望远镜起一些滑稽的名字，比如“甚大天线阵”

and The Overwhelmingly Large Telescope,

和“极大望远镜”，

but somehow these just feel inadequate. 語氣意圖

但不知为何，这些名字放到这儿似乎就不太够用了。

We don't have to sit around and debate whether or not an alien can build a telescope this big. 短語動詞

我们不必干坐着争论外星人能否建造这么大的望远镜。

Einstein's theory of relativity actually gives us the answer.

爱因斯坦的相对论实际上给了我们答案。

General relativity tells us that matter curves spacetime,

广义相对论告诉我们，物质会使时空弯曲，

and the more mass you have,

质量越大，

the more it curves space.

使空间弯曲的程度就越大。

If you put enough mass in one spot,

如果你在一个地方放置了足够的质量，

the spacetime curvature will be so extreme that it must collapse on itself, 語法

时空曲率将会达到极其极端的程度，以至于它必须向内坍缩，

forming a black hole.

形成一个黑洞。

In fact,

事实上，

a ball of glass 28 light minutes across

一个直径为28光分的玻璃球

will have enough concentrated mass to collapse into a black hole.

其集中的质量足以使其坍缩成一个黑洞。

So yes,

所以，是的，

in theory,

理论上，

the view of a dinosaur is out there in space,

恐龙的影像确实存在于太空深处，

but sadly no aliens will ever get a glimpse of them. 短語搭配

但遗憾的是，没有任何外星人能一睹它们的真容。

The script for this video was written by Dr. Matt Caplan

本视频的脚本由马特·卡普兰博士撰写，

and adapted from a post on his website,

并改编自其网站上的一篇文章，

quirksandcoffee.com.

quirksandcoffee.com。

Do you have any thoughts about his premise?

你对他的假设有什么看法吗？

Let us know in the comments.

请在评论区告诉我们。

And if you liked this video,

如果你喜欢这个视频，

be sure to check out our other video called Could We Travel to TRAPPIST-1?

请一定要去看看我们的另一个视频《Could We Travel to TRAPPIST-1?》。

Thanks for watching

感谢观看，

and as always,

一如既往，

don't forget to like, share, and subscribe.

别忘了点赞、分享和订阅。

See you next time.

我们下次见。