距離地球6500萬光年外的外星人能看到活著的恐龍嗎？：英語精讀講義

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

當我們想到恐龍時，通常不會想到外星人，

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

但是一位名叫麥特·卡普蘭博士的人

recently asked a very fascinating question about these two subjects.

最近問了一個關於這兩個主題的非常有趣的問題。

In his search for an answer,

在尋找答案的過程中，

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、黑洞和望遠鏡等主題。

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

和他一起在這個影片系列 The Infographics Show 中探索，

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

6500萬光年外的外星人能看到活著的恐龍嗎？

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

別忘了訂閱並點擊小鈴鐺，這樣你就能成為我們通知小隊的一員。

In theory, the answer is yes.

理論上，答案是肯定的。

Light that left Earth 65 million years ago

6500萬年前離開地球的光

is now 65 million light years away.

現在距離我們6500萬光年。

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

所以，如果外星人知道該把望遠鏡指向哪裡，他們就能看到恐龍。

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

但是，任何人，即使是技術超發達的外星人，

to build a telescope powerful enough?

有可能造出足夠強大的望遠鏡嗎？

Light takes time to travel. 片語搭配

光傳播需要時間。

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

所以，看著任何東西都等同於回顧過去。

And the farther away it is,

離得越遠，

the farther back in time you see.

你能看到的時光就越久遠。

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

例如，如果你的眼睛距離你觀看這個影片的螢幕大約兩英尺，

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

那麼你看到的這段影片大約是2奈秒前的畫面。

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

這基本上是瞬間的，並且比人類的反應時間快得多。

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

所以光速延遲不會打亂我們的日常生活。

But if you look at the moon,

但如果你看月亮，

the light left it about a second ago,

光大約在一秒鐘前離開了它，

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

這個時間足以導致在與阿波羅太空人通訊時出現明顯的停頓。

For the sun,

對於太陽來說，

it's closer to 8 minutes.

接近8分鐘。

So if for some crazy reason the sun disappeared,

所以，如果出於某種瘋狂的原因，太陽消失了，

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

那麼地球上的人大約在8分鐘內都不會知道。

When astronomers look through their telescopes at distant stars,

當天文學家透過望遠鏡觀察遙遠的恆星時，

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

他們看到的是許多年前的恆星。

Coincidentally, this is one way astronomers measure distance.

巧合的是，這也是天文學家測量距離的一種方法。

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

光年僅僅是光在一年內傳播的距離，

conveniently tying distance and age into one number. 文法

方便地將距離和年齡結合成一個數字。

So again,

所以，再次強調，

in theory,

理論上，

the light that left the Earth millions of years ago

數百萬年前離開地球的光

is now millions of light years away.

現在已經在數百萬光年之外。

And in that light is a glimpse of dinosaurs.

而在這束光中，就隱藏著恐龍的一瞥。

Since the dinosaurs went extinct 65 million years ago,

既然恐龍在6500萬年前滅絕了，

then the closest alien that could see dinosaurs,

那麼能夠看到恐龍的最近的外星人，

if he knew where to point his telescope,

如果他知道該把望遠鏡指向哪裡，

is 65 million light years away.

是在6500萬光年之外。

But in practice, 表達脈絡

但在實際操作中，

it's much harder because the Earth is small

這要困難得多，因為地球很小，

and 65 million light years is a long distance.

而且6500萬光年是一段很長的距離。

For perspective, 表達脈絡

為了讓你有個直觀的了解，

the vast majority of the visible stars in the night sky

夜空中絕大多數肉眼可見的恆星，

are within about 1,000 light years of us.

都在距離我們大約1000光年以內。

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

銀河系的直徑大約為10萬光年。

The nearest galaxy,

最近的星系，

Andromeda,

仙女座星系，

is about 2.5 million light years away.

距離我們約250萬光年。

At 65 million light years,

在6500萬光年的距離上，

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

我們的外星天文學家將處於遙遠的室女座星系團中。

So,

所以，

if these aliens want to see dinosaurs,

如果這些外星人想看恐龍，

they're going to need a big telescope.

他們需要一台很大的望遠鏡。

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

人類天文學家目前幾乎只能勉強分辨出我們銀河系內的近鄰行星，

let alone extragalactic planets.

更不用說銀河系外的行星了。

In fact,

事實上，

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

關於銀河系外系外行星的觀測報告寥寥無幾。

One is the Andromeda and the other is cheating.

一個是在仙女座星系，另一個則有點「作弊」。

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

它距離地球只有2000光年，

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

因為它是在一次星系合併中被銀河系捕獲的。

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

那麼，望遠鏡是如何讓我們或外星人看穿宇宙的呢？

Consider an analogy. 表達脈絡

讓我們打個比方。

Imagine the sun is constantly casting an enormous barrage 慣用語

想像太陽不斷向四面八方發射出密密麻麻的

of little tiny bouncy balls in all directions.

小彈力球。

These balls are photons or individual particles of light.

這些球就是光子，或者說是單個的光粒子。

On Earth,

在地球上，

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

一些球會從暴龍身上彈開，然後進入你的眼睛，

so your brain will be able to register, 用詞

因此你的大腦就能夠察覺：

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

「喔，那是暴龍。我要死了。」

The farther you are from the T-Rex, 文法

你離暴龍越遠，

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

進入你眼睛的球就越少，因此也就越難看到暴龍。

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

還有些球會擊中暴龍，然後反彈到太空中，在宇宙中穿梭。

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

望遠鏡是由透鏡和面鏡組成的，用於將大量這類太空球

over a wide area to a small collector

從廣闊的區域重新聚焦到一個小收集器上，

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

這樣我們就能獲得如同擁有一隻超級大眼睛般的好處。

And the farther you want to see,

你想看得越遠，

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?

那麼外星人的望遠鏡需要多大呢？

Fundamentally,

從根本上說，

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

由於光的量子特性，給定的透鏡聚焦光線的能力是有限的。

No matter how super intelligent these aliens are, 文法

無論這些外星人有多麼超級智能，

they can't cheat fundamental physics. 慣用語

他們也無法違背基礎物理學。

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

利用我們已知的人造透鏡的解析度極限，

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

物理學家可以計算出，一塊透鏡的直徑需要超過3600萬英里，

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

也就是大約地球到太陽距離的三分之一。

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

這個透鏡會填滿水星大約一半的軌道，

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

而它只能夠讓外星人將地球看作一個像素點。

And if that wasn't impossibly huge enough already,

如果這還不夠大得離譜的話，

these aliens wanted to see dinosaurs,

別忘了這些外星人想看的是恐龍，

not just the Earth.

而不僅僅是地球。

If you want to resolve a dinosaur, 用詞

如果你想分辨出一隻恐龍，

even as just a dot,

哪怕只是一個小點，

then the telescope lens needs to be much bigger,

望遠鏡的透鏡需要大得多，

4.4 light years across.

直徑達到4.4光年。

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

這樣一個望遠鏡可以輕鬆地塞進我們的太陽與最近的恆星系統

Alpha Centauri.

半人馬座阿爾法星之間。

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

人類天文學家常常給他們的望遠鏡起一些滑稽的名字，比如「甚大天線陣」

and The Overwhelmingly Large Telescope,

和「極大望遠鏡」，

but somehow these just feel inadequate. 語氣意圖

但不知為何，這些名字放到這兒似乎就不太夠用了。

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

我們不必乾坐著爭論外星人能否建造這麼大的望遠鏡。

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

愛因斯坦的相對論實際上給了我們答案。

General relativity tells us that matter curves spacetime,

廣義相對論告訴我們，物質會使時空彎曲，

and the more mass you have,

質量越大，

the more it curves space.

使空間彎曲的程度就越大。

If you put enough mass in one spot,

如果你在一個地方放置了足夠的質量，

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

時空曲率將會達到極其極端的程度，以至於它必須向內坍縮，

forming a black hole.

形成一個黑洞。

In fact,

事實上，

a ball of glass 28 light minutes across

一個直徑為28光分的玻璃球

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

其集中的質量足以使其坍縮成一個黑洞。

So yes,

所以，是的，

in theory,

理論上，

the view of a dinosaur is out there in space,

恐龍的影像確實存在於太空深處，

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

但遺憾的是，沒有任何外星人能一睹牠們的真容。

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

本影片的腳本由麥特·卡普蘭博士撰寫，

and adapted from a post on his website,

並改編自其網站上的一篇文章，

quirksandcoffee.com.

quirksandcoffee.com。

Do you have any thoughts about his premise?

你對他的假設有什麼看法嗎？

Let us know in the comments.

請在留言區告訴我們。

And if you liked this video,

如果你喜歡這個影片，

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

請一定要去看看我們的另一個影片《Could We Travel to TRAPPIST-1?》。

Thanks for watching

感謝觀看，

and as always,

一如既往，

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

別忘了按讚、分享和訂閱。

See you next time.

我們下次見。