What light can teach us about the universe - Pete Edwards

關於宇宙，「光」教我們的事 - 彼特‧愛德華

譯者: Aaron Shoo 審譯者: Adrienne Lin

宇宙何時並且如何形成？

How and when did our universe begin?

How did it get to look like this?

怎麼形成今天的樣貌？

How will it end?

又會怎麼終結？

Humans have been discussing these questions

人類自古就對這些問題爭論不休

for as long as they've been around without ever reaching much agreement.

至今沒有定論

Today, cosmologists are working hard to find the answers.

今日的宇宙學家努力地尋找答案

But how can anyone hope to find concrete answers to such profound questions?

但這麼深奧的問題真的有解嗎？

而且面對這麼龐大未知的宇宙

And how is it possible to explore and study something as huge as the universe,

我們又要用什麼方式去探索、研究呢？

most of which we'll never be able to reach?

答案就是「光」

The answer is light.

And although light from distant parts of the universe

雖然宇宙另一端的光

可能要花幾十億年才能到達地球

can take billions of years to reach us,

it carries six unique messages that, when put together,

但光中攜帶的六個獨特訊息 整合在一起時

can disclose an amazing amount of information to astronomers

只要天文學家懂得解讀 就能帶來許多有用的資訊

who know how to look for it.

就像陽光折射出現彩虹

Just as sunlight can be split up into the familiar rainbow,

splitting the light from distant objects exposes different patterns of colors

我們分析遠處的光也能 依據不同的光源畫出不同的光譜

depending on its source.

This distinctive light barcode can reveal not only an object's composition,

這些特殊的「光條碼」 不只能讓我們了解光源的組成

but also the temperature and pressure of its constituent parts.

也能了解其上的溫度與氣壓

光還帶來更多訊息

There's even more we can discover from light.

如果你在月台上等過火車 就可能注意到

If you've ever stood on a train platform, you might have noticed

that the train sounds different depending on its direction

火車往不同的方向行駛 聽起來不太一樣

當火車開向你 音調好像會升高

with the pitch ascending when it approaches you

and descending when it speeds away.

往遠處駛離時 音調好像會降低

But this isn't because the train conductor is practicing for a second career.

這可不是因為列車長在練習交響樂

Rather, it's because of something called the Doppler effect

而是因為被稱作 「都卜勒效應」的物理現象

where sound waves generated by an approaching object are compressed,

聲波在聲源靠近時會被壓縮

while those from a receding object are stretched.

而逐漸遠離的聲源會拉長聲波

But what has this to do with astronomy?

那這又怎麼運用在天文學呢？

Sound does not travel through a vacuum. In space, no one can you hear you scream!

聲音在真空狀態是不會傳遞的

在宇宙中尖叫也沒人聽得見

But the same Doppler effect applies to light whose source is moving at exceptional speed.

但在光源以特定速度移動時 也可以觀察到「都卜勒效應」

If it's moving towards us, the shorter wavelength

如果天體朝我們移動 會測到比較短的波長

will make the light appear to be bluer.

所以看起來會比較藍

While light from a source that's moving away

而當天體朝遠處離開我們

will have a longer wavelength, shifting towards red.

會測到比較長的波長而且偏紅

So by analyzing the color pattern in the Doppler shift of the light

所以藉由天文望遠鏡 分析天體光圖的「都卜勒效應」

from any object observed with a telescope, we can learn what it's made of,

既可以了解他們的組成、

how hot it is and how much pressure it's under,

溫度、壓力、

是否在移動、朝哪個方向、多快

as well as whether it's moving, in what direction and how fast.

而這六項數據 就是光攜帶的六個訊息

And these six measurements, like six points of light,

reveal the history of the universe.

向我們揭露宇宙的歷史

The first person to study the light from distant galaxies was Edwin Hubble,

第一個研究遙遠星系的是「愛德溫‧哈伯」

and the light he observed was redshifted.

而他所觀察的光是偏紅色的

The distant galaxies were all moving away from us,

代表遙遠的星系正離我們而去

and the further away the were, the faster they were receding.

而且越遠的移動越快

Hubble had discovered our universe is expanding,

哈伯發現我們的宇宙正在膨脹

providing the first evidence for the Big Bang theory.

提供了「大爆炸理論」的第一個相關證據

同時提出了現在的宇宙

Along with the idea that the visible universe has been constantly expanding

是從高密度的一個小點持續擴張而成

from a densely packed single point,

one of this theory's most important predictions

這個理論的重要假設之一

是早期的宇宙是由兩種氣體： 「氫氣」和「氦氣」所組成

is that the early universe consisted of just two gases: hydrogen and helium,

in a ratio of three to one.

比例是3：1

And this prediction can also be tested with light.

這個假設也可以用光證明

If we observe the light from a remote, quiet region of the universe and split it,

如果我們觀察分析 來自一個遙遠寧靜區域的光

we do indeed find the signatures of the two gases in just those proportions.

我們會發現兩種氣體 按上述比例存在的證明

Another triumph for the Big Bang.

又再度支持了「大爆炸理論」的推論

However, many puzzles remain.

然而還是有許多未解的謎團

Although we know the visible universe is expanding,

雖然我們知道宇宙在膨脹

gravity should be applying the brakes.

「萬有引力」 應該會像剎車一樣減緩膨脹

但從遙遠垂死恆星的觀測數據來看

But recent measurements of light from distant dying stars

show us that they're farther away than predicted.

他們比我們預期的位置更遠

So the expansion of the universe is actually accelerating.

意思是宇宙的擴張其實在加速

有某種力量在推動膨脹

Something appears to be pushing it,

and many scientists believe that something is dark energy,

許多科學家相信 那就是所謂的「黑暗能量」

占了宇宙的2/3 並持續地分裂整個宇宙

making up over 2/3 of the universe and slowly tearing it apart.

Our knowledge of the behavior of matter and the precision of our instruments

我們對於物質行為的知識 和儀器的精密

means that simply observing distant stars can tell us more about the universe

讓我們只要觀察遙遠的星體

就可以比我們所想的更了解宇宙

than we ever thought possible.

但還是有許多謎團 比如說「黑暗能量」的本質

But there are other mysteries, like the nature of dark energy

upon which we have yet to shed light.

等待我們去發掘