詹姆斯·韋伯如何改變了天文學：英語精讀講義

This is MIRI, the mid-infrared camera onboard the James Webb telescope. 文化背景

這就是MIRI，詹姆斯·韋伯太空望遠鏡上的中紅外線相機。

Watch what happens when light enters the camera.

看看光線進入相機時會發生什麼事。

A complex series of mirrors and filters direct and split the light up into different wavelengths,

一系列複雜的反射鏡和濾光片將光線引導並分離成不同的波長，

which are then resized and directed onto the sensors.

然後調整其大小並將其投射到感測器上。

With this camera,

有了這台相機，

Webb can see extremely distant stars and galaxies

韋伯望遠鏡就能看到極其遙遠的恆星和星系，

that are completely invisible to the human eye.

而這些對人類肉眼來說是完全不可見的。

This is only possible by cooling the camera down to just 6° above absolute zero. 文化背景

只有將相機的溫度降至僅比絕對零度高6°，這一切才有可能。

But why does it need to be so cold?

但是它為什麼需要這麼冷呢？

In this video,

在這段影片中，

we're going to look at how Webb captures infrared light 文化背景

我們將了解韋伯是如何捕捉紅外線的，

and how a simple sound like this

以及像這樣簡單的聲音

is used to cool its camera all the way down to a mind-boggling temperature. 講解

是如何被用來將其相機的溫度一路降至令人難以置信的水平的。

We'll also be giving away this LEGO ISS model,

我們還將送出這個樂高國際太空站模型，

so stick around to the end of the video 片語動詞

所以請看到影片最後，

to see how you could win.

看看你如何能夠贏得它。

All of the cameras onboard James Webb detect infrared light,

詹姆斯·韋伯望遠鏡上的所有相機都能探測到紅外線，

which is invisible to the human eye.

而這在人類肉眼看來是不可見的。

As light travels through space,

當光在太空中傳播時，

its wavelength is constantly being stretched.

它的波長在不斷被拉長。

If something is far enough away, 文法

如果某個物體足夠遙遠，

the light will be stretched so much that it is no longer visible by the time it reaches us. 文法

光線就會被拉伸得非常長，以至於在到達我們這裡時就不再可見了。

This means there is a physical limit on how far we can see into space.

這意味著我們能夠看到多遠的太空存在著一個物理極限。

Since MIRI's sensors are made from arsenic and silicon,

由於MIRI的感測器是由砷和矽製成的，

it can detect this super stretched infrared light and see beyond that limit.

它可以探測到這種被極度拉長的紅外線，從而突破這個極限。

These sensors work like regular camera sensors

這些感測器就像普通相機感測器一樣運作，

by converting photons of light into an electrical signal.

透過將光子轉換成電子訊號。

But in order to detect the faint signals of infrared light,

但是，為了探測到微弱的紅外線訊號，

the sensors on MIRI have to be extremely sensitive.

MIRI上的感測器必須極其靈敏。

Increasing the sensitivity, however, introduces a lot of noise. 用詞

然而，提高靈敏度會引入大量雜訊。

Whenever we point a camera at something,

每當我們將相機對準某個東西時，

its sensor isn't just detecting what we want it to see.

它的感測器並不僅僅在探測我們想讓它看到的東西。

There is so much more light bouncing around us that our eyes simply can't detect.

在我們周圍有太多我們的眼睛完全無法察覺的漫反射光線。

This can trick the pixels in the sensor into registering random levels of light, 文法

這會讓感測器中的像素誤以為偵測到了隨機的光照強度，

creating a layer of noise in the image.

從而在影像上產生一層雜訊。

If the thing you are looking at has a bright enough signal,

如果你在觀察的物體具有足夠明亮的訊號，

it will stand out much more compared to the noise. 片語動詞

它在雜訊面前就會顯得非常突出。

However, if the thing you are trying to image is faint,

然而，如果你試圖成像的物體很暗淡，

like the infrared light from a galaxy,

比如來自星系的紅外線，

you'll need to increase the sensitivity of the sensor,

你就需要提高感測器的靈敏度，

which in turn will drastically increase the noise. 表達脈絡

但這反過來又會大幅增加雜訊。

Since Webb is detecting infrared light,

由於韋伯正在探測紅外線，

the problem gets even worse.

問題變得更加嚴重。

Every object in our universe emits heat energy,

我們宇宙中的每一個物體都會發出熱能，

some of which is in the form of light.

其中一部分以光的形式存在。

Most objects aren't quite hot enough to emit visible light,

大多數物體還不夠熱，無法發出可見光，

but they do emit a lot of infrared light.

但它們確實會發出大量的紅外線。

The hotter the object, 文法

物體越熱，

the more infrared light it will emit,

它發出的紅外線就越多，

which is essentially how thermal imaging cameras work.

這基本上就是熱像儀的工作原理。

Because of this, James Webb itself would emit so much infrared light

正因為如此，詹姆斯·韋伯望遠鏡本身就會發出大量的紅外線，

that its sensors would be completely drowned out. 片語動詞

以至於它的感測器會被完全淹沒。

And so, in order to limit the amount of infrared light produced by the telescope,

因此，為了限制望遠鏡產生的紅外線數量，

its cameras need to be kept at a temperature of -234°.

它的相機必須保持在-234°的溫度。

That is extremely cool,

這簡直太冷酷了，

just like Wondrium, the sponsor of today's video.

就像今天影片的贊助商Wondrium一樣。

Wondrium is a learning platform where you can explore a variety of subjects,

Wondrium是一個學習平台，你可以在這裡探索各種學科，

including some of my favorites,

包括我最喜歡的一些，

technology, science, and space exploration.

技術、科學和太空探索。

One of the best ones I came across was the search for exoplanets, 片語動詞

我偶然發現的最好的課程之一是關於尋找系外行星的，

which tells you all about the technologies and methods

它告訴你所有關於技術的與方法的知識，

used to discover new planets beyond our solar system,

這些技術和方法被用來發現我們太陽系以外的新行星，

just like those used on the James Webb telescope.

就像詹姆斯·韋伯望遠鏡上使用的那些一樣。

Wondrium offers a diverse collection of videos, tutorials, and documentaries,

Wondrium提供了各種各樣的影片、教學和紀錄片，

giving you the opportunity to learn from experts and hear their firsthand experiences. 片語搭配

讓你有機會向專家學習，並聽取他們的第一手經驗。

Plus, with new offers every month,

另外，透過每個月推出的新優惠，

you'll never run out of new and exciting things to discover. 片語動詞

你永遠不會缺少可以發現的令人興奮的新事物。

You can enjoy all of their courses ad-free from anywhere on any device.

你可以在任何設備的任何地方享受他們所有無廣告的課程。

And best of all,

最棒的是，

they're offering the Primal Space community a free trial starting today.

他們從今天開始為Primal Space社群提供免費試用。

If you're looking to challenge yourself and expand your knowledge,

如果你想挑戰自己並擴展自己的知識，

then Wondrium is the perfect place for you.

那麼Wondrium是你完美的選擇。

Don't wait any longer.

別再等了。

Head to the link in the description below for your Wondrium free trial.

點擊下方描述中的連結即可獲得Wondrium的免費試用。

In order for MIRI to operate at -267°, 文法

為了讓MIRI在-267°下運行，

it's located behind the massive five-layer sunshield.

它被放置在巨大的五層遮陽板後面。

This alone reflects so much heat

單單這個就反射了如此多的熱量，

and cools Webb's cameras down to around -234°.

並將韋伯相機的溫度降至約-234°。

But, since MIRI is much more sensitive than the other cameras,

但是，由於MIRI比其他相機敏感得多，

it faces an even bigger problem, dark current. 文化背景

它面臨著一個更棘手的問題：暗電流。

This is where the atoms inside the sensor itself vibrate and mistakenly register a photon of light, 表達脈絡

暗電流就是感測器內部的原子振動，並錯誤地記錄為一個光子，

creating more noise.

從而產生更多的雜訊。

Since temperature is just a measure of how fast an atom vibrates, 片語搭配

由於溫度只是衡量原子振動有多快的一個指標，

lowering the temperature will lower the vibration and therefore reduce the amount of dark current.

降低溫度將減緩振動，從而減少暗電流的數量。

Even at -234°,

即使在-234°，

the vibration of these atoms would be too much for MIRI's sensor.

這些原子的振動對MIRI的感測器來說也太大了。

And so, they have to be cooled all the way down to -267°,

因此，它們必須被一路降溫到-267°，

just 6° above absolute zero.

僅比絕對零度高出6°。

At this temperature,

在這個溫度下，

the atoms in the sensor are almost completely still,

感測器中的原子幾乎是完全靜止的，

drastically reducing the noise and allowing the faint infrared signals to shine through.

從而極大地減少了雜訊，讓微弱的紅外線訊號能夠透射出來。

But how did NASA take these sensors all the way down to -267°?

但是NASA是如何將這些感測器一路降至-267°的呢？

The cooling process all starts here,

降溫過程都是從這裡開始的，

at the bottom of the telescope,

位於望遠鏡的底部，

with a device called a pulse tube. 文化背景

有一個叫做脈衝管的裝置。

Inside these tubes are two pistons,

這些管內有兩個活塞，

which move back and forth to compress the helium into the pulse tube. 片語搭配

它們前後移動以將氦氣壓縮到脈衝管中。

Since this movement would create a lot of unwanted vibration,

由於這種運動會產生大量不必要的振動，

these pistons have to move in the exact opposite direction

這些活塞必須在完全相反的方向上移動，

with precision timing to cancel out each other's movement. 片語動詞

並擁有精確的計時，以抵消彼此的運動。

These pistons move very quickly,

這些活塞移動得非常快，

just like a speaker,

就像揚聲器一樣，

to create a low-frequency sound wave with a frequency of 30 Hz.

產生頻率為30 Hz的低頻聲波。

This sound wave travels down the tube

這種聲波順著管道傳播，

and gets compressed once it reaches the end,

一旦到達末端就會被壓縮，

creating an area of higher pressure.

從而形成一個較高壓力的區域。

Then, as it bounces back in the opposite direction,

然後，當它沿相反方向反彈時，

it expands, creating an area of low pressure

它會膨脹，形成一個低壓區域，

before being compressed once again.

然後再一次被壓縮。

If the next wave is sent out exactly as the previous one returns, 文法

如果下一個波的發出恰逢上一個波的返回，

it means the frequency perfectly matches that of the tube. 文法

這意味著頻率與管道的頻率完全匹配。

This creates a standing wave 文化背景

這就產生了一個駐波，

where the areas of high and low pressure remain in the same place.

高壓區和低壓區停留在同一個地方。

By tripling the frequency,

透過將頻率提高到三倍，

it causes the waves to combine and create a stationary wave

這會使波形組合，並形成一個駐波，

with multiple areas of high and low pressure.

具有多個高壓和低壓區域。

Since temperature and pressure are related,

由於溫度和壓力是相關的，

this also leads to areas of high and low temperature.

這也會導致出現高溫和低溫區域。

This alone wouldn't change the overall temperature

單靠這一點並不會改變整體溫度，

because the hot and cold parts simply cancel each other out.

因為高溫和低溫部分僅僅是相互抵消了。

But, if there was a way to extract the hot parts, 文法

但是，如果有辦法把高溫部分提取出來，

then the temperature would start to drop.

那麼溫度就會開始下降。

And so, three heat exchangers

因此，三個熱交換器，

made of thin metal sheets 片語搭配

由薄金屬片製成，

are placed at the points where the hot and cold gas meet.

被放置在冷熱氣體交匯的地方。

These allow the gas to pass through whilst also absorbing some of its temperature, 用詞

它們允許氣體通過，同時也吸收了它的一些溫度，

causing a heat gradient to form. 文法

從而形成溫度梯度。

The heat from the hot side is pulled out

熱端的熱量被抽取出來，

and sent to the radiators via a heat exchanger.

並透過熱交換器送到散熱器中。

Then, the cold temperatures on the other side are also drawn out. 片語動詞

然後，另一側的低溫也隨之被抽調。

This causes the temperature to drop from 27° all the way down to -256°

這就導致溫度從27°一直下降到-256°

at the final heat exchanger.

在最後一個熱交換器處。

But how is this used to cool the sensors located at the opposite end of the telescope?

但這是如何被用來冷卻位於望遠鏡另一端的感測器的呢？

Next to the pulse tube is another set of pistons

脈衝管旁邊是另一組活塞，

that compress helium in a completely separate line of tubing.

它們在一條完全獨立的管道中壓縮氦氣。

This line passes through the cold parts of the pulse tube's heat exchangers,

這條管線穿過脈衝管熱交換器的寒冷部分，

cooling the helium all the way down to around -256°.

把氦氣一路冷卻到約-256°。

But still the helium isn't quite cold enough. 文法

但是，氦氣依然不夠冷。

From there, the helium goes on a long journey,

從那裡，氦氣開始了漫長的旅程，

winding its way up through 10 m of thin tubing until it reaches the cold head assembly. 慣用語

蜿蜒盤旋穿過10公尺的細管，直到到達冷頭組件。

Inside, there is another heat exchanger and a tiny hole less than 1 mm in diameter. 片語搭配

在裡面，有另一個熱交換器和一個直徑小於1公釐的小孔。

The helium is pushed through the hole

氦氣被推過這個孔，

and undergoes something called the Joule-Thomson effect. 文化背景

經歷了一種叫做焦耳-湯姆森效應的過程。

As the gas moves through the hole,

當氣體穿過這個孔時，

it gets compressed before quickly expanding on the other side. 文法

它先是被壓縮，然後在另一側迅速膨脹。

This rapid expansion causes the pressure to drop, 文法

這種迅速的膨脹導致壓力驟降，

cooling the gas very quickly.

從而非常迅速地冷卻氣體。

This is why blowing air through our mouth is colder

這就是為什麼透過嘴巴吹氣會比較涼快，

if we make a smaller hole with our lips.

只要我們用嘴唇撅成一個小一點的孔。

On James Webb,

在詹姆斯·韋伯望遠鏡上，

this cools the helium all the way down to just -267°.

這能將氦氣一路冷卻至僅-267°。

From here, the helium flows on to copper plates attached to the back of MIRI's sensors,

從這裡開始，氦氣流向附在MIRI感測器背面的銅板，

cooling them down to the required temperature.

將它們冷卻到所需的溫度。

After that, the helium has done its job 慣用語

在那之後，氦氣就完成了它的工作，

and it flows back down the telescope where the entire process begins again.

然後它回流到望遠鏡底部，整個過程又重新開始。

When NASA began designing James Webb,

當NASA開始設計詹姆斯·韋伯望遠鏡時，

no cryocooler with this level of cooling existed.

這種製冷水平的低溫冷卻器還不存在。

And so, engineers had to really push the boundaries of physics, 慣用語

因此，工程師們必須真正突破物理學的界限，

all while conforming to the limits of fitting it into a space telescope. 文法

同時還要克服將其塞進太空望遠鏡的尺寸限制。

And now,

那麼現在，

time for something really special.

到了一個特別的環節。

The winner of the previous giveaway is Daniel Weinman.

上一期抽獎的贏家是Daniel Weinman。

Congratulations.

恭喜你。

But, as always,

但是，像往常一樣，

we'll be giving away another awesome space prize in the next video.

我們將在下一個影片中送出另一個超棒的太空獎品。

To win this amazing LEGO space station model,

為了贏得這個超讚的樂高太空站模型，

sign up at the link below

請在下方的連結註冊，

and leave a comment saying how long you think James Webb will operate for. 文法

並留下評論，說說你認為詹姆斯·韋伯望遠鏡將運行多長時間。

Thank you very much for watching

非常感謝您的觀看，

and I'll see you in the next video.

我們在下個影片見。