水下爆炸（與Alan Sailer一起學科學！）- Smarter Every Day 63：英語精讀講義

It's me Destin,

我是 Destin，

welcome back to Smarter every day.

歡迎回到《Smarter Every Day》。

So today I'm in California

今天我在加利福尼亞，

and I have the great privilege of introducing the man 片語搭配

我非常榮幸能向大家介紹這個人——

Alan Sailer.

Alan Sailer。

Hello.

大家好。

Alan Sailer is, if you don't know,

如果你不知道的話，Alan Sailer 是

one of the best high speed photographers

目前從事這門藝術的

that currently does the art.

最頂尖的高速攝影師之一。

So I'm here in his garden back behind his house

所以我現在就在他家屋後的花園裡，

and we're going to basically study explosions

我們打算用一些鞭炮

underwater with some firecrackers.

來研究水下爆炸現象。

You typically do it with the high speed photography method, right?

你通常用高速攝影的方法來拍，對吧？

Yeah, it's just a instant though.

對，不過那只是一瞬間。

Instant of detonation

引爆的一瞬間，

and I'm really looking forward to seeing uh

而我真的很期待看到，呃

time.

時間的變化。

Yeah.

對。

Exactly.

沒錯。

It's not just one moment.

不只是一個瞬間。

This is a M320 Miro Phantom camera

這是一台 M320 Miro Phantom 攝影機，

and what do you hope to learn here?

你希望在這裡學到什麼？

I just want to be impressed. 語氣意圖

我只希望大開眼界。

So uh do it.

所以，呃，開始吧。

Three, two, one, zero.

三，二，一，零。

All right.

好的。

Pretty cool.

太酷了。

Let's look at the video.

我們來看看影片。

Oh, look at that ripple.

哦，看看那波紋。

Yeah.

是啊。

Okay, so we decided we wanted a lower exposure time 用詞

好了，所以我們決定降低曝光時間，

and also a higher frame rate.

同時提高幀率。

So what we're going to do is we're going to change the lens. 文法

那麼我們要做的就是更換鏡頭。

Three, two, one, zero.

三，二，一，零。

About 20 ft.

大概20英尺。

Yeah.

是啊。

Man, the uh

天哪，那個，呃

I wonder if that was from impact or if

我想知道那是撞擊造成的，還是

if the bottle itself... It sucks in.

瓶子本身……它吸進去了。

There's cavitation that appears on the top

頂部出現了空化現象，

if you looked at the photograph.

如果你看了照片的話。

Yeah?

是嗎？

Yeah.

對。

All right, let's just look at the video.

好吧，我們還是直接看影片吧。

All right, I have a scientific mystery

好了，我遇到了一個科學謎題，

that I need your help figuring out. 片語動詞

需要你們幫我解開。

Let's first define what an explosion is, right? 表達脈絡

首先我們來定義一下什麼是爆炸，好嗎？

So basically it's a rapid formation of gas

簡單來說就是氣體的快速形成，

and you have it contained in some type of mechanical device

你把它裝在某種機械裝置裡，

and it increases pressure

它的壓力會不斷增加，

and that mechanical restraining device will eventually fail

而那個機械約束裝置最終會承受不住，

and blow outwards, correct?

向外炸開，對吧？

But here's the question.

但問題來了。

After each shot, I would go find the bottle on the ground

每次拍攝後，我都會在地上找到那個瓶子，

and the bottle would be sucked in on the top 片語動詞

而瓶子頂部是向內凹陷的，

instead of blown out like you would think.

而不是你想像的那樣向外炸開。

This is counterintuitive 用詞

這有違直覺，

and we have to figure out why.

我們必須弄清楚原因。

My theory is that as the bottle blows up on the bottom, 表達脈絡

我的理論是，當瓶子在底部爆炸時，

it begins to shoot up like a rocket.

它會像火箭一樣向上發射。

And when it does this, it starts to wrinkle like grandma legs

在這個過程中，它開始像老奶奶的腿一樣起皺，

if you can see it as it pushes the rest of the bottle forward.

你可以看到它推動瓶子剩餘部分向前運動。

Now, the cap has more mass than the sidewalls of the bottle.

蓋子的質量比瓶子側壁更大。

So my theory was that the bottle was pushing the cap,

所以我的理論是，瓶身在推蓋子，

but the cap weighs too much

但蓋子太重了，

and so the bottle is outrunning the cap. 用詞

導致瓶身跑得比蓋子還快。

Alan on the other hand disagreed with me. 表達脈絡

但 Alan 卻不同意我的看法。

My position is that after detonation,

我的觀點是，在引爆之後，

there's nothing but high pressure in the bottle. 片語搭配

瓶子裡除了高壓什麼都沒有。

But Alan referenced me back to some of his photos from his Flickr stream.

但 Alan 讓我看了一些他 Flickr 相簿裡的照片。

He always sees bubbles after detonation, always.

他在引爆後總是能看到氣泡，總是如此。

What causes bubbles to form in a liquid? 文法

什麼會導致液體中形成氣泡？

Of course, cavitation.

當然是空化作用。

A phase diagram is a fancy chart that uses pressure and temperature 用詞

相圖是一種利用壓力和溫度

to describe what state the matter should be in.

來描述物質應該處於何種狀態的複雜圖表。

We're located about right here, which is 23°C.

我們大概在這個位置，也就是23攝氏度。

Now, there's only a couple of ways we can go from liquid over to vapor.

現在，我們只有幾種方法可以從液態轉變為氣態。

One is we can move along the right here and increase the temperature.

一是我們可以沿著右邊這條線移動，也就是升高溫度。

I don't think we're heating the water up enough in order to do that. 片語搭配

我認為我們把水加熱的程度還不足以達到這個效果。

So I would conclude that Alan is correct. 表達脈絡

所以我得出結論：Alan 是對的。

I believe we are lowering the pressure enough 文法

我認為我們把壓力降得足夠低，

that we go beyond this vapor boundary and turn into vapor.

以至於越過了這個汽化邊界，變成了蒸汽。

And all we have to do to turn it back into a liquid is repressurize. 文法

而我們要把它變回液態，只需重新加壓即可。

Okay, let's look at the cavitation.

好了，我們來看看空化現象。

Immediately after detonation, we're seeing bubbles all over the bottle.

引爆後立刻，我們可以看到瓶子上全是氣泡。

That's interesting, but 150 microseconds later on the next frame,

這很有趣，但在 150 微秒後的下一幀中，

all the bubbles seem to be confined in one area. 文法

所有氣泡似乎都被限制在了一個區域內。

Basically, the shock waves are bouncing off the sides of the cylindrical bottle on the inside 片語動詞

基本上，衝擊波在圓柱形瓶子內部的側壁上反彈，

and they're bouncing back toward each other

它們相互反彈，

and then they're interfering with each other 用詞

然後相互干涉，

and creating a low pressure spot.

產生了一個低壓區。

I think that's pretty cool

我覺得這很酷，

because you can already see the cap beginning to suck in.

因為你已經能看到蓋子開始向內吸了。

On the next frame,

在下一幀中，

you can see what I call the wrinkly grandma leg effect. 表達脈絡

你可以看到我所謂的‘起皺的老奶奶腿效應’。

Now, I think it's pretty interesting that the bubble is collapsing from the left to the right,

我覺得很有趣的是，氣泡從左向右坍縮，

which might mean that's a compression wave going towards the front of the bottle. 表達脈絡

這可能意味著有一道壓縮波正向瓶子前方傳播。

But what's confusing to me 文法

但讓我困惑的是，

is the cap of the bottle is still being sucked in.

瓶蓋仍然在被往裡吸。

So I convinced Alan to do a self-portrait with me,

所以我說服 Alan 跟我一起拍個自拍影片，

but what I didn't realize is this self-portrait would reveal more information 表達脈絡

但我沒意識到，這段自拍影片透露出的資訊

than any of the other videos.

比其他任何影片都多。

At the point of detonation,

在引爆的那一刻，

clearly we have high pressure in the bottle.

很明顯瓶內產生了高壓。

Then you can see the lid suck in

然後你可以看到蓋子往裡吸，

and then check that out, the lid shoots off. 語氣意圖

接著看那裡，蓋子被炸飛了。

So that implies to me that you have low pressure and then high pressure. 表達脈絡

所以這對我來說意味著，先是低壓，然後是高壓。

Once the fluid is blown out of the bottom of that bottle, 文法

一旦液體從那個瓶子的底部被炸出，

it begins to pull fluid out of the top of the bottle with it.

它就開始把液體也從瓶子頂部拉出來。

So we have an oscillation in pressure. 用詞

所以我們的壓力出現了振盪。

Where have we seen something like that before? 表達脈絡

我們以前在哪裡見過類似的情況？

Sometimes when I'm drinking with a straw,

有時我用吸管喝水，

I like to put my finger over the end of the straw 片語搭配

我喜歡把手指按在吸管的末端，

and bring the fluid up out of the cup.

把液體從杯子裡提出來。

And then I'll release my finger

然後我鬆開手指，

and watch what the liquid does.

觀察液體會怎麼變化。

It oscillates.

它會振盪。

That's pretty cool and I think that's caused by fluid momentum 用詞

這挺酷的，我認為這是流體動量

or the inertia of the fluid itself.

或者說是流體本身的慣性造成的。

So this momentum effect of fluid applies to what we're doing too. 片語搭配

所以這種流體動量效應也適用於我們正在做的實驗。

As the fluid is blown out of the bottom of that bottle,

當液體從那個瓶子底部被炸出時，

you can see that it starts to pull liquid out of the top of the bottle

你可以看到它開始把液體從瓶子頂部拉出來，

and collapse the sidewalls of the bottle.

並導致瓶子側壁坍塌。

That's pretty cool too.

這也非常酷。

So seriously, thanks for your time.

說真的，感謝你的時間。

It's way more fun to think this through with you. 講解

和你一起思考這些問題要有趣得多。

Anyway, if you want the high speed footage,

總之，如果你想要這些高速攝影素材，

feel free to download it. 語氣意圖

請隨意下載。

Draw me some pictures

給我畫些圖，

and show me what you think the shock waves are doing on the video.

告訴我你認為影片中的衝擊波在做些什麼。

This guy did it.

這傢伙畫了。

I don't think he's exactly right,

我覺得他畫得不完全對，

but he took a good stab at it. 慣用語

但他做了一次很好的嘗試。

I'm Destin,

我是 Destin，

you're getting smarter every day.

你正在天天變聰明。

Have a good one. 片語搭配

祝你愉快。

One, zero.

一，零。

By the way,

順便說一句，

Alan Sailer grows very good apricots.

Alan Sailer 種的杏子非常好吃。

The Russians have developed a way to use

俄羅斯人已經開發出一種方法，利用

cavitation to create a bubble on the front of the torpedo.

空化作用在魚雷前端製造一個氣泡。

This is called super cavitation. 用詞

這被稱為超空泡現象。

If you fly the torpedo in that bubble,

如果讓魚雷在那個氣泡中飛行，

you have way less drag and you can move that torpedo way fast.

阻力會大大減小，並且可以讓魚雷移動得非常快。