水下爆炸（与Alan Sailer一起学科学！）- Smarter Every Day 63：英语精读讲义

It's me Destin,

我是 Destin，

welcome back to Smarter every day.

欢迎回到《天天变聪明》。

So today I'm in California

今天我在加利福尼亚，

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

我非常荣幸能向大家介绍这个人——

Alan Sailer.

Alan Sailer。

Hello.

大家好。

Alan Sailer is, if you don't know,

如果你不知道的话，Alan Sailer 是

one of the best high speed photographers

目前从事这门艺术的

that currently does the art.

最顶尖的高速摄影师之一。

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

所以我现在就在他家屋后的花园里，

and we're going to basically study explosions

我们打算用一些鞭炮

underwater with some firecrackers.

来研究水下爆炸现象。

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

你通常用高速摄影的方法来拍，对吧？

Yeah, it's just a instant though.

对，不过那只是一瞬间。

Instant of detonation

引爆的一瞬间，

and I'm really looking forward to seeing uh

而我真的很期待看到，呃

time.

时间的变化。

Yeah.

对。

Exactly.

没错。

It's not just one moment.

不只是一个瞬间。

This is a M320 Miro Phantom camera

这是一台 M320 Miro Phantom 摄像机，

and what do you hope to learn here?

你希望在这里学到什么？

I just want to be impressed. 語氣意圖

我只希望大开眼界。

So uh do it.

所以，呃，开始吧。

Three, two, one, zero.

三，二，一，零。

All right.

好的。

Pretty cool.

太酷了。

Let's look at the video.

我们来看看录像。

Oh, look at that ripple.

哦，看看那波纹。

Yeah.

是啊。

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

好了，所以我们决定降低曝光时间，

and also a higher frame rate.

同时提高帧率。

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

那么我们要做的就是更换镜头。

Three, two, one, zero.

三，二，一，零。

About 20 ft.

大概20英尺。

Yeah.

是啊。

Man, the uh

天哪，那个，呃

I wonder if that was from impact or if

我想知道那是撞击造成的，还是

if the bottle itself... It sucks in.

瓶子本身……它吸进去了。

There's cavitation that appears on the top

顶部出现了空化现象，

if you looked at the photograph.

如果你看了照片的话。

Yeah?

是吗？

Yeah.

对。

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

好吧，我们还是直接看录像吧。

All right, I have a scientific mystery

好了，我遇到了一个科学谜题，

that I need your help figuring out. 短語動詞

需要你们帮我解开。

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

首先我们来定义一下什么是爆炸，好吗？

So basically it's a rapid formation of gas

简单来说就是气体的快速形成，

and you have it contained in some type of mechanical device

你把它装在某种机械装置里，

and it increases pressure

它的压力会不断增加，

and that mechanical restraining device will eventually fail

而那个机械约束装置最终会承受不住，

and blow outwards, correct?

向外炸开，对吧？

But here's the question.

但问题来了。

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

每次拍摄后，我都会在地上找到那个瓶子，

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

而瓶子顶部是向内凹陷的，

instead of blown out like you would think.

而不是你想象的那样向外炸开。

This is counterintuitive 用詞

这有违直觉，

and we have to figure out why.

我们必须弄清楚原因。

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

我的理论是，当瓶子在底部爆炸时，

it begins to shoot up like a rocket.

它会像火箭一样向上发射。

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

在这个过程中，它开始像老奶奶的腿一样起皱，

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

你可以看到它推动瓶子剩余部分向前运动。

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

盖子的质量比瓶子侧壁更大。

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

所以我的理论是，瓶身在推盖子，

but the cap weighs too much

但盖子太重了，

and so the bottle is outrunning the cap. 用詞

导致瓶身跑得比盖子还快。

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

但 Alan 却不同意我的看法。

My position is that after detonation,

我的观点是，在引爆之后，

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

瓶子里除了高压什么都没有。

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

但 Alan 让我看了一些他 Flickr 相册里的照片。

He always sees bubbles after detonation, always.

他在引爆后总是能看到气泡，总是如此。

What causes bubbles to form in a liquid? 語法

什么会导致液体中形成气泡？

Of course, cavitation.

当然是空化作用。

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

相图是一种利用压力和温度

to describe what state the matter should be in.

来描述物质应该处于何种状态的复杂图表。

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

我们大概在这个位置，也就是23摄氏度。

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

现在，我们只有几种方法可以从液态转变为气态。

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

一是我们可以沿着右边这条线移动，也就是升高温度。

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

我认为我们把水加热的程度还不足以达到这个效果。

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

所以我得出结论：Alan 是对的。

I believe we are lowering the pressure enough 語法

我认为我们把压力降得足够低，

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

以至于越过了这个汽化边界，变成了蒸汽。

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

而我们要把它变回液态，只需重新加压即可。

Okay, let's look at the cavitation.

好了，我们来看看空化现象。

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

引爆后立刻，我们可以看到瓶子上全是气泡。

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

这很有趣，但在 150 微秒后的下一帧中，

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

所有气泡似乎都被限制在了一个区域内。

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

基本上，冲击波在圆柱形瓶子内部的侧壁上反弹，

and they're bouncing back toward each other

它们相互反弹，

and then they're interfering with each other 用詞

然后相互干涉，

and creating a low pressure spot.

产生了一个低压区。

I think that's pretty cool

我觉得这很酷，

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

因为你已经能看到盖子开始向内吸了。

On the next frame,

在下一帧中，

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

你可以看到我所谓的‘起皱的老奶奶腿效应’。

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

我觉得很有趣的是，气泡从左向右坍缩，

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

这可能意味着有一道压缩波正向瓶子前方传播。

But what's confusing to me 語法

但让我困惑的是，

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

瓶盖仍然在被往里吸。

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

所以我说服 Alan 跟我一起拍个自拍录像，

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

但我没意识到，这段自拍录像透露出的信息

than any of the other videos.

比其他任何视频都多。

At the point of detonation,

在引爆的那一刻，

clearly we have high pressure in the bottle.

很明显瓶内产生了高压。

Then you can see the lid suck in

然后你可以看到盖子往里吸，

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

接着看那里，盖子被炸飞了。

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

所以这对我来说意味着，先是低压，然后是高压。

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

一旦液体从那个瓶子的底部被炸出，

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

它就开始把液体也从瓶子顶部拉出来。

So we have an oscillation in pressure. 用詞

所以我们的压力出现了振荡。

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

我们以前在哪里见过类似的情况？

Sometimes when I'm drinking with a straw,

有时我用吸管喝水，

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

我喜欢把手指按在吸管的末端，

and bring the fluid up out of the cup.

把液体从杯子里提出来。

And then I'll release my finger

然后我松开手指，

and watch what the liquid does.

观察液体会怎么变化。

It oscillates.

它会振荡。

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

这挺酷的，我认为这是流体动量

or the inertia of the fluid itself.

或者说是流体本身的惯性造成的。

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

所以这种流体动量效应也适用于我们正在做的实验。

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

当液体从那个瓶子底部被炸出时，

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

你可以看到它开始把液体从瓶子顶部拉出来，

and collapse the sidewalls of the bottle.

并导致瓶子侧壁坍塌。

That's pretty cool too.

这也非常酷。

So seriously, thanks for your time.

说真的，感谢你的时间。

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

和你一起思考这些问题要有趣得多。

Anyway, if you want the high speed footage,

总之，如果你想要这些高速录像的素材，

feel free to download it. 語氣意圖

请随意下载。

Draw me some pictures

给我画些图，

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

告诉我你认为视频中的冲击波在做些什么。

This guy did it.

这家伙画了。

I don't think he's exactly right,

我觉得他画得不完全对，

but he took a good stab at it. 習語

但他做了一次很好的尝试。

I'm Destin,

我是 Destin，

you're getting smarter every day.

你正在天天变聪明。

Have a good one. 短語搭配

祝你愉快。

One, zero.

一，零。

By the way,

顺便说一句，

Alan Sailer grows very good apricots.

Alan Sailer 种的杏子非常好吃。

The Russians have developed a way to use

俄罗斯人已经开发出一种方法，利用

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

空化作用在鱼雷前端制造一个气泡。

This is called super cavitation. 用詞

这被称为超空泡现象。

If you fly the torpedo in that bubble,

如果让鱼雷在那个气泡中飞行，

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

阻力会大大减小，并且可以让鱼雷移动得非常快。