极限慢镜头下的声悬浮 - Smarter Every Day 134：英语精读讲义

Hey, it's me Destin.

嘿，我是 Destin。

Welcome back to Smarter Every Day.

欢迎回到 Smarter Every Day。

I am in Chicago.

我现在在芝加哥。

Anthony picked me up in his awesome Mustang and told me to come to this building 短語動詞

Anthony 开着他炫酷的 Mustang 来接我，并叫我来这栋大楼，

because we're going to film acoustic levitation.

因为我们要拍摄声悬浮。

What is this?

这是什么？

This is an acoustic levitator.

这是一个声悬浮器。

Uh it's single axis,

呃，它是单轴的，

which means that we only control things on one axis here. 表達脈絡

意思是这里只能在一个轴上控制物体。

Um so we have two horns or transducers.

嗯，我们有两个号角或换能器。

Um Any time I see an oscilloscope I get excited. 語法

嗯，每次我看到示波器都会很兴奋。

So am I gonna hear it on the camera?

那么能在摄像机里听到它的声音吗？

You'll so the main frequency we're using again is 22kHz

你会的，我们主要使用的频率依然是 22kHz，

which is higher than human hearing.

这超出了人类的听觉范围。

Um what you'll be hearing are sub-harmonic around 17-18kHz

嗯，你能听到的将是 17-18kHz 左右的次谐波。

But I can just put a low pass filter on the audio 用詞

但我可以在音频上加一个低通滤波器，

and I can I'm guessing that you cut it out, 短語動詞

我想你们会把它剪掉的，

yeah. Okay.

是的。好的。

Turn it up 短語動詞

调高一点，

and on the oscilloscope you'll see

你会在示波器上看到，

the two waves from each of the two horns.

两个号角各自产生的声波。

Well, let's stinking levitate something, dude. 用詞

好了，老兄，我们赶紧来悬浮点什么吧。

So that's just a Styrofoam ball.

这是一个泡沫球。

And the spoon has all those slots and

勺子上有很多缝隙，

so the sound passes right through it.

声音可以直接穿过去。

No way. 語氣意圖

不是吧。

And then I can just...

然后我只需……

And by sound you mean pressure? 語氣意圖

你说的声音是指压力吗？

Yeah, the sound waves, which are pressure waves.

对，声波，也就是压力波。

I mean,

我的意思是，

but you can see the wave length spacing basically between these.

你基本上可以看到它们之间的波长间距。

That's stinking awesome.

真是太棒了。

You may have seen sound drawn like this,

你可能见过像这样画出来的声音，

but it's a bit too simplified. 語法

但这有点过于简化了。

A real sound wave actually looks like this.

真正的声波其实长这样。

The bright parts are the higher pressure

较亮的部分是高压，

and the darker parts are the low pressure.

较暗的部分是低压。

These ripples move along at the speed of sound.

这些涟漪以音速移动。

When you have two identical sound waves and you line them up just right, 講解

当你有两个相同的声波，且将它们完全对齐时，

they no longer act like waves moving across the room. 語法

它们就不再像穿过房间的声波那样运动了。

If you have a wave coming from this side

如果有一个波从这边过来，

and another wave coming from the other side,

另一个波从另一边过来，

they become what's called a standing wave. 講解

它们就会变成所谓的“驻波”。

You get a spot right here where there's a pressure flipping on and off

在这里你会得到一个压力不断开、关翻转的点，

and a spot right here where the pressure isn't changing at all.

而在这里你会得到一个压力完全没有变化的点。

There's no oscillation.

没有任何振荡。

If you flip this thing upright and then you put something tiny right inside that little pocket,

如果你把这玩意竖起来，然后在这个小空隙里放进一个微小的物体，

you can use that air pressure to bump something up against the force of gravity.

你就可以利用气压把物体往上推，以对抗重力。

So it ends up looking like this Ping-Pong paddle. 短語動詞

所以它最后看起来就像这个乒乓球拍一样。

The particle wants to drop,

粒子想要掉落，

but it keeps getting knocked back up by the high pressure wave below it. 語法

但它不断被下方的高压波推回去。

And that is acoustic levitation.

这就是声悬浮。

So if it works with foam,

如果它对泡沫有效，

it should work with water, right?

那对水也应该有效吧？

Anthony uses a syringe to balance little drops of water on top of that oscillating wave.

Anthony 用注射器将小水滴平衡在振荡波的顶部。

Just like the Ping-Pong ball,

就像乒乓球一样，

you can see it bouncing up and down.

你可以看到它在上下跳动。

Look at the one on the bottom

看看底部的那个，

bouncing up and down trying to find its spot.

它在上下跳动寻找自己的位置。

Another cool thing is the fact that if I make the water drops too big,

另一件很酷的事情是，如果我把水滴弄得太大，

they always seem to explode.

它们似乎总是会爆炸。

Why would it do that? 語氣意圖

为什么会这样？

It happens just a little too fast to see with the naked eye. 講解

它发生得有点太快了，肉眼看不清。

I flew home wishing I had some way of bringing together the acoustic levitation machine 講解

飞回家后，我希望有办法能把这台声悬浮机

and a high-speed camera.

和高速摄像机结合起来。

10 months went by. 短語動詞

10 个月过去了。

I had no way of doing this, 短語搭配

我没有办法做到，

but then I got a call from Ford.

但后来我接到了 Ford 的电话。

They wanted to know if I could do any sound experiments 語法

他们想知道我能否在好莱坞的

on American Idol out in Hollywood.

《美国偶像》里做一些声音实验。

We have 2 hours with the most amazing setup I've ever worked with, 語法

我们有两个小时的时间，使用我所合作过最棒的设备：

an ultrasonic levitation device

一台超声波悬浮装置，

and two really fast high-speed cameras.

和两台真正快的高速摄像机。

We're gonna do 20,000 frames per second with the V2511

我们将用 V2511 拍摄每秒 20,000 帧，

and we're gonna do 7500 frames per second with the V711.

并用 V711 拍摄每秒 7500 帧。

I didn't want to just make a TV segment. 表達脈絡

我不想只做一个电视片段。

I actually wanted to hang out with these guys 短語動詞

我其实想和这些家伙待在一起，

and teach them something new about sound.

教他们一些关于声音的新知识。

Hi, I'm Jax.

嗨，我是 Jax。

I'm Rayvon.

我是 Rayvon。

I'm Clark.

我是 Clark。

I'm Tyanna.

我是 Tyanna。

I'm Nick.

我是 Nick。

All right,

好了，

so we're not gonna pretend like these guys don't know what's up 講解

我们就不假装这些家伙不知道怎么回事了，

cuz we've already done a segment

因为我们已经录过一段了，

and they're actually you know how this works now, right?

他们实际上已经知道这是怎么运作的了，对吧？

Yeah, okay.

是的，没错。

Come over here and let's show everybody how it works.

过来这边，我们给大家展示一下这是怎么运作的。

It looks to me like just an amp. 語氣意圖

在我看来，它就像个扩音器。

Okay.

好的。

And when I turn up the amplitude,

当我调大振幅时，

the sound waves through the horns

通过号角传出的声波

will come down against each other

会自上而下相互碰撞，

and it'll make a column

它会形成一个柱状空间，

where you can actually suspend liquid or you know things of physical

你可以在那里悬浮液体，或者说实体物质。

That's right.

没错。

That's right.

没错。

Did he get it right?

他说对了吗？

I think he did.

我觉得对了。

There's an equation that dictates how big a raindrop can be, okay? 用詞

有个方程式决定了雨滴能有多大，好吗？

So the pressure that's on the inside of the drop

水滴内部的压力，

is determined by two times the surface tension 講解

由两倍的表面张力

divided by the radius.

除以半径来决定。

If the drop gets too big,

如果水滴变得太大，

what happens?

会发生什么？

It explodes.

它会爆炸。

It explodes.

它会爆炸。

We're recording high-speed video of these drops that we're levitating

我们正在录制正在悬浮的水滴的高速视频，

and then we're ramping up the amplitude, 短語動詞

然后我们增加振幅，

which is the same as changing the pressure, right?

这就等同于改变压力，对吧？

So once we do that,

所以一旦我们这么做，

the pressure gets so great 語法

压力变得如此之大，

that the surface tension can't hold the drop together any more 短語動詞

以至于表面张力再也无法将水滴凝聚在一起，

and then it just ruptures.

然后它就破裂了。

It overcomes that internal pressure

它克服了内部压力，

and you get an explosion.

于是就爆炸了。

All right,

好了，

I hope you enjoyed this episode of Smarter Every Day.

希望你喜欢这期 Smarter Every Day。

I'm not obligated to say anything about any product, 用詞

我没有义务为任何产品说好话，

but Ford was awesome.

但是 Ford 真的很棒。

Seriously, they let me do awesome science on national TV

说真的，他们让我在国家电视台上展示很棒的科学，

and they made all that happen.

是他们促成了这一切。

So thank you very much, Ford.

所以非常感谢你，Ford。

I

我

appreciate that.

真的很感激。

Also, I did not have to get a Ford Focus at the airport, 語法

还有，我本不一定要在机场租一辆 Ford Focus，

but I wanted to check it out 短語動詞

但我想试一下，

and I'm happy with it.

而且我很满意。

So, there you go.

好了，就是这样。

Please support Ford.

请支持 Ford。

They supported Smarter Every Day.

他们支持了 Smarter Every Day。

I don't have to say that.

我不一定要说这些，

I hope you believe me.

但希望你们相信我。

Also,

还有，

please consider subscribing if you learned something

如果你学到了新知识，请考虑订阅我们，

or checking us out at Smarter Every Day on Patreon.

或者在 Patreon 上的 Smarter Every Day 看看我们。

I am Destin.

我是 Destin。

You're getting smarter every day.

你正在每天变得更聪明。

Have a good one. 語氣意圖

祝你有美好的一天。

I'm with you.

我同意。

Okay,

好了，

teach me something else.

再教我点别的吧。

Um so one kind of cool thing...

嗯，有件挺酷的事……

Oh shit.

噢，糟了。

What could you be possibly doing that's more important than acoustic levitation? 語氣意圖

你到底在干嘛，能比声悬浮还重要？