为什么宇航员在月球上留下了反射器！(ft. MinutePhysics) - Smarter Every Day 73：英语精读讲义

It's me Destin.

我是 Destin。

Welcome back to Smarter Every Day.

欢迎回到 Smarter Every Day。

So, did you know that in the '60s and '70s, 表達脈絡

那么，你知道在 60 和 70 年代，

when the astronauts went to the Moon in the Saturn V rocket,

当宇航员乘坐土星 5 号火箭登月时，

they actually left experiments on the surface of the Moon?

他们其实在月球表面留下了一些实验设备吗？

In fact, there's one that's still there today 表達脈絡

事实上，有个设备今天还在那里

and it's still operating.

并且仍在运作。

We're still getting data out of it.

我们依然能从中获取数据。

But before I explain

但在我解释

that, I kind of need to go to the bathroom. 語氣意圖

那个之前，我得先去趟洗手间。

All right.

好吧。

Here where I went to grad school,

这是我读研的地方，

we shared this building with NASA,

我们和 NASA 共用这栋楼，

which is interesting because every time I go wash my hands 語法

这很有趣，因为每次我去洗手

after using the bathroom,

（上完洗手间后），

I think about the Moon.

我都会想到月球。

Check this out. 語氣意圖

来看看这个。

On one wall,

在一面墙上，

we have a mirror,

我们有一面镜子，

and on the other wall we have a mirror and they're lined up.

而在另一面墙上我们也有一面镜子，而且它们对齐了。

Now, all this makes for some pretty interesting fun stuff. 短語動詞

现在，这一切构成了非常有趣的现象。

But what I want to talk about today is right here. 表達脈絡

但我今天想谈的是这里。

Look at that.

看那个。

No matter where you go in the room, 語法

无论你走到房间里的哪个地方，

you always see the camera lens

你总是能看到相机的镜头

right in the corner of the mirror.

正好在镜子的角落里。

This has pretty serious implications 短語搭配

这有着相当重要的意义

for NASA science on the Moon.

对 NASA 在月球上的科学研究来说。

Now, it's so important that I've asked Henry from MinutePhysics

这非常重要，所以我请来了 MinutePhysics 的 Henry

to explain it to you.

来为你们解释。

Let's check it out.

我们来看看吧。

A corner reflector like this one

像这样的角反射器

is an ingenious and beautifully simple device.

是一个巧妙又极具简单美感的装置。

It takes advantage of the fact that a mirror mirrors one dimension of the world. 短語搭配

它利用了镜子能镜像反映世界一个维度的原理。

If you have a second mirror,

如果你有第二面镜子，

you can reverse back to how you started.

你就可以反转回最初的样子。

But if the second mirror is at 90° to the first,

但如果第二面镜子和第一面呈 90 度角，

now when you mirror back,

现在当你反射回去时，

the world will have rotated 180°.

世界将旋转 180 度。

So, if you send a beam of light into a corner reflector,

所以，如果你把一束光射入角反射器，

regardless of what direction you send it in 語法

不管你射入的方向如何，

or what direction the corner reflector is oriented,

或者角反射器的朝向如何，

it'll come back rotated 180°

它都会旋转 180 度返回

into a parallel return path to its source.

进入一条平行于光源的返回路径。

If you look here at the top of the camera,

如果你看看相机顶部，

you can see that my name is mirrored.

你可以看到我的名字被镜像反转了。

But if I bring it over here to the side in the corner,

但如果我把它拿到这边的角落里，

look at that.

看看这个。

You can read it.

你可以读出来了。

You can probably see it a little bit better with my shirt.

看我的衣服可能会看得更清楚一点。

Can't read it?

读不出来？

Now you can.

现在你可以了。

That's because you're seeing a reflection of a reflection.

这是因为你看到的是反射的反射。

But look at this.

但看看这个。

If I look back at the corner and then I tilt the camera up,

如果我看着角落然后把相机向上倾斜，

I'm no longer aligned. 語法

我就不再对齐了。

I can't see the lens anymore.

我再也看不到镜头了。

Now, that tells me that I'm not in a true return path 表達脈絡

这告诉我，我不在一条真正的返回路径上

like he tried to explain to me.

就像他试图向我解释的那样。

That's because those mirrors

这是因为这些镜子

are only reflecting in the two horizontal directions.

只在两个水平方向上反射。

There's no mirror reflecting back to you in the vertical direction.

没有镜子在垂直方向上向你反射。

If you have a third mirror at a right angle, 短語搭配

如果你有成直角的第三面镜子，

everything will be mirrored,

一切都会被镜像，

reversed,

反转，

and mirrored again.

然后再被镜像。

So, your name will be backwards.

所以，你的名字会倒过来。

But at least now you can move your camera or eyes around however you want. 語法

但至少现在你可以随心所欲地移动相机或眼睛。

And as long as you can still see all three mirrors, 語法

只要你还能看到全部三面镜子，

you'll see a reflection of yourself in the middle.

你就会在中间看到你自己的反射。

Mathematically, if you want to reverse a vector, 語法

从数学上讲，如果你想反转一个向量，

you need to reverse each of its components,

你需要反转它的每一个分量，

and so you need three mirrors

所以你需要三面镜子

to get full retroreflection in 3D. 用詞

来实现 3D 的全向逆反射。

One mirror for each dimension.

每个维度一面镜子。

Oh, this is just like the reflectors on the road.

哦，这就像路上的反光镜一样。

If you look real close at this one that my wife hit with a lawn mower,

如果你仔细看看这个被我妻子用割草机撞过的东西，

you can see that they're actually just little bitty corner reflectors. 用詞

你可以看到它们其实就是小小的角反射器。

Exactly,

没错，

but those are imperfect on purpose 短語搭配

但它们是故意做得不完美的，

because a high precision corner reflector would bounce the light back 短語動詞

因为高精度的角反射器会把光反弹回

to your car's headlights and not your eyes.

你汽车的车头灯里，而不是你的眼睛里。

Oh!

哦！

Well, I just happen to have an array of high precision corner reflectors 短語搭配

好吧，我刚好有一组高精度的角反射器

here with me in Germany.

带在我身边，在德国。

And what's that?

那是啥？

It's Johan,

这是 Johan，

the laser guy from the Netherlands.

来自荷兰的激光达人。

You remember him, right?

你还记得他吧？

This corner reflector is so precise,

这个角反射器非常精确，

I can set it here on this bridge,

我可以把它放在这座桥上，

go all the way upriver to the next bridge,

一路逆流而上到下一座桥，

hit it with a laser,

用激光照射它，

and I'll still get a reflection even though it's snowing. 語法

尽管在下雪，我仍然能看到反射。

Check it out.

来看看。

What are you doing, Johan?

你在干嘛，Johan？

I'm warming up my laser. 短語動詞

我在预热我的激光器。

All right.

好吧。

And uh why are you doing that?

呃，你为什么要那样做？

To get it to the right temperature because it's very temperature sensitive. 講解

为了让它达到合适的温度，因为它对温度非常敏感。

Oh, okay.

哦，好的。

All right.

好吧。

Can you ping the reflector? 用詞

你能照射一下反射器吗？

There it is.

在那儿呢。

Clearly,

很明显，

you're getting a return.

你收到了返回的光。

That's what, like 500 m away,

大概有 500 米远吧，

would you say? 語氣意圖

你觉得呢？

350.

350。

How do you know that?

你怎么知道的？

I counted the steps.

我数了步数。

Okay,

好的，

so here's the question. 表達脈絡

那么问题来了。

If Johan is able to get a really good reflection

如果 Johan 能够在

at 350 m away in the snow

350 米外，在雪地中

with a handheld laser

用手持激光器

that he's having to blow on to keep alive, 習語

（甚至还要对着它吹气来保持温度），获得极好的反射，

then what are we able to do if we put

那么如果我们把

a high precision laser reflector on the Moon?

一个高精度激光反射器放在月球上，我们能做到什么？

In fact,

事实上，

that's what Apollo

那正是阿波罗计划

did. What was it?

所做的。那是几号来着？

Apollo what?

阿波罗几号？

Apollo 11,

阿波罗 11 号，

14,

14 号，

and 15.

和 15 号。

They put retroreflectors on the Moon,

他们在月球上放置了后向反射器，

and we're still using it for experiments to this day. 短語搭配

而且直到今天我们仍在使用它们进行实验。

Right.

对的。

Experiments like monitoring the distance to the Moon.

诸如监测地月距离这样的实验。

If you count how long it takes a photon to get to the Moon and back, 語法

如果你计算一个光子到达月球并返回需要多长时间，

you can just multiply by the speed of light,

你只需乘以光速，

divide by two,

除以二，

and figure out the distance to the Moon within centimeters. 短語動詞

就能将地月距离精确到厘米级别。

Exactly,

完全正确，

Henry.

Henry。

So, if you shoot the Moon with a laser,

所以，如果你用激光射向月球，

2.56 seconds later,

2.56 秒后（返回），

divided by two,

除以二，

1.28 light seconds to the Moon.

到月球就是 1.28 光秒。

So, if you do the math, 短語搭配

所以，如果你算一下，

that ends up to about this far from the Earth.

大概就是离地球这么远的距离。

Anyway,

不管怎样，

this is useful for understanding

这有助于理解

the detailed nuances of the Moon's rotation and orbit,

月球自转和轨道的细微变化，

measuring movement of tectonic plates here on Earth,

测量地球上构造板块的运动，

and even testing

甚至可以用来检验

the fundamental principles of general relativity.

广义相对论的基本原理。

Corner reflectors are not just used in optics. 語法

角反射器不仅用于光学。

You can also use it for any type of reflected electromagnetic radiation.

你也可以将它用于任何类型的反射电磁辐射。

Here in Frankfurt, Germany,

在德国法兰克福这里，

there's a bridge with long posts

有一座桥，长长的柱子

coming off the big pylons there under the bridge.

从桥下那些巨大的桥墩上伸出来。

We've got a big boat about to go under the bridge. 語法

有一艘大船正准备从桥下经过。

And if you look at the very end,

如果你看最末端，

there's corner reflectors.

那里有角反射器。

Only they're not mirrors, 表達脈絡

只是它们不是镜子，

they're just metal.

只是金属而已。

He's using a radar

他正在使用雷达

to guide off of those corner reflectors,

依靠那些角反射器来导航，

so he doesn't hit the bridge.

这样他就不会撞到桥上。

It's basically a passive lighthouse, 習語

它基本上是一个无源灯塔，

only it's not light,

只不过发出的不是光，

it's radar.

而是雷达。

Cool.

酷。

So, corner reflectors are like a lighthouse

所以，角反射器就像一座灯塔

that tells you its distance,

告诉你它的距离，

except better because they don't need their own source of power. 講解

只是更好，因为它们不需要自己的电源。

That's why they were a good experiment to leave on the Moon. 表達脈絡

这就是为什么把它们留在月球上是个很棒的实验。

Actually,

实际上，

the Apollo astronauts left other junk on the Moon, too. 用詞

阿波罗宇航员还在月球上留下了其他的废品。

Come over to my channel,

来我的频道，

MinutePhysics,

MinutePhysics，

and I'll tell you all about it.

我会告诉你关于它的一切。

That's how the Apollo guys

这就是阿波罗的小伙子们

went to the bathroom in the command module.

在指令舱里上洗手间的方式。

How'd they do it on the lunar module?

他们在登月舱里是怎么解决的？

Imagine it's fairly similar.

我想应该挺相似的。

Oh.

哦。

Do you realize that there might be poop on the Moon.

你意识到月球上可能有便便吗。

We gotta think this through! 講解

我们得好好想想这个！

Wow.

哇。

I didn't even think about that.

我甚至都没想过那个。

We always talk about the other stuff that they sent.

我们总是谈论他们送上去的其他东西。

Did they leave their poop on the Moon?

他们把便便留在月球上了吗？

I imagine they must 語法

我想他们肯定是

have because like why would you bring that back? 語氣意圖

留了，因为你干嘛要把它带回来？

When I go hiking,

当我去徒步时，

I try to find the perfect spot.

我试图寻找最完美的地点。

That guy has won that game.

那个家伙赢得了那场游戏。

That's like the most distant porta-john. 文化背景

那就像是最遥远的移动厕所。

The most distant porta-john

最遥远的移动厕所

On the lunar landers on the Moon.

在月球上的登月舱里。