when the astronauts went to the moon in the Saturn 5 rocket, they actually

當太空人乘坐土星5號火箭登上月球的時候，他們實際上

left experiments on the surface of the moon? In fact there's one that's still there today

在月球表面留下實驗？其實有一個'的，今天還在那裡呢

and it's still operating. We're still getting data out of it. But before I explain that,

和它'仍然運行。我們仍在獲取數據。但在我解釋之前。

I kind of need to go to the bathroom. [Toilet Flush]

我需要去洗手間。[沖廁所]

Alright. Here where I went to grad school we shared this building with NASA, which is interesting because every time I

好吧，我在這裡讀研究所學生的地方在這裡，我去了研究生院 我們共享這個建築與美國宇航局， 這是有趣的，因為每一次我

go wash my hands after using the bathroom, I think about the moon. Check this out.

上完廁所後去洗手，我想到了月亮。看看這個。

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

一面牆上我們有一面鏡子，另一面牆上我們有一面鏡子，他們'排成一排。

Now all this makes for some pretty interesting fun stuff, but what I want to talk about today

現在，所有這些都是一些很有趣的東西，但我今天想談的是

is right here. Look at that. No matter where you go in the room,

是在這裡。看看這個不管你去哪裡，在房間裡，

you always see the camera lens right in the corner of the mirror. This has pretty

你總是看到相機鏡頭就在鏡子的角落裡。這有相當

serious implications for NASA science on the moon. Now it's so important

對美國宇航局在月球上的科學有嚴重的影響。現在，它是如此重要

that I've asked Henry from MinutePhysics to explain it to you. Let's check it out.

我請MinutePhysics的Henry給你解釋一下。讓我們來看看。

(Henry) A corner reflector like this one is an ingenious and beautifully

(Henry)像這樣的轉角反射器是一個巧妙而精美的。

simple device. It takes advantage of the fact that a mirror mirrors one dimension

簡單的設備。它利用鏡面反射一維的事實

of the world. If you have a second mirror, you can reverse back to how you started.

的世界。如果你有第二面鏡子，你可以反向回到你開始的地方。

But if the second mirror is at 90 degrees to the first, now when you mirror back,

但如果第二面鏡子與第一面鏡子成90度，現在當你鏡子回。

the world will have rotated 180 degrees. So if you send a beam of light

世界將自轉180度所以如果你發出一束光

into a corner reflector, regardless of what direction you send it in or what direction the

角反射器，不管你把它送到什麼方向，或者是什麼方向，都可以把它變成一個角反射器。

corner reflector is oriented, it’ll come back rotated 180 degrees into a

角反射器的方向，它將回來旋轉180度成為一個 "角反射器"。

parallel return path to its source. (Destin) If you look here at the top of the camera you can see that my name

平行返回路徑到它的源頭。(Destin)如果你看這裡，在相機的頂部，你可以看到我的名字是...

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

是鏡像的。但如果我把它帶到這邊的角落。

look at that. You can read it. You can probably see it a little bit better with my shirt.

你看那個。你可以讀它。你可能可以看到它與我的襯衫更好一點。

Can't read it.. Now you can. That's because you're seeing a reflection of a reflection.

看不懂現在你可以了。那是因為你看到的是倒影的倒影。

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

但你看這個。如果我回頭看角落，然後我把相機傾斜起來。

I'm no longer aligned. I can't see the lens any more. Now that tells me that I'm not

我不再對準了 I'm no longer aligned.我不能'看鏡頭了。現在，這告訴我，我不。

in a true return path like he tried to explain to me. (Henry) That's because those mirrors are

就像他試圖向我解釋的那樣，在一個真正的返回路徑中(亨利)那是因為那些鏡子是：

only reflecting in the two horizontal directions. There's no mirror reflecting back to you

只在兩個水準方向反射。沒有鏡子反射到你的身上

in the vertical direction. If you have a third mirror at a right angle, everything will

在垂直方向上。如果你有第三面直角的鏡子，所有的東西將

be mirrored, reversed, and mirrored again, so your name will be backwards.

被鏡像、反轉、再鏡像，所以你的名字會被反過來。

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

但至少現在你可以隨心所欲地移動你的相機或眼睛。

and as long as you can still see all three mirrors, you’ll see a reflection of yourself

只要你還能看到三面鏡子，你就能看到自己的影子。

in the middle. Mathematically, if you want to reverse a vector, you need to reverse each of its components,

在中間。數學上，如果你想反轉一個向量，你需要反轉它的每一個分量。

and so you need three mirrors to get full retroreflection in 3D.

所以你需要三面鏡子才能在3D中獲得完整的逆反射。

One mirror for each dimension. (Destin) Oh. This is just like the reflectors on the road.

每個維度都有一面鏡子。(Destin) Oh.這就像路上的反光鏡一樣 This is just like the reflectors on the road.

If you look real close at this one that my wife hit with the lawn mower you can see that they're actually

如果你看真正的接近這一個，我的妻子打與割草機，你可以看到，他們實際上'。

just little bitty corner reflectors. (Henry) Exactly! But those are imperfect.

只是小小的角落反射器(亨利) 沒錯!但這些都是不完美的.

On purpose, because a high precision corner reflector would bounce the light back

故意的，因為高精度的角反射器會把光反射回來。

to your car's headlights and not your eyes. (Destin) Ohh! Well I just happen to have

你的車的前燈，而不是你的眼睛。哦，我只是碰巧有...

an array of high precision corner reflectors here with me in Germany. And what's that?

高精度角反射器的陣列，在德國和我在一起。那是什麼？

It's Johan, the laser guy from the Netherlands. You remember him right?

我是Johan 來自荷蘭的那個脈衝光男。你還記得他吧？

This corner reflector is so precise,

這個角反射器太精確了。

I can set it here on this bridge, go all the way up river to the next bridge,

我可以把它設置在這座橋上，一直走到下一座橋的河上。

hit it with a laser and I'll still get a reflection, even though it's snowing.

用脈衝光打它，我'仍然會得到一個反射，即使它'下雪。

Check it out.

看看吧

What are you doing Johan?!

你在做什麼，Johan？

(Johan) I'm warming up my laser. (Destin) [laughs] Alright.

我在給我的激光器熱身呢。好吧

And ah.. Why are you doing that? - To get it to the right temperature.

你為什麼要這麼做？- 為了讓它達到合適的溫度。

Because it's very temperature sensitive. - Oh OK. Alright can you ping

因為它對溫度非常敏感。- 哦，好吧。好吧，你可以PING

the reflector? There it is. Clearly you're

反射器？就是這樣顯然你

getting a return. That's what? Like 500 meters away would you say? - 350

得到回報。那是什麼？像500米遠你會說？- 350

- How do you know that? - I counted steps. [laugh]

- 你怎麼知道的？- 我數過步數。[笑]

- OK so here's the question. If Johan is able to get a really good reflection

- 好吧，所以這裡'的問題。如果Johan能夠得到一個非常好的反映。

at 350 metres away, in the snow, with a hand-held laser

在350米外的雪地上，用手持激光器

that he's having to blow on to keep alive, then what are we able to do if we put

他不得不吹上維持生命，那麼我們能夠做什麼，如果我們把他的。

a high precision laser reflector on the moon. In fact,

月球上的高精度脈衝光反射器。事實上，

that's what Apollo did. What was it, Apollo what? - 11, 14 and 15.

那是阿波羅所做的。是什麼，阿波羅什麼？

- Apollo 11, 14 and 15. They put retro-reflectors on the moon

- 阿波羅11號、14號和15號他們在月球上安裝了逆向反射器。

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

而我們'至今還在用它做實驗。

(Henry) Right. Experiments like monitoring the distance to the moon. If you count how long it takes a photon

(亨利) 對像監測到月球的距離這樣的實驗。如果你計算一個光子需要多長時間...

to get to the moon and back, you can just multiply by the speed of light, divide by two

要想往返月球，你只需乘以光速，再除以二即可

and figure out the distance to the moon, within centimeters. (Destin) Exactly Henry.

並計算出到月球的距離，在釐米之內。(Destin) 正是亨利。

So if you shoot the moon with a laser...

所以，如果你用脈衝光射向月球... ...

2.56 seconds later, divided by two, 1.28 light

2.56秒後，除以二，1.28光景。

seconds to the moon. So if you do the math that ends up to about... this far from the Earth.

到月球的時間是幾秒鐘所以，如果你計算一下，最後大約... ...離地球這麼遠。

(Henry) Anyway, this is useful for understanding the detailed nuances of the

(Henry)無論如何，這對於理解細節上的細微差別是很有用的。

moon’s rotation and orbit, measuring movement of tectonic plates here on earth,

月球的自轉和軌道，測量地球上構造板塊的運動。

and even testing the fundamental principles of general relativity. (Destin) Corner reflectors are not

甚至檢驗廣義相對論的基本原理。(Destin)角反射器不是

just used in optics, you can also use it for any type of reflected electromagnetic radiation.

只是用於光學領域，你也可以用它來處理任何類型的反射電磁輻射。

Here, in Frankfurt Germany, there's a bridge with long

在德國法蘭克福，這裡有一座橋，橋上有長長的橋。

posts coming off the big pylons there under the bridge. We've got a big boat

橋下的大塔架上的柱子。我們有一艘大船

about to go under the bridge. So if you look at the very end, there's corner reflectors. Only they're not

即將進入橋下。所以如果你看最後，有'的角反射器。我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意思是說，我的意

mirrors, they're just metal. He's using a radar to guide

鏡子，他們只是金屬。他用雷達來引導。

off of those corner reflectors so he doesn't hit the bridge. It's basically

所以他不會撞到橋上。基本上

a passive lighthouse, only it's not light, it's radar.

被動燈塔，只是它'不是光，它'的雷達。

(Henry) Cool! So corner reflectors are like a lighthouse that tells you its distance,

(亨利) 酷！所以角反射器就像燈塔一樣，可以告訴你它的距離。

except better because they don’t need their own source of power. That’s why they were a good experiment to leave

除了更好，因為他們不需要自己的力量來源。這就是為什麼他們是一個很好的實驗離開

on the moon. Actually, the Apollo astronauts left other junk on the moon too.

在月球上。其實，阿波羅太空人也在月球上留下了其他垃圾。

Come over to my channel, MinutePhysics, and I’ll tell you all about it.

來我的頻道，MinutePhysics，我會告訴你一切。

[Music]

[音樂]

That's how the Apollo guys went to the bathroom, in the command module.

阿波羅的人就是這樣去上廁所的，在指揮艙裡。

How'd they do it on the lunar module? (Henry) Imagine it's fairly similar.

他們在月球艙上是怎麼做的?想象一下，這很相似。

They probably left it on the moon though. Do you realise there might be.. - There might be poop on the moon. We gotta think this through! [laugh]

他們可能把它留在了月球上，雖然。你知道可能有...我們得好好想想！[笑]

I didn't even think about that. We always talk about the other

我甚至沒有想到這一點。我們總是談論其他

stuff that they sent. (Henry) Did they leave their poop on the moon? [laughs]

他們送來的東西(亨利)他們把他們的大便留在月球上了嗎?[笑]

I imagine they must have, because like why would you bring that back? - When I go hiking I try to find the perfect

我想他們一定有，因為像你為什麼要把它帶回來？- 當我去遠足，我試圖找到完美的。

spot. That guy has won that game. [laugh]

斑。這傢伙已經贏得了這場比賽。[笑]

(Henry) The most distant porta-john. [laugh] The most distant porta-john is the

(Henry)最遙遠的門診部。[笑]最遙遠的門診部是指：

on the lunar landers on the moon.

在月球上的登月者。

[ Captions by Andrew Jackson ] captionsbyandrew.wordpress.com

[字幕由安德魯-傑克遜] captionsbyandrew.wordpress.com

Captioning in different languages welcome. Please contact Destin if you can help.

歡迎使用不同語言的字幕。如果你能幫忙，請聯繫Destin。