things: first, the wake isn't simple (like the perfectly straight shock wake of a supersonic

事情：首先，尾翼並不簡單（就像超音速飛機完美的直線震盪尾翼那樣）。

projectile is) - it's a fascinating, feathery, ripple-y pattern.

彈丸是）--這是一種迷人的、羽毛狀的、波紋狀的圖案。

And second, that feathery pattern looks the same - same angle, same repeating pattern

其次，那個羽毛狀的圖案看起來是一樣的--同樣的角度，同樣的重複圖案

of ripples along the edge, same reverse arcs in the middle - it looks more or less the

沿著邊緣的波紋，中間同樣的反向弧線--它看起來或多或少地有了些許的變化。

same regardless of whether it's made by a duck, a kayak or a ship, even though they're

不管是鴨子、皮划艇還是船做的都一樣，即使它們是。

all moving at different speeds and the waves are very different sizes.

都在以不同的速度運動，而波浪的大小卻大不相同。

The reason water wakes always have this particular shape and pattern is because of the surprising

水滸傳之所以總是有這種特殊的形狀和圖案，是因為出人意表的

physics of water waves.

水波的物理學。

While there's a single speed of light waves, and a single speed of sound waves, there's

雖然光波的速度是單一的，聲波的速度也是單一的。

no single speed of water waves.

沒有單一的水波速度。

In water, longer waves travel faster, while shorter waves travel slower.

在水中，較長的波浪行進速度較快，而較短的波浪行進速度較慢。

This phenomenon where different wavelength waves travel at different speeds is known

這種不同波長的波以不同速度傳播的現象稱為

as dispersion, and it makes water waves both interesting and complicated.

作為分散，它使水波既有趣又複雜。

Like a boat wake.

就像一個船尾。

To explain the shape of a boat wake, we'll start by looking at water waves of just a

為了解釋船尾的形狀，我們先看一下水波的形狀。

single wavelength (and speed).

單一波長（和速度）。

A boat traveling across this simpler water creates a series of circular waves - if the

船在這種簡單的水面上行駛，會產生一連串的圓形波浪--------若是

water waves are faster than the boat, the waves encircle it, but you don't get a wake.

水波比船快，波浪包圍了它，但你不會有驚濤駭浪。

If the waves are slower than the boat, the boat outruns them and the circles all add

如果波浪比船慢，船就會超過波浪，圈圈都會加。

together to create a V-shaped wake.

一起形成一個V形的尾巴。

And if the waves are even slower, the boat will outrun them even more and they'll add

如果海浪再慢，船就會比它們更快，它們就會增加。

together to a narrower V shape.

合在一起，形成一個較窄的V形。

Slower waves make narrower wakes.

較慢的波浪使波浪更窄。

Faster waves make wider wakes.

波浪更快，浪花更寬。

But we need to remember that water waves are waves, that is, they repeat themselves.

但我們要記住，水波就是波，就是重複。

So every circular wave is really the first of a series of circular waves.

所以每一個圓波其實都是一系列圓波中的第一個。

This means that instead of creating just one v-shaped wake, a moving boat creates a train

這意味著，移動的船不是隻產生一個V形的水花，而是產生一連串的水花。

of v-shaped wakes that are each exactly one wavelength apart.

的V形波浪，每個波浪正好相隔一個波長。

The reason a real boat doesn't make straight v-shaped wakes is that a real boat makes waves

真正的船之所以不會產生直的V形波浪，是因為真正的船會產生波浪。

of many different wavelengths.

許多不同波長的。

And because of dispersion, different wavelengths travel at different speeds: the longer ones

由於色散的存在，不同波長的傳播速度不同：較長的是

travel faster and shorter ones travel slower.

走得快，短的走得慢。

Faster waves create wider wakes, and because faster waves also have longer wavelengths,

較快的波浪會產生較寬的波浪，而且因為較快的波浪也有較長的波長。

that means that wider wakes are further apart.

這意味著，更寬的湖泊更遠的距離。

Similarly, slower waves create narrower wakes, and because slower waves also have shorter

同樣，較慢的波浪會產生較窄的波浪，而且由於較慢的波浪也有較短的波浪，是以，較慢的波浪會產生較窄的波浪。

wavelengths, narrower wakes are closer together.

波長較窄的波段，距離較近的波段。

When you add together narrow, closely spaced wakes, with wider, more widely spaced wakes,

當你把窄小的、間隔緊密的湖泊，與寬大的、間隔較寬的湖泊加在一起。

with even wider, even more widely separated wakes, and so on, voilá!

與更寬、更寬分開的湖泊，以此類推，voilá!

The shape of a boat wake!

船尾的形狀!

Look at the beautiful repeating feathery ripples out on the edge, and the wider repeating arcs

你看，美麗的重複的羽毛狀波紋在邊緣出，還有更寬的重複的弧線。

inside the wake itself.

內的喚醒本身。

If you replace these sharp lines with smoother waves at the appropriate angles and spacings,

如果你以適當的角度和間距將這些尖銳的線條換成更平滑的波浪。

you get an even more convincing boat wake.

你會得到一個更有說服力的船尾。

And we can do the same again in 3D to get a really realistic-looking boat wake.

而且我們還可以用3D技術再做一次同樣的處理，以獲得一個看起來非常逼真的船尾。

So in summary: wakes have the shape they do because water waves travel at different speeds.

所以綜上所述：湖泊之所以有這樣的形狀，是因為水波的傳播速度不同。

Slower water waves create narrow, closely spaced V-shaped wakes, and faster water waves

較慢的水波會產生窄小的、間隔緊密的V形波浪，而較快的水波則會產生窄小的、間隔緊密的V形波浪。

create wider V-shaped wakes that are further apart.

形成較寬的V形波浪，距離較遠。

When you add all these different v-shaped patterns together, at the correct angles and

當你把所有這些不同的V形圖案加在一起，以正確的角度和

spacings determined by water's dispersion relation, you end up with the unique shape

由水的分散關係決定的間距，你最終會得到獨特的形狀。

of a water wake.

的水醒。

SPONSORSHIP MESSAGE: Watch an extended, ad-free version of this

贊助資訊。觀看本片的無廣告擴展版

video on Nebula.

星雲上的視頻。

Ok, there are some caveats to the science in this video, and you can find out about

好吧，這段視頻中的科學有一些注意事項，你可以瞭解一下。

them in the extended version over on Nebula, the Streamy-award-nominated independent streaming

他們的加長版在Nebula上，獲得Streamy獎提名的獨立流媒體。

service that's the co-sponsor of this video.

服務，是這個視頻的聯合贊助商。

Nebula was created by and for a collection of educational video creators including Real

星雲是由和教育視頻創作者集合創作的，包括Real

Engineering, Mike Boyd, Up and Atom, Jordan Harrod - and me - and Nebula has partnered

工程部、邁克-博伊德、Up和Atom、喬丹-哈羅德--還有我--和星雲合作了。

with CuriosityStream, which offers thousands of documentaries and nonfiction titles to

與CuriosityStream合作，該公司提供了數千部紀錄片和非小說類書籍，以滿足用戶的需求。

give you access to both in one go!

讓你一次就能獲得這兩樣東西!

I recommend Magic Numbers, Hannah Fry's fun series about mathematics: how it's influenced

我推薦《神奇的數字》，漢娜-弗萊關於數學的趣味系列：它是如何影響的。

science, how science has influenced math, the question of whether math is invented or

科學，科學是如何影響數學的，數學是發明還是

discovered, and more.

發現，以及更多。

Sign up for CuriosityStream using the link in the description and you'll also get access

使用描述中的鏈接註冊CuriosityStream，您還可以訪問

to Nebula, including the extended version of this video as well as an ad-free viewing

到星雲，包括該視頻的擴展版以及免廣告觀看。

experience across the site.

整個網站的體驗。

Oh yeah, and you'll also get 26% off an annual subscription to CuriosityStream.

哦，對了，你還可以享受到26%的優惠，每年訂閱《好奇心流》。