They flood the sky with brilliant bursts

它們在天空中泛起了燦爛的火花

of scarlet, emerald, and ivory,

猩紅、翡翠和象牙的。

but never blue.

但絕不是藍色的。

Pyrotechnicians have tried to produce

煙火師曾試圖製造

blue fireworks for centuries,

幾百年來，藍色的煙花。

and they have yet to succeed.

而他們還沒有成功。

Why is blue so elusive?

為什麼藍色如此難以捉摸？

John Conkling: The blue has been

約翰-康克林。藍色已被

very, very difficult to achieve

千難萬難

at a level comparable to the greens and reds and whites,

處於與綠色和紅白相媲美的水準。

just because it's a stability issue at high temperatures.

只是因為這是在高溫下的穩定性問題。

[Narrator] That's John Conkling.

[旁白]那是約翰-康克林。

He's one of the world's leading experts in pyrotechnics,

他是世界頂尖的煙火專家之一。

and he says the problem comes down to chemistry.

他說，問題歸結為化學。

You see, to make fireworks,

你看，做煙花。

you need four basic components:

你需要四個基本組件。

fuel (usually gunpowder),

燃料（通常是火藥）；

a compound that produces color,

一種能產生顏色的化合物。

a fuse,

保險絲。

and glue to hold it all together.

和膠水將其固定在一起。

You mix this stuff up into what's called a pellet,

你把這些東西混合成所謂的顆粒。

and then shoot it into the air.

然後將其射向空中。

When the fuse burns up,

當保險絲燒燬後。

it sets off the gunpowder, which explodes.

它引爆了火藥，爆炸了。

That explosion heats up those color-producing compounds,

這種爆炸會把那些產色化合物加熱。

causing them to glow.

導致他們發光。

And it turns out...

結果發現...

Conkling: The hotter you can get the molecules

康克林。你能讓分子越熱越好

in your flame, the more emission you're gonna get,

在你的火焰，更多的排放 你會得到。

so the brighter and more intense the flame color's gonna be.

所以，越是明亮和更強烈的火焰顏色的會是。

[Narrator] But there's a limit,

[旁白]但這是有限度的。

because temperatures that are too hot

因為溫度太高

will break down those molecules and wash out the color.

會分解這些分子，洗出顏色。

But some molecules are hardier than others.

但有些分子比其他分子更堅韌。

Strontium chloride, the compound used to make red fireworks,

氯化鍶，是用來製作紅色煙花的化合物。

can withstand at least 1,500 degrees Fahrenheit.

可以承受至少1500華氏度的高溫。

That's hotter than some lava.

這比岩漿還熱。

But to make a blue firework, you need copper chloride,

但要做藍色的煙花，需要氯化銅。

which is much more fragile.

這一點要脆弱得多。

As soon as it gets hot enough to blaze blue,

只要天氣熱到藍天白雲的程度。

at least 1,000 degrees Fahrenheit,

至少1,000華氏度。

it starts to break down.

它開始分解。

So pyrotechnicians need to find a mixture

所以煙火師需要找到一種混合物

that gets hot enough to set off the blue compound

足夠熱的藍色複合物。

but not so hot that it destroys the color.

但又不至於熱到破壞顏色。

Conkling: It's a delicate balance.

康克林這是一個微妙的平衡。

[Narrator] And even after centuries of searching,

[旁白]即使經過幾個世紀的尋找，

we still haven't discovered the right one,

我們仍然沒有發現正確的一個。

nor have we found a more stable replacement

也沒有找到更穩定的替代品

for copper chloride.

為氯化銅。

And even if we do, we'd better hope that it's cheap

即使我們這樣做，我們最好希望它是便宜的。

and nontoxic.

且無毒。

Conkling: Arsenic, for example, has been used

康克林。例如，砷已經被用於

in some old fireworks formulations,

在一些老煙花配方中。

but obviously an arsenic compound

但顯然是一種砷化合物

is not something you wanna put up in the smoke

不是你想放的東西在煙霧中

where people are watching the fireworks.

在那裡人們正在觀看煙花。

[Narrator] To be fair, we've gotten close-ish.

[旁白]公平地說，我們已經接近了。

Conkling: There's some respectable pale blues

康克林。有一些值得尊敬的淡藍調。

that are used more in special effects,

在特效中使用較多的。

where the audience is a little closer to the action,

在這裡，觀眾離行動更近一些。

and usually the color is more visible.

且通常顏色比較明顯。

It's been a long search, and we're not there yet.

我們找了很久，還沒找到。

[Narrator] But there's still hope for bright blue.

[旁白]但明亮的藍色仍有希望。

Conkling: Certainly it's possible,

康克林。當然，這是可能的。

as there are people working on it,

因為有人在努力。

so there could be a breakthrough one of these days.

是以，有可能有一個突破的這些天。

[Narrator] And even if we never find that brilliant blue,

[旁白]即使我們永遠也找不到那片燦爛的藍色

there's still plenty to get excited about on the horizon,

還有很多事情可以讓人興奮。

like fireworks that burst into different shapes

如同煙花般綻放出不同的形狀

and patterns, even letters.

和圖案，甚至字母。

So maybe one day we can have an American-flag firework

也許有一天，我們可以有一個美國國旗的煙花。

for the Fourth of July.

為國慶節。

We just need to get that blue.

我們只需要得到那個藍色的。