They were vast improvement over the dangerous tradition of putting actual flaming candles in a very, very dry tree, but in doing so he also invented a new kind of headache ...

相較於將燃燒的蠟燭插在乾燥的樹上這危險的傳統，實屬是一大進步但這樣又產生了一個令人頭痛的問題

How… how did this happen? I was so careful last year…

呃...怎麼會這樣。我去年很小心的阿...

Scientists have spent a lot of time thinking about how things get tangled.

科學家花了很長時間去想要怎麼讓所有事情不再糾結

And it turns out it’s just the rules of the universe.

而這就是宇宙運行的規則。2007年，物理學家揭示了任何超過2公尺的線

In 2007, physicists showed for any cord longer than about 2 meters, knots aren’t rare, they’re almost guaranteed to happen.

是非常容易打結的，這幾乎是保證會發生的事。數學式有點複雜

Though the math is a little complex, but think of it as the most frustrating example of entropy you’ve ever encountered:

但想想，這裡有個你一定遇過最令人感到挫折的例子

There’s always only one way for a string of lights to be untangled, but with a few turns, there’s billions, or trillions or more ways for them to get tied up.

只有走直線可以讓一條燈泡線不打結，而只要幾個彎

Stupid Edison. I bet Tesla would have figured this out.

就會有幾十億或是幾兆，甚至更多的可能性會讓線糾纏在一起

On Christmas Eve, 1968, the astronauts of Apollo 8 became the first humans to orbit another world.

真是蠢的愛迪生。但我相信特斯拉會解決這問題的

The next day, on Christmas, they radioed back a very important observation from their vantage point above Earth.

在1968年的聖誕夜裡，阿波羅八號的太空人們，也是人類首次，在另一個世界裡運行

"Roger, please be informed there is a Santa Claus"

隔天，也就是聖誕節，因他們有比在地球上有更好的視野

Well, if NASA said it, it’s gotta be true!

所以他們用無線電發回一個他們觀察到的重要訊息

According to reliable sources, Santa’s sleigh is pulled by a team of reindeer, the most famous one being, of course, Rudolph.

「請注意，我們看到了聖誕老人」

But Rosie might be a more appropriate name.

好吧，既然NASA都這樣說了，那應該是真的吧！

Male reindeer, and caribou, they’re the same species, shed their antlers during the winter, and that means Santa’s reindeer are all female.

根據可靠消息指出，聖誕老人的雪橇是由一群馴鹿拉著走的

Reindeer vision is uniquely adapted for Santa’s nighttime flight.

而其中最有名的一隻，當然就是魯道夫拉。但也許蘿西才是更適合的名字

To cope with the months of darkness at northern latitudes, the inside of a reindeer’s eyes change from gold-colored in summer to blue in winter, which scatters more light onto their retina.

雄性馴鹿，也就是北美馴鹿。在冬天他們的鹿茸會脫落

So how do they fly? Would you believe that reindeer are buoyant?

這表示聖誕老人馴鹿都是雌性的

(singing) Reindeers float better than people.

而馴鹿的視覺的確是很特別而能夠適應聖誕老的夜間的飛行

But they’re huge, how could that be true? Oh well it’s physics, you follow?

為了適應高緯度的黑暗，在夏天，馴鹿的眼睛內部是金色的

Their hairs, they're hollow, They insulate much better than you… it’s true.

而當冬天來到，則會變藍，這樣可以讓視網膜聚集更多的光線

A reindeer’s coat contains two kinds of hairs:

至於他們怎麼飛行？你相信馴鹿是有浮力的嗎？

A layer of short, dense hair covered with a mesh of longer, hollow hairs.

(歌聲)馴鹿比人類還能夠飄浮

This traps a layer of air in between, which insulates them from the cold, just like those puffy jackets that we wear.

但它們很大隻耶，怎麼可能浮得起來？嗯，這就是物理，懂嗎？

This insulation works so well, not only can snow land on reindeer’s backs and not melt, with a little jog they can overheat, even in temperatures down to -40 Celsius.

牠們的毛髮，是中空的，牠們比你還能夠保暖...這是真的

Reindeer have 25% more blood vessels packed in their nasal cavities than we do, so they get rid of excess heat through their noses.

馴鹿的外皮有兩種毛髮: 一層柔軟，濃密的毛

This makes their noses glow on a thermal camera, and sometimes they even look red to the naked eye.

上面再覆蓋一層網狀中空的長毛。這能夠讓空氣存於毛內這樣可以隔離冷空氣，就像你穿上厚厚的夾克一樣

But even with his team of flying reindeer, how does Santa get around the world in a single night?

因為隔離效果很好，不只是堆積在馴鹿背上的落雪不會融化

There’s only so many hours in a day. Well, luckily, he’s got more than 24 of them.

甚至牠們在攝氏零下40度的環境中走一小段路還會感到太熱

If Santa starts delivering presents at, say, 10 p.m. at the international date line and travels west with the rotating Earth, he can circle the globe without losing any time.

馴鹿在鼻腔中的血管比人類多25%，所以他們可以

Then he can reverse course until kids wake up at 6 AM, giving him 32 hours total to deliver presents.

從鼻子排出多餘的熱氣。你用熱像儀探測就能看到牠們鼻子周圍是亮的

Let’s assume Santa delivers gifts to all 2.2 billion children on Earth, because hey, it’s Christmas after all.

而且有時牠們的眼睛甚至看起來是紅色的

At 2.3 children per household, that’s 944 million stops.

但就算聖誕老人擁有一群能飛的馴鹿，他要怎麼在一個晚上環繞世界一周？

How far does he have to travel?

一天也不過就這麼多小時。好吧，很幸運地，他有超過24小時的時間

There’s about 24.6 million square miles of habitable land on Earth, so if we average out the space between every chimney, that gives us about .026 square miles per household.

假如聖誕老人在晚上10點在從國際換日線開始發送禮物

If every house occupies an evenly spaced square 0.16 miles apart, Santa’s sleigh has to cover more than 150,000,000 miles in 32 hours, which means an average speed of more than 1,300 miles per second.

而且一路向西走，因為地球是由西向東自轉，他環繞地球一圈就不會浪費任何時間

That’s about 130 times faster than NASA’s New Horizons probe, which is the fastest of all fast human things.

繞完一圈後他還可以反方向行走，一直到早上6點孩子們起床前，這讓他共有32小時可以發送禮物

Ignoring the fact that at those speeds, Santa’s sleigh would burst into flames from air resistance, that gives St. Nick less than 1/10,000th of a second between each delivery.

現在假設聖誕老人要發禮物給地球上22億的小孩，因為

Even if he stopped and got going again instantly at each house, he’d experience acceleration 1.8 billion times Earth’s gravity.

嗯，這是聖誕節嘛。一個家庭平均有2.3位小孩，所以有9億4千4百萬戶要發

If we assume the jolly old fella weighs around 330 pounds, that’s a thrust equivalent to about a million and a half Space Shuttle engines.

這樣他要走多少路呢？

In other words, he’d be a bowl full of jelly. Literally.

地球上人類的居住地占地約2千4百萬6千平方英哩

This doesn’t take into account his payload of gifts, either.

假設我們平均分配給每根煙囪，則每戶人家占地約0.026平方英哩

At two pounds of presents per child, that comes to four and a half billion pounds of Christmas cargo.

假設各戶均勻分佈，那麼各戶之間則相距0.16英哩

The world’s largest cargo plane, the Antonov-225, can carry about 550,000 pounds, meaning we’d need a fleet of almost 8,000 to deliver Christmas.

那麼聖誕老人的雪橇會在32小時內跑上150,000,000英哩，這代表了

Not only is that pretty bad for the environment, I’m pretty sure you’d hear them flying over your street on Christmas Eve.

他行進的均速會達到每秒1,300英哩。這差不多是人類世界裡速度最快的

Clearly, Santa uses other methods.

NASA最新的水平探測儀速度的130倍

I suppose he could generate stocking-to-stocking wormholes, or have spacetime warp drive on board his sleigh, but I’ve got a different theory.

先不管速度有多快，聖誕老人的雪橇行進時會因為空氣阻力的關係化成一團火球

There’s a prediction in quantum mechanics that says every possible observation for the universe is real, that every timeline that can happen, does happen.

而且聖誕老人只有十萬分之一秒的時間能從一戶人家送禮物到另一戶人家

The universe that we live in is just one of of infinite, parallel possibilities.

而且他要用18億倍地球重力的加速度在某一戶停下，然後立即啟程到下一戶

Schrodinger’s cat, for instance, isn’t alive or dead inside the box, it’s both.

我們假設這位帶給人們歡樂的老傢伙體重約330磅

This universe contains just one of many possible outcomes.

這推進力等於是太空梭引擎的1500萬倍

What if on Christmas eve, Santa creates a universe for all of us, there is one of him for every home, and his real magic is that every Christmas morning, he ties all of our timelines back together, when we open the box to see what’s inside.

在這種狀況下，他可能會變成一碗果醬。不誇張地

Ever wonder why eggnog is the only nog?

這也還沒將它雪橇上禮物的重量考慮進去。假設一位小孩的禮物2磅重

The nog part of its name probably refers to a small mug called a noggin used centuries ago in England to serve alcoholic beverages.

這會讓這輛聖誕貨運雪橇重達45億磅

Why don’t you use your noggin, and subscribe to It’s Okay To Be Smart? Happy holidays, and stay curious.

目前世界上最大的Antonov-225運輸機可以裝5550,000磅的貨物