屁的科学：英语精读讲义

Hey, Vsauce. Michael here.

嘿，这里是 Vsauce，我是 Michael。

And today we are going to talk about farts.

今天我们来聊聊屁。

What are they?

屁究竟是什么？

How do they define us?

它们如何定义我们？

And how much weight do we lose every time we fart?

每次放屁，我们会减轻多少体重？

Now, it's easy to think that talking about farts is immature, 語法

说到屁，很容易让人觉得这是个幼稚的话题，

but they are incredibly complicated.

但屁其实复杂得不可思议。

And by analyzing them because they're funny, 語法

而当你因为觉得屁好笑而去分析它们时，

you can accidentally learn a lot of science.

说不定会意外学到许多科学知识。

Plus, we are in great company. 習語

况且，和我们志同道合的可都是大人物。

Mozart wrote songs and poems about flatulence,

莫扎特曾写过关于肠胃胀气的歌曲和诗歌，

and even Benjamin Franklin once wrote an essay titled Fart Proudly.

就连本杰明·富兰克林也写过一篇题为《自豪地放屁》的文章。

So, first things first, 短語搭配

那么，先说最基本的问题：

where do farts come from?

屁是从哪里来的？

A lot of the gas that makes up a fart comes from the outside 短語動詞

构成屁的气体有很大一部分来自外界，

because you swallowed it.

因为是你把它们吞下去的。

That's right.

没错。

You swallow a lot of air when swallowing spit or food or beverage.

吞咽口水、食物或饮料时，你会吞下大量空气。

Now, some of this will come back up as a burp.

其中一部分会以打嗝的形式从上面返回来。

But if it doesn't soon enough, 短語搭配

但如果它没有及时出来，

it will go deeper into your digestive system.

就会深入你的消化系统。

But it's where the other portion of the gas

但构成屁的另一部分气体

that makes up a fart comes from that makes farts so unique.

来自哪里，才是屁如此独特的关键。

No two people's farts smell alike. 語法

没有两个人的屁闻起来完全一样。

The pungent part of a fart is unique to you,

屁里那股刺鼻的味道是你独有的，

and it comes from things that are inside you and are not you.

它来自你体内那些并不属于“你”的东西。

Inside your intestines are completely separate organisms, 語法

你的肠道里住着一些完全独立的生物，

bacteria and microbes that digest food you haven't or can't.

也就是细菌和微生物，它们会消化你尚未或无法消化的食物。

Now, these little guys have a great collective name,

这些小家伙有一个很棒的统称：

gut flora. 用詞

肠道菌群。

And because they are so much smaller than the average human cell, 語法

因为它们比普通人体细胞小得多，

their numbers are staggering. 用詞

所以数量多得惊人。

Believe it or not, your body contains about 10 trillion cells. 語氣意圖

信不信由你，人体大约有10万亿个细胞。

But the number of bacteria and microorganisms inside your intestines

但你肠道内的细菌和微生物数量

is nearly 100 trillion.

却接近100万亿。

As these microorganisms digest food that you haven't or can't,

当这些微生物消化你尚未或无法消化的食物时，

they produce helpful things like vitamin K.

它们会产生维生素K等有益物质。

But they also produce chemicals

但它们也会产生一些化学物质，

that lead to the reason that farts smell. 短語搭配

而这正是屁有臭味的原因。

And we all fart every day,

而且我们每个人每天都会放屁，

about a pint of fart every day.

每天放出的屁大约有一品脱。

And if you say that you don't fart,

如果你说自己从不放屁，

you probably release that gas when you're in the bathroom

那你很可能是在上厕所时排出了这些气体，

or at night when you're asleep and your muscles are more relaxed.

或者在夜里睡着、肌肉更放松时排了出去。

But if this amount of gas used to be inside you, 語法

可如果这么多气体原先在你体内，

and now it's not,

现在却不在了，

that must mean that every time you fart you lose mass,

那就说明每次放屁，你都会失去一些质量，

you lose weight.

也就是减轻一些体重。

But how much weight?

但到底会轻多少？

Well, luckily, some researchers have already figured this out. 短語動詞

幸运的是，已经有研究人员算出了答案。

Assuming this average chemical makeup of a fart, 語法

假设屁的平均化学组成是这样，

and what studies have shown is the typical volume of a fart,

再结合研究显示的典型单次屁量，

it can be calculated 語法

就可以算出，

that the average fart weighs about 3/100 of a gram.

一个屁平均重约3/100克。

And the part of it that actually stinks only weighs 0.0008 grams.

其中真正发臭的部分只有0.0008克。

Okay, so a fart weighs 3/100 of a gram.

好吧，也就是说，一个屁重3/100克。

I mean, what does that really mean? 表達脈絡

可这到底意味着什么呢？

Well, here's a fun way to think about it. 表達脈絡

我们可以用一种有趣的方式来理解。

As you move further away from the center of the Earth, 語法

当你离地心越来越远时，

the gravitational attraction between the two of you decreases and your weight decreases.

你与地球之间的引力会减弱，你的体重也会下降。

In fact, according to this fantastic book about the scale of things, 短語搭配

事实上，根据这本讲述万物尺度的精彩著作，

your weight decreases by about 0.5% for every 6 mi you are above Earth.

你每升到离地球表面6英里的高度，体重就会减少约0.5%。

In fact,

事实上，

the average fart causes you to lose an amount of weight

一次普通的放屁让你减轻的体重，

equivalent to being about a third of an inch further from Earth. 短語搭配

相当于让你离地球远了大约1/3英寸。

The way your gut flora process the food that you eat and influence how your farts smell

你的肠道菌群如何处理你吃下的食物，又如何影响屁的气味，

was established within the first 2 to 3 months of your life.

在你出生后的头两三个月里就已经确定了。

When you're first born,

你刚出生时，

your gastrointestinal tract is completely sterile. 用詞

胃肠道是完全无菌的。

There are no microorganisms living in it.

里面没有任何微生物。

In fact, unlike the rest of your life,

事实上，与此后一生不同，

the very first poop that you take is almost completely sterile.

你生平第一次排出的便便几乎是完全无菌的。

It's so significant,

它非常特别，

it has a special name, meconium. 用詞

还有一个专门的名字：胎粪。

Now, I will spare you any pictures, 短語搭配

我就不放图片刺激大家了，

but if you ever want to call someone a poop head,

但如果你以后想骂某人是“屎脑袋”，

try instead calling them a meconium head.

不妨改叫他“胎粪脑袋”。

It's like a poop head, but with no experience. 習語

就像“屎脑袋”，只不过毫无经验。

As soon as you leave your mother, 語法

你一离开母体，

you begin collecting microorganisms inside your digestive system.

消化系统里就开始聚集微生物。

In fact, within the first 5 to 10 minutes of being born,

事实上，在出生后的头5到10分钟内，

the gut flora that you have are almost exactly equivalent

你的肠道菌群几乎完全等同于

to the microorganisms living in your mother's birth canal.

你母亲产道内的微生物。

Now, later, these microorganisms come from your environment,

此后，这些微生物会来自你周围的环境，

especially from what you eat, milk, or formula.

尤其是你吃下的东西、母乳或配方奶。

This early in your life,

在生命这么早的阶段，

microorganisms train your immune system to not attack them. 短語搭配

微生物会训练你的免疫系统，让它不要攻击它们。

And so, within the first 2 or 3 months of your life,

因此，在你出生后的头两三个月里，

whatever microorganisms are there have largely established themselves 語法

当时存在的微生物基本都会站稳脚跟，

as the exact colonial makeup of your gut flora

形成你肠道菌群确切的群落构成，

for your entire life.

并伴随你一生。

That's all cool, but how loud can a fart get? 表達脈絡

这些都很酷，但屁究竟能有多响？

Well, the Guinness Book of World Records doesn't know.

这个嘛，《吉尼斯世界纪录》也不知道。

In fact, there are a lot of records it doesn't keep,

事实上，它并不收录许多纪录，

some of which it doesn't keep because they're dangerous. 語法

其中一些是因为太危险才不收录。

For instance, speed drinking.

比如速饮比赛。

It's possible to open up your throat

人确实可以把喉咙完全打开，

and literally pour a liquid straight down your esophagus into your belly.

直接把液体顺着食管灌进肚子里。

But it is really dangerous and should never be done by anybody.

但这极其危险，任何人都绝不应该尝试。

Now, burping, they do have records of. 語法

不过，打嗝倒是有纪录的。

The world record for the largest burp belongs to Paul Hunn from the United Kingdom,

最大声嗝的世界纪录由英国的Paul Hunn保持，

whose burp registered 109.9 dB, 用詞

他的嗝测得109.9分贝，

about as loud as a car horn. 語法

差不多和汽车喇叭一样响。

Oh, and also, many of these microorganisms that live inside your gut

另外，生活在你肠道里的许多微生物

and digest food and make farts smell bad

会消化食物，让屁变臭，

also create gases that are flammable.

同时也会产生可燃气体。

We've all seen this, and it is very, very true.

这种场面我们都见过，而且它千真万确。

The MythBusters even did an episode where they proved that farts can be lit on fire, 短語搭配

《流言终结者》甚至拍过一集，证明屁确实可以被点燃，

but the episode was deemed too gross and never aired. 用詞

但那集被认为太恶心，最终没有播出。

Another thing you should know about farts is that when you hold them in, 短語動詞

关于屁，你还应该知道一件事：当你憋屁时，

many of the gases inside them will get reabsorbed back into your bloodstream 短語搭配

其中许多气体会被重新吸收进血液，

through the intestinal lumen.

这个过程会经由肠腔进行。

Now, the smelly stinky stuff doesn't travel this way,

不过，那些又臭又难闻的物质不会这样转移，

but the nutrient stuff like oxygen will.

但氧气等有用的成分会。

And the bloodstream brings these gases back to the lungs

血液会把这些气体带回肺部，

where you exhale them.

然后由你呼出去。

So, if you hold in your farts a lot,

所以，如果你经常憋屁，

you, in a way, will have literal fart breath. 語氣意圖

某种意义上，你呼出的气就真的成了“屁气”。

The Fitzroy River turtle does one better. 習語

菲茨罗伊河龟更胜一筹。

It can do what I like to call a reverse fart. 語氣意圖

它能做到一件我喜欢称为“反向放屁”的事。

Because it spends so much time underwater,

因为它大部分时间都待在水下，

it's developed a way to breathe through its butt. 短語搭配

所以进化出了用屁股呼吸的方法。

It actually can get up to 68% of the oxygen it needs

它所需的氧气中，实际上多达68%

by simply opening up that cavity

都可以仅靠打开那个腔体，

and getting oxygen from the water.

从水中获取。

Finally, I want to leave you with the art of the fart. 表達脈絡

最后，我想用“屁的艺术”为今天收尾。

The way your farts sound is determined 短語搭配

你的屁声听起来如何，

by their speed and the shape of their exit.

取决于气体的速度和出口的形状。

But a select few can not only make themselves create flatus on command, 講解

但有极少数人不但能随心所欲地放屁，

but can also modulate the pitch and tone of their farts. 短語搭配

还能调节屁的音高和音色。

These people are known as flatulists. 短語搭配

这些人被称为“放屁表演家”。

And one of the most famous right now is Mr. Methane.

当今最著名的人物之一就是Mr. Methane。

Amazing, right?

很厉害，对吧？

Well, now that we've talked about farts, 表達脈絡

好了，屁聊完了，

let's move on to outer space on youtube.com/spacelab.

接下来到youtube.com/spacelab聊聊外太空吧。

Go over there now,

现在就去那里，

and you can ask me any question about outer space that you want.

你可以向我提出任何想问的太空问题。

And every week I will answer three of them.

每周我都会回答其中三个。

So, what are you waiting for? 語氣意圖

还等什么呢？

Go check that out. 短語動詞

快去看看吧。

And as always, thanks for watching.

和往常一样，感谢观看。