What are they? How do they define us?

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

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

But they're incredibly complicated. And by analysing them because they're funny,

you can accidentally learn a lot of science. Plus, we're in great company.

Mozart wrote songs and poems about flatuants and even Benjamin Franklin once wrote an essay

titled "Fart Proudly." So first things first - where do farts come

from? A lot of the gas that makes up a fart comes

from the outside, because you swallowed it. That's right, you swallow a lot of air when

swallowing spit or food or beverage. Now, some of this will come back up as a burp.

But if it doesn't, soon enough it will go deeper into your digestive system.

But it's where the other portion of the gas that makes up a fart comes from that makes

farts so unique. No two people's farts smell alike.

The pungent part of a fart is unique to you and it comes from things that are inside you

and are not you. Inside your intestines are completely separate

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

Now these little guys have a great collective name - Gut Flora.

And, because they're so much smaller than the average human cell, their numbers are

staggering. Believe it or not, your body contains about

10 trillion cells. But the number of bacteria and microorganisms

inside your intestines is nearly 100 trillion. As these microorganisms digest food that you

haven't or can't, they produce helpful things like vitamin K, but they also produce chemicals

that lead to the reason that farts smell. And we all fart, every day.

About a pint of fart every day. And if you say that you don't fart, you probably

release that gas when you're in the bathroom or at night when you're asleep and your muscles

are more relaxed. But if this amount of gas used to be inside

you and now it's not, that must mean that every time you fart you loose mass, you loose

weight. But how much weight?

Well, luckily, some researchers have already figured this out.

Assuming this average chemical make up of a fart, and with studies that have show what

is the typical volume of a fart, it can be calculated that the average fart weighs about 3

hundredths of a gram. And a part of it that actually stinks only

weighs 0.0008 grams. Okay, so a fart weighs 3 hundredths of a gram,

I mean, what does that really mean? Well, here's a fun way to think about it.

As you move further away from the centre of the Earth, the gravitational attraction between

the two of you decreases and your weight decreases. In fact, according to this fantastic book

about the scale of things, your weight decreases by about 0.5% for every 6 miles you are above

Earth. In fact, the average fart causes you to loose

an amount of weight equivalent to being about a third of an inch further from Earth.

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

was established within the first two to three months of your life.

When you're first born, your gastrointestinal track is completely sterile.

There are no microorganisms living in it. In fact, unlike the rest of your life, the

very first poop that you take is almost completely sterile.

It's so significant it has a special name - meconium.

Now, I will spare you any pictures, but if you ever wanna call someone a poop head, try instead

calling them a meconium head. It's like a poop head, but with no experience.

As soon as you leave your mother, you begin collecting microorganisms inside your digestive

system. In fact, within the first 5 to 10 minutes

of being born, the gut flora that you have are almost exactly equivalent to the microorganisms

living in your mother's birth canal. Now later, these microorganisms come from

your environment, especially from what you eat - milk or formula.

This early in your life, microorganisms train your immune system to not attack them and

so, within the first 2 or 3 months of your life, whatever microorganisms are there have

largely established themselves as the exact colonial make up of your gut flora for your

entire life. That's all cool, but how loud can a fart get?

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

In fact, there are lot of records it doesn't keep, some of which it doesn't keep because

they're dangerous. For instance, speed drinking.

It's possible to open up your throat and literally pour a liquid straight down your esophagus

into your belly. But it is really dangerous and should never

be done by anybody. Now burping, they do have records of.

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

burp registered 109.9 decibels - about as loud as a car horn.

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

and make farts smell bad also create gases that are flammable.

We've also seen this and it is very very true. The Mythbusters even did an episode where

they prove that farts can be lit on fire, but the episode was deemed too gross and never

aired. Another thing you should know about farts

is that when you hold them in, many of the gases inside them will get reabsorbed back

into your bloodstream through the intestinal lumen.

Now, the smelly, stinky stuff doesn't travel this way, but the nutrients stuff, like oxygen,

will. And the bloodstream brings these gases back to the

lungs where you exhale them. So if you hold in your farts a lot, you, in

a way, will have literal fart breath. The Fitzroy River turtle does one better.

It can do what I like to call a reverse fart. Because it spends so much time under water,

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

It actually can get up to 68% of the oxygen it needs by simply opening up that cavity

and getting oxygen from the water. Finally, I want to leave you with the art

of the fart. The way your farts sound is determined by

their speed and the shape of their exit, but a select few can not only make themselves

create flatus on command, but can also modulate the pitch and tone of their farts.

These people are known as flatulists and one of the most famous right now is Mister Methane.

Amazing, right? Well, now that we've talked about farts, let's

move on to outer space, on YouTube.com/SpaceLab. Go over there now and you can ask me any question

about outer space that you want and every week, I will answer 3 of them.

So, what are you waiting for? Go check that out...

And as always,

thanks for watching.