Episode 4 The Secrets of Everything

Humans are an incredible species,

we've found ways to talk to each other on opposite sides

of the world, we've discovered cures for terrible diseases

and some of us have even left this planet to explore space.

But there's still so much left to find out.

I'm Greg Foot. Ever since I was a kid, I've been into science.

I've always been asking questions and taking things apart to understand how they work.

I was the kid trawling through rock pools

and the one that tried to turn his bike into an aeroplane.

I even went on to do a science degree.

And I'm still asking questions.

-This is going to hurt, right?

-Yeah.

And I reckon a lot of you are too.

And that's what this series is all about.

Getting to the bottom of all those questions

that never get properly answered, to reveal the secrets of everything.

This time on The Secrets of Everything.

GUN BLASTS

Can body armour really save your life?

Did it stop the bullet?

Why boomerangs come back.

Usually.

It may not look like it, but there's a lot of physics going on in this bent bit of wood.

'And everything you need to know about being buried alive.'

I feel weak.

But first, the secrets of us.

When I was born, the world record for the 100m stood at 9.93 seconds.

Now, 28 years later, it's 9.58 seconds.

So are humans destined to get faster and faster, or is there a limit,

and if the fastest man on the planet can run at 27mph,

why can't I?

We've only got two legs, you put one in front of the other,

you can't really go faster or you're probably going to break yourself.

We're just going to get taller and slimmer.

Yeah, we're constantly evolving.

I reckon we'll definitely get faster.

We will. In a couple of years' time, we'll be running faster than cars.

Right, to find out why I'm not a record-breaking sprinter,

I first need to see how far off the mark I am.

-Set.

-'Not great.'

At least one second slower than the slowest man here.

Wow, they were quick!

Granted, those guys train three days a week.

That's not the only reason they beat me.

My speed is limited by the amount of force I exert through my legs

when I move.

Each step you take, you're pushing down on the ground.

And it may not feel like it, but the ground is pushing back up

with the same amount of force.

And that's what propels you along.

The greater the force you push through your leg muscles, the faster you go.

By running over a pressure pad,

I'll measure how much force each one of my sprinting steps makes.

The higher the score, the faster I should be able to run.

Force is measured in newtons.

When I'm just standing around being geeky, I normally exert a force

of around 800 newtons.

But what happens when I run?

OK, so this says when I was running, I was pushing down on the ground

with a force of 2,057 newtons,

which is pretty much three times bigger

than when I'm just standing still.

But the reality is, to get anywhere near an Olympic medal,

you'd need to exert a force of four times your resting body weight.

And if you don't make the grade, blame your parents,

because a lot of it is in the genes.

The force that we can generate in our legs is limited by our muscles,

and they're made up of two types of muscle fibres,

The first is type one.

This type of muscle is also called slow twitch

and it's great for endurance sports like marathons.

But there's another type of muscle called fast twitch,

or type two muscle fibres.

And they're used for short, explosive bouts of exercise.

We are each born with a mix of these two types of fibres,

and whilst we can tone up what we have,

we can't really do anything about what nature's dished up to us.

Fast sprinters have been shown to have a genetic make-up

of 70% type two fibres, so to find out why I'm not winning any races,

I need to see what's going on inside these pins.

I've had my muscle analysed. Oh!

I felt that!

And its 53% type one, 47% type two.

Not a winning combination.

But even if humans were able to do the impossible

and have 100% type two muscle fibres,

there would still be a limit to how fast we could run.

And that's because, with only two legs,

we are just not built to run like the wind.

Unlike this little design beauty.

Four long legs, a huge heart and a massive 8m stride

means a cheetah can run at over 60mph.

Now, there's no way I'm going to be able to get a bigger heart

and I'm going to struggle to make myself lighter or more streamlined,

but there is something I can do about the longer legs.

These are pro jump stilts, similar to the carbon fibre blades

that the record breaker sprinter Oscar Pistorius runs on.

By lengthening my stride, they should make me run faster.

The problem people have with long legs, though,

is they tend to move them slowly which cancels out that advantage.

But Usain Bolt has rewritten the rulebook.

At 6ft 5in, he's got long legs that are also fast.

But could I have him with a pair of these on?

Could weak genes and the wrong muscles really be swept aside

by a pair of pogo sticks?

Move over, Usain!

SIREN BLARES

ENGINE POWERS UP

SCREECHING

TRIUMPHANT MUSIC PLAYS

BURGER BURPS AND BREAKS WIND

I don't normally look at what's happening in the sink,

but it makes you ponder the urban legend -

does water really swirl the opposite direction

down the plug hole, down under?

To get to the bottom of this watery little number,

you first need to know a bit about how the world goes round.

This is a revolutionary bit of technology from the '80s.

It's called a lazy Susan.

Imagine that it's the Earth and we're looking down on it.

So that's the North Pole and this is going to be the equator.

I'm going to draw the path that a current of air would take,

moving from the North Pole to the equator.

Straight line, nothing special about that,

but set the Earth rotating counterclockwise

and draw the same current of air.

This time you get a curve, because now the earth is spinning,

the current of air veers to the right.

But if you're in the southern hemisphere,

it feels to you as if the Earth is spinning in the other direction,

and that means that the current of air veers the opposite way.

This is called the Coriolis effect.

It causes hurricanes to spin anticlockwise above the equator

and clockwise below it.

So if I want to find out if this has any impact on our urban legend,

I need an assistant in Australia.

-Hi, Lindsay, it's Greg.

-Hi, Greg!

-Hiya!

I'd like to do an experiment. I'd like to rest an old urban legend.

What we need is a sink and we need to fill the sink up.

So I'm going to carry you over to my sink.

You want me to fill it up?

Yes, please!

OK.

So Lindsay and I can clearly see which way the water drains away,

we're going to put some herbs into the mix.

-Have you got some herbs?

-Well, actually, my housemate just happens to exfoliate with oregano,

so there is some right here.

Perfect!

OK, so, three, two, one.

Mine is going...

clockwise.

Oh!

-Oh, oh!

-Anticlockwise.

So they are different.

All right, let's not just leave it there with one attempt!

Three, two, one, go!

Mine is going...

anticlockwise!

No... Yes! Anticlockwise this time.

What's yours?

Really? Mine's going...

Anticlockwise as well!

Anticlockwise.

So we're now both anticlockwise.

Looks like the urban myth is going down the plughole.

But we need to make sure.

Try it once more?

Yes, please, in the name of science.

-OK. All right.

-Three, two, one.

Mine's going and it's going anti-clockwise.

Mine's going anti-clockwise again.

Is it? So both exactly the same.

-So it doesn't really look like the urban legend stands up, does it?

-Nope.

So each time you drain you never know which way it will go.

When you fill up your sink,

you're causing all that water to juggle round all over the place

and even if you leave it to settle, it's still moving ever so slightly.

That spinning is then exaggerated as the water gets squeezed down into the narrow plughole.

The truth is it's not the spin of the earth that affects the way water drains away at all.

It's all down to the shape of your sink and the power of your tap,

so the urban legend is false.

In Kill Bill, Uma Thurman was put in a box by her evil nemesis

and buried six feet under. Now, Uma escaped, but that's a film.

If you were buried alive, would that really be the end?

I would try and dig myself out, but getting out the coffin's the hard bit.

I'd just kind of surrender to the experience, I think.

Bang like hell and try to kick the coffin open.

Scratch through with your nails.

Sleep a while and wait for them to find you.

To answer this gruesome question I'm going to get myself buried.

This seems to be a perfect place. Looks like they've got a track record.

You might think that it's impossible to escape being buried alive

because you'd suffocate pretty quickly.

So, first up, I want to work out how much time I've got to escape

before the lack of oxygen finishes me off.

And because I haven't got a total death wish,

I've got an ambulance and a doctor standing by to make it all end happily.

I'm going to seal you in now.

-Right. So this is Perspex so you can see me.

-I can see you the whole time.

The clock starts ticking the moment my captor closes the coffin lid.

-So I'm going to seal you in.

-Great.

From now on, all I've got to breathe

is the air sealed into the box with me.

Ned's going to measure the oxygen in blood

and the makeup of the air trapped in the coffin.

As I breathe in oxygen I breathe out carbon dioxide or CO2

and after just three minutes it's the CO2 which starts causing problems.

That's the alarm.

That's our safety feature to know we're going far out of the normal.

-Oh, great(!) So, even though that alarms gone off, we're still going?

-We're still going.

The CO2 that's building up in my blood

makes it a lot harder for my blood cells to take up any oxygen

even if it's there in the air that I'm breathing.

There's a battle going on inside me.

The more carbon dioxide there is in my blood,

the less space there is for the oxygen needed to keep me alive.

And because, like me, the carbon dioxide can't escape

it's getting more concentrated in the air

and in my blood and struggling to get out just makes things worse.

Got to act like I was trying to break out.

Using your muscles, using more oxygen, producing more carbon dioxide.

I just feel really, like, groggy.

Ned's decided I've had enough.

-So we're going to get you out of there.

-Fresh air, come on.

Oh!

So the question is how long would I survive

if I was really buried alive?

Ah, man.

When you're fighting to get out the box,

we saw the oxygen levels dropping by about 0.5% in a minute,

-so you've probably got about, if you're really going for it, 16 minutes maximum.

-Ah, man.

So when it comes to being buried alive, time is definitely not on your side.

Next up, I want to find out whether it's possible

to break out of a coffin in less than 16 minutes.

But this time Health And Safety have advised that a little oxygen wouldn't go amiss.

Ready to start the stopwatch? Three, two, one, go.

# Shut up and let me go

# This hurts, I tell you so

# For the last time you will kiss my lips

# Now, shut up and let me go. #

Not much space in these things.

Argh!

# Shut up and let me go. #

Five minutes 20.

It's taken me just over five minutes to break out the coffin,

but if I had truly been six feet under

I would still have had an awful lot of digging to do.

-You ready?

-Yep.

So we've rigged up this escape tunnel

to see whether I could get through in the ten minutes I've got left.

Top up on the oxygen.

Go, good luck.

# Making my escape, making my escape

# Tell myself that everything's in shape, everything's in shape... #

Well, sadly that's 16 minutes over.

Ah, what, so I'm dead?

I feel like I've been vacuum packed.

Someone in the movies escaping from being buried alive?

It's just not possible.

# We can be happy underground... #

-Pub?

-Let's.

-Pub.

I don't know if they'll serve me like this, to be honest.

"Oh, where have you been?" "Oh, I've been buried alive."

Here's Professor Logic. How do you do, professor?

Professor Logic is a busy man. So much to see, so much to learn,

so much to measure.

It's a miserable day, but Professor Logic doesn't mind bad weather.

For him it's simply a chance to find out more about the world.

Today, Professor Logic is puzzled.

He knows that clouds contain many tonnes of water

but he also knows they float in the sky,

so he's off to take a closer look.

What can you see, professor? Tiny little drops of water?

May I?

Gosh, professor, the drops of water are so small

that they're being held up by the air molecules.

No wonder they don't fall out of the sky.

But why are they in the sky in the first place?

That's very pretty, professor.

What is it?

It's water?

I see, the sun heats up the surface of the sea

and water evaporates into the sky and when it cools down way up there

it condenses back into tiny droplets of water.

But the drops are so small that they float about in clouds

until the tiny drops form bigger ones and spoil all the fun.

Professor Logic, I think it's time to get back to the lab now.

Throw a stick...

and it doesn't come back.

But throw a bent stick that's been nicely shaped...

Yes! Now it may not look like it, but there's an awful lot of physics going on in this bent bit of wood.

So why do boomerangs come back?

If there's anyone I know who can help me, it's a man who is a chemist,

practical engineer, a meteorologist and...

Polish musician?!

He is Doctor Zbigniew Szydlo.

I just call him doc.

I need you to cut out some shapes that look like this boomerang.

-Yep, no problem.

-Then we can do a few test flights

and work out the vital ingredients that give this boomerang flight.

First things first, I want to show doc my boomerang-throwing skills

That was pants.

Yeah, I may not be able to catch it very often

but even a muppet like me can get it to fly in a nice big circle.

But what is it that makes a boomerang fly?

Now this may look like a flattish bit of wood

but, in fact, it's a cunning bit of engineering.

If you look down one of the blades, you'll see that actually one side is thick and the other side is thin.

What you've got is the basic aeroplane wing shape,

and it's exactly the same on this side too.

What you've basically got are two plane wings.

Wings create a force called lift and it's what makes a boomerang fly.

Right, here we go, yes.

But it doesn't explain why they have a habit of returning to their owners.

That's all to do with the way boomerangs spin as they fly through the air.

Things that spin, like this gyroscope, act in a very weird way.

If I tip this forwards, it spins round.

That is not me doing it.

They call that gyroscopic procession.

So by tipping something that's spinning, you get it to turn,

just like when you were showing off on your bike hands free.

But what's this got to do with boomerangs?

If I now move the wheel through the air,

the spokes at the top are moving even faster

because they've got the initial speed plus the speed of me moving it through the air.

Same for the boomerang.

Its wings move faster through the air at the top of its spin so tipping force is greatest up there.

It forces it like that, tips it down and around it goes.

The gyroscopic procession. Crazy-ass physics,

but we're pretty much there explaining why boomerangs come back.

Of course, doc already knew all of this

so it's time to see what he's come up with.

Right, Greg, here it is. As you asked I've shaved off there

at the top in the middle, cut them into here, so to make it lighter in the middle, heavier on the outside,

Let's hope it does the trick. The moment of truth.

Come on, come on, ah!

All right so I didn't catch it but it did come back.

And spinning things, gyroscopes, are in loads of our technology

from smart phones to games consoles, satellites to spaceships.

The modern world explained by a bent stick.

In some jobs you have to be prepared for pretty much anything,

including the possibility of being shot at

and bulletproof vests come as part of the kit.

But what I want to know is just how can a vest protect human flesh

from the impact of a speeding bullet,

and can they ever be 100% bulletproof?

To answer this one, I've come to meet a man who knows a thing or two about bullets.

What would happen if you weren't wearing a bulletproof vest?

What we've got here is a pig's leg from the butchers

and we're going to fire a bullet into it

and see if we can see anything interesting.

It's not that usual to be using your Sunday lunch as target practice

but, anatomically, pigs are a pretty close match to us

which makes them excellent stunt doubles.

Three, two, one.

Wow, that was loud.

That's a tiny, tiny hole.

Did it go through, that's the question.

And yes it did. Soft targets like flesh,

bullets find it very easy to just punch their way through.

It looks like the 900mph bullet has ripped a clean line through the pig.

But because we can't see what happened on the inside,

we're going to fire at transparent ballistics gel,

developed by scientists to represent human tissue.

What we can see left is this one trail,

this cavity that the bullet has left as it passed through.

To stand any chance of protecting our soft flesh from a speeding bullet,

you'd expect a bulletproof vest to be rock hard

but that isn't always the case.

This is light and it's really flexible as well.

Well, the reason for that is this is made of multiple layers of Kevlar

which is essentially made from a plastic,

and it's a soft type body armour.

Lets see what it does.

Three, two, one...

Right, well, look, that's where it went through.

You can see it where it struck.

Did it stop the bullet?

Yes, it did.

What a material. What a material. A plastic that can stop bullets.

Now, if you think of when you kick a football to a football net,

the football net catches the football,

and that's what the Kevlar is doing, except that in this case

the net is very, very strong and that's what catches the bullet.

Although Kevlar is very effective against handgun fire,

it's pretty much useless against rifle rounds.

Yeah, two holes, gone through.

Time to bring out the daddy of all bulletproof vests.

So what we've got here is a face plate

and this face plate would have a ceramic tile inside.

-Ceramic? So what, like your plates at home?

-So, not dissimilar.

It seems we've upgraded from a football net to a dinner plate.

It's going to have to be some piece of crockery to stop a 2,000mph rifle bullet.

It's gone about half the way through the ceramic

but it's not come through the back. So that sniper rifle bullet

went straight through Kevlar but not through this.

The fact is there are thousands of different types of ceramic

and the stuff inside the vest is nearly as hard as diamond.

As the bullet comes into contact with the ceramic,

the energy of the bullet is being spread over that much larger area.

-So the Kevlar is like a football net catching the ball?

-Quite.

And this is like just putting up a riot shield and it just bouncing back off.

That's right, an disruptor so it can't penetrate through.

Good stuff, wow, pretty impressed with that.

Sniper rifle - and you're still going to be alive.

So they may look like a plastic net and a very strong dinner plate

but, together, they're the technology that really do make bulletproof vests...

..well, bulletproof.

There are still plenty more secrets out there.

Next time, discover how good swearing is at helping with pain...

-BLEEP! BLEEP! BLEEP!

-It's going.

..spontaneous combustion - the facts...

It feels nice and warm here,

but the rest of the room is still completely untouched.

Do you reckon you'll be able to hit me from up there?

..and the truth behind the legend - could a falling penny ever prove fatal?

Let's do this.

The things they make me do for science.

Subtitles by Red Bee Media Ltd