down to 1 mm (0.04 in) tall,

about the size of a frog's egg?

Actually no,

too many creepy crawly predators,

let's go smaller.

What if you shrunk to 10 micrometers (0.0004 in),

the size of an animal cell.

That's pretty cool,

but I think we can go even smaller.

How about 100 nanometers (0.000004 in),

the size of a virus?

That's better, but we're not in the mood

to be swallowed by white blood cells.

So let's keep going.

What if you shrunk to 1 angström,

the size of the atom?

Oh yeah,

I think we have a winner.

If you shrunk to the size of an atom,

would it be a fantastic voyage?

Or a death sentence?

From "Gulliver's Travels"

to "Alice in Wonderland"

to "Ant-man,"

the idea of shrinking

has fascinated us for a long time.

The atom, in all its splendor, is tiny.

I mean really, really tiny.

Measuring in at 1 angström.

To put that in perspective,

if you were to blow up an atom 1 billion times,

it would only get as big as a tennis ball.

While shrinking seems like

it would be an amazing superpower,

it would actually be a deadly fight for survival.

The first hurdle you're going to have to deal with

is your mass.

If you shrunk without changing your mass,

there would be so much compression

that for an ant-sized person,

the pressure underneath your tiny feet

would be ten thousand times greater

than at your normal size.

It would be like a single, ant-sized leg

pushing down 70 kg (155 lbs) on each step.

Next, you would have to deal with your body

turning against you.

Your new, smaller size

will affect almost every aspect of your biology.

For example,

if you shrunk be approximately 2.5 cm (1 in) tall,

the surface area of your body,

through which you lose heat,

would decrease about 5,000 times.

Your lung area would be 5,000 times smaller,

but you could still get

the supply of oxygen you need.

The way you extract oxygen from the air

is dependent on the surface area of your lungs.

As you get smaller

the area of your lungs is larger

than the volume of your lungs,

which means there's more than enough

air to go around.

But you're not out of the woods yet.

You would need to provide your body

with more fuel,

a lot more fuel.

This is because

the rate at which you produce heat

is proportional to the mass of your body.

The only way to generate more heat

is to increase your metabolic rate dramatically!

This means you have to eat nonstop

as the food needs to be digested

in order to produce heat.

You would have to eat as much food

as your body weighs,

every day, just to stay alive.

And this is just for a 2.5 cm (1 in)

version of you.

You'll have even more dangers to face

when you're atom-sized.

During your shrinking process,

you'll notice the world getting bigger …

and then darker.

It's estimated that if you decreased in size

to approximately one 10,000th of your size,

the lenses in your eyes would stop working

in just-visible light.

Or, that may just be you passing out.

When you take the big step

of squeezing your feet into microscopic shoes,

one single oxygen molecule

will look like Mount Everest to you.

You're literally smaller than an oxygen molecule.

How long can you hold your breath?

So, if you feel up to the challenge,

could you even pull this off?

The big problem with shrinking down

to the size of an atom

is that the atoms in your body

can't be made any smaller.

And your body contains more atoms

than the number of stars

we can see in the Universe.

You'd have to remove some excess baggage.

Is it possible to remove

the atoms in your body?

Imagine a mosaic image,

a picture made entirely out of smaller pictures.

Much like these images,

our body consists of DNA,

built up by molecules consisting of atoms.

If you started removing pictures

from your mosaic image,

you might be able to remove a few

and still see a resemblance to the original.

But there is a limit.

After a while,

the image would no longer make sense.

This is also true of DNA.

We might be able to remove atoms

from the molecules building up the DNA,

but eventually ,we would reach a limit

and make a mess of your human body.

So until you solve that problem,

no shrinking for you.

But if you manage to conquer all the challenges,

you would be able to experience

the insane world of quantum mechanics.

If you could learn to live in this environment,

you could have a blast tunneling

and jumping through impenetrable barriers

on your path to chart the microverse.

Truth be told though,

it's probably easier living at the size we are.

Mostly because we don't have to deal

with things like giant spiders.

But what if that wasn't the case?

What if spiders were the size of humans?

Well, that's a story for another WHAT IF.