into some hidden worlds inside your own body

using the scanning electron microscope.

These microscopes use a beam of electrons

to illuminate things that are too small

to be seen by the photons of visible light.

And to put this in context,

if you mentally divide one tiny millimeter

into a thousand parts,

each one of those parts is a micrometer,

or micron for short.

If you then divide one micron

into another thousand parts,

each one of those is a nanometer.

And it's nanometers and microns

that are the domain

of the scanning electron microscope.

So, let's start with something on the body

that we can measure at about 100 microns wide,

and that would be a human hair,

which now you can see is covered with scales,

just like all of our hairs,

and in fact, just like all mammal hairs.

We're going to plunge into the body now,

and we've landed in the thyroid gland.

Here we're looking at proteins

that are being secreted into a storage chamber

where they are going to develop

into the mature thyroid hormones

before being released into the body.

And at this point you might be wondering

if these colors are real.

The answer is no.

Electron images only happen in black and white.

I often colorize my images for various reasons,

but I don't change the structures,

so the strucutres that you're seeing

are all exactly as they were

when I photographed them in the microscope.

We're going to take a detour

and zoom in on the heart muscle now.

And the heart muscle has this curious structure

that's kind of like corrugated cardboard.

That's what allows the heart to expand and contract as it's beating.

Let's go look at a lung with pneumonia.

Here we've got a white blood cell

poking around in an air sac,

looking for something to clean out

like a little vacuum cleaner.

This is your immune systems at work.

So what are the kinds of things

that we don't want to be breathing,

besides bacteria and viruses?

Well, we all know to stay away from asbestos

and now we can see why.

This is a close-up view of the mineral

that asbestos is made from,

and now you can see that it's composed of

many tiny, fine little needles.

Each one of those needles is a single crystal.

And in this picture, they're begininng to pry apart

and tangle up into a spiky mess,

not for breathing.

What else might we want to avoid breathing?

Well, how about diesel fuel?

We're looking here at the particles of diesel soot,

and these are extraordinarily tiny.

In fact, each one of these little particles

is only about 50 nanometers wide.

We'll go and look at some blood now.

We've got a collection

of nice, fat, happy, healthy red blood cells,

but they're all tangled up in a network of fibers.

This is how the body makes a blood clot.

And so, it surrounds a group of red blood cells

and other cells, and traps them

so the blood can't flow.

We've got two more blood cells here,

but they're not normal

like the ones in the blood clot image.

These are distorted.

You can see that they're curling up

and beginning to grow what's going to become spikes.

These are sickle cells

and these are what cause the condition

of sickle cell amenia.

We've gone into the mouth now

and we've landed on dental plaque,

which you can see is covered with bacteria,

and in fact dental plaque is host

to about 1,000 different species of bacteria.

Lovely to think about.

And now we are on to other teeth.

We're on the surfaces of the,

or the internal surfaces of the teeth themselves.

The smaller one is a baby tooth

that had just fallen out of the mouth

of a young friend of mine,

and I want to call your attention to the little holes.

Those little holes are the tops

of a whole network of tiny little tubes

that circulate nourishing fluids inside your teeth.

And we can see those tubes

a little better in the larger picture

because some of them are in cross-section.

But in fact, this larger picture is showing you

a portion of a tusk, which you may know

is simply a great big, elongated tooth,

so you would expect to see the same features

between your teeth and a tusk.

But that larger tusk picture is also rough

by comparison to the young baby tooth.

That's because it's many, many thousands of years old.

It's also partly fossilized.

And, between these two pictures,

now you can see how your teeth relate

to the tusk of an Ice Age mammoth.

We're shooting up north now into the brain,

and we can see these pink cells down at the bottom.

Those are the neurons of memory.

And I'm going to leave you with this picture

because I know you're going to take

a lot of happy memories away

from your exciting day at TED

and now you can visualize where those memories

are being stored in your own brain.

Thank you.