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So why...

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So why is the fact that
an electron is a wave,

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why is that so important?

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Well, first of all, because
it sets up this detective

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story of the electron set up
this new theory that's coming,

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quantum mechanics, right?

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But also, it immediately, just
like we started painting with

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them, right-- remember that was
one of my why this matters--

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we also realized that
we could see with them.

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We could see with electrons.

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Because if electrons
are waves, then

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I can shine them just
like I shine light

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and see what it shows me, right?

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It can illuminate matter.

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So if you look at the
frequency here of light,

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this is an electromagnetic
spectrum-- radio, microwave,

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infrared, visible, UV.

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Now, here's the thing.

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If you want to see
something, some feature size,

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you're limited by the
wavelength of the light.

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It can't be bigger than the
features you're looking at,

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roughlyish, OK?

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That's what you'll-- so if
you're trying to see something

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tiny, but the wavelength
of light is really big,

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you won't see it.

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So we need-- let's say
we want to see atoms.

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Let's say we want to see
atoms, or even more, nuclei.

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Look at how tiny.

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Those are 10 to the minus n,
10 to the minus 12 meters.

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Those are x-rays or gamma rays.

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But the problem is, if we
shine x-rays on things--

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and we will do that when
we look at crystals--

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but if we shine
x-rays, it's very hard

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to then collect them and
make a photographic image,

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OK, at least one that
gets you that resolution.

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And gamma rays are even
harder to catch, all right?

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But see, here's the thing.

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The electrons give you
exactly what you need.

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Because if we do this
math for an electron--

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so bring this one back down--

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if we do this math
for an electron,

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well, I'm going to use--

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oh, I thought I
had the middle one.

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So if I have an electron-- let's
suppose I have an electron that

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is--

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electron, I'm going to say I
accelerate it over 100 volts.

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I'm going to take
an electron, and I'm

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going to put it over 100 volts.

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I'm going to give it some
kinetic energy, right?

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So it's kinetic energy is then
going to equal 100 eV, right?

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OK, so now I've got an electron
moving with a kinetic energy

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that's 100 eV.

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Now you can convert
this to joules,

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and you can set this equal
to 1/2 mv squared, right,

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mass of the electron times
its velocity squared.

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And then once you have the
velocity, so you get the V.

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And then once you have that, you
get the momentum, the p, right?

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And then once you have that,
you get the wavelength, right?

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So I can go now from
something that's easy to do.

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100 volts is a lot, but in a
lab safe, not in your dorm.

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You could apply 100
volts to an electron,

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get it going at this speed.

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And once you know the speed,
you know the momentum.

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And if you know mv, then
you know it's wavelength.

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In that case from
this relationship,

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you would get that it's
about 0.12 nanometers.

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But look at this.

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The wavelength of a simply
accelerated electron

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is right where I need it.

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It's right where I need it.

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It's an Angstrom, right?

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So now, if I take advantage
of the wavelengths of the wave

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nature of electrons and I
shine them on materials,

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then I can see
materials that way.

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And I can see them
at that scale.

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And we do that all
the time, all the time

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in many, many different areas of
technology and research today.

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We use electrons to image.

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In fact, the best
images you can get

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are made with
electrons, all right?

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Here's an example
of using what's

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called a scanning electron
microscope, all right?

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So you see a butterfly, but you
want to really see a butterfly,

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or we can go even further.

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And instead of just
drawing pictures

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of this these beautiful
materials made of carbon--

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those are called nanotubes.

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This is called graphene.

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Gesundheit.

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It's a single sheet of carbon
atoms, one atom thick material.

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Notice with these
materials every single atom

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is a surface atom.

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That's pretty cool.

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They also have lots of
other cool properties.

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And I'll give you examples
throughout other lectures

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of how these kinds of
materials can be used.

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But for now, I'm talking
about seeing them.

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And this is what happens
when you actually

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look at them with an electron.

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That's a nanotube.

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And here is a
picture of graphene.

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The only reason we
can see graphene

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is because we have electrons.

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And we take advantage of the
wave nature of those electrons.

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Well, you say, well, OK.

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But why does that matter?

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Well, that matters
tremendously, because one

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of the first experiments that
really did what Feynman, what

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Richard Feynman wanted--

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Richard Feynman predicted
the field of nanotechnology

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50 years ago.

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He gave a famous
speech at Caltex

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called There's Plenty
of Room at the Bottom.

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He's also an amazing teacher,
and he taught actually

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the double slit experiment.

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I highly recommend you
Googling that lecture.

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And he said that someday,
you can put the atom

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where you want, all right?

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And the first time that was
done was in 1989 by IBM.

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They had 35 xenon atoms.

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They moved them around.

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But the point is, you couldn't
realize nanotechnology.

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You couldn't realize the
ability to actually move atoms

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if you can't see them, right?

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And this, the ability to
see what you were doing

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changed everything.

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It changed everything.

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And nature had been doing this.

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And I love these examples.

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So nature has been doing
nanotech for a long time,

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all right?

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So you have the inner
ear of the frog.

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It's a cantilever that is
sensitive to a few nanometers

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of movement.

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The frog can actually hear that.

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You've got features
in the ant's eye.

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I love the silk moth.

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The male silk moth has a single
molecule detection system

139
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onboard that can sense a
single molecule pheromone.

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It can detect a female silk moth
two miles away, two miles away.

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We have nothing like that.

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We have no
technologies like that.

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I can't even tell if
someone's in the next room.

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I have to look at my
phone or something.

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This is because of
nanotechnology, that kind

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00:07:02,821 --> 00:07:04,923
of detection system, all right?

147
00:07:04,923 --> 00:07:08,293
But it was the ability to
see atoms and molecules

148
00:07:08,293 --> 00:07:11,596
with electrons that
kind of blew open

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00:07:11,596 --> 00:07:13,498
this entire field, all right?

150
00:07:13,498 --> 00:07:14,966
And it's made it
so that we can now

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00:07:14,966 --> 00:07:17,302
try at least to rival nature.

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Here is one example.

153
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You're not just seeing
graphene, but check this out.

154
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You're seeing a single
atom of graphene,

155
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and you're seeing what
happens under a certain kind

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of irradiation.

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And you're seeing this hole.

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And you're seeing the hole grow.

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And that's really
important, because something

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I care a lot about
are membranes, right?

161
00:07:35,220 --> 00:07:36,788
And another one of
these matters, I'll

162
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tell you about membranes.

163
00:07:37,823 --> 00:07:41,293
But here, I'm actually making
the thinnest possible membrane

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that you could make because
it's only one atom thick.

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And I'm controlling
how I make that.

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But I would never know what
my controls do if I couldn't

167
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see it in real time, all right?

168
00:07:51,536 --> 00:07:53,805
So this is my why this matters.

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It's seeing things
at this scale.