WEBVTT

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This evening, I will show you something
that you won't be able to see.

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And it's precisely
because you can't see it

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that you will see it.

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And to start us off, one little question:

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What is the colour of gold?

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Yellow.

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Golden.

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Yes, you're right.

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Look.

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In this vial, I have some water

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and some little flakes of gold,

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somewhat like in a snow globe.

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The gold is beautiful and golden.

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But my gold ...

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is not golden.

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My gold,

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it's this colour here.

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My gold is ruby-red.

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In this vial, I have some water
and some nanoparticles of gold.

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The nanoparticles of gold
are little grains of material,

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infinitely small, invisible to the eye.

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However, I can show them to you,
I took a photo of them.

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Here they are.

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Aren't they magnificent?

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This gold, I heard about it
for the first time at university,

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in my second year.

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One morning, I went to a lecture,

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a little tired from revising
the night before,

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and I remember the professor coming in -

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he had a splendid, white beard -

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and he put down on the demonstration bench
in front of the board

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a hot plate with a beaker
that had some water in it.

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He mixed in two liquids,
switched on the device,

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and started his lecture.

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20 minutes later, the solution
that had been transparent -

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it had been water -

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became red,

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red like in my vial,
ruby-red, red like TEDx!

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He had just made nanoparticles of gold.

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I was blown away.

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I wanted to know more.

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The colour!

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The colour.

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And the colour comes from an interaction

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between the light
and my nanoparticles of gold.

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We call this phenomenon
localised surface plasmon resonance.

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I fell in love with it.

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(Laughter)

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Afterwards,

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when I spoke about my nanoparticles
of gold to people around me,

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generally, it was something
they had never heard of,

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and sometimes, those who had
already heard about it

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tended to view it
with incertainty, negatively.

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They associated it with sanitary
or ecological risks.

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And I can understand why.

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Because historically,
there are many examples

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of materials that have proved
dangerous to man.

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For example,

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does anyone recognise this object?

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It's not a quiz, you just need
to guess it's a water jug.

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It's a water jug that was sold
in the 1910s in the United States.

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Let's look at the advertisement.

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"Here's Health!"

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That's the promise it makes.

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Let's read the text.

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"To keep that health,
you must keep Nature's laws.

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They are simple and easy to keep;

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but if they are broken,

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Nature exacts a heavy penalty
from each and every one.

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Get plenty of sleep, exercise
and wholesome fun.

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Avoid overwork, all other excesses,

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eat fresh, natural foods,
breathe fresh air,

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and drink plenty of fresh, invigorating,
natural ... radioactive water

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from the Radium-Spa."

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Yes, this object offers you,
provides you with,

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water that is radioactive.

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Don't start saying
that it's typically American.

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We had the same thing in France:

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Tho-Radia, a company that sold
cosmetics at the same time.

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"Healthy lipstick!"

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And what did Tho-Radia
put in their cosmetics?

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Ah well, some radium and thorium.

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For those who don't know,

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these are two chemical elements
that are extremely radioactive:

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ultimately, these cosmetics
won't give you anything but cancer.

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(Laughter)

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That was meant to be serious.

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To sum it up, when you think about it,

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a simple, naïve, overtrusting ignorance,
mixed with some negligence,

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made way for a catastrophe.

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It's what gave way to a distrust
in the population today

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in relation to this kind of novelty.

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That's understandable.

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But is it really the fault of radium?

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Radium isn't a problem in itself;
it's the ignorance we had about it.

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We know today that we don't need
to dismiss ignorance, on the contrary.

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We should interested ourselves in it,

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confront it, study it,
understand it better ...

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and take advantage of it.

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Get to know it ...

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let's get to know my nanoparticles.

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Well, I've already shown you the red ones,
which are spherical and of gold.

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But if, instead of the spheres,
we have some minute gold rods,

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my gold is going to be blue.

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If instead of using gold,
I change the metal,

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and I try silver,

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it can be orange,

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or it can be purple,

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or it can be -

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what do I have in my pocket? -

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yellow.

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It'll be more helpful with a photo.

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You can see in the photo
that should come up

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that, in general,
we can have different colours

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just by changing
whether its gold or silver,

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by changing the shape of these particles.

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We can even go a little bit further.

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I have one last thing in my pocket.

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It's a little disc.

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And if you look at this sheet here ...

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if I put the disc above my lamp,

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you might say, "Well,
the disc must be blue!"

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However, if I show you
the colour of the disc,

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this one is opaque and orange.

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This phenomenon is called bichromatism,

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a property of nanoparticles,

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where the colour of the object itself
is different from that projected.

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However, there's something -

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Before I go on,

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you mustn't put words into my mouth.

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Here, I'm showing you
some gold, some nanoparticles,

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but I'm not saying that they are harmless.

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In this case, it's in solution, in water,
or in some solid material,

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there's no problem.

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If I had, for example, some mercury,

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or radium, which, of course,
is radioactive,

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you would need to take more precautions
because it would be dangerous.

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Put succinctly, you just need
to handle it appropriately.

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You just have to be careful.

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Well, just what are
these nanoparticles useful for?

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Well, I personally,
during my work at university,

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used this gold to develop a gas sensor,

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a hydrogen sensor,
for applications in energy.

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But that's not what I want
to talk to you about this evening.

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This evening, I want to show you
that this gold is also your treasure.

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To show this, I have this image.

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Here we have a cell.

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We see its body in green,

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the nucleus in blue, where the DNA is,
the heart of the cell.

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The little carpet of red stars
are my gold nanoparticles.

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So, why do scientists mess around

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putting my gold
nanoparticles in their cells?

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Well, the fact is that this cell
is a human cell and it is cancerous.

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It is diseased.

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But the effect that gives the red colour
to my gold will have another effect:

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my nanoparticles will heat up.

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Not a lot, my vial isn't hot,

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but enough to heat up the cancerous cell,

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and it will die.

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Healthy cells, they will survive.

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Ultimately, in this vial I have
a potential treatment for cancer

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that today shows very promising results

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for patients taking part
in clinical trials.

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And it's very often the case

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that nanoscience, nanotechnology,

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comes up with some
very interesting findings

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with the potential
to really improve our daily lives.

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We have learned a great deal
in recent decades.

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But what I can tell you is, is that,
yes, when you wake up in the morning

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and on the radio there's about
a peak in particle pollution,

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you should worry.

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Because then, yes, they are dangerous.

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But it is still no time
to completely forget science.

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It's no time to be taken in by hype,

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it's no time to fall for
marketing propaganda.

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Let's take a totally idiotic example.

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We all more or less agree
that a diet of natural food

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is considered a good thing.

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But that's not all there is to it:

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tobacco is natural,

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radium is natural and yet ...

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We must take a critical approach,

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whether it's GMO or organic food,

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or climate change, and so on, and so on.

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Ultimately then, with education
and a critical approach,

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we will have confidence in science,
confidence in our researchers.

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That way, we will generate innovation,

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and thereby learn even more.

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For the people here tonight

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who are themselves
scientists, researchers,

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academics of whatever discipline,

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I have a favour to ask of you:

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Don't let non-experts speak in your name.

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Don't leave a void to be filled in
by whomever or whatever.

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We need to hold out a hand.

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Just as here this evening at TEDx,
we must be accessible,

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we must be open.

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For those of you who work in other fields,

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those of you who aren't
academic staff members,

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don't hesitate to look to us,

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be prepared to have faith in us.

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Come to meet us, in person.

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Any day you like, you can send us
an email with a question you have.

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Because all this learning,
all this knowledge,

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it needs to be accessible to everyone.

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It must be allowed to create
beauty in our world,

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and form a legacy, one of our humanity.

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Thinking about it,

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coming back to my nanoparticles,

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they're a bit like people:

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there are good ones,

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there are bad ones,

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and you can even fall in love with them.

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Thank you.

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(Applause)