WEBVTT

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When I was a boy, my dad used to
pick me up after school.

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I was about 11 years old,
in Geneva, Switzerland,

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and he'd drive me across town 


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to the site of the Large Hadron Collider,
in Geneva,

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which was called the European
Center for Nuclear Research, at the time.

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It's where they discovered
the Higgs boson a few years ago.


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There was a remarkable man there,
Rafael Carreras,

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who used to give weekly lectures
called in French

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'Science Pour Tous' which means
'Science for Everybody'.

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There were people from all walks of life
who attended these lectures.

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There were school boys like me, 
janitors at CERN, professors, housewives.

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A whole mix of people were attending
that stuff who gave up their lunch hour.

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They were also working people.

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There were two things that struck me
about these lectures.

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The first thing was that people were
doing this not for any personal benefit,

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there was no credit, no remuneration,

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but they were just doing it
because it interested them.

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I thought this was rather wonderful
and sort of put a light bulb in my head

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that maybe you could go through life doing
what interests you rather than

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what doesn't interest you in order to,
then, do what interests you.

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You could short-circuit things. 
(Laughter)

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The other thing I liked is, Dr. Carreras
was always encouraging.

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I'd often go
and ask him questions and so on.

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He never looked down on me as a kid.


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There weren't any stupid questions.

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You could go and ask him anything


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and there was always stuff to be learned

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and I liked this environment so much,


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I think it set me on a path
to ending up here

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where I am a professional scientist
talking to you.

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Even before then, 
my dad used to read me stories

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from the 'Winnie the Pooh' books

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and there's a picture here 
of Winnie the Pooh and Piglet

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searching for a Heffalump.

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A Heffalump's a very rare 
and unusual thing

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that had almost, maybe never, been seen.

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But they got circumstantial evidence here.


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They' ve seen footprints in the snow

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and this has encouraging them,

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maybe if we continue work 
a little bit harder,

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maybe we could find this thing.

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So the basic difference betweeen me 
and Winnie the Pooh in this picture

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is that he's looking down
and I look up for a living.

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So, we scientists, in particular,

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the subject of this talk is to look for
the first stars

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and galaxies to form after the Big Bang.

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They're rare and unusual objects.
We think they are very different

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to the stars and galaxies
that we can see around us today.

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But we think they are there.

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We have circumstantial evidence
that makes us think

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that they are there 
so the quest is worth following.

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So I've told you these two anecdotes
maybe a bit from my life

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in order to give the idea 
of a timeline also

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that I sit here today looking in my past

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as we all can towards when I was born,

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and you can see significant events
that shaped your life.

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What's remarkable is that we can do
the same thing for the Universe.

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So the Universe originated in a Big Bang.

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We don't know exactly what banged
or how it banged,

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although, a couple of weeks ago,
we had some indications

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if you followed the science news.

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But we know when it banged
to amazing accuracy.

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So, we know the Big Bang was
the creation of time and space.

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Matter and light happened
14 billion years ago.

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We know the exact number to 1% accuracy.

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As I was bouncing back into my past
at the start of this talk,

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we can do the same thing here in astronomy


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because light travels at finite speed.

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So when we look up at the sky,


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we' re actually looking into the past.

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And for most cases it's not so relevant.


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In the case of the moon 
it's like 2 seconds.

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When you see the moon, 
you see it as it was 2 seconds ago

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because that's how long it takes light
to reach us from the moon.

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Naked eye stars that you can see

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if you go out in the desert 
away from the street

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that may be a few thousand years.

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You see them as if 
they were a few thousand years ago.

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But the most distant object 
you can see with your naked eye

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which is the Andromeda galaxy


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pictured here seen through a telescope,

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is actually 2.4 million years ago.

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So the light has taken 2.4 million years
to reach you.

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Even without the aid of the telescope
you can see this object.

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If you wanted to know
what it looked like today,

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you'd have to wait another 2.4 million years.

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So, the history of Astronomy 
has really been the history of developing

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telescopes and technology to be able 
to push further out into space

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and see even more distant 
and remarkable things.

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This is a picture of an object
known as a comet cluster,

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many thousands of galaxies
like the Milky Way.

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It's so far away that it's seen
250 million years ago, roughly speaking.

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So 250 million years ago,

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here there was a deep sea, 
a deep inland sea.

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We know this because we see
the Kaibab limestones of Red Rock.

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We see these also, just downstream
from Glen Canyon down at Lee's Ferry.

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These tell us the idea of what 
was happening here was very different.

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It wasn't a desert. It was an inland sea.


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But we don't see the thing itself.

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We have circumstantial evidence,
the rocks.

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But here we're seeing the thing itself


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as it was 250 million years ago.

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So I've drawn sort of a timeline


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on the slide we have today 
on the Big Bang.

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The green arrow shows you
when the Earth formed.

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So the Earth is a relatively recent
addition to the Universe.

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It's only been there for a third
of the existence of the Universe.

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For two thirds of the time 
our solar system wasn't even there.

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So how far back can we actually look
with our technology?

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I've drawn here a little red square
on the slide


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which shows the field of view

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of the best instrument that we built
to be able to do this --

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you've certainly heard of it --
it's the Hubble Space Telescope.

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The Hubble Space Telescope
has a very small field of view.

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In other words, it takes
a very small picture of the sky at a time,

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about 100th of the size of the moon.

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If you want to picture that, it's like
coding a grain of sand at arm's length.

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It's a very, very small part of the sky.

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And scientists had the idea 
to try and probe back in time

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would be to take a picture of the sky

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but to take two weeks 
to observe one part of the sky.

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This was a remarkable idea to look 
at a nondescript, not a part of the sky

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we'd thought
it wasn't anything interesting,


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but just to see what's out there.

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What we found was remarkable.

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Here's one of the most famous images
ever taken in astronomy.

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It's a Hubble Ultra-Deep Field.

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In an area the size of the grain of sand
held at arm's length,

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you see ten thousand galaxies here.

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They're not stars in our Milky Way.


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They're separate individual galaxies,
like our Milky Way.

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In this image, about ten of them
are seen as they were

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13.3 billion years ago,

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which is to say
the light started on this journey

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long before the solar system ever formed.

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For most of that journey,
the Sun and the Earth didn't exist.

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You know, the Sun and the Earth formed
and then life evolved and so on,

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we built telescopes and boom,
we capture this light.


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It's utterly remarkable.

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But those are not the first galaxies.


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Remember, we are looking
for the first stars and galaxies.

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This is one of the major
scientific adventures, I think,

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of the 21st century

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which is going to play out
in the next ten years.

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So we sit here and we look
at this Hubble Deep Field.

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How do we select then the ten galaxies,


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the one in a thousand galaxies
that are the most distant.

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It's so simple that I thought
I'd just tell you today.

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What we do is not a technical description.


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We take a picture at visible wavelengths
of the Hubble-Deep Field

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and one at infrared wavelengths.

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The galaxies which can be seen
in the infrared image,

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but cannot be seen in the visible image,
those are the ones.

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There's just a few of them,
there's just ten of them.

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Those are the ones that are seen
13.3 billion years ago.

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To summarize my story so far --

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if I can get the next slide, there it is.

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We sit here in the Milky Way
and we look further and further back

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with more sophisticated telescopes.


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And we look further and further 
back in time

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13.3 billion years so far with the Hubble.


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But we have another piece of information

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which is the cosmic background radiation.

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The cosmic background radiation
which is seen at radio wavelengths

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tells us what was happening
in the Universe


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only roughly half a million years 
after the Big Bang.

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We know there was a time from the staff,


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the outermost shell that's colored
green and yellow and blue there,

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that there was a time when there were 
no stars and galaxies in the Universe.

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That's what that tells us.

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But it tells us another important thing,


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which is that on its journey,
the slide on its way to us

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was modified by stars and galaxies,

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the first generation of stars and galaxies


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that we haven't yet detected.

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That's a sort of Heffalump effect.
The footprints.


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We see the footprints
of the things we're looking for

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but we haven't seen the thing itself yet.

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So in order to find these things that
we're looking for,

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we need to devise new tools.

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The history of astronomy has been
the remarkable improvements

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we've been added for 400 years
with the telescope.

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Galileo's telescope 
had a lens about this big


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and this is a next generation
of telescopes being built in Chile.

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This is a European
Extremely Large Telescope --

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running out of names for telescopes now. 
(Laughter)

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But the mirror --

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The mirror is about the size of this room

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so it's a gigantic tool for looking back
into space ever further.

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As you saw from before, 
we need visible and infrared light

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in order to study these objects.


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In the infrared, we' re building

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what is the successor to the Hubble
Space Telescope

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which is what's called
the James Webb Space Telescope.

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This is just one sixth of it shown here.

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So it's a gigantic instrument.

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It's so big that it won't fit
into a rocket.

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So they are going to have to fold it up
like insect wings or something,

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put it in there, send it out into space,
take it out, unfold it

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and then it's going to take what we hope

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are the images 
of the first stars and galaxies.

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It's also going to explore planets

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and other things
that are of great interest to us.

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So, what do we expect to find?


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The way we do astronomy
is illustrated in this video here,

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is astronomy and science 
is a constant dialogue, really,

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between theories or our conjectures 
about the way things ought to be,

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which is shown in the movie here,

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and the way they actually are,
which is shown in the stills.

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So in the movie here, 
you can see two galaxies,


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like the Milky Way and Andromeda
that are on a collision.

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This is a calculation done in a computer.

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Once in a while, they freeze the movie


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and because it's a computer simulation

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you can view it any way you like,

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and then they try and compare it,

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to actual images of galaxies nearby


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to see how good a job we have

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at understanding interactions
between galaxies.

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In the case of the most distant 
stars and galaxies,

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we've only done half of this.

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We have our conjectures,
but we don't have the observations.

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So what can we expect to see?
How is this going to play out?

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Based on the history of astronomy,


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I think I can best tell it 
with an anecdote.

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Howard Carter, when they discovered
Tutankhamun's tomb,

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they were in a sort of narrow corridor

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and he was the first to see the tomb
in modern times,

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and he had a candle 
and in the flickering light he could see

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this vast array of treasures of gold 
and statues of animals and things.

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The others behind him -- 
he didn't say anything,


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and they were like: 'What do you see?'

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And he said, 'Wonderful things',
'Wonderful things'.

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And I think that's what we can expect

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in our science in the future.

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But as well as learning about the Universe

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which is going to be tremendously exciting,


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I think, science teaches a lot about
our humanity, ourselves as human beings.

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For those of you 
who don't know the Pooh story,


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the punchline to this one is

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they actually didn't find the tracks
of the Heffalump, unfortunately.

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They were looking at
their own tracks in the snow.

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But they learned something 
about themselves in this adventure

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and about what they were.


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We do this too, when we do science.

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We learn our position in the Universe,
but we also learn about ourselves.

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And the European Center for Nuclear Research
which has many --

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several Nobel prizes 
have been awarded there.

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I didn't tell you this far,
it was built really

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out of the ashes of Europe after WWII.
Europe had been at war.

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I am an immigrant from Europe.

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For most of the 20th century
for reasons that weren't clear,

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but all these countries, 
for religious, cultural, ethnic reasons

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were at each other's throats.

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And the idea is 
maybe there is another way.


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What if we work together?

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What if people from these countries
that had been at war

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showed that by working together, 
overcoming their prejudice,


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we can do good science?

00:12:03.237 --> 00:12:04.916
And history of CERN has shown

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that when you do this 
you can achieve wonderful things.

00:12:07.045 --> 00:12:08.824
Wonderful things!

00:12:08.824 --> 00:12:10.346
Thank you.

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(Applause)