Transcriber: Rhonda Jacobs Reviewer: Peter van de Ven
Last summer in France, many refugees arrived and were helpless and homeless.
And so the French government asked my university
to host, as emergency housing, 70 of them.
They came from Afghanistan, Somalia, Eritrea, Chad, Mali, etc.
So my university president,
she decided to make their stay the most enjoyable as possible.
And we decided together with her to make events for them
because they were staying only three weeks.
I decided to organize them star parties.
What is a star party?
A star party is a nice event - you bring telescopes, you bring people,
you look at the stars - it's at night, obviously -
you look at the planets, the stars,
you discuss about the world and everything.
It was an amazing success.
We shared love; we shared ideas; we shared testimonies;
we shared views of the world.
It was an amazing event.
And we get connections to each other,
which we didn't have at the beginning, because we didn't know each other.
What makes these connections so special between us and all the stars?
I guess it's curiosity and culture.
We were so intensively curious to each other,
we had to share many things about culture,
that the connection was made immediately.
And I think culture and curiosity is likely what builds us as humans.
During the star party - obviously, as an astrophysicist,
I was there to help them, show the stars and the planets -
and quickly came questions like, "Where do we come from?"
"What are the planets are made of?"
"What is our universe made of?"
"Where do we come from, as universe, planets, galaxy and life?"
And these are some of the main questions mankind is asking itself
since basically forever: Where do we come from?
As an astrophysicist, a university professor,
I had the great pleasure to participate in a major space mission
from the European Space Agency, it's called Planck,
where we observed the first light of the universe
to answer these kind of questions.
Where do we come from? What is the age of the universe?
What is the universe made of?
And this amazing image shows you the first light of the universe.
It's called the Cosmic Microwave Background.
I won't be too technical tonight,
it's just the first light that is released
a few fraction of the time of the age of the universe
after the Big Bang.
So it's like an image of the universe at its infancy.
This image is purely fantastic.
It is the best-ever image you can imagine to have of the early universe.
From this image we learn a lot.
We run millions of mathematical models of the universe
and we compare with this image.
And from that, we got many impressive results.
I will show you one of these results.
This result is a two-day composition of the universe as we understand it.
To this universe composition -
actually, energy density, but you don't care tonight about that.
Today composition is like this.
It's what you call the cosmic pie,
or, since we're in France, cosmic Camembert.
Let's stick with the French way.
About 70 percent of the universe is made of dark energy.
We have no idea what it is,
but we think it's responsible for the accelerated expansion of the universe.
I could spend hours on that, but I won't do it tonight, obviously.
Then there is about 25 percent, a quarter, of dark matter.
Dark matter is a matter - we have no idea what it is -
but we're pretty sure it's there
because it attracts and it forms galaxies that we are seeing.
And then we are left with about five percent of what we know,
what we see;
it's basically ordinary matter: it's you, it's me,
it's planets, stars and everything.
So out of all that, what we all know as matter is just five percent.
How come that scientists, brilliant maybe, scientists are able to put a number -
what we know, it is fairly easy,
but what we don't know.
How do we do that?
How we put numbers? Because I told you we don't know any reason it's true.
Let me do this analogy.
Around this room, there is some air.
If you do that, you can feel the air.
You can breathe it, enjoy the air.
Have you ever seen any particle of air with your eyes?
Have you seen a molecule of oxygen
or carbon dioxide
or nitrogen 2? N2, I mean.
I guess never.
So you know air is here.
You feel it, but you have never seen it.
We do the same.
We have never seen dark matter nor dark energy.
But we have the magic science tool.
It's called equation of state.
Equation of state tells you
what is the relation between pressure and density of something.
And we can measure the pressure of the air and its density.
And believe it or not,
we can measure the pressure that dark energy has on the universe,
hence, density.
And we can do the same with dark matter.
That's where we can get these numbers from.
It still doesn't tell us what it is,
and that's one of the main questions of today's astrophysics and cosmology
and origin science.
That's why we are building right now in Europe,
still with the European Space Agency and what we do here in Paris-Saclay,
a new space mission that will completely revolutionize our vision.
This mission, it's called Euclid,
and in the next decade, we will be able to see billions of galaxies,
billions of galaxies across the whole sky.
And these images won't tell us what dark matter or dark energy is,
but it will tell us
what is the effect of dark energy on the expanding universe on one side,
and what is the effect of dark matter
and structuring the matter on the other side.
To do that,
we are building the biggest-ever camera to be launched into space.
You see the size?
Six hundred million pixels - I mean, this big.
And it will be a major breakthrough
to understand what could be dark matter and dark energy
when we compare it to the models.
So I talked to you about the Big Bang, dark matter, dark energy.
What is the connection between those exciting science topics
and today's everyday life?
I guess the connection is that these results
and these amazing images that we provide to the public and for science -
I guess it's the next slide -
allows us to be inspired.
As I mentioned, mankind is always looking for its origin -
where do we come from?
And this image is taken from Mars.
Mars at sunset looks like this.
And you have a tiny dot -
maybe you don't see it, but it's there -
it's our planet.
Our planet is just a tiny dot seen from Mars.
So these nice images that we see,
that come from science
and that we study to better understand the universe,
have such a major power to enhance our vision of the universe,
to give us a view on what the world is.
And in this respect, science shares the same preciousness as art and culture.
Because art and culture are also ways to provide us with a view of the world:
What is the world?
What's your place in it?
What should be the world?
And what should be at stake?
So science, culture and art,
to me, share the same characteristics of vision to the world.
So what I was mentioning about science
basically drives all human thinking as well as art and [culture].
So,
art, science and culture share the same characteristics.
You need just to be open minded, to be creative,
and to -
to be creative, that's enough,
that's difficult enough to share these characteristics.
And from that, I think we should not think about science
as a separate part of society or the world, same as culture and art,
but everything is the same as we argue.
So next time you will be looking at the sky,
at the night sky - planets, stars on your summer nights -
maybe you can think about dark matter, dark energy, science,
but also art, culture, creativity, open mind, and ...
cosmic Camembert.
Thank you.
(Applause)