Do you know what astrophysics is for?
Finally,
why do we devote budgets that may seem consistent,
while we have much more immediate problems on a daily basis?
I am a scientist, proud to be,
and I have always been fascinated by stars and the cosmos.
This passion goes back to my childhood:
one day, my parents took me to visit the observatory of Haute Provence,
not far from here, near Forcalquier.
And I was literally subjugated
by this large telescope two meters in diameter.
Since that day,
I made the project to work in astrophysics.
So after long studies, it became a reality.
At the same time, I have always been attracted by technology.
So, I tried to associate these two dimensions in my professional project.
In fact, today I make instruments for astronomers,
and more precisely cameras, ultra fast, ultra sensitive,
which are used in astronomy.
Because we have to see that …
astronomy is, above all, a science of observation.
Our current technology does not allow us to do
than flea jumps into the cosmos.
So, the man went to the moon.
He sent probes all over the solar system.
And today, the probe furthest from us,
it is the Voyager 1, which was launched in 1977.
It is twenty billion kilometers from us.
Twenty billion kilometers can seem like a huge number.
But this figure, we must compare it with the distance that separates us
of the star closest to us: it is Proxima du Centaure.
This star is 40 000 billion kilometers from us.
Forty thousand billion!
Can someone in the room tell me
how many zeros after 4?
(Laughter)
Well, I see I’m not dealing with maths!
This figure is here.
It’s a 4 followed by thirteen zeros.
It’s huge!
Even me, I can not imagine this distance.
We will try to bring things back to scale.
If we assume that the star closest to us, Proxima,
is located in New York, 6,000 km from us,
well today, the Voyager probe,
would be three kilometers from us, at the Estaque.
(Laughter)
And if it had to go to Proxima Centauri,
well it would take him 78,000 years.
Yet the Voyager probe is largely speeding,
because it travels at 62,000 km / h.
Fortunately for her, we have not yet installed radars in the cosmos.
All this to tell you that
finally, to study all these stars that are extremely distant,
we can only use information
which is directly and easily accessible to us:
it’s light.
We can get a lot out of the light.
Giono said:
“When the mysteries are very clever, they hide in the light. “
What can we deduce?
We will be able to deduce the speed, the temperature, the pressure, the density,
and, more interestingly, the chemical composition.
But then, finally,
why give yourself the means for these observations?
Humanity has been asking a question for a long time,
who is: “Are we alone in the universe? “
Because finally we looked for life elsewhere than on Earth,
in particular, with these probes that are part of the solar system.
But today, we have not found life anywhere but on Earth.
And yet it would be enough to find it in only one other place,
on one other planet,
to be sure that statistically,
it exists in abundance in the universe,
and therefore the appearance of life on Earth is not a single fact,
nor an accident.
So this quest for life elsewhere,
it started with another question that astronomers asked themselves:
“Are there other solar systems?
Are there other planets around stars other than the Sun,
what are called: exoplanets or extrasolar planets? “
This answer has been around for a very short time.
We have since 1995,
the date on which the first extrasolar planet was discovered.
It was discovered, by the way, with the telescope
from the Haute-Provence observatory, the very one that fascinated me, child.
In fact, since that time, since 1995,
so in twenty years, we have discovered so far,
more than 3,000 extrasolar planets.
And this figure is accelerating.
I let you imagine, in twenty years,
how many extrasolar planets we will know.
And, even more interesting,
in fact, very recently, a few months ago,
we discovered a planet that is potentially habitable
around the nearest star around Proxima du Centaure.
So this planet, here it is!
Obviously, it’s an artist’s view since, as I explained to you,
it’s still very difficult to go there.
So, it’s the planet as we imagine it.
In fact, of these planets, we have very few images.
All these planets were discovered by indirect means,
which would be very difficult to explain today.
And yet, having images of planets is essential.
Because if you want to determine the composition on the surface,
first you have to make the image to analyze the light.
We will thus be able to determine if on the surface, there is oxygen,
there is water, and if we are lucky, why not, discover life,
if, for example, chlorophyll is detected.
So why do not we have images of these extrasolar planets?
Because it’s something very difficult to do in fact.
First, the brightness of the planet
is about a million times less than the star that houses it.
Still very big numbers, to put things back,
it’s like trying to see the glow of a candle,
next to a marine lighthouse.
And then, you need images of an extraordinary detail,
of extraordinary precision.
If we were to see the planet around Proxima Centauri,
and if we go back to our human scale,
with Proxima Centaurus in New York, 6,000 km from us,
well, see this planet in fact,
would be like trying to see a pinhead
which would be located one meter from a marine lighthouse,
itself located 6,000 km from us.
You see the difficulty.
And yet, we did not give up and we invented instruments
which allow us to make these images.
To counter these difficulties,
we first invented what are called coronographs.
A coronograph will mask the light of the star
so that we will not be dazzled by the star itself,
and we can go see the planet, which is much weaker next to it.
After, as I told you, we need images of extraordinary quality,
an extraordinary detail.
There, things get a little complicated.
Because the light that comes from the stars,
it must first cross the atmosphere and there, it will be disturbed
by what is called atmospheric turbulence.
Atmospheric turbulence, what is it?
Anyone can see it, it is enough, in summer, to look over a road
when it’s hot,
and we see the images that are, a little, swirling.
Atmospheric turbulence, that’s it.
And that’s what will degrade the quality of star images.
So, we invented a system called adaptive optics.
It’s a very complicated process, but roughly speaking,
it’s a question of going to analyze the images that we have with the telescopes,
and several thousand times a second,
we will operate an optical system
which will correct the disturbances of atmospheric turbulence,
to restore the quality of the images.
So, in fact, what do we get on arrival?
You have here the image of a star,
which, on the left, was observed without adaptive optics,
– so the star is a kind of halo –
and right, using an adaptive optics system.
And there, we realize that what we actually believed, to be a single star,
is actually a double star.
So here we see the power and the interest
adaptive optics.
So, images by this double process, we have since 2010.
We have very few, but we have, since 2010.
The first was made by an American Caltech team.
This picture is here.
As I told you, we do not see the star.
She was masked by the coronograph.
The star should be at the green cross.
The bright spots that are in the picture,
are actually images of planets.
Unfortunately, on this picture,
the planets are twenty, thirty, and sixty times the distance between the Earth and the Sun.
So the temperature on their surface is very, very cold,
And so, these planets certainly do not shelter life.
To find planets that shelter life,
we have to make images of planets that are much closer
of the star that houses them.
So that means more adaptive optics systems
and that is precisely where I intervene.
This is where I intervene with my double passion,
that of stars, and that of technology,
with these cameras I told you about at the beginning,
which are both extremely fast and extremely sensitive.
Since they are extremely fast, much more than those
used before in adaptive optics systems,
we will be able to have images with a better definition.
And they are extremely sensitive, so sensitive that they are capable
to see an elemental grain of light, a single photon.
In adaptive optics systems,
we will be able to observe much weaker stars
than what we observed before,
– so more stars, more chance to see planets,
more chance to see planets close to their star.
Then, we will be able to analyze their light and determine
what is the composition on their surface and if, why not, there is life or not.
This technology that we have developed is so remarkable,
that it interests the largest space agency in the world,
– I obviously want to talk about NASA –
who asked us, little Marseillais,
to help him make the cameras of his future space telescope.
NASA, they even came here to see us, in Marseille.
And it was not to look for lavender
nor to drink pastis.
(Laughter)
So, today,
these adaptive optics systems
are being deployed a little bit everywhere,
in the big observatories around the planet.
These systems are starting to produce their data.
I bring my modest contribution
producing these cameras with outstanding performance.
And in fact, we are at the dawn of a revolution.
So, back to our original question:
finally, why all this science?
I strongly believe that a society can not move forward
only if there is scientific development.
Simply because science brings technological progress.
But not only.
I have to tell you something.
It is because I am intimately convinced of the existence of an extraterrestrial life.
Do we understand well: I do not speak obviously
little green men
who would visit us in their flying saucer, no.
I’m talking about a life, on another planet,
that we could detect as I told you.
Finally, for me,
the question is not that of the existence of life
but rather to know where and when we will find it.
Now, let’s imagine together what will be the impact of such a discovery.
What impact will such a discovery have on politics,
on the economy,
on culture,
on metaphysics,
on religion.
Man would no longer be alone in the universe.
Yes, astrophysics is essential.
It is essential like any science since it brings its lot
technological improvements on a daily basis.
But above all,
it is essential for its impact on consciousness.
Because when man becomes aware
that indeed, he is a citizen of the universe,
I’m sure it will change
our way of seeing each other,
and how we act more responsibly for our future.
Thank you.
(Applause)
”
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