0:00:08.250,0:00:12.292
Have you ever asked yourself[br]about the actual nature of the universe?

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I'm not talking about[br]any abstract universe but our universe,

0:00:15.418,0:00:18.417
the one in which we all live,[br]the one where you are now.

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Have you ever thought about[br]what you body was really made of?

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Or the air you breathe[br]or even the very chair you are sitting on?

0:00:25.876,0:00:27.999
If the answer is yes,

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then you might have noticed[br]that around you

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you can find clues[br]that can help you decode all that.

0:00:36.876,0:00:40.210
For example, if I grab my glass,[br]you see there is water in it,

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and I throw it at you, here,

0:00:42.083,0:00:44.709
some of you would move aside a little.

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Nobody in this room,[br]or anywhere else on Earth

0:00:47.628,0:00:51.502
ever thought that once[br]you throw the water,

0:00:51.542,0:00:55.001
it would stop halfway in the air[br]turn around and go back into my glass.

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And why is that?

0:00:56.052,0:01:00.750
We all have this feeling[br]that some laws of Nature actually exist,

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and that those very laws cannot be broken.

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The aim of theoretical physics[br]is to figure out what those laws are.

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One have to admit that, as humans,[br]we are rather good at that.

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Just to give you an idea: since Newton,

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we can all describe every single thing[br]that is happening around us,

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including the state of objects.

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That, we know how to do.

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But since Newton,[br]we went a little further than that.

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We even entered a world[br]that goes beyond our senses.

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A world in which our intuition[br]no longer applies.

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It is a wonderful world,[br]and I'll tell you why.

0:01:34.835,0:01:37.876
In 1905, Albert Einstein taught us

0:01:37.876,0:01:41.958
that light is made of[br]tiny pieces of energy.

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In Latin, "tiny pieces"[br]would be translated as "quanta."

0:01:45.461,0:01:49.584
What Einstein and other fellows did,[br]was to open us up on a new world,

0:01:49.585,0:01:52.918
the world of quantum mechanics[br]and quantum physics,

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a tiny world that is the world of[br]luminous rays.

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I'll ask you to imagine that, for a[br]moment, you are in 1942 in Paris,

0:02:02.250,0:02:06.082
where a young scientist[br]just got his thesis published

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He is 32, and his name[br]is Louis de Broglie,

0:02:08.459,0:02:10.918
and he states something extraordinary.

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In support of his calculations,[br]he states the light that is around us,

0:02:14.711,0:02:19.501
and this matter[br]that your bodies are made of

0:02:19.542,0:02:21.522
are not that different from one another.

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The matter would actually[br]be made of those tiny pieces of energy.

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That would mean that matter itself[br]would follow the laws of quantum science.

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And for this,

0:02:31.876,0:02:34.752
De Broglie achieved the dream[br]of every PhD student on earth

0:02:34.753,0:02:38.001
when receiving a Nobel Prize[br]for his thesis, 7 years later.

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And that's not so bad after all.

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On the founding fathers of quantum physics

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immediately got his hands on this idea

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and started to work on trying to find out

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how the whole world[br]of the infinitely small works.

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And guess what?

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He succeeded in finding an equation

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that he named the Schrödinger's equation.

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It describes the way particles behave[br]within our universe.

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In a few words, he did[br]for the world of the infinitely small

0:03:10.918,0:03:12.689
what Newton did for the world around.

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If you shoot an arrow,[br]Newton would tell you where it will land.

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If you throw a particle,

0:03:17.918,0:03:20.836
well, Schrödinger would tell you[br]what it will become.

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Unfortunately, in the world[br]of the infinitely small,

0:03:24.466,0:03:25.877
particles are no arrows.

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They are not even like small balls.

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Instead, you have to imagine a kind[br]of cloud filled with small balls

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that are either present or missing,[br]that exist or don't exist

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and that are overlaid[br]and that are almost everywhere.

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Schrödinger's equation describes[br]how this cloud will evolve through time.

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what he eventually found was very strange.

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Just to give you an idea

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of what it could mean[br]from our world's perspective,

0:03:52.918,0:03:55.541
he came up with a thought experiment

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he named the Schrödinger's cat experiment.

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Here it goes: in this box, there is a cat.

0:04:06.375,0:04:07.834
(Mioawing)

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It might have been sleeping.[br]Anyhow, there is a cat.

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But there is more than a cat.

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It didn't sound very happy,[br]because on its side

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Schrödinger placed, and so did I,[br]a radioactive substance.

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What is a radioactive substance?[br]It is a substance we can split into two.

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That's why the first row had to sign[br]the legal discharge earlier,

0:04:27.626,0:04:28.940
it's radioactive in there.

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So, we have a substance[br]that can be split into two

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without us knowing in advance[br]whether or not it will happen.

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So, there is this little substance inside

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and with the one I place here,[br]there is a 50/50 chance it will break,

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or be blown apart between now[br]and the end of the experiment.

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But Schrödinger did not only did that.

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With this little substance,[br]he added a device, as smart as sadistic,

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that would release a poison[br]and eventually kill the cat

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in case the substance blows away.

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If on the contrary the substance[br]stays as is, the cat is safe.

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The laws of quantum physics tell us[br]as long as no-one has looked inside,

0:05:08.849,0:05:10.660
as long as no-one opened the box,

0:05:10.667,0:05:16.334
the radioactive substance has blown away[br]but at the same time, hasn't.

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It means the poison has[br]and hasn't been released.

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Consequently, the cat inside[br]is not dead or alive, but dead and alive.

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It sounds completely insane, I agree.

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But after all, that's what maths[br]tells us, and they are positive.

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If the laws of quantum physics[br]as we know them are correct

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then Schrödinger and his equation[br]will tell you that in this box,

0:05:41.209,0:05:42.645
the cat is both dead an alive.

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Let's have look.

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(Miaowing)

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Well, at least it's not dead,[br]which is good.

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But you see, there was only one cat

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as you might have expected[br]and you might be a bit relieved

0:05:55.501,0:05:57.460
that the cat is alive and not dead.

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As for me, it disturbs a lot[br]that there is only one cat inside.

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I believe in maths[br]and all the physics that's behind it,

0:06:04.627,0:06:07.918
and if maths says[br]that there should be two cats inside

0:06:07.918,0:06:12.041
the questions is:[br]where is the dead cat now?

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It should then be there but is not.[br]So where is it?

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As crazy as it sounds,

0:06:17.709,0:06:21.210
scientists are actually paid[br]to try and answer this very question.

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(Laughter)

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They were even paid for years.

0:06:24.959,0:06:28.917
Schrödinger published[br]this thought experiment in 1935.

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For a decade after that, maybe even two,

0:06:32.959,0:06:36.501
almost all the scientist on earth[br]have been looking for the dead cat.

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Up until a young American[br]named Hugh Everett III

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came up with an incredible solution.

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He thought to himself that if Einstein[br]and De Broglie were really right,

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which seemed to be the case,

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then light and matter are quantum

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since our whole universe[br]is made of light and matter,

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then, there is no reason at all[br]that the universe itself

0:06:57.460,0:06:59.041
would not be quantum.

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And consequently, a superposition[br]within its different states,

0:07:02.168,0:07:03.959
where there are many possibles.

0:07:03.960,0:07:08.543
What he means is[br]that when I opened the box,

0:07:08.584,0:07:10.291
two cats were inside

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and when I opened it,[br]our whole universe split into two:

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one where we live now[br]and where the cat is alive,

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and the other where it was dead.

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This very universe[br]would be universe parallel to ours

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that would remain forever.

0:07:25.626,0:07:28.085
At the end of one his lessons[br]on quantum physics,

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Einstein told his students,

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"If you understood what I said,[br]it means I wasn't clear enough."

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(Laughter)

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Hugh Everett III[br]didn't get the Nobel Prize

0:07:38.667,0:07:41.459
because he published[br]this paper with his thesis

0:07:41.460,0:07:44.584
on the contrary, he abandoned physics,[br]thinking it was rubbish.

0:07:44.585,0:07:45.708
(Laughter)

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He might have been right though.

0:07:47.419,0:07:49.417
But at the time, to check his theory

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would mean we would need to see[br]every single atom.

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See them in their overlapping state,

0:07:55.042,0:07:57.125
to try them out[br]and actually observe them.

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Then again, at this time,[br]it was experimentally out of the question.

0:08:00.375,0:08:01.750
But not now anymore.

0:08:01.918,0:08:03.374
At the end of 1990s,

0:08:03.375,0:08:06.084
in the Teacher Training College's[br]laboratories in Paris

0:08:06.085,0:08:09.250
Pr. Serge Haroche's team[br]succeeded in creating

0:08:09.292,0:08:13.210
an experiment categorized[br]as "Schrödinger's cat-like."

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It wasn't with a cat,[br]but with big atoms and light.

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And from this experiment,[br]he could see that atoms

0:08:23.167,0:08:25.625
were in overlapping states.

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The same kind as a cat[br]both dead and alive.

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He even saw those two states vanish[br]to leave space for only one,

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and, in a certain way, to give birth[br]to the world we got used to living in.

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This very experiment got him[br]the Nobel Prize in Physics 3 years ago.

0:08:43.918,0:08:47.833
We started in 1924[br]with Louis de Broglie's Nobel Prize

0:08:47.834,0:08:51.335
and arrived in 2012 with Serge Haroche's,

0:08:51.375,0:08:56.042
following an idea where we traveled[br]different times and lands.

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Why did I tell you all this?

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Why did we follow the hare-brain ideas[br]of all those loony scientists

0:09:02.419,0:09:06.667
talking about cats dead-alive cats[br]and parallel universe all over the place?

0:09:06.668,0:09:07.750
Is it of any use?

0:09:07.876,0:09:11.001
I could honestly understand[br]that you wouldn't get

0:09:11.117,0:09:13.147
why we actually fund research.

0:09:13.167,0:09:15.666
But, it turns out you'd be wrong.

0:09:15.667,0:09:18.917
From Broglie's discoveries[br]to Schrödinger's equation

0:09:18.959,0:09:22.376
many everyday life objects[br]have seen the light of day:

0:09:22.377,0:09:25.918
computers, mobile phones, lasers

0:09:26.501,0:09:30.124
and almost all medical equipment[br]you can find in a hospital.

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But some of you will ask,[br]"What about Haroche's discovery?"

0:09:33.021,0:09:35.251
Well, it turns out that it allows for

0:09:35.252,0:09:39.292
a new industrial[br]and technology revolution.

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By succeeding in considering[br]the cat as both dead and alive

0:09:43.959,0:09:47.041
he opened the way[br]to computers of the future

0:09:47.042,0:09:49.416
that they call quantum computers.

0:09:49.417,0:09:52.082
A quantum computer is a machine

0:09:52.083,0:09:56.417
that uses the overlay[br]of atoms state within its heart.

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Does that makes sense?

0:09:58.667,0:10:02.251
Thanks to this system,[br]those small atoms and those machines

0:10:02.252,0:10:06.500
are capable of calculating[br]as if they were

0:10:06.501,0:10:09.500
in billions of different[br]parallel universes at the same time.

0:10:09.501,0:10:14.501
This means a single one of these computers[br]would make all of the computers

0:10:14.584,0:10:16.834
we have nowadays, look like abaci.

0:10:16.965,0:10:19.079
That's just that simple.

0:10:19.667,0:10:23.917
Fundamental research[br]is a rather understated discipline,

0:10:23.918,0:10:25.877
that can sometimes be completely secret.

0:10:25.878,0:10:29.249
Yet, it is the origin of many revolutions

0:10:29.250,0:10:31.082
and the genies behind them

0:10:31.083,0:10:34.208
can emerge anytime and anywhere.

0:10:34.209,0:10:38.209
Here is an example, Serge Haroche,[br]the same man we talked about earlier,

0:10:38.334,0:10:42.043
who was born in Casablanca, Morocco[br]and arrived in France when he was 12.

0:10:42.083,0:10:45.166
As a small digression,[br]I'd like to pinpoint the fact

0:10:45.167,0:10:48.876
if we had closed our borders back then,[br]France would have lost a Nobel Prize

0:10:48.877,0:10:51.418
and its hypothetical[br]and amazing applications.

0:10:51.419,0:10:53.959
(Applause)

0:10:58.375,0:11:01.876
Scientific knowledge[br]belong to every single person,

0:11:01.876,0:11:05.959
you, me, newborns here,[br]or somewhere else on Earth.

0:11:05.959,0:11:08.875
It is our duty to share and pass it on.

0:11:08.876,0:11:11.293
It is for everyone's sake[br]that I tell you this.

0:11:11.294,0:11:14.439
Besides, it is very likely[br]that, in the future,

0:11:14.440,0:11:18.043
a child from another country[br]will hold the keys of our future here

0:11:18.083,0:11:22.233
and not of a parallel universe.

0:11:22.233,0:11:23.564
Thank you very much.

0:11:23.564,0:11:25.176
(Applause)