00:00And if we were not the only species technologically developed developed to have fallen the earth,
00:05don't start to be afraid of people around you.
00:07I assure you that they are human.
00:09I'm talking about an entire civilization, avancing,
00:11which would have existed millions of years ago,
00:14before it started.
00:17It's a strange idea, certainly, but not impossible.
00:20This is a big question.
00:22If it had really existed,
00:24would we be able to know it?
00:26So honest, we are obsessed with the perspective of discovering an extraterrestrial intelligence,
00:32so that we almost neglect the possibility of an advanced civilization and already prospering here,
00:38on Earth.
00:40Before the appearance of the human,
00:42even before the dinosaurs,
00:44and it could be possible that even if they are still alive,
00:48but where to look for them?
00:50It's precisely what is the hypothesis silurian.
00:55This name comes from an extraterrestrial species of Doctor Who.
00:59But the scientific idea which s'y attache diffère sensiblement.
01:03The researchers don't want to determine if a human civilization has existed,
01:08that to respond to a more subtle question.
01:10If it had really existed,
01:12would we have the least chance to find the trace?
01:14In other words,
01:16do we have the necessary tools to prove it?
01:18Because, after all,
01:19nothing else exists.
01:20We have the same species.
01:23Since the 18th century,
01:25we built an industry,
01:26we built an industry,
01:28and our technology has ceased to be perfected.
01:30It has so much progressed
01:31that it perturbed today
01:32the climate
01:33and the earth ecosystems.
01:35If this trajectory continues,
01:37it is not absurd to imagine
01:39that one day,
01:40humanity could open it.
01:42So,
01:43we have to admit it,
01:44this apocalyptic and hypothetical scenario
01:45and hypothetical,
01:46it has for but to illustrate the theory.
01:48Imagine,
01:49so,
01:49our human world deprived of humans
01:50to ensure the function.
01:52At first,
01:53nothing would really change.
01:55Then,
01:56a few,
01:57a few,
01:58a few,
01:58a few changes began to accumulate.
01:59The oil companies and the nuclear power
02:02and the nuclear power
02:03continue a few times.
02:05Until,
02:05a pan here,
02:07a valve rompue by there,
02:09provoque suddenly
02:09a catastrophe.
02:11Explosions,
02:12fumée
02:13and flames
02:13déchirant the sky.
02:15With the years,
02:17the bitumen
02:17would be fissured,
02:18the scent of the fragile
02:19poussets.
02:20A few years later,
02:22it would become
02:23herbe folle,
02:24then buisson
02:25before
02:26becoming an arbre
02:27capable
02:28to fend the roads.
02:29Finally,
02:30our wooden buildings
02:31will be placed
02:32to real estate
02:33and this process
02:34would not stop there.
02:36Ponts,
02:37immeubles,
02:38the ciel
02:38would end up by
02:39evaporate.
02:40Even the materials
02:41that we believe
02:42eternally,
02:43like the plastic,
02:44would end up by
02:45being absorbed
02:46by the soil.
02:47Hundreds of millions
02:48years later,
02:50the earth would be
02:51entirely remodeled.
02:52All the direct traces
02:52of our civilization
02:54would disappear.
02:55The fossils
02:56themselves
02:56even
02:56they would
02:57the most
03:01big cities
03:02would fall
03:04in an instant
03:05at the
03:06geological level.
03:08Imagine
03:08that now
03:09the earth
03:09becomes a new
03:11civilization
03:12intelligent.
03:12The scientists
03:13of this future
03:14are trying to demonstrate
03:16that we,
03:17humans,
03:18have really existed.
03:19They would have
03:20a colossal task
03:22before
03:22without any
03:23human origin
03:24human origin
03:24still intact.
03:26They should
03:26rely on
03:27the geological
03:28features of
03:29our activities,
03:30these traces
03:31inscrites
03:31in the rocks
03:32or the minerals
03:33that tell the history
03:34of the planet.
03:35They would have
03:36to examine
03:36without doubt
03:37the carbon
03:37carbon
03:38for example.
03:40But even so,
03:41the indices
03:41would remain
03:41evident for
03:43reasons
03:44that we will be
03:44in a moment.
03:46In reality,
03:47it would be
03:48as hard for us
03:49to do
03:49the
03:50ancient
03:51technology
03:51disappeared.
03:52We would not
03:53find any statues
03:54or buildings.
03:56Nothing would have
03:57existed after millions
03:58of years.
03:59However,
04:00if they existed,
04:01their needs
04:02would have been
04:03to produce
04:05huge amounts
04:06of energy
04:06and food.
04:08And it would have
04:09left
04:10geological
04:11comparable.
04:12of a huge
04:13carbon
04:14atmospheric
04:16sudden,
04:17an increase
04:18of the level
04:18of the mers.
04:19And if one day
04:20we found such a trace,
04:22it would be a real
04:24jackpot.
04:24Maybe it would indicate
04:25that an intelligent
04:26human civilization
04:27would have existed.
04:30It would be
04:31easy to say,
04:31right?
04:32It is precisely
04:32where the hypothesis
04:34silurienne
04:34in 2018,
04:36the physician
04:37Adam Frank
04:38and the climatologist
04:39Gavin Schmidt
04:39decided to
04:40make sure
04:41to answer
04:42a great question.
04:44If an advanced civilization
04:45had lived on Earth
04:47a long time,
04:49would we be able
04:49to know it?
04:51Their conclusion
04:51is prudently.
04:52Probably not.
04:53Retrouver
04:54concrete
04:54of a society
04:55would be extremely complex.
04:58And two main reasons
04:59explain it.
05:00First,
05:01it is difficult
05:02to distinguish
05:03the
05:04geological
05:05origin
05:05human
05:06from natural processes.
05:08For example,
05:09a rise
05:10of the temperature
05:10during a given period
05:11of a given period
05:12of a given period
05:13of an industrial
05:14or simply
05:15of a natural phenomenon?
05:17Let's take an example.
05:18What we observe
05:19today in the climate
05:20reminds
05:21some past episodes
05:22called
05:23hyperthermics.
05:24One of them
05:25was produced
05:25it's about 55
05:27million years
05:27when the world
05:28temperature
05:29jumped
05:30at about 8 degrees.
05:31celsius.
05:32Or,
05:33these
05:34hyperthermics
05:34happened
05:35during a period
05:36of intense
05:36activity
05:37tectonics
05:38and the
05:38volcano
05:38were
05:41so natural.
05:44But you
05:45see the idea.
05:46Maybe
05:47at a time
05:47more ancient,
05:49other
05:49phenomena
05:49and improbable
05:52could result
05:52from a
05:54disparaged society.
05:55However,
05:56it would be an extreme
05:57difficulty.
05:58There is a second
05:59reason for which
06:00we could never find
06:02their traces.
06:03Plus a civilization
06:04avancée
06:04perdure,
06:05plus she leaves
06:06tangible signs
06:07of its existence.
06:09But here is the paradox.
06:10For subsisting
06:11so long,
06:12she should be
06:13durable.
06:14Or,
06:15more a society
06:15is durable,
06:16more its empreint
06:17on the planet
06:18is reduced.
06:19Un impact
06:19reduced means
06:20less indices
06:21susceptible
06:22to us.
06:23You see the paradox?
06:24Les civilizations
06:26les plus aptes
06:27à survivre
06:27à travers le temps
06:28sont justement
06:29celles qui laissent
06:29le moins de traces.
06:31Ainsi,
06:31une société reposant
06:33principalement
06:33sur l'énergie solaire
06:34et éolienne
06:35ne produirait
06:36presque aucun indice
06:37durable,
06:38contrairement à une
06:39civilisation alimentée
06:40par l'énergie fossile.
06:41Ainsi,
06:42la réponse semble claire.
06:44Il serait extrêmement difficile,
06:45voire impossible,
06:47de prouver qu'une
06:47ancienne civilisation avancée
06:49est vécue ici avant nous.
06:51Cela ne signifie pourtant
06:52pas qu'elle n'a jamais existé.
06:53En vérité,
06:55nous ne possédons toujours
06:56pas les instruments
06:56nécessaires pour explorer
06:58avec précision
06:59des périodes aussi
06:59reculées de l'histoire
07:00terrestre.
07:01Nous devons donc
07:03garder l'esprit ouvert.
07:04Pour l'heure,
07:05vous imaginez sans doute
07:07cette civilisation
07:07disparue sous des traits
07:09humanoïdes,
07:10deux bras,
07:11deux jambes,
07:11se mouvant comme nous.
07:13Mais certains chercheurs
07:14envisagent
07:14une possibilité
07:15plus inattendue.
07:16Et si nous cherchions
07:17simplement au mauvais
07:18endroit ?
07:19Et si ces êtres
07:20avaient été…
07:21marins ?
07:22Je parle des céphalopodes,
07:24pieuvres,
07:26sèches
07:26et calmars.
07:28Ces animaux possèdent
07:29un système nerveux élaboré
07:31et un comportement
07:32d'une complexité remarquable.
07:33Ils peuvent altérer la couleur
07:35et les motifs de leur peau
07:37en quelques secondes,
07:38émettre des signaux émotionnels
07:40tels que la colère,
07:41et même hypnotiser leurs proies.
07:43Et si c'était eux,
07:44la civilisation ancienne
07:46que nous évoquons depuis le début ?
07:47Commençons par la version
07:49allégée de cette théorie.
07:50Ces espèces auraient de pu apprendre
07:52à cohabiter de manière organisée.
07:54Comme les premiers humains,
07:56elles auraient pu transformer
07:57leur environnement,
07:58peut-être en cultivant
07:59certaines ressources sous-marines
08:01et en chassant d'autres espèces
08:03jusqu'à l'extinction.
08:04Ce serait, en un sens,
08:06une forme primitive
08:07d'organisation sociale.
08:09Même si tel avait été le cas,
08:11ils n'ont jamais atteint
08:12ce que nous qualifierions
08:14de véritablement avancés.
08:16Après tout,
08:17nul ne voit de calamars
08:18bâtir des vaisseaux spatiaux,
08:20ni de pieuvres œuvrés
08:22dans le domaine de l'informatique.
08:23Ils n'ont connu
08:24ni révolution industrielle,
08:26ni essor spatial.
08:28Et puisqu'ils ne forment pas
08:29une société dite
08:30technologique,
08:32ils ne sauraient constituer
08:33la réponse à l'hypothèse
08:34silurienne.
08:36En somme,
08:36nous restons sans preuves tangibles.
08:38D'ailleurs,
08:39dans la communauté scientifique,
08:41cette idée a hérité
08:43d'un surnom ironique,
08:44l'hypothèse la plus fascinante
08:46et probablement la plus fausse.
08:48Cependant,
08:49même si la probabilité
08:50demeure infime,
08:51cette théorie soulève
08:52une question essentielle.
08:53Que laisserons-nous,
08:54nous autres humains,
08:55derrière nous
08:56dans plusieurs millions d'années ?
08:57Les réponses
08:58à cette interrogation
08:59pourraient bien nous aider
09:00à comprendre comment détecter,
09:02au-delà de notre planète,
09:04d'éventuelles espèces avancées
09:05disparues depuis fort longtemps.
09:07pour le jour
09:07de la vie,
09:07de la vie.
09:07La vie.
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