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A man lies down under a
tree in ancient China, sometime
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around the year 300 before
the common era, and falls asleep.
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His name is Zhuangzu.
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His friends call him Zhou.
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He is a thinker, a poet, a man who has
turned down a government job because he'd
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rather sit by a river and talk with his
students about the nature of things.
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It's a warm afternoon.
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The grass is soft, the air is still,
and he drifts off.
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In his sleep, he becomes a butterfly.
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He flutters from flower to flower,
wherever he likes, happy with himself,
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doing exactly as he pleases.
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The wings are real to him.
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The wind under them is real to him.
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There's no thought in
his head about being
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anyone else, because
there isn't anyone else.
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There's only this small, bright creature
in the afternoon light.
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Then he wakes up, and there
he is, solid and unmistakable,
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lying under the tree in his
own heavy body, Zhou again.
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Arms, legs, a stiff back from the ground.
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He sits up.
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And here's the problem.
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He can't tell which one is true.
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Was he Zhou who dreamed
he was a butterfly, or is he
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a butterfly who is right now
dreaming that he is Zhou?
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He looks at his hands, and they feel like
hands.
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He remembers his whole life, and it feels
like a lie.
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But the butterfly felt
like a butterfly, and
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the butterfly's afternoon
felt just as complete.
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Nothing inside the experience gives him a
way to check.
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Every proof he could
offer would be offered from
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inside, whichever dream
he happens to be in.
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The story ends with a short line.
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Zhuangzhu says there must be some
difference between Zhou and the butterfly,
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and then he names what connects them.
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He calls it the transformation of things.
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That's the whole story.
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A few sentences written
down more than 2,000 years
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ago, and people are still
arguing about what it means.
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Now, you know the
feeling at the centre of it,
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even if you've never
read a word of Zhuangzi.
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It's the feeling of waking up in the
middle of the night, or from a long
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afternoon nap, and for a few seconds,
not knowing anything.
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Not where you are, not what day it is,
not even who you are.
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There's just awareness floating,
without a name attached to it,
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and then the self comes back.
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It comes back the way you find your page
in a book you've put down.
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You flip through, a little lost,
and then your eyes land on the right
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paragraph, and everything slots into
place.
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Oh, that's me, that's my room,
that's my life, and it's Tuesday.
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The strange part is
how quickly you stop
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noticing that the self
had to be found at all.
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Zhuangzi noticed.
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He noticed that gap, that moment between
the dream and the return, and he asked a
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question that sounds simple and isn't.
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How do you know which side of the gap
you're standing on?
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We are going to follow that question
through history.
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Start with a butterfly, under a tree,
and end with computer simulation theory.
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The modern argument that the world you're
living in might be a built appearance,
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a constructed experience, running on some
machine.
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Between those two
points, there's a long line of
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people who ask the same
thing in different words.
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We'll meet them one at a time,
in order, and we'll take it slowly.
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But before we go back to the beginning,
there's one more story worth telling,
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because it shows something about how ideas
travel.
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It's not about simulation at all.
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It's about a trip to the moon.
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In 1865, a French
writer named Jules Verne
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published a novel called
From the Earth to the Moon.
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It was an adventure story
written for entertainment,
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and it described the launch
of a manned spacecraft.
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Three men climb inside a hollow metal
capsule.
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The capsule is fired from an enormous
cannon called the Colombiad.
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The cannon is built in Florida.
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The three men travel to the moon,
and on the way home, their capsule falls
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into the Pacific Ocean, where a ship picks
them up.
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Now jump forward a hundred and four years
to July of 1969.
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Apollo 11.
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Three men climb into a capsule.
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The rocket launches from Florida.
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The command module that
carries them is named Columbia,
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which is almost exactly
the name of Verne's cannon.
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At the end of the mission,
the capsule drops into
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the Pacific Ocean, and a
ship picks the three men up.
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Three men.
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Florida.
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A vehicle named Columbia.
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A splashdown in the Pacific.
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Verne wrote all of that before anyone had
flown even an airplane.
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It wasn't prophecy.
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It was inheritance.
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A Russian schoolteacher named Konstantin
Tsykovsky read Verne as a young man,
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and it set him thinking about how a rocket
might really work.
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He went on to write the first serious
mathematics of spaceflight.
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A German named Hermann Oberth read Verne
too, and developed rocket theory of his own.
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And a teenager named Wernher von Braun
read Oberth, and became the engineer who
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built the rockets that eventually carried
astronauts to the moon.
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A story planted a picture in one mind.
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That mind planted it in another.
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Eventually the picture turned into
machinery.
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That's how ideas tend to arrive.
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They show up first as stories, long
before anyone has the tools to build them.
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And the idea of a simulated world has been
travelling through stories for a very long
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time, much longer than the machines that
make it sound plausible today.
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Which brings us back to the butterfly,
because the suspicion hiding inside that
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dream, the suspicion that the
world you wake up into might be
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just another kind of dream, is
much older than any machine.
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Let's go back to Athens, around the year
375 B.C.
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A philosopher named
Plato is writing the book that
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will become his most
famous work, The Republic.
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In Book 7 he stops the argument about justice
and politics and tells a story instead.
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He doesn't tell it himself.
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He gives it to his teacher, Socrates,
who tells it to Plato's older brother,
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a young man named Glaucon.
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Socrates says, Imagine
an underground cave with
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a long opening that
leads up to the daylight.
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In this cave people have lived since
childhood.
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They're chained by the legs and the neck,
so they can't turn their heads.
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All they can do is stare straight ahead at
the cave's back wall.
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Behind them, a long way back, a fire is
burning.
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Between the fire and the prisoners,
there's a raised walkway with a low wall
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along its edge, the way a
puppeteer has a screen in
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front of him, so the
audience can't see his hands.
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Behind that low wall,
people walk back and forth,
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carrying things on their
heads and shoulders.
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Statues, carved animals, tools,
vessels made of stone and wood.
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Some of the carriers talk as they go,
and some stay silent.
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Now think about what the prisoners can
see.
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The fire throws the shadows of those carried
objects onto the wall in front of them.
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That's all they've ever seen.
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They've never seen the fire, the walkway,
the people or each other.
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Only moving shadows.
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And because the cave has an echo when one
of the carriers speaks, the voice bounces
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off the wall, and the prisoners believe
the shadows are speaking.
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So they do what anyone would do.
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They give the shadows names.
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They get good at predicting which shadow
comes next.
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The prisoner who is best at that is
praised and honored, because in that
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world, shadow watching is the only skill
there is.
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To them, those shadows are not a picture
of reality.
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They are reality.
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Then Socrates changes the story.
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Suppose one prisoner is set free.
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Someone unlocks his chains and makes him
stand up and turn around.
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It hurts.
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His neck is stiff, his eyes sting from the
firelight, and when he looks at the
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objects that have been casting the
shadows, he can't make them out.
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If someone told him that everything he'd
seen before was empty, and that he was now
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closer to what's real, he wouldn't believe
it.
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He'd want to turn back to the shadows,
because those at least make sense to him.
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But he's dragged further, up a rough, steep
path out of the cave and into the open air.
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The sun is so bright he's blinded,
he can't see anything at all.
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So he waits, and slowly his eyes adjust.
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First he can only look at shadows on the
ground, then at reflections in water,
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then at the trees and the stones
themselves.
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Then, at night, at the moon and the stars.
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And finally, at last, he can look at the
sun.
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He understands now that the sun is the
source of the seasons, the light,
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the whole visible world.
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The cave was never the world, it was a
small, dark corner of it.
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He feels sorry for his old companions.
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He wants to go back and tell them.
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So he descends into the cave again.
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But there's a problem.
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After the sunlight, his eyes can't see in
the dark.
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When he sits down in his old seat and
tries to compete at naming shadows,
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he does badly.
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The prisoners watch him
stumble, and they conclude
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that going up was a
mistake, it ruined his eyes.
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And Socrates says that if anyone tried to
unchain them and lead them up,
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they'd kill that person if they could get
their hands on him.
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Plato was writing about
education, and about what
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happens to a philosopher
who tries to wake people up.
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Everyone in Athens knew that Socrates
himself had been put to death by the city,
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and Plato had been there to see it.
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But the story carries another idea,
and it's the one that matters for us.
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The images on the wall
are made by someone
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from behind, and the
prisoners can't see who.
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The world they take for granted is a
projection.
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You've sat in that cave.
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It's any dark room with a screen in it.
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A cinema, a bedroom with a laptop, a phone
held an inch from your face at midnight.
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00:15:14,990
All you're looking at is light thrown onto
a flat surface, and for a while you forget
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the room, you forget the projector,
and the shadows are the whole world.
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Plato's question is what you'd do if
someone told you to turn around.
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Now let's move east, to India,
and to a word that has been
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doing the same job as Plato's
cave for a very long time.
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The word is Maya.
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In the oldest Indian texts, the Vedas,
Maya doesn't mean illusion.
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It means power.
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It's the power of a god to make forms
appear, something close to magic,
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the skill of a craftsman who can conjure a
shape out of nothing.
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When a god in the Vedas
creates a horse, a storm,
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or a mountain, that
creative trick is Maya.
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It's not a lie.
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It's a making.
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Over the following centuries, the thinkers
who wrote the Upanishads began to ask,
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what lay behind all those made things?
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And in the eighth century of
the Common Era, a young teacher
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named Shankara gave the
question its most famous answer.
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He was born in the south of India,
travelled the whole country on foot,
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argued with rival schools in public
debates, and wrote commentaries that fixed
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the shape of a school called Advaita
Vedanta.
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The name is plain Sanskrit.
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Advaita means not two.
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Here is what Shankara taught.
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There is one reality, and its name is
Brahman.
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00:17:15,290
Brahman is pure existence, pure awareness,
with no parts and no edges.
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Nothing exists next to Brahman,
because there's no room for a second thing.
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And that means the world you see,
with its mountains, its crowds,
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its separate people, can't be a second
reality sitting beside Brahman.
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It's an appearance resting on Brahman.
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The power that makes the appearance is
Maya.
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To explain how this
works, Shankara used an
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example that every
Indian child still hears.
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Picture a path at dusk.
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00:17:58,910
The light is dim, and on the ground lies a
coil of rope.
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You glance at it, and your heart jumps.
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A snake.
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You freeze, your breath stops,
your body floods with fear.
220
00:18:10,479 -->
00:18:14,330
Then someone brings a lamp, and you see
it's just a rope.
221
00:18:15,344 -->
00:18:17,150
The snake was never there.
222
00:18:19,189 -->
00:18:21,150
Now look carefully at what happened.
223
00:18:21,865 -->
00:18:24,030
The fear was completely real.
224
00:18:25,329 -->
00:18:27,870
Your pounding heart was not an illusion.
225
00:18:28,620 -->
00:18:33,310
The snake, though, had no existence at
all, and yet it was seen.
226
00:18:34,360 -->
00:18:36,950
What did the work was a mistake of the
mind.
227
00:18:37,875 -->
00:18:41,330
It took the rope and laid a snake over it.
228
00:18:42,404 -->
00:18:46,030
Shankara called this adhyasa,
superimposition.
229
00:18:48,859 -->
00:18:52,030
And his claim is that the whole world is
like that.
230
00:18:52,715 -->
00:18:54,450
Brahman is the rope.
231
00:18:55,729 -->
00:19:00,650
The world of separate things is the snake
our mind lays over it.
232
00:19:01,394 -->
00:19:04,610
The experiences are real as experiences.
233
00:19:06,294 -->
00:19:09,510
The thing we think we're experiencing is a
projection.
234
00:19:12,009 -->
00:19:15,476
Shankara didn't say the
world is simply nothing,
235
00:19:15,477 -->
00:19:18,730
because that would
make everyday life absurd.
236
00:19:20,309 -->
00:19:22,110
He set out three levels.
237
00:19:23,479 -->
00:19:28,350
At the top is the absolute level,
where only Brahman exists.
238
00:19:30,079 -->
00:19:36,490
In the middle is the everyday level,
where tables, rivers, and people function
239
00:19:36,514 -->
00:19:40,401
perfectly well, and where
you must pay your bills
240
00:19:40,402 -->
00:19:43,490
and look both ways
before crossing the road.
241
00:19:46,970 -->
00:19:50,271
And at the bottom is
the illusory level, the
242
00:19:50,272 -->
00:19:53,650
snake in the rope, the
dream you have tonight.
243
00:19:54,399 -->
00:19:58,910
Each level cancels the one below it when
you wake up to the one above.
244
00:20:00,209 -->
00:20:02,630
The snake dissolves when the lamp comes
on.
245
00:20:04,029 -->
00:20:11,030
The everyday world, Shankara said,
dissolves in the same way when knowledge
246
00:20:11,154 -->
00:20:13,170
of Brahman dawns.
247
00:20:15,470 -->
00:20:21,430
There's one more idea in the Indian tradition,
and it changes the mood of everything.
248
00:20:22,549 -->
00:20:26,010
It's called lila, which means play.
249
00:20:27,419 -->
00:20:31,430
Some teachers asked why Brahman,
who is complete and lacks nothing,
250
00:20:31,934 -->
00:20:33,750
would produce a world at all.
251
00:20:34,334 -->
00:20:36,630
Their answer was that it needs no reason.
252
00:20:37,710 -->
00:20:38,730
It's play.
253
00:20:40,490 -->
00:20:46,230
A king who has everything still might
dance, simply because dancing is joyful.
254
00:20:47,949 -->
00:20:52,370
The world in this picture isn't a trap or
a punishment.
255
00:20:53,659 -->
00:20:59,370
It's the absolute enjoying itself,
hiding from itself on purpose,
256
00:21:00,450 -->
00:21:04,517
the way you do in a game
of hide and seek, where the
257
00:21:04,518 -->
00:21:08,370
point is the delight of
not knowing where you are.
258
00:21:10,464 -->
00:21:12,450
You've watched lila happen.
259
00:21:14,150 -->
00:21:17,028
Think of a small child
on the living room floor,
260
00:21:17,123 -->
00:21:20,730
building a castle out of
cushions, fully inside the game.
261
00:21:22,249 -->
00:21:26,779
The cushions are a
fortress, the dog is a dragon,
262
00:21:26,780 -->
00:21:30,690
and the child's face is
lit with total seriousness.
263
00:21:32,124 -->
00:21:34,710
If you call her name, she doesn't hear.
264
00:21:35,809 -->
00:21:37,770
She isn't confused about what's real.
265
00:21:38,469 -->
00:21:42,870
She's chosen to forget, and the forgetting
is the fun.
266
00:21:45,209 -->
00:21:47,090
Which raises the obvious question?
267
00:21:48,444 -->
00:21:52,570
What would it feel like to be inside such
a game and truly forget?
268
00:21:54,059 -->
00:21:56,170
An old story answers it.
269
00:21:57,804 -->
00:22:01,230
The story is about a sage named Narada.
270
00:22:02,689 -->
00:22:09,430
He's one of the great wandering holy men
of Indian tradition, a master of devotion
271
00:22:09,979 -->
00:22:12,792
who travels between
the worlds, carrying a
272
00:22:12,793 -->
00:22:16,090
stringed instrument and
singing the name of Vishnu.
273
00:22:17,139 -->
00:22:21,110
By every measure, Narada has woken up.
274
00:22:22,989 -->
00:22:26,210
And yet, one day he comes to Vishnu with a
complaint.
275
00:22:27,735 -->
00:22:30,390
Everyone talks about Maya, he says.
276
00:22:31,090 -->
00:22:36,790
The other sages tell stories about how
powerful it is, how hard it was to cross.
277
00:22:37,850 -->
00:22:43,070
Narada has never felt it, so he asks
politely and a little proudly,
278
00:22:43,919 -->
00:22:46,850
Lord, will you show me your Maya?
279
00:22:48,754 -->
00:22:49,950
Vishnu smiles.
280
00:22:51,349 -->
00:22:55,210
He says it can't really be explained,
only experienced.
281
00:22:57,409 -->
00:23:00,310
And then he does something that sounds
almost silly.
282
00:23:01,550 -->
00:23:07,630
They're walking across a hot desert together,
and Vishnu stops and says he's thirsty.
283
00:23:09,574 -->
00:23:14,350
Would Narada go to that village over there
and fetch him a cup of water?
284
00:23:15,694 -->
00:23:16,790
Narada goes.
285
00:23:17,669 -->
00:23:22,450
He reaches the village, walks up to the
first house and knocks.
286
00:23:23,479 -->
00:23:28,345
The door opens and a young
woman stands there, and something
287
00:23:28,346 -->
00:23:32,390
happens to him that he
hasn't felt in his whole long life.
288
00:23:33,289 -->
00:23:34,610
He forgets the errand.
289
00:23:35,364 -->
00:23:36,510
He forgets Vishnu.
290
00:23:37,190 -->
00:23:38,190
He stays.
291
00:23:39,859 -->
00:23:41,150
He marries her.
292
00:23:42,149 -->
00:23:44,950
Her father gives him land and a house.
293
00:23:45,864 -->
00:23:49,130
The years go by in the plain, steady way
years do.
294
00:23:49,604 -->
00:23:52,330
Children are born, one after another.
295
00:23:54,050 -->
00:23:59,850
Narada ploughs his fields and mends his
roof and argues with neighbours over fences.
296
00:24:00,949 -->
00:24:02,510
He worries about the harvest.
297
00:24:03,340 -->
00:24:05,410
He lies awake over a sick child.
298
00:24:06,469 -->
00:24:13,170
He grows older, and the family grows
around him, and everything he was before
299
00:24:13,419 -->
00:24:17,670
drops out of his mind, like a coat left on
a hook.
300
00:24:19,769 -->
00:24:23,690
Then one season, the rains come and don't
stop.
301
00:24:24,974 -->
00:24:27,670
The river swells and rises over its banks.
302
00:24:29,094 -->
00:24:33,290
Water pours through the village,
and the house starts to give way.
303
00:24:34,570 -->
00:24:39,450
Narada grabs his wife and children,
but the current is stronger than he is.
304
00:24:40,289 -->
00:24:47,890
One by one, they're torn out of his arms,
his wife, his children, the house itself.
305
00:24:48,949 -->
00:24:55,650
At the end, he's thrown alone onto a muddy
bank, soaked and empty-handed,
306
00:24:56,190 -->
00:24:58,770
crying out the names of people who are
gone.
307
00:25:01,099 -->
00:25:06,290
And right then, through the roar of the
water, he hears a calm voice at his shoulder.
308
00:25:07,850 -->
00:25:10,550
Narada, where is my water?
309
00:25:11,134 -->
00:25:13,150
I've been waiting for you.
310
00:25:14,450 -->
00:25:15,450
He looks up.
311
00:25:16,129 -->
00:25:17,310
There is no flood.
312
00:25:17,894 -->
00:25:21,210
There's no village, no river, no mud.
313
00:25:22,029 -->
00:25:27,950
He's standing in the desert, in the same
dry sun, and Vishnu is beside him,
314
00:25:28,130 -->
00:25:29,130
smiling.
315
00:25:29,519 -->
00:25:31,430
Barely a moment has passed.
316
00:25:32,195 -->
00:25:37,250
The whole life, the marriage, the
children, the grief, all of it fit into
317
00:25:37,251 -->
00:25:39,890
the time it takes to walk to a door and
back.
318
00:25:40,814 -->
00:25:44,310
And Vishnu says gently, this is Maya.
319
00:25:46,509 -->
00:25:50,310
You've done this yourself, in smaller
form.
320
00:25:51,244 -->
00:25:56,310
Everyone has had the dream that felt like
years, where you lived through a whole
321
00:25:57,549 -->
00:26:05,250
job, a whole romance, a whole disaster,
and then your alarm went off, and you
322
00:26:05,499 -->
00:26:09,590
checked the clock, and found you'd been
asleep for 11 minutes.
323
00:26:11,549 -->
00:26:17,570
For a few seconds afterward, the grief or
the joy still sits in your chest.
324
00:26:18,759 -->
00:26:21,979
And the strange
part is how real it still
325
00:26:21,980 -->
00:26:25,770
feels, even though you
know where it came from.
326
00:26:28,089 -->
00:26:32,750
Let's jump forward to the second and third
centuries of the common era.
327
00:26:35,709 -->
00:26:39,930
To a scattered movement of teachers and
writers around the Roman Mediterranean,
328
00:26:41,204 -->
00:26:45,290
in Alexandria, in Syria, in Rome.
329
00:26:46,790 -->
00:26:53,050
They're known as the Gnostics, from the
Greek word, gnosis, which means knowledge.
330
00:26:54,210 -->
00:26:59,730
Not knowledge as in facts, but knowledge
as in recognition, the way you know a face.
331
00:27:01,259 -->
00:27:04,878
And they told a story
about where the world came
332
00:27:04,928 -->
00:27:08,670
from, that turns the
usual story upside down.
333
00:27:10,789 -->
00:27:15,510
The version we know best is in a text
called The Secret Book of John.
334
00:27:16,450 -->
00:27:21,750
It begins with a god so far beyond
everything that no word fits him.
335
00:27:22,649 -->
00:27:28,990
He is the one, without limit, without
name, impossible to describe.
336
00:27:30,069 -->
00:27:34,819
From him come beings of
pure light, called eons, and
337
00:27:34,820 -->
00:27:38,870
together they fill a perfect
realm named the fullness.
338
00:27:40,235 -->
00:27:44,022
The last of these beings
to appear is a female
339
00:27:44,023 -->
00:27:46,870
figure named Sophia,
which means wisdom.
340
00:27:49,689 -->
00:27:51,310
And Sophia makes a mistake.
341
00:27:52,619 -->
00:27:58,375
She wants to bring forth a
being of her own, so she does it
342
00:27:58,376 -->
00:28:02,090
alone, without her partner and
without the father's approval.
343
00:28:03,209 -->
00:28:07,550
What she produces is nothing like the
radiant beings around her.
344
00:28:08,314 -->
00:28:11,090
It's misshapen, with burning eyes.
345
00:28:14,004 -->
00:28:18,490
The text describes it as a snake with a
lion's head.
346
00:28:19,344 -->
00:28:20,610
Sophia is ashamed.
347
00:28:21,509 -->
00:28:26,470
She throws her child out of the fullness
and hides him inside a bright cloud,
348
00:28:27,154 -->
00:28:28,910
and she names him Yaldabaoth.
349
00:28:31,930 -->
00:28:36,450
Yaldabaoth grows up alone, with no idea
where he came from.
350
00:28:37,169 -->
00:28:41,610
He has some of his mother's power in him,
and he uses it.
351
00:28:42,609 -->
00:28:49,990
He creates twelve rulers, called archons,
and they in turn create more, until there
352
00:28:50,239 -->
00:28:55,210
are three hundred and sixty five of them,
one for each day of the year.
353
00:28:58,019 -->
00:29:02,930
Together they build the physical world,
using the pattern of the fullness they
354
00:29:03,129 -->
00:29:05,070
half remember inside Yaldabaoth.
355
00:29:06,054 -->
00:29:09,790
But because the builder is ignorant,
the copy comes out wrong.
356
00:29:12,230 -->
00:29:19,930
And Yaldabaoth, standing over his
creation, announces, I am God,
357
00:29:20,134 -->
00:29:22,470
and there is no other God beside me.
358
00:29:24,279 -->
00:29:28,328
That sentence is a
deliberate echo of the Hebrew
359
00:29:28,329 -->
00:29:32,130
Bible, where God speaks
nearly the same words.
360
00:29:34,870 -->
00:29:40,130
The Gnostics were saying that the creator
in Genesis is Yaldabaoth, a proud,
361
00:29:40,250 -->
00:29:42,950
blind, lesser power who thinks he's alone.
362
00:29:43,939 -->
00:29:48,890
Behind him, unseen, stands a greater God
he has never met.
363
00:29:50,479 -->
00:29:52,350
Now here's the part that matters most.
364
00:29:54,529 -->
00:30:00,230
When Yaldabaoth breathes life into the
first human, some of his mother,
365
00:30:00,489 -->
00:30:04,090
Sophia's power, flows out of him and into
the body.
366
00:30:05,204 -->
00:30:07,750
So humans are not only matter.
367
00:30:09,450 -->
00:30:16,770
Inside each of us, according to the
Gnostics, is a divine spark, a fragment of
368
00:30:16,819 -->
00:30:22,990
the true light, trapped in a world built by
someone who doesn't know what he's holding.
369
00:30:25,989 -->
00:30:27,890
The Archons see the problem.
370
00:30:29,069 -->
00:30:33,003
They set the first humans
in a garden, stocked with
371
00:30:33,004 -->
00:30:36,570
pleasures, to keep them
attached to the material world.
372
00:30:38,490 -->
00:30:43,688
And when Adam and Eve and
their son Seth begin to wake up,
373
00:30:43,689 -->
00:30:47,490
Yaldabaoth makes them
drink the water of forgetfulness.
374
00:30:49,749 -->
00:30:53,690
But the text says he can't fully erase
what he's done.
375
00:30:54,609 -->
00:31:01,610
The capacity to remember stays dormant
inside them, and inside their descendants,
376
00:31:02,404 -->
00:31:04,950
and what wakes it is Gnosis.
377
00:31:06,989 -->
00:31:12,430
The sudden recognition that you are not
what you thought, that the world you're in
378
00:31:12,431 -->
00:31:16,720
is a made thing, and that you come from
somewhere else.
379
00:31:18,859 -->
00:31:22,210
For centuries, almost all of this was
lost.
380
00:31:23,114 -->
00:31:27,770
The Gnostics were condemned by church
leaders, and their books were destroyed.
381
00:31:29,339 -->
00:31:34,790
What survived were the angry descriptions
written by their enemies.
382
00:31:37,390 -->
00:31:45,390
Then, in December of 1945, a farmer
digging for fertilizer near the town of
383
00:31:45,489 -->
00:31:49,870
Nag Hammadi in Upper Egypt struck a sealed
clay jar.
384
00:31:52,250 -->
00:31:59,850
Inside were 13 ancient books, bound in
leather, containing more than 50 texts,
385
00:32:00,454 -->
00:32:03,210
among them the Secret Book of John.
386
00:32:04,269 -->
00:32:10,490
For the first time in 1600 years,
the Gnostics could speak for themselves.
387
00:32:11,999 -->
00:32:14,430
And look at what we've put on the table.
388
00:32:16,539 -->
00:32:23,090
A prisoner in a cave who has to be turned
toward the light, a player in a divine
389
00:32:23,091 -->
00:32:29,690
game who has chosen to forget,
and between them, Plato's freed man,
390
00:32:30,474 -->
00:32:34,570
who climbs out and sees that the shadows
were made by someone.
391
00:32:37,239 -->
00:32:40,050
All three ideas were already in the room.
392
00:32:41,969 -->
00:32:48,070
The Gnostics simply asked the darkest
version of the question, what if the one
393
00:32:48,070 -->
00:32:51,230
who made the world doesn't want you to
wake up?
394
00:32:54,009 -->
00:32:59,250
Let's move forward, a long
way forward, to the winter
395
00:32:59,251 -->
00:33:04,230
of 1619 and a small room
in the German town of Ulm.
396
00:33:04,839 -->
00:33:10,150
A young Frenchman named René Descartes is
23 years old.
397
00:33:11,364 -->
00:33:15,909
He's a gentleman volunteer in
the army of the Duke of Bavaria,
398
00:33:15,910 -->
00:33:19,350
and the war he's meant to
join has paused for the cold.
399
00:33:20,650 -->
00:33:22,310
Snow has stopped the roads.
400
00:33:24,429 -->
00:33:29,196
So he rents a room with
a big tiled stove, and for a
401
00:33:29,197 -->
00:33:33,270
whole day, he does nothing
but sit beside it and think.
402
00:33:34,629 -->
00:33:40,310
He's been studying mathematics and
philosophy for years, and he's become
403
00:33:40,310 -->
00:33:45,690
convinced that most of what people call
knowledge rests on nothing solid.
404
00:33:46,969 -->
00:33:48,830
He wants to find a foundation.
405
00:33:49,689 -->
00:33:51,410
He just doesn't know how.
406
00:33:54,239 -->
00:33:58,360
That night, the night of
the 10th of November,
407
00:33:58,361 -->
00:34:02,100
he goes to bed and he
has three dreams in a row.
408
00:34:04,249 -->
00:34:08,380
In the first, a whirlwind seizes him and
spins him around.
409
00:34:09,440 -->
00:34:13,288
He tries to walk, but
his right side is weak,
410
00:34:13,289 -->
00:34:16,540
and he has to lean
over to stay upright.
411
00:34:18,970 -->
00:34:23,505
In the second, a clap of thunder
wakes him inside the dream,
412
00:34:23,506 -->
00:34:27,239
and he sees sparks of fire
scattered all over the room.
413
00:34:29,100 -->
00:34:35,360
In the third, he finds two books on a table,
a dictionary, and a collection of poems.
414
00:34:36,460 -->
00:34:41,360
He opens the poems, and his eyes land on a
line by the Roman poet Ossonius.
415
00:34:43,480 -->
00:34:45,780
What path in life shall I follow?
416
00:34:49,440 -->
00:34:52,600
Here's the detail that makes this story
belong here.
417
00:34:54,764 -->
00:34:59,020
Descartes didn't wait until morning to
make sense of what he was seeing.
418
00:35:02,150 -->
00:35:07,830
According to his early biographer,
a French priest named Adrien Baillet,
419
00:35:08,170 -->
00:35:13,210
who had access to Descartes' private
papers, he began interpreting the dream
420
00:35:13,310 -->
00:35:15,250
while he was still dreaming it.
421
00:35:18,010 -->
00:35:21,974
Part of his mind stood
off to one side and said,
422
00:35:21,975 -->
00:35:25,390
this is a dream, and
here is what it means.
423
00:35:27,205 -->
00:35:34,010
That's the exact feeling Zhuangzi
described 2,000 years earlier being inside
424
00:35:34,011 -->
00:35:40,650
an experience and at the same moment
wondering about it from just outside.
425
00:35:43,654 -->
00:35:47,690
When Descartes woke, he took the night as
a call-in.
426
00:35:48,730 -->
00:35:53,890
He decided his life's work would be to
rebuild human knowledge from the ground
427
00:35:55,215 -->
00:35:58,450
up, using the clarity of mathematics as
his guide.
428
00:36:00,590 -->
00:36:08,490
And that decision, made beside a stove in
a rented room, set off the work that led
429
00:36:08,491 -->
00:36:15,030
to Cartesian coordinates, the grid of X
and Y lines you used in school,
430
00:36:15,735 -->
00:36:19,303
to plot points on a graph,
which let geometry and
431
00:36:19,304 -->
00:36:22,690
algebra speak to each
other for the first time.
432
00:36:23,720 -->
00:36:28,550
It also led to the book that opens modern
Western philosophy.
433
00:36:31,110 -->
00:36:34,750
He spent most of his adult life dodging
attention.
434
00:36:37,750 -->
00:36:45,750
After he moved to the Netherlands in 1628,
he changed his address again and again 18
435
00:36:45,751 -->
00:36:52,150
times in about 20 years and he told people
to keep his whereabouts secret.
436
00:36:55,640 -->
00:37:01,690
His motto was a line he borrowed from the
Roman poet Ovid, who lives well hidden,
437
00:37:03,070 -->
00:37:04,070
lives well.
438
00:37:05,420 -->
00:37:10,310
He wanted quiet, because the ideas he was
working on were dangerous.
439
00:37:11,330 -->
00:37:14,490
Church authorities across
Europe were nervous
440
00:37:14,565 -->
00:37:17,390
about anyone who
questioned the old teachings.
441
00:37:19,820 -->
00:37:23,690
In the end, quiet was the one thing he
gave up.
442
00:37:25,230 -->
00:37:32,250
In 1649, Queen Christina of Sweden,
a brilliant young ruler who collected
443
00:37:32,251 -->
00:37:35,769
scholars the way other
monarchs collected
444
00:37:35,770 -->
00:37:38,780
jewels, invited him to
her court in Stockholm.
445
00:37:39,570 -->
00:37:42,250
He hesitated, then accepted.
446
00:37:45,010 -->
00:37:50,290
And the Queen, it turned out, liked to
hold her lessons at five in the morning in
447
00:37:50,390 -->
00:37:54,130
a freezing palace, in the dead of a Nordic
winter.
448
00:37:56,190 -->
00:37:59,658
A man who had spent
his life sleeping late beside
449
00:37:59,659 -->
00:38:03,510
warm stoves was now
dragged out of bed in the dark.
450
00:38:06,050 -->
00:38:09,890
By February of 1650, he had caught
pneumonia.
451
00:38:11,000 -->
00:38:13,830
He died in Stockholm at the age of 53.
452
00:38:16,990 -->
00:38:21,780
But go back to that stove, because the
scene is one you can recognize.
453
00:38:23,370 -->
00:38:28,202
Think of a quiet evening
by a fireplace, or by a heater,
454
00:38:28,203 -->
00:38:31,610
or just in a chair with a
blanket across your knees.
455
00:38:32,710 -->
00:38:37,610
The room is warm, the light is low,
and your mind starts drift.
456
00:38:39,430 -->
00:38:42,690
And then, out of nowhere, a small strange
thought.
457
00:38:44,240 -->
00:38:45,790
Am I awake right now?
458
00:38:46,590 -->
00:38:48,070
Is this really happening?
459
00:38:49,470 -->
00:38:55,910
You look at your hands, you notice the
fire crackling, and everything seems solid.
460
00:38:56,950 -->
00:38:59,930
Yet the question doesn't fully go away.
461
00:39:00,939 -->
00:39:04,910
That small odd flicker is exactly where
Descartes began.
462
00:39:06,230 -->
00:39:11,510
And what he did with that flicker,
in the years after, that night,
463
00:39:12,034 -->
00:39:16,490
became the most famous attempt in history
to answer it.
464
00:39:19,320 -->
00:39:26,880
22 years after that night in Ulm in 1641,
Descartes finally published the full plan.
465
00:39:28,220 -->
00:39:32,814
The book is called The
Meditations on First Philosophy, and
466
00:39:32,815 -->
00:39:38,220
it's written like a diary of six
days, one meditation per day.
467
00:39:40,380 -->
00:39:44,520
On the first day, he does something that
no one had done so openly.
468
00:39:45,920 -->
00:39:50,360
He sits down and tears out everything he
can't be sure of.
469
00:39:52,000 -->
00:39:53,500
His method is simple.
470
00:39:55,120 -->
00:40:00,880
If a belief can be doubted even slightly,
he sets it aside as if it were false.
471
00:40:02,100 -->
00:40:07,460
Not because it is false, but because he
wants a foundation with no cracks in it.
472
00:40:08,050 -->
00:40:12,180
So he starts at the bottom of the pile,
the senses.
473
00:40:14,135 -->
00:40:18,820
Everything he knows about the world came
to him through sight, hearing,
474
00:40:19,320 -->
00:40:24,420
touch, that the senses have fooled him
before.
475
00:40:25,520 -->
00:40:31,440
A square tower seen from far away looks
round, a stick in water looks bent.
476
00:40:32,535 -->
00:40:39,540
If something has tricked him even once, he
reasons it's unwise to trust it completely.
477
00:40:42,330 -->
00:40:45,340
Then he reaches the argument that made the
book famous.
478
00:40:47,490 -->
00:40:53,840
He says, Right now, I'm sitting here by
the fire, wearing my dressing gown,
479
00:40:54,124 -->
00:40:56,440
with this piece of paper in my hands.
480
00:40:57,634 -->
00:40:59,480
Nothing could seem more certain.
481
00:41:01,480 -->
00:41:04,520
But I've had exactly this experience in
dreams.
482
00:41:06,130 -->
00:41:08,999
I've dreamed I was
sitting by the fire in my
483
00:41:09,000 -->
00:41:12,820
dressing gown, and
it felt exactly like this.
484
00:41:13,230 -->
00:41:15,770
And then I woke up in bed, undressed.
485
00:41:18,140 -->
00:41:23,160
He goes looking for some sure sign that
separates waking from dreaming.
486
00:41:24,600 -->
00:41:29,640
Some stamp that real experience carries
and dream experience lacks.
487
00:41:30,735 -->
00:41:32,260
And he can't find one.
488
00:41:33,584 -->
00:41:37,687
Every feature he can think
of, the vividness, the detail,
489
00:41:37,688 -->
00:41:41,520
the sense of being present
has shown up in dreams too.
490
00:41:42,034 -->
00:41:43,700
Asleep, we're convinced.
491
00:41:45,244 -->
00:41:46,900
Awake, we're convinced.
492
00:41:48,814 -->
00:41:51,560
The feeling of certainty is the same in
both.
493
00:41:54,000 -->
00:41:58,580
So the whole world of things he can see
and touch might be a dream.
494
00:41:59,870 -->
00:42:04,040
But he notices that dreams are built from
simple parts.
495
00:42:05,340 -->
00:42:11,040
The way a painter builds even an imaginary
monster from real shapes and colours,
496
00:42:12,365 -->
00:42:15,400
something must stay solid underneath.
497
00:42:16,064 -->
00:42:19,480
And he finds it in arithmetic and
geometry.
498
00:42:20,640 -->
00:42:27,520
Whether he's awake or asleep, two plus
three still makes five, and a square still
499
00:42:27,820 -->
00:42:28,900
has four sides.
500
00:42:30,579 -->
00:42:33,940
Mathematics doesn't depend on whether the
world is there.
501
00:42:35,990 -->
00:42:37,940
Then he takes the final step.
502
00:42:39,570 -->
00:42:42,620
He asks, what if even that is a trap?
503
00:42:43,930 -->
00:42:49,880
He imagines a being which he calls a
malicious demon who is supremely powerful
504
00:42:49,881 -->
00:42:55,340
and supremely cunning and who has put all
his effort into deceiving Descartes,
505
00:42:56,464 -->
00:42:59,240
not just in dreams, in everything.
506
00:43:01,260 -->
00:43:08,860
The sky, the earth, colours, shapes,
sounds, his own hands, his own body,
507
00:43:09,960 -->
00:43:14,280
all of it could be an illusion this demon
has laid out as bait.
508
00:43:15,674 -->
00:43:18,188
The demon could even
arrange for Descartes
509
00:43:18,189 -->
00:43:21,180
to go wrong every time
he adds two and three.
510
00:43:23,140 -->
00:43:26,200
Notice what that imagined demon actually
does.
511
00:43:27,000 -->
00:43:34,260
He sits outside, unseen, and feeds a single
mind a complete and consistent false world.
512
00:43:35,049 -->
00:43:38,880
Every sight, every sound arrives on
schedule.
513
00:43:40,629 -->
00:43:43,760
The person inside has no way to catch the
trick.
514
00:43:44,820 -->
00:43:52,520
If you strip away the word demon and put
in the word machine, you have the modern
515
00:43:52,521 -->
00:43:57,160
simulation story written down almost 400
years ago.
516
00:43:59,480 -->
00:44:02,748
Descartes holds the
thought steady and what
517
00:44:02,749 -->
00:44:06,100
happens next is the turn
that made him immortal.
518
00:44:08,934 -->
00:44:13,320
In the second meditation, he asks whether
anything survives the demon.
519
00:44:15,789 -->
00:44:17,080
And something does.
520
00:44:18,325 -->
00:44:21,300
Suppose the demon is deceiving him about
everything.
521
00:44:22,490 -->
00:44:24,330
Then there must be someone being deceived.
522
00:44:27,020 -->
00:44:31,660
If Descartes doubts, he must exist to do
the doubting.
523
00:44:32,714 -->
00:44:36,120
If the demon tricks him, he must exist to
be tricked.
524
00:44:37,300 -->
00:44:42,510
No matter how hard the demon works,
he can never make Descartes into nothing
525
00:44:43,400 -->
00:44:45,760
while Descartes is thinking he is
something.
526
00:44:47,200 -->
00:44:51,834
So the sentence, I
am, I exist, is true every
527
00:44:51,835 -->
00:44:55,680
single time he says it
or holds it in his mind.
528
00:44:57,620 -->
00:45:04,160
The more famous version, I think,
therefore I am, had appeared four years
529
00:45:04,161 -->
00:45:07,760
earlier in the Discourse on Method of
1637.
530
00:45:09,540 -->
00:45:11,540
In French, it reads,
531
00:45:16,000 -->
00:45:20,266
It's the one fixed point, the
place where the doubting
532
00:45:20,267 -->
00:45:23,700
stops, and from there
he starts to climb back up.
533
00:45:26,120 -->
00:45:32,100
His rebuilding is quick, and many readers
have found it the weakest part of the book.
534
00:45:34,250 -->
00:45:40,460
He argues that he has an idea of a perfect
being in his mind, and that an imperfect
535
00:45:40,461 -->
00:45:44,120
creature could not have invented such an
idea by himself.
536
00:45:45,730 -->
00:45:53,680
So a perfect God must exist, and a perfect
God would not be a deceiver.
537
00:45:54,990 -->
00:45:58,460
Therefore the clear ideas God gave him can
be trusted.
538
00:45:59,420 -->
00:46:05,420
The physical world is real, and the demon
is a thought experiment and nothing more.
539
00:46:07,280 -->
00:46:11,500
He puts the floor back under the house,
and it rests on God.
540
00:46:13,700 -->
00:46:15,200
But the damage was done.
541
00:46:16,400 -->
00:46:19,913
Once readers saw the
demon, they couldn't stop
542
00:46:19,914 -->
00:46:23,320
seeing him, and you meet
his descendants every day.
543
00:46:24,450 -->
00:46:32,080
You pick up your phone, and a video
starts, a bridge collapsing, a politician
544
00:46:32,530 -->
00:46:38,180
saying something outrageous, a face that
moves exactly like a real face.
545
00:46:40,380 -->
00:46:43,780
For a second you stop and wonder,
is this real?
546
00:46:44,710 -->
00:46:45,760
Did that happen?
547
00:46:47,680 -->
00:46:48,760
Was it filmed?
548
00:46:49,314 -->
00:46:50,540
Or generated?
549
00:46:50,714 -->
00:46:51,714
Or edited?
550
00:46:52,174 -->
00:46:54,200
You can't tell from the picture alone.
551
00:46:54,800 -->
00:47:00,400
That small hesitation, that gap between
what you're shown and what you can trust,
552
00:47:01,044 -->
00:47:03,760
is the question Descartes asked by the
fire.
553
00:47:04,060 -->
00:47:07,860
Now asked by millions of people,
at once.
554
00:47:11,009 -->
00:47:14,320
Descartes also wonders about the people he
sees.
555
00:47:15,720 -->
00:47:21,920
In that same second meditation, he does
something that sounds like a joke and isn't.
556
00:47:23,580 -->
00:47:26,220
He looks out of his window at the street
below.
557
00:47:27,750 -->
00:47:33,780
He sees hats and coats moving along the
pavement, and he says that he calls them men.
558
00:47:35,910 -->
00:47:39,460
But all he actually sees are hats and
coats.
559
00:47:41,114 -->
00:47:45,400
Underneath them, for all his eyes can
tell, there could be machines,
560
00:47:46,240 -->
00:47:50,640
clockwork, figures, built to walk and
gesture like people.
561
00:47:52,380 -->
00:47:57,700
These machines are called automata,
and in his day they were real.
562
00:47:59,044 -->
00:48:02,440
Europe's wealthy built them for their
gardens.
563
00:48:03,440 -->
00:48:07,340
Statues that moved when a visitor stepped
on a hidden plate.
564
00:48:08,344 -->
00:48:10,920
Mechanical figures that played music.
565
00:48:11,579 -->
00:48:14,360
Bronze birds that sang from the branches.
566
00:48:15,705 -->
00:48:17,220
Descartes knew them well.
567
00:48:19,350 -->
00:48:23,635
So when he says the figures in
the street might be automata,
568
00:48:23,636 -->
00:48:27,640
he's pointing at something
he's seen with his own eyes.
569
00:48:29,340 -->
00:48:31,900
He settles the matter by judgement.
570
00:48:32,654 -->
00:48:34,400
He decides they're men.
571
00:48:36,050 -->
00:48:37,240
But how would he know?
572
00:48:38,500 -->
00:48:42,860
That question stayed with him,
and in the discourse on method,
573
00:48:43,075 -->
00:48:44,220
he gives an answer.
574
00:48:45,900 -->
00:48:50,360
He imagines a machine built to look
exactly like a human body.
575
00:48:51,230 -->
00:48:52,260
Could it fool us?
576
00:48:53,000 -->
00:48:55,520
He says no, and he gives two tests.
577
00:48:56,220 -->
00:48:57,540
The first is language.
578
00:48:58,400 -->
00:49:04,360
A machine could be built to utter words,
even to respond to a poke by saying,
579
00:49:05,415 -->
00:49:06,900
you're hurting me.
580
00:49:08,890 -->
00:49:15,260
But it could never arrange its words in
different ways to reply sensibly to
581
00:49:15,261 -->
00:49:20,640
everything said in its presence,
the way even the dullest person can.
582
00:49:22,760 -->
00:49:24,500
The second is flexibility.
583
00:49:26,260 -->
00:49:32,960
A machine might do one task perfectly,
but it would fail at others, because it
584
00:49:33,335 -->
00:49:37,540
acts from the arrangement of its parts,
and not from understanding.
585
00:49:40,020 -->
00:49:43,757
Hold on to that first test,
because it's a proposal for
586
00:49:43,758 -->
00:49:48,280
how to tell a person from
a machine by talking to it.
587
00:49:49,890 -->
00:49:54,328
Three centuries later, a
mathematician in England will
588
00:49:54,329 -->
00:49:58,940
take up exactly that question,
and we'll meet him soon.
589
00:50:00,589 -->
00:50:03,940
Now notice what Descartes' own answer
implies.
590
00:50:05,080 -->
00:50:09,574
For him, the body is a
machine, not just the street
591
00:50:09,575 -->
00:50:14,520
figures, but every human
body and every animal body too.
592
00:50:15,460 -->
00:50:22,100
The heart pumps, the limbs move,
the eyes focus, all by mechanical rules
593
00:50:22,200 -->
00:50:23,860
like the gears in a clock.
594
00:50:26,100 -->
00:50:30,160
What makes a person more than a machine is
something else entirely.
595
00:50:32,360 -->
00:50:39,380
It's the mind, a thinking thing, with no
size and no weight and no place in space.
596
00:50:40,395 -->
00:50:44,020
So Descartes ends up with two kinds of
stuff in the world.
597
00:50:45,060 -->
00:50:48,921
Matter, which fills space
and obeys mechanical
598
00:50:48,922 -->
00:50:52,300
laws, and mind, which
thinks and doesn't.
599
00:50:54,000 -->
00:50:56,660
That split has a famous nickname.
600
00:50:59,080 -->
00:51:05,700
In 1949, an Oxford philosopher named
Gilbert Ryle published a book called The
601
00:51:05,900 -->
00:51:12,140
Concept of Mind, and he mocked Descartes'
picture as the ghost in the machine.
602
00:51:14,295 -->
00:51:19,320
A ghost living inside a mechanical body,
steering it from within.
603
00:51:20,400 -->
00:51:27,780
Ryle thought the picture was a mistake,
but he named it so well that the phrase
604
00:51:27,930 -->
00:51:34,700
stuck and it's still the way most people
picture themselves without ever saying so.
605
00:51:36,439 -->
00:51:39,530
And that picture matters here because of
where it puts you.
606
00:51:41,620 -->
00:51:45,314
In Descartes' version,
the real you isn't part
607
00:51:45,315 -->
00:51:49,200
of the machinery,
the self sits outside it.
608
00:51:50,140 -->
00:51:54,875
The body can run on its
own, like the figures in the
609
00:51:54,950 -->
00:51:59,360
garden, while you, the thinker,
watch from somewhere beyond.
610
00:52:00,544 -->
00:52:02,060
Hold on to that image.
611
00:52:03,480 -->
00:52:09,540
A self standing outside the mechanism will
come back, in a very different form,
612
00:52:10,484 -->
00:52:11,920
at the end of this story.
613
00:52:13,940 -->
00:52:19,687
Next, Ireland in the early 1700s,
and a man who read Descartes
614
00:52:19,737 -->
00:52:23,860
and decided the whole
picture had one piece too many.
615
00:52:24,875 -->
00:52:27,000
His name is George Berkeley.
616
00:52:28,920 -->
00:52:32,690
He was born in 1685,
grew up in County
617
00:52:32,691 -->
00:52:37,140
Kilkenny, and went to
Trinity College in Dublin.
618
00:52:39,540 -->
00:52:44,140
Where he was so quick that he was teaching
there before he turned 30.
619
00:52:45,654 -->
00:52:48,780
Later he became a bishop in the Church of
Ireland.
620
00:52:50,480 -->
00:52:53,854
But before any of
that, at the age of 25,
621
00:52:53,855 -->
00:52:57,500
he published a short
book with a long title.
622
00:52:59,055 -->
00:53:03,060
A treatise concerning the principles of
human knowledge.
623
00:53:05,770 -->
00:53:11,840
The year was 1710, and the book is built
around a single, startling fame.
624
00:53:12,600 -->
00:53:13,840
There is no matter.
625
00:53:17,110 -->
00:53:20,266
Now, Berkeley didn't
mean that the world is
626
00:53:20,267 -->
00:53:23,220
empty, or that your
coffee cup is imaginary.
627
00:53:24,480 -->
00:53:28,480
He meant something narrower, and you can
follow it with an apple.
628
00:53:28,960 -->
00:53:29,960
Pick one up.
629
00:53:30,780 -->
00:53:32,780
What do you actually have in your hand?
630
00:53:33,360 -->
00:53:40,060
A certain red colour, a certain smooth
coolness, a smell sweet and a little
631
00:53:40,061 -->
00:53:47,100
sharp, a taste when you bite it,
a round shape you can feel and see.
632
00:53:49,154 -->
00:53:53,520
Berkeley asks you to list everything you
can truly say about the apple,
633
00:53:54,064 -->
00:53:58,260
and notice that every item on the list is
something you experience.
634
00:53:59,985 -->
00:54:05,460
Colour is an experience of the eyes,
smell is an experience of the nose,
635
00:54:06,600 -->
00:54:12,280
taste, touch, shape, all of it arrives as
sensation.
636
00:54:14,750 -->
00:54:16,900
So where is the apple itself?
637
00:54:17,700 -->
00:54:23,900
The thing the philosophers of his day said
was hiding behind the colour, and the
638
00:54:23,901 -->
00:54:27,240
smell and the taste, holding them
together.
639
00:54:28,610 -->
00:54:31,649
Those philosophers
called it material
640
00:54:31,650 -->
00:54:35,360
substance, a kind of
invisible stuff underneath.
641
00:54:36,874 -->
00:54:39,700
Berkeley says to try to picture it.
642
00:54:41,340 -->
00:54:47,240
Take away the colour, the smell,
the taste, the shape, and see what's left.
643
00:54:48,154 -->
00:54:49,440
Nothing is left.
644
00:54:50,290 -->
00:54:53,100
You can't even imagine what it would be.
645
00:54:54,650 -->
00:54:57,745
The apple, he concludes,
is the collection of
646
00:54:57,746 -->
00:55:00,940
those qualities, gathered
together in a mind.
647
00:55:01,799 -->
00:55:03,820
Nothing lies behind them.
648
00:55:05,820 -->
00:55:08,860
He put this in three Latin words that are
still quoted.
649
00:55:09,899 -->
00:55:11,820
Esi est, percipi.
650
00:55:12,560 -->
00:55:14,220
To be is to be perceived.
651
00:55:15,570 -->
00:55:20,460
For a thing like an apple, existing and
being perceived are the same fact.
652
00:55:22,705 -->
00:55:24,840
You can already see the objection.
653
00:55:26,740 -->
00:55:30,768
If the apple exists only
when someone perceives it,
654
00:55:30,769 -->
00:55:33,840
what happens to the apple
when you leave the room?
655
00:55:35,620 -->
00:55:41,800
Does the whole kitchen vanish every time
you walk out and flash back when you return?
656
00:55:43,624 -->
00:55:47,600
Berkeley was bothered by this too,
and he had an answer.
657
00:55:51,150 -->
00:55:55,450
The kitchen goes on because there is
always a mind perceiving it.
658
00:55:56,830 -->
00:56:01,850
That mind is God who sees every corner of
the world at every moment.
659
00:56:03,140 -->
00:56:08,370
Nothing ever drops out of sight because
God's attention never lapses.
660
00:56:09,780 -->
00:56:16,570
A tree in an empty field, a coin at the
bottom of the sea, a room with nobody in
661
00:56:17,470 -->
00:56:22,050
it, all of them stay in existence because
they stay in God's view.
662
00:56:24,270 -->
00:56:27,410
Hold that thought because look at what it
describes.
663
00:56:29,254 -->
00:56:34,030
A world whose parts are held in being by a
perceiver outside them.
664
00:56:35,679 -->
00:56:37,070
Berkeley meant God.
665
00:56:38,244 -->
00:56:42,210
Later on, someone will give us the same
role to something else.
666
00:56:44,530 -->
00:56:47,590
Not everyone found the argument
persuasive.
667
00:56:49,850 -->
00:56:57,550
In 1763, ten years after Berkeley's death,
the writer Samuel Johnson was out walking
668
00:56:57,551 -->
00:57:00,570
with his friend and biographer James
Boswell.
669
00:57:03,030 -->
00:57:09,030
They'd been discussing Berkeley's theory,
and Boswell remarked that it was
670
00:57:09,130 -->
00:57:12,730
impossible to refute, though nobody
believed it.
671
00:57:15,670 -->
00:57:19,257
Johnson strode over to a
large stone, kicked it so hard
672
00:57:19,258 -->
00:57:24,310
that his foot bounced
back and said, I refute it thus.
673
00:57:27,700 -->
00:57:33,030
It's a wonderful scene, and philosophers
have been arguing about it ever since.
674
00:57:34,940 -->
00:57:39,610
Because Berkeley would have said that
Johnson had just proved his point.
675
00:57:40,670 -->
00:57:45,810
What Johnson felt was the hardness of the
stone, the pressure on his toe,
676
00:57:46,194 -->
00:57:47,750
the sound of the impact.
677
00:57:48,955 -->
00:57:51,390
Every bit of it was sensation.
678
00:57:52,984 -->
00:57:55,630
Kicking the stone gave him more
experiences.
679
00:57:57,174 -->
00:57:59,970
And Berkeley never denied experiences.
680
00:58:01,110 -->
00:58:03,670
He denied the invisible stuff underneath.
681
00:58:06,595 -->
00:58:10,170
You've had a small version of Berkeley's
puzzle yourself.
682
00:58:12,354 -->
00:58:14,870
Think of the light inside your
refrigerator.
683
00:58:17,750 -->
00:58:19,710
You open the door and it's on.
684
00:58:20,920 -->
00:58:26,590
You close the door and the light is hidden
from you, and you've probably wondered,
685
00:58:27,230 -->
00:58:33,310
as nearly everyone does at some point,
whether it really stays on in there or
686
00:58:33,460 -->
00:58:36,050
switches off the moment the door shuts.
687
00:58:38,670 -->
00:58:42,407
You can't check without
opening the door, and
688
00:58:42,408 -->
00:58:45,830
the moment you do,
you've changed the test.
689
00:58:47,804 -->
00:58:51,930
You're relying on a guess about what
happens when no one is looking.
690
00:58:53,185 -->
00:58:56,230
Berkeley's answer is that someone always
is.
691
00:58:58,425 -->
00:59:04,570
Let's go to Königsberg, a Prussian city on
the Baltic coast, and to a small,
692
00:59:04,910 -->
00:59:06,890
neat man named Immanuel Kant.
693
00:59:08,430 -->
00:59:14,090
He was born there in 1724 and died there
in 1804.
694
00:59:14,745 -->
00:59:17,070
And in between, he almost never left.
695
00:59:19,690 -->
00:59:20,750
He didn't travel.
696
00:59:21,510 -->
00:59:22,550
He didn't marry.
697
00:59:24,090 -->
00:59:29,950
And he organized his days with such
precision that the story spread through
698
00:59:29,951 -->
00:59:34,550
the city that housewives set their clocks
by his afternoon walk.
699
00:59:37,210 -->
00:59:42,197
Every day, at the same hour,
he put on his coat, took his cane,
700
00:59:42,198 -->
00:59:46,830
and strolled the same path
along the same row of lime trees.
701
00:59:48,590 -->
00:59:52,170
The path is still called the Philosopher's
Walk.
702
00:59:53,730 -->
00:59:59,970
It's a funny picture, because this
punctual man in the middle of a tiny
703
00:59:59,971 -->
01:00:04,910
provincial routine was about to turn the
history of thought around.
704
01:00:07,950 -->
01:00:12,537
In 1781, when he was
57, Kant published The
705
01:00:12,538 -->
01:00:18,190
Critique of Pure Reason,
and he revised it in 1787.
706
01:00:19,255 -->
01:00:21,810
It's a famously difficult book.
707
01:00:23,360 -->
01:00:26,610
And its core idea can be said in a
sentence.
708
01:00:27,890 -->
01:00:30,975
Everyone before him had
assumed that our minds
709
01:00:30,976 -->
01:00:35,170
adjust themselves to
fit the objects out there.
710
01:00:35,920 -->
01:00:37,070
Kant flipped it.
711
01:00:38,660 -->
01:00:43,077
He proposed that the
objects, as we experience them,
712
01:00:43,078 -->
01:00:46,770
adjust themselves to fit
the structure of our minds.
713
01:00:48,940 -->
01:00:50,130
Here's how that works.
714
01:00:51,390 -->
01:00:52,890
Think about space.
715
01:00:54,450 -->
01:00:59,450
You see a cup on a table and the cup is
over there and you are over here.
716
01:01:00,450 -->
01:01:03,350
Kant asks where that over there comes
from.
717
01:01:04,165 -->
01:01:05,590
Did you learn it from the cup?
718
01:01:06,510 -->
01:01:10,277
He says no, because
to see any object at all
719
01:01:10,278 -->
01:01:13,170
you must already be
placing it somewhere.
720
01:01:15,869 -->
01:01:19,770
Space isn't something you find among the
things you perceive.
721
01:01:21,860 -->
01:01:28,230
It's the form your perceiving takes,
the way a camera can only record images in
722
01:01:28,330 -->
01:01:30,230
the format its sensor allows.
723
01:01:32,365 -->
01:01:33,690
Time is the same.
724
01:01:34,634 -->
01:01:38,630
Every moment you live through arrives in a
before and an after.
725
01:01:39,640 -->
01:01:44,190
And that sequence belongs to the way you
take in experience.
726
01:01:47,540 -->
01:01:50,880
And cause and effect works the same way.
727
01:01:51,820 -->
01:01:57,480
When you see a glass fall and then shatter
you see the one thing producing the other
728
01:01:57,880 -->
01:02:01,000
but the producing is added by your mind.
729
01:02:01,720 -->
01:02:08,080
A raw stream of sensation contains no
labels saying this made that.
730
01:02:10,520 -->
01:02:12,280
So Kant draws a line.
731
01:02:13,450 -->
01:02:20,040
On one side are appearances, the world as
it shows up for creatures built like us,
732
01:02:20,194 -->
01:02:24,820
laid out in space, running through time
linked by cause.
733
01:02:26,100 -->
01:02:31,220
On the other side is whatever exists apart
from our way of perceiving it,
734
01:02:31,325 -->
01:02:33,920
which he called the thing in itself.
735
01:02:36,340 -->
01:02:37,920
We can know the first.
736
01:02:39,800 -->
01:02:45,480
We can never know the second because to
know anything we have to run it through
737
01:02:45,481 -->
01:02:51,620
our own forms and that means we never meet
the thing in itself without them.
738
01:02:54,765 -->
01:02:59,660
Now this idea hit some readers like a wave
of cold water.
739
01:03:00,710 -->
01:03:07,820
In the spring of 1801 a 23 year old
Prussian officer and writer named Heinrich
740
01:03:07,821 -->
01:03:12,020
von Kleist read Kant and fell into a
crisis.
741
01:03:12,670 -->
01:03:15,740
He wrote to his fiance in a state of
shock.
742
01:03:18,510 -->
01:03:24,620
He said it was as if everyone had green
glasses fused to their eyes.
743
01:03:26,640 -->
01:03:32,560
They'd see everything in green and
conclude that objects really were green,
744
01:03:33,260 -->
01:03:38,320
but they could never tell whether the green
belonged to the objects or to the glasses.
745
01:03:41,255 -->
01:03:47,220
And so Kleist wrote, we can't decide
whether what we call truth is truly true
746
01:03:48,095 -->
01:03:50,140
or only seems so to us.
747
01:03:51,100 -->
01:03:54,731
His hope of finding a truth
that would outlast death
748
01:03:54,732 -->
01:03:59,560
collapsed and he said that his
one great aim in life had sunk.
749
01:04:01,294 -->
01:04:04,160
Scholars call this episode The Kant
Crisis.
750
01:04:05,780 -->
01:04:10,260
Kleist took it hard, but notice what Kant
had actually done.
751
01:04:11,600 -->
01:04:18,080
Berkeley had said there's no matter, only
minds and their ideas held in being by God.
752
01:04:18,939 -->
01:04:21,040
Kant refused to go that far.
753
01:04:22,440 -->
01:04:25,160
He insisted the thing in itself is there.
754
01:04:26,020 -->
01:04:28,600
It just lies forever beyond our reach.
755
01:04:31,050 -->
01:04:38,200
So if you picture our experience as a
screen, Berkeley stands firmly on the
756
01:04:38,201 -->
01:04:41,721
consciousness side,
saying that the screen is
757
01:04:41,722 -->
01:04:46,700
all there is and a greater
mind is projecting it.
758
01:04:48,540 -->
01:04:53,660
Kant stands at the edge of the screen and
says there is something behind it,
759
01:04:53,910 -->
01:04:55,420
but we'll never see what.
760
01:04:57,580 -->
01:05:02,329
Those are two different ways of
living with the same uncertainty,
761
01:05:02,330 -->
01:05:06,660
and the rest of this story
will keep returning to both.
762
01:05:09,875 -->
01:05:13,140
You already live inside a small version of
Kant's idea.
763
01:05:14,500 -->
01:05:18,580
Think of a pair of sunglasses,
the dark kind.
764
01:05:20,060 -->
01:05:26,640
When you first put them on, everything
looks dim and brownish, and you notice it
765
01:05:26,641 -->
01:05:31,680
right away, but wear them for an afternoon
and something odd happens.
766
01:05:33,420 -->
01:05:39,260
Your eyes are just, the tint disappears
from your attention, and the world just
767
01:05:39,360 -->
01:05:40,560
looks like the world.
768
01:05:43,775 -->
01:05:50,080
Then you pull them off, and the sudden
brightness startles you, and you realize
769
01:05:50,081 -->
01:05:54,220
the whole time you'd been seeing through a
filter you'd stopped noticing.
770
01:05:59,189 -->
01:06:04,170
Kant's claim is that we all wear a pair
like that from birth, and that we never
771
01:06:04,320 -->
01:06:05,320
get to take them off.
772
01:06:08,270 -->
01:06:13,890
Let's jump to 1950, and a mathematician
named Alan Turing.
773
01:06:16,795 -->
01:06:22,110
He's 38 years old, working at the
University of Manchester in England.
774
01:06:23,610 -->
01:06:28,990
He's already famous inside a small circle
for his work on the theory of computation,
775
01:06:30,360 -->
01:06:34,057
and for breaking German
naval ciphers during the
776
01:06:34,058 -->
01:06:37,870
war, though that second
part is still a state secret.
777
01:06:40,290 -->
01:06:46,670
In October of that year, he publishes a
paper in a philosophy journal called Mind.
778
01:06:48,130 -->
01:06:52,378
The title is Computing
Machinery and Intelligence,
779
01:06:52,379 -->
01:06:54,970
and the first
sentence is a question.
780
01:06:55,944 -->
01:06:57,310
Can machines think?
781
01:06:59,165 -->
01:07:01,670
Turing doesn't try to answer it.
782
01:07:02,090 -->
01:07:07,890
He says the question is badly built,
because nobody agrees on what think means,
783
01:07:08,364 -->
01:07:11,550
and arguing about the word will go on
forever.
784
01:07:13,610 -->
01:07:19,130
So he swaps it for a different question,
one that can actually be tested.
785
01:07:20,500 -->
01:07:22,730
He calls it the Imitation Game.
786
01:07:24,850 -->
01:07:26,290
Here's how it works.
787
01:07:28,090 -->
01:07:31,210
There are three players in three separate
rooms.
788
01:07:31,874 -->
01:07:33,270
One is a judge.
789
01:07:34,024 -->
01:07:35,630
One is a human being.
790
01:07:36,144 -->
01:07:37,570
One is a machine.
791
01:07:38,475 -->
01:07:41,510
The judge can't see or hear either of
them.
792
01:07:41,960 -->
01:07:44,740
All he can do is type
questions on a keyboard
793
01:07:44,741 -->
01:07:47,550
and read the typed
answers that come back.
794
01:07:49,510 -->
01:07:54,126
He might ask about poetry,
or arithmetic, or what the
795
01:07:54,127 -->
01:07:57,670
weather's like, or whether
the player had breakfast.
796
01:07:58,779 -->
01:08:02,050
Both players try to convince him they're
the human.
797
01:08:04,160 -->
01:08:08,330
After a while, the judge has to decide
which is which.
798
01:08:09,194 -->
01:08:14,050
If the judge can't reliably tell,
then the machine has passed.
799
01:08:18,395 -->
01:08:20,800
Turing is careful to say what he's
predicting.
800
01:08:23,420 -->
01:08:31,420
He writes that within about 50 years,
so by the year 2000, machines will be good
801
01:08:31,421 -->
01:08:36,285
enough that an average judge
will have no more than a 70%
802
01:08:36,286 -->
01:08:40,399
chance of getting it right
after five minutes of questions.
803
01:08:42,730 -->
01:08:44,779
Notice how modest that is.
804
01:08:45,740 -->
01:08:50,399
He isn't claiming a machine will fool
everyone forever.
805
01:08:51,290 -->
01:08:55,220
He's saying it will fool the judge about
three times out of ten.
806
01:08:57,279 -->
01:09:03,260
Now, the obvious complaint is that fooling
a judge isn't the same as thinking.
807
01:09:05,145 -->
01:09:10,180
A machine might produce clever answers
with nothing going on inside.
808
01:09:11,899 -->
01:09:17,439
Turing saw this coming, and his reply is
the most interesting part of the paper.
809
01:09:19,390 -->
01:09:24,479
He points out that the same doubt applies
to every other person you meet.
810
01:09:28,230 -->
01:09:30,890
You can never get inside another human
head.
811
01:09:31,585 -->
01:09:36,069
You can't feel their thoughts,
only watch what they say and do.
812
01:09:37,870 -->
01:09:42,930
Strictly speaking, nobody can be certain
that anyone else thinks at all.
813
01:09:44,825 -->
01:09:46,950
And yet we don't live in suspicion.
814
01:09:48,780 -->
01:09:54,370
Instead, he says, We adopt a polite
convention that everyone thinks.
815
01:09:55,625 -->
01:10:00,530
We just agree to treat each other that
way, and it makes life possible.
816
01:10:01,530 -->
01:10:06,004
His proposal is to extend the
same courtesy to a machine
817
01:10:06,005 -->
01:10:10,290
that behaves in conversation
the way a person does.
818
01:10:11,940 -->
01:10:13,430
That's the same puzzle.
819
01:10:15,110 -->
01:10:20,730
Descartes left at the window with the hats
and coats, now with a test attached.
820
01:10:22,870 -->
01:10:28,510
Turing then goes through nine objections
people might raise, and answers each one.
821
01:10:29,970 -->
01:10:35,590
Some are religious, only God gives souls,
so machines can't think.
822
01:10:36,520 -->
01:10:40,810
Some are mathematical, about what any
machine can't compute.
823
01:10:42,350 -->
01:10:47,471
One is called the argument
from consciousness, which
824
01:10:47,472 -->
01:10:50,890
says a machine can't
really feel what it writes.
825
01:10:53,690 -->
01:11:00,930
And one comes from Ada Lovelace,
a mathematician who, in 1843, wrote notes
826
01:11:00,931 -->
01:11:04,550
on an early mechanical computer designed
by Charles Babbage.
827
01:11:06,560 -->
01:11:12,350
She wrote that the machine has no
pretensions whatever to originate anything.
828
01:11:13,950 -->
01:11:17,030
It can do whatever we know how to order it
to perform.
829
01:11:18,615 -->
01:11:23,250
Machines, she said, only follow
instructions.
830
01:11:25,415 -->
01:11:27,510
Turing's reply is gentle.
831
01:11:29,120 -->
01:11:35,830
He says machines surprise their builders
constantly, because nobody can hold all
832
01:11:35,905 -->
01:11:39,010
the consequences of a program in their
head at once.
833
01:11:40,560 -->
01:11:46,230
A person who writes the rules doesn't
necessarily know what they'll produce.
834
01:11:47,730 -->
01:11:52,970
Originality, he suggests, may be less
mysterious than it sounds.
835
01:11:55,750 -->
01:12:03,750
The paper ends by imagining that we might
build a machine that learns the way a
836
01:12:03,751 -->
01:12:08,510
child does, rather than one that's filled
with finished knowledge.
837
01:12:09,960 -->
01:12:12,990
It's a startlingly modern thought for
1950.
838
01:12:14,770 -->
01:12:20,910
Now, you've met a descendant of Turing's
test, probably this week.
839
01:12:22,150 -->
01:12:28,250
You land on a website and before it lets
you in, a small box appears with the
840
01:12:29,175 -->
01:12:30,390
words, I'm not a robot.
841
01:12:32,115 -->
01:12:36,350
Sometimes it asks you to click on every
picture with a traffic light.
842
01:12:37,230 -->
01:12:41,150
You're being tested by a machine to prove
you aren't one.
843
01:12:43,450 -->
01:12:47,879
The system has a name,
CAPTCHA, which was
844
01:12:47,880 -->
01:12:51,050
created in 2003 at
Carnegie Mellon University.
845
01:12:53,030 -->
01:12:57,209
The letters stand for
completely automated public
846
01:12:57,210 -->
01:13:00,930
Turing test to tell
computers and humans apart.
847
01:13:02,880 -->
01:13:08,990
It's Turing's imitation game run
backwards, with the computer as the judge
848
01:13:09,740 -->
01:13:12,510
and you as the player trying to pass.
849
01:13:15,130 -->
01:13:19,543
While Turing was building the
idea out of logic and arithmetic,
850
01:13:19,544 -->
01:13:23,450
a different kind of person
was building it out of plot.
851
01:13:25,870 -->
01:13:29,304
Novelists and screenwriters
were asking a question
852
01:13:29,379 -->
01:13:32,650
the mathematicians
hadn't dared to put in print.
853
01:13:35,500 -->
01:13:37,690
What would it be like to live inside one?
854
01:13:40,950 -->
01:13:44,795
The man who answered
it first, at full length,
855
01:13:44,796 -->
01:13:48,530
was an American writer
named Daniel Galloway.
856
01:13:50,720 -->
01:13:56,470
He had been a fighter pilot in the Second
World War, was badly injured when his
857
01:13:56,471 -->
01:14:04,010
plane crashed in 1943, and afterward
worked as a newspaper man in Louisiana,
858
01:14:04,750 -->
01:14:07,650
writing science fiction in the evenings.
859
01:14:09,930 -->
01:14:15,050
In 1964, he published a novel called
Simulacron 3.
860
01:14:16,470 -->
01:14:21,570
In Britain, and later in America,
it was also sold under a second title,
861
01:14:22,295 -->
01:14:23,690
Counterfeit World.
862
01:14:25,980 -->
01:14:30,930
The setup is simple, and it's worth
following step by step.
863
01:14:32,115 -->
01:14:36,870
A company has built a machine that holds
an entire city inside it.
864
01:14:37,450 -->
01:14:44,450
The city is a copy of an ordinary American
town, with streets, shops, offices,
865
01:14:44,635 -->
01:14:47,850
bars, and about a hundred thousand
inhabitants.
866
01:14:49,390 -->
01:14:52,790
These inhabitants are not drawings or
recordings.
867
01:14:53,760 -->
01:15:00,390
Each one is a program that thinks,
wants, worries, and falls in love.
868
01:15:03,210 -->
01:15:08,240
The company doesn't build this for fun,
it builds it for market research.
869
01:15:09,965 -->
01:15:15,580
If a business wants to know how people
will react to a new soap, a new slogan,
870
01:15:16,140 -->
01:15:21,660
or a new kind of car, it no longer needs
to run a poll in the real world.
871
01:15:23,610 -->
01:15:26,617
It feeds the product
into the simulated city,
872
01:15:26,618 -->
01:15:29,920
and watches what the
simulated people do.
873
01:15:31,680 -->
01:15:33,520
And here's the cruel detail.
874
01:15:34,900 -->
01:15:37,340
The people inside the city don't know.
875
01:15:38,300 -->
01:15:45,560
They go to work, they argue with their
neighbours, they buy the products they're
876
01:15:45,561 -->
01:15:51,960
shown, and not one of them suspects that
their whole existence is an experiment,
877
01:15:53,220 -->
01:15:58,400
running on someone else's electricity for
someone else's profit.
878
01:16:01,695 -->
01:16:04,180
The hero is a man named Douglas Hall.
879
01:16:04,930 -->
01:16:10,040
He's a technical director at the company,
and he works with the machine every day.
880
01:16:11,040 -->
01:16:13,200
Then his world starts to slip.
881
01:16:14,580 -->
01:16:21,200
The inventor of the project, a brilliant
man named Hannon Fuller, dies suddenly,
882
01:16:21,635 -->
01:16:23,720
and the circumstances are strange.
883
01:16:24,900 -->
01:16:32,260
Soon afterward, a colleague named Morton
Lynch is standing right next to Hall when
884
01:16:32,261 -->
01:16:36,560
he vanishes, not walks away, not leaves
the room.
885
01:16:38,100 -->
01:16:40,560
He's there one moment and gone the next.
886
01:16:42,900 -->
01:16:45,812
And the part that
frightens Hall most is that
887
01:16:45,813 -->
01:16:48,520
nobody else remembers
Lynch ever existed.
888
01:16:49,710 -->
01:16:51,140
Records have changed.
889
01:16:52,210 -->
01:16:55,320
People look at Hall blankly when he asks.
890
01:16:57,080 -->
01:17:02,180
A man has been erased from the world,
and only Hall holds the memory.
891
01:17:04,400 -->
01:17:05,900
Hall begins to fall apart.
892
01:17:07,585 -->
01:17:15,260
He suspects he's going mad, but the more
he investigates, the more he notices small
893
01:17:15,261 -->
01:17:20,020
wrongnesses, details that don't fit,
gaps where something should be,
894
01:17:20,460 -->
01:17:25,560
and slowly, step by step, a terrible idea
settles on him.
895
01:17:28,430 -->
01:17:33,400
If he is running a simulated city,
whose people don't know they're simulated,
896
01:17:34,565 -->
01:17:40,180
then what proves that the world he lives
in isn't one level of the same arrangement?
897
01:17:41,840 -->
01:17:49,120
Maybe his own reality is a machine inside
another machine, and the people above him
898
01:17:49,121 -->
01:17:56,860
are watching, and Lynch was simply deleted
by someone with access to the controls.
899
01:18:00,035 -->
01:18:02,490
That's the move that makes the book
matter.
900
01:18:03,650 -->
01:18:10,910
It isn't only that a computer can hold a
world, it's that the people who build such
901
01:18:10,911 -->
01:18:16,950
worlds might themselves be living in one,
and that they could find out only through
902
01:18:16,951 -->
01:18:22,230
cracks, through the odd detail that
doesn't add up.
903
01:18:24,170 -->
01:18:25,810
The story didn't fade.
904
01:18:27,690 -->
01:18:35,390
In 1973, the German director Reiner Werner
Fassbinder turned it into a two-part
905
01:18:35,391 -->
01:18:41,450
television film called Welt am Draht,
which means World on a Wire.
906
01:18:43,710 -->
01:18:49,770
Fassbinder shot it in long, cold,
mirror-filled rooms, and the glass and
907
01:18:49,771 -->
01:18:53,630
reflections make you feel that every wall
might be a screen.
908
01:18:56,180 -->
01:19:02,850
Then, in 1999, the novel came back as a
Hollywood film called The Thirteenth
909
01:19:02,875 -->
01:19:10,390
Floor, set partly in 1937 Los Angeles,
inside a simulated past.
910
01:19:12,280 -->
01:19:19,330
That was the same year The Matrix opened,
so the idea reached a very large audience
911
01:19:19,380 -->
01:19:23,810
twice in a few months, from two different
directions.
912
01:19:26,170 -->
01:19:30,070
And Galloway's central trick is one you
can see in business today.
913
01:19:31,825 -->
01:19:34,990
Think about how companies test
advertisements.
914
01:19:36,745 -->
01:19:43,030
A firm gathers a panel of ordinary people,
shows them several versions of a
915
01:19:44,455 -->
01:19:51,430
commercial, and measures what each version
does, where their eyes go, which one they
916
01:19:51,431 -->
01:19:55,690
remember, which one makes them reach for
their wallets.
917
01:19:57,575 -->
01:20:01,150
Online, it happens constantly and
invisibly.
918
01:20:02,810 -->
01:20:06,124
A website shows
different versions of a page
919
01:20:06,125 -->
01:20:09,390
to different visitors
and tracks every click.
920
01:20:11,750 -->
01:20:14,690
You were almost certainly in such a test
this week.
921
01:20:15,400 -->
01:20:18,670
You didn't sign up for it and no one told
you.
922
01:20:20,600 -->
01:20:25,350
Your behaviour was just a data point in a
result you'll never see.
923
01:20:28,800 -->
01:20:34,180
Galloway's simulated city was that same
arrangement taken one step further,
924
01:20:34,820 -->
01:20:39,204
with the panel living inside
the experiment, and the
925
01:20:39,205 -->
01:20:43,300
researcher beginning to
wonder who is watching him.
926
01:20:45,230 -->
01:20:50,400
Now let's talk about the writer who lived
the strangest version of the idea.
927
01:20:51,220 -->
01:20:52,880
His name is Philip K.
928
01:20:52,920 -->
01:20:53,920
Dick.
929
01:20:55,120 -->
01:21:03,060
And by the late 1970s, he had written
dozens of novels and more than a hundred
930
01:21:03,061 -->
01:21:07,060
short stories about worlds that turn out
to be false.
931
01:21:08,480 -->
01:21:14,760
Men who wake up inside manufactured towns,
cities where reality shifts overnight,
932
01:21:15,400 -->
01:21:18,280
people who can't trust their own memories.
933
01:21:19,820 -->
01:21:21,280
He wrote them as fiction.
934
01:21:23,180 -->
01:21:28,740
Then something happened to him that made
him wonder whether he'd been writing
935
01:21:28,865 -->
01:21:29,865
reports.
936
01:21:33,360 -->
01:21:38,152
On the 24th of September,
1977, Dick stood in
937
01:21:38,153 -->
01:21:42,480
front of an audience in
the French city of Metz.
938
01:21:44,670 -->
01:21:49,600
He was the guest of honour at the second
Metz International Science Fiction
939
01:21:49,850 -->
01:21:55,020
Festival, and the speech was held in the
city hall on the Place d'Armes.
940
01:21:56,200 -->
01:22:02,060
It was one of only three times he ever
left the United States.
941
01:22:04,230 -->
01:22:11,260
He was a nervous traveller and a famously
unreliable convention guest, but the
942
01:22:11,261 -->
01:22:16,220
organiser had flown to California and
talked him into it over lunch and two
943
01:22:16,395 -->
01:22:17,520
bottles of red wine.
944
01:22:19,110 -->
01:22:23,543
The title he'd chosen
was, If you find this
945
01:22:23,544 -->
01:22:27,440
world bad, you should
see some of the others.
946
01:22:30,120 -->
01:22:32,760
The crowd expected a novelist's
entertainment.
947
01:22:35,100 -->
01:22:39,418
What they got was a man in
a flat, monotone voice telling
948
01:22:39,419 -->
01:22:43,300
them that we are living in a
computer-programmed reality.
949
01:22:45,610 -->
01:22:49,718
He said the only clue we
have is when some variable
950
01:22:49,719 -->
01:22:53,480
is changed and an
alteration in our reality occurs.
951
01:22:55,870 -->
01:22:58,760
Then he gave an example you can try on
yourself.
952
01:23:01,165 -->
01:23:03,840
Deja vu, he said, is the sign.
953
01:23:04,820 -->
01:23:10,220
That strange sense of having lived this
exact moment before is the trace of a
954
01:23:10,221 -->
01:23:15,040
previous version of the world,
left behind when the program was altered
955
01:23:15,840 -->
01:23:17,940
and the past was quietly rewritten.
956
01:23:20,790 -->
01:23:22,700
He didn't offer this as a plot.
957
01:23:24,430 -->
01:23:29,920
He offered it as something he believed and
the reason was a series of experiences
958
01:23:30,120 -->
01:23:31,380
three years earlier.
959
01:23:34,320 -->
01:23:42,760
In February and March of 1974, Dick
called them 2374 after the month and year.
960
01:23:43,450 -->
01:23:46,100
He was in pain from a dental procedure.
961
01:23:48,720 -->
01:23:51,955
And a delivery woman
came to his door wearing
962
01:23:51,956 -->
01:23:55,200
a small gold necklace
in the shape of a fish.
963
01:23:56,220 -->
01:24:00,604
When the sunlight caught
it a beam of pink light
964
01:24:00,654 -->
01:24:04,640
struck him and he said
knowledge poured into his mind.
965
01:24:08,390 -->
01:24:10,580
He believed it, told him.
966
01:24:11,120 -->
01:24:17,220
His young son had an undiagnosed hernia
and when he took the boy to a doctor,
967
01:24:17,475 -->
01:24:19,100
the doctor confirmed it.
968
01:24:20,660 -->
01:24:26,220
For weeks afterward he saw visions,
heard information in his head and became
969
01:24:26,221 -->
01:24:29,545
convinced that the Roman
Empire had never ended
970
01:24:29,546 -->
01:24:33,200
and that he was living
in two eras at once.
971
01:24:35,560 -->
01:24:39,600
He spent the rest of his life trying to
understand what had happened.
972
01:24:40,710 -->
01:24:45,108
He filled notebooks and
typed pages every night
973
01:24:45,109 -->
01:24:50,280
a private record that
grew to about 8,000 pages.
974
01:24:51,150 -->
01:24:57,840
It's called the exegesis, a word that
means a close interpretation of a sacred
975
01:24:57,841 -->
01:25:04,380
text and the text he was interpreting was
his own experience.
976
01:25:06,595 -->
01:25:11,640
And the framework he reached for was the
one we met in the Gnostic section.
977
01:25:14,480 -->
01:25:20,000
He decided the world we see is a false
layer and that behind it works a living
978
01:25:20,001 -->
01:25:25,271
intelligence, which he
sometimes called a programmer,
979
01:25:25,321 -->
01:25:29,500
sometimes a vast, active
living information system.
980
01:25:30,960 -->
01:25:36,140
Like the Gnostics, he believed we have
forgotten what we are.
981
01:25:37,264 -->
01:25:42,240
And that moments of strange clarity are
the memory trying to return.
982
01:25:46,665 -->
01:25:49,150
The speech itself did not go well.
983
01:25:51,050 -->
01:25:56,510
Dick had been asked to cut about 20
minutes at the last minute and the version
984
01:25:56,511 -->
01:26:01,250
he delivered no longer matched the
prepared text his interpreter was holding.
985
01:26:03,490 -->
01:26:07,130
The French listeners heard something
different from what he said.
986
01:26:08,305 -->
01:26:09,930
People left arguing.
987
01:26:11,960 -->
01:26:16,229
The author Harlan Ellison
recalled the audience
988
01:26:16,230 -->
01:26:19,650
looking stunned as
though hit with a hammer.
989
01:26:21,210 -->
01:26:27,690
One fan told Dick's friend Roger Zelazny
he thought Dick was starting a religion.
990
01:26:29,790 -->
01:26:34,183
Dick himself a few years
later called the speech
991
01:26:34,184 -->
01:26:37,710
nonsense writing that it
made no sense whatever.
992
01:26:39,220 -->
01:26:43,890
He said something goes haywire in his
brain when he writes speeches.
993
01:26:45,180 -->
01:26:50,750
And he imagines he's a reincarnation of
Zoroaster bringing news of God.
994
01:26:53,170 -->
01:26:57,770
And yet the idea outlived the botched
delivery.
995
01:26:58,795 -->
01:27:01,550
Because you felt the thing he was
describing.
996
01:27:02,685 -->
01:27:09,750
You walk into a room you've never entered,
a friend's kitchen, a hotel lobby and for
997
01:27:09,751 -->
01:27:13,270
one second the whole scene arrives
pre-recorded.
998
01:27:14,945 -->
01:27:16,910
You know what the next person will say.
999
01:27:17,880 -->
01:27:20,870
The light on the floor seems already
familiar.
1000
01:27:22,170 -->
01:27:26,735
Then it slips away and
you're left with a small
1001
01:27:26,736 -->
01:27:30,070
cold jolt as if the world
had skipped a frame.
1002
01:27:31,425 -->
01:27:33,270
Dick's answer was that it did.
1003
01:27:35,790 -->
01:27:41,556
While Dick was imagining a
programmed world, an engineer in
1004
01:27:41,557 -->
01:27:45,310
Germany had already built
the machine that could run one.
1005
01:27:46,150 -->
01:27:52,150
And he had started asking whether the
universe was a machine of the same kind.
1006
01:27:54,260 -->
01:27:56,290
His name was Konrad Zuse.
1007
01:27:57,710 -->
01:28:04,010
He was born in Berlin in 1910,
trained as a civil engineer and went to
1008
01:28:04,360 -->
01:28:05,630
work designing aircraft.
1009
01:28:06,745 -->
01:28:09,430
The job was a misery of arithmetic.
1010
01:28:10,410 -->
01:28:15,810
Every wing and every strut meant pages of
calculations done by hand.
1011
01:28:17,010 -->
01:28:23,490
And Zuse, tired of it, decided to build
something that could do the sums for him.
1012
01:28:25,255 -->
01:28:31,390
He built it in his parents' living room in
1941 in Berlin.
1013
01:28:32,425 -->
01:28:37,290
In the middle of the war, he finished a
machine called the Zid 3.
1014
01:28:39,440 -->
01:28:42,950
It was made from about 2000 telephone
relays.
1015
01:28:44,250 -->
01:28:47,903
The clicking switches
used in phone exchanges,
1016
01:28:47,904 -->
01:28:50,890
many of them salvaged
from scrapped equipment.
1017
01:28:52,520 -->
01:28:55,964
It could be given a
program on a strip of
1018
01:28:55,965 -->
01:28:59,150
punched film and carry
it out automatically.
1019
01:29:02,780 -->
01:29:07,970
That makes the Z3 the first working
programmable computer in the world.
1020
01:29:10,600 -->
01:29:15,870
Zuse worked almost entirely on his own,
without any contact with the
1021
01:29:15,871 -->
01:29:21,702
mathematicians in Britain and
America, who were chasing the
1022
01:29:21,703 -->
01:29:26,730
same goal and bombing raids
destroyed the machine in 1943.
1023
01:29:29,120 -->
01:29:36,510
Then, in 1969, he published a small book
with a strange title, Recknender Raum,
1024
01:29:37,135 -->
01:29:39,250
which means Calculating Space.
1025
01:29:40,560 -->
01:29:42,850
Its claim is stated plainly.
1026
01:29:43,815 -->
01:29:47,010
The universe, Zuse argued, is a
computation.
1027
01:29:48,445 -->
01:29:52,584
Space itself is divided
into a grid of tiny cells,
1028
01:29:52,634 -->
01:29:56,110
and each cell holds a
simple piece of information.
1029
01:29:57,890 -->
01:30:03,210
At every tick of a cosmic clock,
each cell looks at its neighbours,
1030
01:30:03,925 -->
01:30:07,290
and updates itself according to fixed
rules.
1031
01:30:09,035 -->
01:30:12,390
A structure like that is called a cellular
automaton.
1032
01:30:14,570 -->
01:30:21,350
Everything we call matter, motion and
energy would be patterns moving across the
1033
01:30:21,351 -->
01:30:26,810
grid, the way a pattern of lip bulbs can
seem to travel across a sign.
1034
01:30:28,990 -->
01:30:31,130
His book gives a small example.
1035
01:30:32,460 -->
01:30:38,250
Picture two digital particles,
each one a little cluster of cell states,
1036
01:30:38,965 -->
01:30:41,310
drifting toward each other across the
grid.
1037
01:30:42,525 -->
01:30:45,250
When they meet, the rules take over.
1038
01:30:47,840 -->
01:30:53,150
The cells where they overlap are updated
according to the rule, and when the update
1039
01:30:53,325 -->
01:30:59,250
is finished, the two clusters are gone,
and a third has appeared in their place.
1040
01:31:00,905 -->
01:31:05,370
Two particles went in, and one new
particle came out.
1041
01:31:06,740 -->
01:31:11,370
To us, that looks like a collision that
produced something new.
1042
01:31:12,420 -->
01:31:15,870
To the grid, it's one step of arithmetic.
1043
01:31:18,110 -->
01:31:20,190
Notice how much Zeus is claiming.
1044
01:31:21,740 -->
01:31:25,248
He isn't saying that
the universe resembles
1045
01:31:25,249 -->
01:31:28,750
a computer, or that a
computer can model it.
1046
01:31:29,370 -->
01:31:37,170
He's saying physics itself is computation,
and that what we observe as natural law is
1047
01:31:37,171 -->
01:31:41,530
a program running at a scale too fine for
us to see.
1048
01:31:43,730 -->
01:31:47,575
Physicists mostly
ignored the book, but the
1049
01:31:47,576 -->
01:31:51,410
idea had been planted
and it didn't stay put.
1050
01:31:52,910 -->
01:31:59,950
Soon after Zeus' book, someone invented a
small grid you could watch on a screen
1051
01:32:00,400 -->
01:32:03,557
with just a few rules
and showed the world
1052
01:32:03,558 -->
01:32:06,890
what such a universe
might look like in motion.
1053
01:32:10,730 -->
01:32:18,730
Let's go to 1970, to the month of October,
when a simple grid starts to move.
1054
01:32:20,810 -->
01:32:25,890
A British mathematician named John Conway,
who was teaching at Cambridge,
1055
01:32:26,570 -->
01:32:32,390
had been playing with a pencil and a sheet
of squared paper, looking for the simplest
1056
01:32:32,391 -->
01:32:36,270
set of rules that could produce something
life-like.
1057
01:32:38,670 -->
01:32:43,990
Martin Gardner, who wrote the mathematical
games column for Scientific American,
1058
01:32:44,930 -->
01:32:49,090
printed Conway's invention that month,
and readers went wild.
1059
01:32:50,600 -->
01:32:56,510
It's called the game of life, and it isn't
really a game, because nobody plays it.
1060
01:32:59,030 -->
01:33:00,750
You set it up and watch.
1061
01:33:02,620 -->
01:33:03,890
Here's the whole thing.
1062
01:33:04,920 -->
01:33:09,130
You have a grid of squares stretching out
in every direction.
1063
01:33:11,320 -->
01:33:13,890
Each square is either alive or dead.
1064
01:33:15,485 -->
01:33:20,610
At every tick, each square looks at its
eight neighbours and follows three rules.
1065
01:33:22,940 -->
01:33:29,090
A living square with two or three living
neighbours stays alive, a living square
1066
01:33:29,340 -->
01:33:35,930
with fewer than two dyes of loneliness, and
one with more than three dyes of crowding.
1067
01:33:37,695 -->
01:33:42,510
A dead square with exactly three living
neighbours comes to life.
1068
01:33:43,965 -->
01:33:47,510
That's all, and nothing else is ever
added.
1069
01:33:49,469 -->
01:33:51,370
Now try a tiny example.
1070
01:33:53,065 -->
01:33:55,630
Set up three living squares in a row.
1071
01:33:56,630 -->
01:34:02,130
At the next tick, the two n squares each
have only one neighbour, so they die,
1072
01:34:02,155 -->
01:34:05,620
while the squares above and
below the middle one each
1073
01:34:05,621 -->
01:34:08,950
have exactly three
neighbours, so they come alive.
1074
01:34:10,540 -->
01:34:13,610
The horizontal bar becomes a vertical bar.
1075
01:34:14,905 -->
01:34:17,810
Tick again and it flips back.
1076
01:34:18,850 -->
01:34:21,270
Three squares blinking forever.
1077
01:34:23,500 -->
01:34:29,670
From rules that small, whole creatures
appear, there's a five square shape called
1078
01:34:29,770 -->
01:34:34,334
a glider, which crawls
diagonally across the
1079
01:34:34,335 -->
01:34:38,310
grid, rebuilding
itself every four ticks.
1080
01:34:39,990 -->
01:34:44,337
There are guns that fire
gliders and patterns that
1081
01:34:44,338 -->
01:34:48,530
multiply and structures that
collide and leave wreckage.
1082
01:34:52,310 -->
01:34:58,640
Through the winter of 1970, people stayed
up at university computers, watching
1083
01:34:58,641 -->
01:35:03,172
colonies grow and die, and
Conway's grid became the
1084
01:35:03,173 -->
01:35:06,460
first universe anyone
could hold in their hands.
1085
01:35:07,220 -->
01:35:09,540
A few rules and a world.
1086
01:35:13,230 -->
01:35:21,230
Two years later, in 1972, a young engineer
named Alan Alcorn was handed an assignment
1087
01:35:21,231 -->
01:35:24,310
at a brand new California company called
Atari.
1088
01:35:25,610 -->
01:35:33,610
His boss, Nolan Bushnell, told him to
build a simple tennis game and he
1089
01:35:33,710 -->
01:35:38,630
pretended it was a big contract,
so Alcorn would take it seriously.
1090
01:35:39,730 -->
01:35:44,570
It was really a training exercise,
meant to teach Alcorn the hardware.
1091
01:35:45,170 -->
01:35:51,990
He built it anyway with two paddles,
a bouncing square dot and a score.
1092
01:35:52,550 -->
01:35:53,770
He named it Pong.
1093
01:35:56,340 -->
01:36:01,730
He put a prototype in a bar called Andy
Capp's Tavern, in Sunnyvale.
1094
01:36:03,550 -->
01:36:07,055
A couple of days later,
the bar's owner phoned
1095
01:36:07,056 -->
01:36:10,010
Atari to say the machine
had stopped working.
1096
01:36:11,465 -->
01:36:16,590
Alcorn drove over, opened the cabinet,
and found the problem at once.
1097
01:36:17,620 -->
01:36:22,130
The coin box was so jammed with quarters
that it couldn't hold anymore.
1098
01:36:24,000 -->
01:36:25,450
The game hadn't broken.
1099
01:36:26,060 -->
01:36:27,510
It had been too popular.
1100
01:36:30,550 -->
01:36:38,550
Meanwhile, in 1989, an old physicist,
named John Archibald Wheeler, the man who
1101
01:36:38,650 -->
01:36:42,871
had given black holes their
name, gave a lecture where
1102
01:36:42,872 -->
01:36:46,130
he summed up a lifetime
of thought in three words.
1103
01:36:46,795 -->
01:36:47,795
It from bit.
1104
01:36:49,205 -->
01:36:51,970
A bit is a single yes or no answer.
1105
01:36:53,390 -->
01:36:59,550
His claim was that every particle and
every field gets its existence from such
1106
01:36:59,551 -->
01:37:04,410
answers that physical things arise from
information.
1107
01:37:06,490 -->
01:37:09,650
And you've been inside a small version of
that idea.
1108
01:37:11,720 -->
01:37:13,650
Think of any video game world.
1109
01:37:14,445 -->
01:37:17,050
A mountain range stretching to the
horizon.
1110
01:37:18,155 -->
01:37:19,530
A river that glitters.
1111
01:37:20,660 -->
01:37:23,510
A forest where leaves move in the wind.
1112
01:37:24,620 -->
01:37:26,510
None of it is made of anything.
1113
01:37:27,465 -->
01:37:30,190
Underneath every tree is a list of
numbers.
1114
01:37:31,870 -->
01:37:36,830
And underneath every sunrise is a set of
rules running over and over.
1115
01:37:38,030 -->
01:37:42,070
The world you see is what the rules look
like from inside.
1116
01:37:44,650 -->
01:37:49,750
Next, 1981, and a philosopher at Harvard
named Hilary Putnam.
1117
01:37:51,090 -->
01:37:56,410
He had a gift for taking an old puzzle and
building it a new house.
1118
01:37:57,610 -->
01:38:04,110
In a book called Reason, Truth and
History, he took Descartes' demon,
1119
01:38:04,390 -->
01:38:08,075
the unseen deceiver
feeding a mind a false
1120
01:38:08,076 -->
01:38:11,370
world, and swapped the
demon for a laboratory.
1121
01:38:13,970 -->
01:38:16,190
Here's the scene he asks you to picture.
1122
01:38:18,420 -->
01:38:21,973
A surgeon removes a
person's brain and drops it
1123
01:38:21,974 -->
01:38:25,330
into a vat of nutrient
fluid that keeps it alive.
1124
01:38:27,520 -->
01:38:33,190
The nerve endings are wired to a computer,
and the computer sends in electrical
1125
01:38:33,191 -->
01:38:40,650
signals that match exactly what the brain
would receive if its owner were walking
1126
01:38:40,651 -->
01:38:45,610
down a street, eating dinner, or talking
to a friend.
1127
01:38:48,070 -->
01:38:54,010
The brain has the full experience of a
normal day, the colours, the voices,
1128
01:38:54,725 -->
01:38:56,630
the feel of the pavement.
1129
01:38:57,630 -->
01:39:01,038
It can't tell anything is
wrong, because every
1130
01:39:01,039 -->
01:39:04,070
sense it has comes
through that one cable.
1131
01:39:06,290 -->
01:39:08,310
Then Putnam stretches it.
1132
01:39:09,055 -->
01:39:13,230
Suppose the person who did this isn't even
there anymore.
1133
01:39:14,660 -->
01:39:19,550
Suppose every thinking being in the
universe is a brain in a vat, and the
1134
01:39:19,551 -->
01:39:25,750
computer feeding them runs on its own,
with no scientist and no plan.
1135
01:39:27,130 -->
01:39:29,010
That's just how things are.
1136
01:39:31,090 -->
01:39:35,510
Now comes the twist, and it's the part
that made the example famous.
1137
01:39:36,290 -->
01:39:42,910
Putnam asks could a brain in a vat say
truthfully I am a brain in a vat?
1138
01:39:43,785 -->
01:39:45,150
His answer is no.
1139
01:39:45,735 -->
01:39:47,470
Think about what words do.
1140
01:39:49,710 -->
01:39:56,950
When you say the word tree, it points at
trees, because trees, over a long chain of
1141
01:39:56,951 -->
01:40:02,470
events, have actually affected the people
who taught you the word.
1142
01:40:03,815 -->
01:40:07,070
Words reach out to real things through
real contact.
1143
01:40:09,040 -->
01:40:14,470
But a brain in a vat has never met a tree,
or a vat.
1144
01:40:15,010 -->
01:40:18,570
Every tree it has ever seen was a pattern
of signals.
1145
01:40:19,410 -->
01:40:23,250
So when it says tree, the word connects to
those patterns.
1146
01:40:24,740 -->
01:40:28,534
And when it says vat,
the word connects to the
1147
01:40:28,535 -->
01:40:32,530
pattern of a vat, not to
the real thing it sits in.
1148
01:40:35,105 -->
01:40:42,350
The sentence, I am a brain in a vat,
spoken from inside, can never touch the
1149
01:40:42,550 -->
01:40:44,090
facts it claims to describe.
1150
01:40:46,190 -->
01:40:51,750
Putnam thought this showed the idea
defeated itself, and philosophers have
1151
01:40:51,751 -->
01:40:55,190
been arguing about whether he's right ever
since.
1152
01:40:58,025 -->
01:41:03,000
Whatever the verdict, notice where the
self sits in his picture.
1153
01:41:04,650 -->
01:41:11,040
You are still a brain, you're still a lump
of living tissue in a physical container,
1154
01:41:11,485 -->
01:41:14,660
made of the same matter as everything
else.
1155
01:41:15,920 -->
01:41:21,380
The deception is total, but the one being
deceived is a physical object.
1156
01:41:23,315 -->
01:41:27,460
Nothing in the setup suggests there's
anything more to you than that.
1157
01:41:29,430 -->
01:41:32,864
And this is a picture you
already know, because
1158
01:41:32,865 -->
01:41:35,920
a film took it and
put it on every screen.
1159
01:41:37,820 -->
01:41:44,240
In The Matrix, people lie in pods,
their bodies kept alive by machines,
1160
01:41:44,385 -->
01:41:47,760
while a shared computer world plays in
their heads.
1161
01:41:49,060 -->
01:41:53,760
That's Putnam's vat, enlarged to the size
of a civilization.
1162
01:41:56,940 -->
01:42:04,940
In 1988, a robotics researcher at Carnegie
Mellon University named Hans Moravec
1163
01:42:05,240 -->
01:42:08,540
published a book called Mind Children.
1164
01:42:10,900 -->
01:42:15,960
Moravec had spent years building robots
that could find their way around a room,
1165
01:42:16,810 -->
01:42:19,700
and he'd begun to think about where the
work was heading.
1166
01:42:20,840 -->
01:42:25,540
His book gives a surprising answer,
toward us.
1167
01:42:28,180 -->
01:42:33,300
His central idea is that the mind is a
pattern, not a substance.
1168
01:42:34,560 -->
01:42:38,821
What makes you you
isn't the particular atoms in
1169
01:42:38,822 -->
01:42:42,440
your skull, which are
replaced all the time anyway.
1170
01:42:43,295 -->
01:42:48,180
It's the arrangement, the way signals flow
between your brain cells.
1171
01:42:49,500 -->
01:42:55,200
If that's true, the pattern could in
principle live somewhere else.
1172
01:42:56,890 -->
01:42:59,740
To show how, he describes a procedure.
1173
01:43:00,800 -->
01:43:04,340
Imagine a surgeon with a very fine robotic
instrument.
1174
01:43:05,850 -->
01:43:09,320
You're lying awake on the table,
fully conscious.
1175
01:43:11,310 -->
01:43:16,242
The machine takes one neuron,
one brain cell, and replaces
1176
01:43:16,243 -->
01:43:20,120
it with a tiny circuit that
does exactly the same job.
1177
01:43:21,395 -->
01:43:26,080
It receives the same signals, and sends
the same signals onward.
1178
01:43:26,965 -->
01:43:28,600
You feel nothing different.
1179
01:43:31,135 -->
01:43:35,280
Then the machine replaces a second neuron,
then a third.
1180
01:43:35,885 -->
01:43:38,500
After a thousand, nothing has changed.
1181
01:43:39,260 -->
01:43:45,760
After a million, you're still talking,
still thinking, still the same person,
1182
01:43:46,230 -->
01:43:47,540
and you'd say so.
1183
01:43:49,670 -->
01:43:53,643
Keep going, and eventually
every neuron has been
1184
01:43:53,644 -->
01:43:57,080
swapped, and your whole
mind runs on a machine.
1185
01:43:58,140 -->
01:44:00,340
At no point did you cross a line.
1186
01:44:01,185 -->
01:44:05,560
At no point did you notice a moment of
death, or of change.
1187
01:44:06,485 -->
01:44:09,580
The pattern stayed, and so you stayed.
1188
01:44:11,980 -->
01:44:18,080
Once a mind is a pattern running on a
machine, new things become possible.
1189
01:44:18,760 -->
01:44:22,231
It can be copied the
way a file is copied,
1190
01:44:22,232 -->
01:44:25,420
and the copy wakes up
with all the memories.
1191
01:44:26,970 -->
01:44:29,560
It can be saved in case of an accident.
1192
01:44:32,020 -->
01:44:37,680
And it can be given a world to live in,
a place built entirely of computation,
1193
01:44:38,700 -->
01:44:44,920
since a mind made of circuits has no
particular need for a body made of flesh.
1194
01:44:48,030 -->
01:44:53,240
Moravec described a future where human
minds step out of their bodies,
1195
01:44:54,160 -->
01:44:58,500
and into whatever environments they or
their descendants choose to build.
1196
01:45:01,650 -->
01:45:07,230
Remember that Descartes put the self outside
the machinery, a ghost in the mechanism.
1197
01:45:08,850 -->
01:45:10,610
Moravec does the opposite.
1198
01:45:11,670 -->
01:45:13,050
For him there is no ghost.
1199
01:45:13,830 -->
01:45:17,490
The self is the pattern, and a pattern can
be moved.
1200
01:45:19,530 -->
01:45:23,270
That idea is the foundation for what comes
next.
1201
01:45:25,210 -->
01:45:30,530
Moravec's thought that a mind can run on
anything that holds the right pattern,
1202
01:45:31,730 -->
01:45:37,090
is the one assumption on which the modern
simulation argument depends.
1203
01:45:38,135 -->
01:45:43,690
If it's true, then a simulated person is
as real as you are.
1204
01:45:45,145 -->
01:45:49,890
And the philosopher who built the whole
argument on top of it was waiting,
1205
01:45:50,300 -->
01:45:52,310
just fifteen years ahead.
1206
01:45:54,670 -->
01:46:00,530
Let's follow a single word through this
story, because it has travelled a long way.
1207
01:46:02,190 -->
01:46:08,050
The word is avatar, and you've used it if
you've ever picked a character for a game.
1208
01:46:08,950 -->
01:46:15,070
It comes from Sanskrit, from the word
avatara, which means descent.
1209
01:46:17,310 -->
01:46:23,570
In the Hindu tradition, it names the
moment a god comes down into the world,
1210
01:46:23,894 -->
01:46:25,170
and takes a body.
1211
01:46:26,710 -->
01:46:33,070
Vishnu, the preserver of the universe,
does this whenever balance breaks down,
1212
01:46:33,820 -->
01:46:35,570
and the world needs setting right.
1213
01:46:38,125 -->
01:46:43,190
He comes as Rama, a prince who rescues his
wife from a demon king.
1214
01:46:44,710 -->
01:46:48,040
He comes as Krishna,
the charioteer who speaks
1215
01:46:48,041 -->
01:46:50,570
to a frightened
warrior on a battlefield.
1216
01:46:51,294 -->
01:46:53,330
The god is not the body.
1217
01:46:54,090 -->
01:47:00,690
The god steps into the body, acts through
it, and remains Vishnu the whole time.
1218
01:47:03,500 -->
01:47:08,994
In the 1980s, the people
designing the first online worlds
1219
01:47:08,995 -->
01:47:13,050
needed a name for the figure
a player controls on screen.
1220
01:47:14,625 -->
01:47:16,090
They reached for this one.
1221
01:47:17,075 -->
01:47:21,110
It fit, because a player does what Vishnu
does.
1222
01:47:22,230 -->
01:47:28,670
A being from outside the world descends
into a form inside it, and moves through it.
1223
01:47:31,090 -->
01:47:39,090
Then in 1992, the novelist Neil Stephenson
published Snow Crash, set partly in a
1224
01:47:39,091 -->
01:47:45,370
shared virtual world he called The Metaverse,
where everyone appears as an avatar.
1225
01:47:47,269 -->
01:47:50,390
The book was a hit, and the word went with
it.
1226
01:47:52,130 -->
01:47:56,560
Now a child choosing a
hat for a cartoon fox uses a
1227
01:47:56,561 -->
01:48:00,270
word that once described
a god entering the world.
1228
01:48:03,530 -->
01:48:10,810
Seven years later, in 1999, the idea reached
the biggest audience it had ever had.
1229
01:48:12,770 -->
01:48:18,930
In The Matrix, a programmer named Neo is
offered a choice by a stranger in black.
1230
01:48:19,930 -->
01:48:25,650
He can swallow a blue pill and go back to
his ordinary life, or swallow a red pill
1231
01:48:25,850 -->
01:48:27,150
and see the truth.
1232
01:48:29,050 -->
01:48:36,950
He takes the red one, and wakes in a slimy
pod, one of millions, each holding a human
1233
01:48:36,951 -->
01:48:43,230
body fed through tubes while a shared
computer world plays in the sleeper's mind.
1234
01:48:44,420 -->
01:48:47,330
It's Putnam's Vat on an industrial scale.
1235
01:48:49,750 -->
01:48:54,890
Early in the film, Neo takes down a
hollowed-out book to hide a disc.
1236
01:48:56,945 -->
01:49:03,250
It's a real book, Simulacra and
Simulation, by the French thinker Jean
1237
01:49:03,251 -->
01:49:09,470
Baudrillard, who argued that modern life
is filled with copies that have no
1238
01:49:09,471 -->
01:49:13,610
original, images that refer only to other
images.
1239
01:49:14,700 -->
01:49:17,670
The filmmakers asked their cast to read
it.
1240
01:49:19,445 -->
01:49:23,130
Baudrillard later said the film had
misunderstood him.
1241
01:49:24,730 -->
01:49:26,890
Still, the shot stayed.
1242
01:49:27,670 -->
01:49:31,410
A book about fake worlds holding the door
to a hidden one.
1243
01:49:32,920 -->
01:49:37,650
A year later, in 2000 came something much
quieter.
1244
01:49:39,025 -->
01:49:42,790
A game designer named Will Wright released
The Sims.
1245
01:49:43,930 -->
01:49:47,695
The player looks down on
a suburban house full of tiny
1246
01:49:47,696 -->
01:49:52,170
people, each with a set of
needs shown as bars on a screen.
1247
01:49:53,085 -->
01:49:57,490
Hunger, sleep, a bathroom, company,
fun.
1248
01:49:58,360 -->
01:50:02,050
If the bars drop too low, the little
person suffers.
1249
01:50:04,635 -->
01:50:09,530
The player decides what they eat,
where they work and who they befriend.
1250
01:50:11,710 -->
01:50:18,070
They speak in a made-up gibberish called
Simlish, so nobody can read their words
1251
01:50:18,660 -->
01:50:22,490
and everybody can read their moods.
1252
01:50:22,990 -->
01:50:29,890
Wright drew on an unlikely source,
a book on architecture called A Pattern
1253
01:50:29,891 -->
01:50:36,550
Language by Christopher Alexander,
which describes how small, repeating
1254
01:50:36,551 -->
01:50:40,690
arrangements of rooms and streets make a
place feel alive.
1255
01:50:42,275 -->
01:50:46,390
And players, being players, did what
players do.
1256
01:50:48,340 -->
01:50:50,210
They built cruel experiments.
1257
01:50:51,810 -->
01:50:56,970
A famous one is to put a sim in the
swimming pool and remove the ladder,
1258
01:50:57,955 -->
01:50:59,010
and then watch.
1259
01:51:00,145 -->
01:51:03,670
The sim swims until it tires and there's
nothing to climb.
1260
01:51:04,670 -->
01:51:09,724
Millions of people spent
their evenings running small
1261
01:51:09,725 -->
01:51:13,330
lives inside a world they
controlled completely.
1262
01:51:15,190 -->
01:51:20,110
It's an easy step from there to a question
nobody could stop asking.
1263
01:51:21,525 -->
01:51:24,050
What if somebody is doing this with us?
1264
01:51:26,470 -->
01:51:31,770
And if you've ever played a game long enough,
you know it follows you into the dark.
1265
01:51:34,130 -->
01:51:40,730
In 2000, a sleep researcher at Harvard
named Robert Stickgold ran an experiment.
1266
01:51:42,490 -->
01:51:47,370
He had volunteers play Tetris,
the game of falling colored blocks,
1267
01:51:48,255 -->
01:51:51,030
for several hours a day over three days.
1268
01:51:52,210 -->
01:51:58,510
Then he woke them as they were drifting
off to sleep and asked what they saw.
1269
01:52:00,495 -->
01:52:02,930
Many of them reported the same thing.
1270
01:52:04,430 -->
01:52:09,110
Blocks drifting down behind their closed
eyes, turning and fitting.
1271
01:52:12,200 -->
01:52:18,400
Even a few patients with severe amnesia
who couldn't remember having played at all
1272
01:52:18,500 -->
01:52:19,960
saw the falling shapes.
1273
01:52:20,840 -->
01:52:22,520
It's called the Tetris Effect.
1274
01:52:24,180 -->
01:52:30,180
Your mind carries the rules of the world
you've been living in right into sleep.
1275
01:52:32,120 -->
01:52:40,000
Now let's talk about 2003 and a
philosopher named Nick Bostrom.
1276
01:52:41,360 -->
01:52:46,580
He was born in Sweden, studied physics,
neuroscience and philosophy.
1277
01:52:47,780 -->
01:52:51,844
And by his early 30s he
was teaching at the University
1278
01:52:51,894 -->
01:52:55,660
of Oxford, where he
spent most of his career.
1279
01:52:57,460 -->
01:53:01,540
His interests ran to large and slightly
alarming subjects.
1280
01:53:02,690 -->
01:53:08,640
The long term future of humanity,
the risks that could end it, and what
1281
01:53:08,840 -->
01:53:11,020
happens when minds can be built.
1282
01:53:12,385 -->
01:53:18,540
In 2003 he published a paper in a
respected academic journal, The
1283
01:53:18,541 -->
01:53:23,440
Philosophical Quarterly, with a title that
reads like a dare.
1284
01:53:26,165 -->
01:53:29,120
Are you living in a computer simulation?
1285
01:53:31,815 -->
01:53:36,041
Up to here everything
we have talked about has
1286
01:53:36,042 -->
01:53:39,880
been a story, a dream,
an image or a hunch.
1287
01:53:42,085 -->
01:53:45,020
Bostrom's paper is different because it's
an argument.
1288
01:53:45,820 -->
01:53:52,180
It starts from a few assumptions and
walks, one step at a time, to a conclusion.
1289
01:53:53,540 -->
01:53:59,300
So let's look at the assumptions first,
because the whole structure stands on them.
1290
01:54:01,380 -->
01:54:04,240
The first is that computing power keeps
growing.
1291
01:54:05,950 -->
01:54:07,480
You've lived through this.
1292
01:54:08,790 -->
01:54:13,620
The phone in your pocket is more powerful
than the room sized machines that guided
1293
01:54:13,845 -->
01:54:15,040
astronauts to the moon.
1294
01:54:18,260 -->
01:54:23,600
Each generation of hardware does more,
faster, in less space.
1295
01:54:25,970 -->
01:54:32,140
Bostrom asks you to imagine that this goes
on for a very long time, thousands of
1296
01:54:32,141 -->
01:54:36,116
years or more, until
a civilization can build
1297
01:54:36,117 -->
01:54:39,880
computers on a scale
we'd find hard to picture.
1298
01:54:41,300 -->
01:54:47,440
Machines the size of planets built from
the best materials physics allows.
1299
01:54:50,035 -->
01:54:55,480
The second assumption is the one we met
with Moravec, and it has a name,
1300
01:54:56,465 -->
01:54:57,740
substrate independence.
1301
01:54:59,260 -->
01:55:02,660
A substrate is the material something runs
on.
1302
01:55:04,055 -->
01:55:10,360
The claim is that consciousness doesn't
depend on what its machinery is made of.
1303
01:55:12,180 -->
01:55:17,600
A mind is a pattern of activity,
and if you reproduce the pattern in enough
1304
01:55:17,800 -->
01:55:22,241
detail, you get the mind
whether the pattern runs on
1305
01:55:22,242 -->
01:55:27,660
the soft, wet tissue of a
brain or on silicon chips.
1306
01:55:30,310 -->
01:55:38,060
If that's right, then a simulated person
built from numbers inside a computer would
1307
01:55:38,061 -->
01:55:44,240
really feel pain, really see colours,
and really wonder about the world.
1308
01:55:45,820 -->
01:55:47,760
Bostrom doesn't prove this.
1309
01:55:48,400 -->
01:55:52,318
He says it's a widely held
position in the philosophy
1310
01:55:52,319 -->
01:55:55,100
of mind, and he takes
it as his starting point.
1311
01:55:58,510 -->
01:56:04,710
Now comes the part that makes the argument
feel less like science fiction and more
1312
01:56:04,860 -->
01:56:05,860
like bookkeeping.
1313
01:56:06,790 -->
01:56:12,530
How much computing would it take to
simulate every human mind that ever lived?
1314
01:56:14,525 -->
01:56:16,770
Bostrom actually runs the numbers.
1315
01:56:18,620 -->
01:56:24,850
He estimates the brain's activity at
somewhere between 10 to the power of 14
1316
01:56:25,950 -->
01:56:30,450
and 10 to the power of 17 operations per
second.
1317
01:56:32,330 -->
01:56:38,070
Multiply that by the number of people who
have ever lived and by the length of a
1318
01:56:38,071 -->
01:56:43,330
human life, and you reach a total for the
entire mental history of humankind.
1319
01:56:44,870 -->
01:56:50,830
Roughly 10 to the 33rd to 10 to the 36th
operations.
1320
01:56:52,780 -->
01:56:56,550
That's a one followed by 33 or more zeros.
1321
01:56:58,050 -->
01:57:05,310
It sounds impossibly large, but set it
beside the machine he has in mind.
1322
01:57:06,650 -->
01:57:12,680
A computer the size of a
planet, he calculates, could carry
1323
01:57:12,755 -->
01:57:16,570
out about 10 to the 40
second operations every second.
1324
01:57:17,875 -->
01:57:19,030
Do the division.
1325
01:57:20,590 -->
01:57:26,210
One such machine could run the whole
mental history of humankind in a tiny
1326
01:57:26,211 -->
01:57:32,370
fraction of a second, and then do it again
and again, millions of times over.
1327
01:57:35,510 -->
01:57:42,290
If a civilisation built a single machine
like that and devoted even a sliver of its
1328
01:57:42,291 -->
01:57:46,758
power to the project, it
could hold more simulated
1329
01:57:46,759 -->
01:57:50,390
lives than have ever
been lived in the flesh.
1330
01:57:53,170 -->
01:57:59,050
You might object that simulating an entire
universe, every atom, every distant star
1331
01:57:59,350 -->
01:58:00,990
would cost far more.
1332
01:58:02,875 -->
01:58:05,750
Bostrom's answer is that it wouldn't need
to.
1333
01:58:06,615 -->
01:58:11,290
A simulation only has to be convincing to
the minds inside it.
1334
01:58:12,500 -->
01:58:17,690
The far side of the moon doesn't have to
be drawn until someone looks.
1335
01:58:19,050 -->
01:58:23,979
The inside of a rock
needn't exist in detail until
1336
01:58:23,980 -->
01:58:27,250
someone breaks it open or
puts it under a microscope.
1337
01:58:31,140 -->
01:58:34,050
Only what is being observed has to be
rendered.
1338
01:58:35,225 -->
01:58:38,350
And the rest can stay in cheap,
rough outline.
1339
01:58:39,800 -->
01:58:43,717
It's the same trick a video
game uses when it draws
1340
01:58:43,718 -->
01:58:46,710
only the part of the world
in front of the camera.
1341
01:58:49,330 -->
01:58:55,770
So Bostrom has a machine of nearly
unlimited power minds that can run on it,
1342
01:58:56,110 -->
01:58:58,950
and a method for keeping the cost low.
1343
01:59:00,805 -->
01:59:02,370
What does he do with them?
1344
01:59:03,770 -->
01:59:07,341
That's the question the
next part answers and it's
1345
01:59:07,342 -->
01:59:10,150
the reason his paper
changed the conversation.
1346
01:59:12,780 -->
01:59:15,630
Here is where Bostrom puts the pieces
together.
1347
01:59:16,530 -->
01:59:21,982
He has a machine of nearly
unlimited power minds that can
1348
01:59:21,983 -->
01:59:26,270
run on it, and a cheap way to
build the world around them.
1349
01:59:27,430 -->
01:59:32,340
From those he draws a conclusion and it
takes the form of three statements.
1350
01:59:34,010 -->
01:59:37,790
At least one of them, he says,
has to be true.
1351
01:59:40,090 -->
01:59:44,636
The first is that almost
no civilization at our level
1352
01:59:44,637 -->
01:59:48,690
survives long enough to
become technologically mature.
1353
01:59:49,940 -->
01:59:57,690
Something stops them first, a war,
a plague, a disaster of their own making,
1354
01:59:58,160 -->
02:00:01,750
and they never build the planet-sized
computers at all.
1355
02:00:03,970 -->
02:00:08,561
The second is that mature
civilizations do exist, but almost
1356
02:00:08,562 -->
02:00:13,410
none of them run detailed
simulations of their ancestors.
1357
02:00:15,010 -->
02:00:21,450
They have the power and simply choose to
spend it on other things.
1358
02:00:22,775 -->
02:00:26,130
The third is that we are almost certainly
living in a simulation.
1359
02:00:29,015 -->
02:00:31,850
The logic behind the third is a matter of
counting.
1360
02:00:33,845 -->
02:00:40,250
Suppose even a small fraction of mature
civilizations do run ancestor simulations.
1361
02:00:42,060 -->
02:00:48,290
Each one can run enormous numbers of them
because the machine is so powerful.
1362
02:00:49,410 -->
02:00:53,347
Soon the simulated people
outnumber the original flesh
1363
02:00:53,348 -->
02:00:58,350
and blood people by thousands
to one, or millions to one.
1364
02:01:01,105 -->
02:01:03,540
Now ask yourself which kind you are.
1365
02:01:04,485 -->
02:01:09,200
If you can't tell from the inside,
the odds say you're one of the many.
1366
02:01:11,190 -->
02:01:14,180
Notice what Bostrom is not saying.
1367
02:01:15,470 -->
02:01:19,240
He never claims the third statement is the
true one.
1368
02:01:20,350 -->
02:01:23,280
He claims only that one of the three must
be.
1369
02:01:24,335 -->
02:01:29,060
And when he looks at them, he finds no
strong reason to prefer any.
1370
02:01:30,590 -->
02:01:34,900
He suggests spreading your belief roughly
evenly among them.
1371
02:01:35,895 -->
02:01:42,360
The first is a grim thought, because it
would mean humanity probably won't make it.
1372
02:01:44,680 -->
02:01:48,545
The second would mean
that advanced civilizations
1373
02:01:48,546 -->
02:01:52,540
all converge on losing
interest in the same project.
1374
02:01:54,200 -->
02:01:58,260
And the third is the one the newspaper
seized on.
1375
02:02:00,700 -->
02:02:04,326
Headlines announced
that an Oxford philosopher
1376
02:02:04,327 -->
02:02:07,220
had declared, we live
in a computer program.
1377
02:02:08,440 -->
02:02:10,500
And that isn't what the paper says.
1378
02:02:12,440 -->
02:02:17,540
He wrote a trillema and the press quietly
deleted two thirds of it.
1379
02:02:19,690 -->
02:02:25,640
Now follow the third option further,
because it opens a staircase going down.
1380
02:02:27,710 -->
02:02:31,956
If our world is a simulation,
the beings who built it might
1381
02:02:31,957 -->
02:02:36,680
themselves be inside one, and
so might the beings above them.
1382
02:02:37,500 -->
02:02:44,460
Worlds could sit inside worlds, layer on
layer, and a stack like that carries a risk.
1383
02:02:47,000 -->
02:02:51,019
Every simulation within
a simulation draws on
1384
02:02:51,020 -->
02:02:54,580
the power of whatever
machine lies at the bottom.
1385
02:02:56,085 -->
02:03:02,620
If one of the simulated civilizations grew
advanced enough to begin running
1386
02:03:02,720 -->
02:03:08,520
simulations of its own, the cost to the
layer below could pile up.
1387
02:03:10,355 -->
02:03:14,940
Whoever runs the lowest level might simply
shut the whole program down.
1388
02:03:16,410 -->
02:03:23,040
So the very success of a simulated world,
its progress toward building simulations,
1389
02:03:24,675 -->
02:03:26,800
could be the thing that ends it.
1390
02:03:29,460 -->
02:03:33,720
Then there's the matter of who the
simulators would be, look at their
1391
02:03:33,721 -->
02:03:39,220
position, they'd have built the world,
and they'd see everything in it.
1392
02:03:40,360 -->
02:03:46,080
They could change the rules, pause time,
or reverse a death.
1393
02:03:48,430 -->
02:03:54,240
They could, if they wished, lift a mind
out of one simulation when it ended,
1394
02:03:54,980 -->
02:03:59,160
and set it down in another, which would
amount to an afterlife.
1395
02:04:00,395 -->
02:04:02,900
Bostrom points this out himself.
1396
02:04:06,170 -->
02:04:11,370
The builders of a simulation would stand
to the people inside it in a relation,
1397
02:04:12,070 -->
02:04:14,590
very like the one we've given to gods.
1398
02:04:16,090 -->
02:04:20,680
All powerful within the
world, hidden from it,
1399
02:04:20,681 -->
02:04:24,130
and not necessarily the
final source of anything.
1400
02:04:26,560 -->
02:04:29,230
You've met that figure before in this
story.
1401
02:04:31,570 -->
02:04:36,774
It's Yaldabaoth, the ignorant
lesser creator of the Gnostics,
1402
02:04:36,775 -->
02:04:39,850
who builds a world and
rules it from behind a cloud.
1403
02:04:40,905 -->
02:04:44,170
Certain, he is the only god there is.
1404
02:04:44,960 -->
02:04:51,350
It's also the company in Galoi's novel,
running its simulated city, and studying
1405
02:04:51,575 -->
02:04:53,550
the people in it for profit.
1406
02:04:56,940 -->
02:05:00,865
Bostrom reached the same
old picture by a new road, with
1407
02:05:00,890 -->
02:05:04,310
computing power, where
the Gnostics had divine error.
1408
02:05:06,690 -->
02:05:13,450
One more thing needs saying plainly,
because the entire argument depends on it.
1409
02:05:15,490 -->
02:05:18,817
Everything Bostrom builds
rests on the assumption
1410
02:05:18,818 -->
02:05:21,430
that computation can
produce consciousness.
1411
02:05:23,350 -->
02:05:29,470
If a program running on a chip can really
feel, then simulated people are people,
1412
02:05:30,070 -->
02:05:31,570
and the counting works.
1413
02:05:34,420 -->
02:05:41,330
If it can't, then a simulation would be a
stage full of empty costumes, with nobody
1414
02:05:41,331 -->
02:05:45,230
inside to be fooled, and the third
statement collapses.
1415
02:05:47,370 -->
02:05:49,970
The argument's strength is its arithmetic.
1416
02:05:50,840 -->
02:05:55,870
Its weakness is that no one has shown the
assumption is true.
1417
02:05:57,610 -->
02:06:04,230
If you want a picture of how this feels,
stand between two mirrors that face each
1418
02:06:04,231 -->
02:06:08,410
other, in a barber shop or a hotel
hallway.
1419
02:06:09,350 -->
02:06:16,510
You see yourself, and behind you another
you, and behind that a third, each a
1420
02:06:16,560 -->
02:06:21,410
little smaller and dimmer, a corridor of
reflections curving away.
1421
02:06:22,660 -->
02:06:28,710
You can't see where it ends, and you can't
tell which of the figures is the first one.
1422
02:06:30,040 -->
02:06:35,610
You only know that from where you stand,
any of them might be.
1423
02:06:37,780 -->
02:06:39,790
Let's go to 2016.
1424
02:06:41,515 -->
02:06:46,450
The year the idea leaves the lecture hall,
and walks out into the street.
1425
02:06:47,550 -->
02:06:54,110
Two events that spring and summer did most
of the work, one in a museum, and one in a
1426
02:06:54,285 -->
02:06:55,610
hotel conference room.
1427
02:06:58,285 -->
02:07:00,010
The museum came first.
1428
02:07:01,210 -->
02:07:07,490
In April, the American Museum of Natural
History in New York held its annual Isaac
1429
02:07:07,491 -->
02:07:11,366
Asimov Memorial Debate,
named after the science
1430
02:07:11,367 -->
02:07:15,530
fiction writer who spent
his career imagining futures.
1431
02:07:17,025 -->
02:07:19,590
The host was Neil deGrasse Tyson.
1432
02:07:21,875 -->
02:07:29,030
The astrophysicist who runs the museum's
planetarium and is probably the most
1433
02:07:29,031 -->
02:07:31,910
recognizable scientist on American
television.
1434
02:07:34,360 -->
02:07:36,450
The question on the program was blunt.
1435
02:07:37,795 -->
02:07:39,830
Is the universe a simulation?
1436
02:07:40,894 -->
02:07:43,670
Tyson put together a panel to argue it
out.
1437
02:07:46,030 -->
02:07:50,344
There was David Chalmers,
the philosopher we'll meet
1438
02:07:50,444 -->
02:07:53,550
again when we reach the
problem of consciousness.
1439
02:07:54,890 -->
02:07:59,814
There was Max Tegmark, a
cosmologist at MIT who has
1440
02:07:59,815 -->
02:08:03,730
written about the universe
as a mathematical structure.
1441
02:08:05,460 -->
02:08:08,550
There was Lisa Randall, a Harvard
physicist.
1442
02:08:10,010 -->
02:08:15,976
There was Zorid Avudi, a young
physicist who had co-written
1443
02:08:15,977 -->
02:08:19,710
a paper on how a simulated
universe might be detected.
1444
02:08:20,950 -->
02:08:26,147
And there was James Gates,
a theoretical physicist who
1445
02:08:26,148 -->
02:08:30,810
works on a branch of
mathematics called supersymmetry.
1446
02:08:33,330 -->
02:08:39,750
The room was full and the mood was not what
you'd expect from a stuffy academic panel.
1447
02:08:41,765 -->
02:08:47,530
Tyson opened the evening by saying that
he'd put the odds at about 50-50.
1448
02:08:49,260 -->
02:08:54,370
He said he found it hard to think of a
strong argument against the idea,
1449
02:08:55,320 -->
02:08:59,695
and that the more he
thought about how far our own
1450
02:08:59,696 -->
02:09:03,650
technology had come,
the less he could dismiss it.
1451
02:09:04,550 -->
02:09:08,960
Coming from a man known
for calm skepticism, that
1452
02:09:08,961 -->
02:09:12,510
was a startling thing to
say in front of a crowd.
1453
02:09:14,950 -->
02:09:16,410
Randall pushed back.
1454
02:09:18,070 -->
02:09:23,690
She argued that nothing in physics gave a
reason to take the possibility seriously,
1455
02:09:24,590 -->
02:09:28,407
and that a hypothesis with
no way of being checked
1456
02:09:28,408 -->
02:09:31,130
wasn't worth much of
the audience's evening.
1457
02:09:32,615 -->
02:09:35,450
That disagreement ran through the whole
debate.
1458
02:09:37,710 -->
02:09:43,110
One side pointing at the logic,
the other at the lack of evidence.
1459
02:09:46,019 -->
02:09:49,250
Then Gates told a story that made the room
go quiet.
1460
02:09:51,130 -->
02:09:57,110
In his work on supersymmetry, a set of
equations that physicists used to describe
1461
02:09:57,111 -->
02:10:01,748
how the basic particles
of nature relate to one
1462
02:10:01,749 -->
02:10:06,330
another, he had come across
something he didn't expect.
1463
02:10:09,410 -->
02:10:15,090
Buried in the mathematics were patterns
that matched error-correcting codes.
1464
02:10:17,470 -->
02:10:23,470
These are the tools a computer uses to
catch and fix mistakes when it sends data,
1465
02:10:24,290 -->
02:10:30,490
the reason a scratch disc can still play
and a garbled message can still be read.
1466
02:10:33,265 -->
02:10:35,630
Gates was careful about what he claimed.
1467
02:10:36,660 -->
02:10:39,070
He didn't say it proved a simulation.
1468
02:10:40,070 -->
02:10:43,478
He said he'd found
strings of computer code
1469
02:10:43,479 -->
02:10:47,170
inside the equations
that describe the universe.
1470
02:10:48,825 -->
02:10:51,810
And he couldn't explain why they were
there.
1471
02:10:54,515 -->
02:11:00,310
A few weeks later, in June, the idea got
its loudest champion.
1472
02:11:01,820 -->
02:11:06,770
At the code conference, a technology
gathering held near Los Angeles,
1473
02:11:07,350 -->
02:11:13,090
someone in the audience asked Elon Musk
whether we might be living in a simulation.
1474
02:11:14,345 -->
02:11:17,070
Musk had thought about it a great deal.
1475
02:11:18,135 -->
02:11:20,770
He said his case came from watching games.
1476
02:11:22,810 -->
02:11:28,690
Forty years ago, he told the crowd,
the best video game in the world was Pong.
1477
02:11:29,545 -->
02:11:32,830
Two rectangles and a dot bouncing between
them.
1478
02:11:34,500 -->
02:11:42,250
Now, four decades later, we have games
with photorealistic three-dimensional
1479
02:11:42,251 -->
02:11:48,970
worlds played by millions of people at once
and the improvement hasn't slowed down.
1480
02:11:50,665 -->
02:11:54,750
Imagine that continuing for another
thousand years or ten thousand.
1481
02:11:56,240 -->
02:12:01,190
Games, he said, will become
indistinguishable from reality.
1482
02:12:03,290 -->
02:12:08,730
And if that's where games are headed,
then either civilizations like ours stop
1483
02:12:08,731 -->
02:12:14,690
before they get there or such games exist
in vast numbers.
1484
02:12:16,310 -->
02:12:21,090
Put those together and the chance that
we're living in what he called base
1485
02:12:21,510 -->
02:12:29,510
reality, the original unsimulated world,
is, in his words, one in billions.
1486
02:12:32,020 -->
02:12:33,490
The clip went everywhere.
1487
02:12:34,395 -->
02:12:39,955
It was short, confident and
easy to repeat and a billionaire
1488
02:12:39,956 -->
02:12:44,870
who builds rockets and electric
cars had said it on a stage.
1489
02:12:47,215 -->
02:12:50,433
Within days it had been
watched by millions of
1490
02:12:50,434 -->
02:12:53,250
people who had never
read a page of Bostrom.
1491
02:12:55,600 -->
02:12:59,370
That's the strange fate of the year in
2016.
1492
02:13:00,855 -->
02:13:05,250
Open any video app now and you can fall
into it.
1493
02:13:06,165 -->
02:13:11,170
Between the cooking videos and the
football highlights, there's a clip of a
1494
02:13:11,171 -->
02:13:15,810
physicist shrugging, another of a tech
executive grinning.
1495
02:13:17,065 -->
02:13:21,330
A third of two strangers
arguing in a podcast
1496
02:13:21,331 -->
02:13:24,490
studio about whether
the sky is rendered.
1497
02:13:27,450 -->
02:13:34,470
A question that once lived in a Chinese
dream and a Greek cave now arrives between
1498
02:13:34,471 -->
02:13:39,690
advertisements with a thumbnail of
someone's astonished face.
1499
02:13:41,450 -->
02:13:47,410
If the idea is a real claim about the
world, someone should be able to check it
1500
02:13:47,510 -->
02:13:52,370
and, in 2012-3, physicists proposed a way.
1501
02:13:53,930 -->
02:13:58,300
Silas Bean, Zora Davudi,
and Martin Savage had
1502
02:13:58,301 -->
02:14:02,650
spent years doing a kind
of simulating themselves.
1503
02:14:05,030 -->
02:14:11,350
Physicists who study the forces inside
atomic nuclei can't solve the equations by
1504
02:14:11,351 -->
02:14:19,010
hand, so they put space onto a fine grid
inside a computer, a lattice of points,
1505
02:14:20,180 -->
02:14:23,970
and let the machine work out how particles
behave on it.
1506
02:14:25,150 -->
02:14:28,850
The grid is an approximation and it leaves
marks.
1507
02:14:30,390 -->
02:14:34,956
Smaller spacing gives a
better picture, but a trace
1508
02:14:34,957 -->
02:14:38,530
of the grid's shape always
remains in the results.
1509
02:14:40,740 -->
02:14:42,730
So the three asked a simple question.
1510
02:14:43,920 -->
02:14:49,770
Suppose our own universe were run the same
way on a lattice with limited resolution.
1511
02:14:50,970 -->
02:14:53,290
Would the grid leave a trace we could
find?
1512
02:14:54,180 -->
02:14:55,850
They worked out that it would.
1513
02:15:00,950 -->
02:15:08,210
The most energetic particles in nature are
cosmic rays which are atomic nuclei flung
1514
02:15:08,211 -->
02:15:12,640
through space at nearly
the speed of light, and the
1515
02:15:12,641 -->
02:15:16,570
very fastest of them would
feel the grid most strongly.
1516
02:15:18,200 -->
02:15:25,150
If space were a lattice, those rays would
show a slight preference for travelling
1517
02:15:25,375 -->
02:15:32,470
along the grid's own directions and the
pattern of where they arrive from would be
1518
02:15:32,570 -->
02:15:35,910
lopsided in a specific way.
1519
02:15:37,800 -->
02:15:40,970
That is a real prediction and it can fail.
1520
02:15:42,070 -->
02:15:43,350
So far it has.
1521
02:15:44,360 -->
02:15:51,410
The detectors that watch for ultra-high
energy cosmic rays have found no such
1522
02:15:51,585 -->
02:15:52,610
lopsidedness.
1523
02:15:53,490 -->
02:15:58,870
That result doesn't close the matter
because a grid finer than our instruments
1524
02:15:58,920 -->
02:16:05,150
can resolve would hide, but the test was a
fair one and it came back empty.
1525
02:16:07,375 -->
02:16:11,130
Others don't think the question is even a
scientific one.
1526
02:16:12,590 -->
02:16:16,421
The physicist Sabine
Hossenfelder has argued
1527
02:16:16,422 -->
02:16:20,810
that the simulation
idea is not science at all.
1528
02:16:21,470 -->
02:16:23,110
Her reasoning is practical.
1529
02:16:24,200 -->
02:16:31,490
To make the claim testable, someone would
have to show how a computer that draws
1530
02:16:31,640 -->
02:16:37,610
only what is being observed could
reproduce every known law of physics
1531
02:16:38,159 -->
02:16:41,150
without a single detectable contradiction.
1532
02:16:44,505 -->
02:16:46,850
Nobody has shown how to do that.
1533
02:16:48,350 -->
02:16:55,389
Physics as we know it is full of delicate
connections where a measurement in one
1534
02:16:55,390 -->
02:17:00,910
place has to agree with a measurement made
somewhere else and a shortcut anywhere
1535
02:17:01,159 -->
02:17:03,670
would risk showing up as a mismatch.
1536
02:17:05,410 -->
02:17:12,430
Until someone demonstrates a working
shortcut, she says the idea is a story,
1537
02:17:12,565 -->
02:17:13,690
however good.
1538
02:17:15,794 -->
02:17:22,350
Frank Wilczek, a Nobel Prize winning
physicist, raises a different objection
1539
02:17:23,249 -->
02:17:24,750
and it's a plain one.
1540
02:17:26,489 -->
02:17:30,999
Fine, he says, suppose
our universe is a simulation
1541
02:17:31,000 -->
02:17:34,430
then what is the thing
running it made of?
1542
02:17:35,365 -->
02:17:38,530
What are the laws that govern that world?
1543
02:17:39,530 -->
02:17:42,583
The argument explains
our universe by pointing to
1544
02:17:42,584 -->
02:17:46,270
another one and then
leaves that one unexplained.
1545
02:17:50,159 -->
02:17:56,170
The philosopher David Chalmers,
who sat on that museum panel in 2016,
1546
02:17:56,755 -->
02:18:01,129
took the question somewhere more
comforting in 2022.
1547
02:18:02,874 -->
02:18:06,100
His book Reality Plus
argues that even if we
1548
02:18:06,101 -->
02:18:09,670
are in a simulation,
nothing important is lost.
1549
02:18:10,425 -->
02:18:12,790
A simulated table is still a table.
1550
02:18:14,849 -->
02:18:19,733
It's made of digital
processes where we thought it
1551
02:18:19,808 -->
02:18:23,830
was made of atoms but it
has its own solid properties.
1552
02:18:24,610 -->
02:18:30,250
You can set a cup on it and it matters to
the people who live with it.
1553
02:18:31,530 -->
02:18:37,790
Learning we were simulated would be like a
physicist learning that matter is built
1554
02:18:37,989 -->
02:18:41,827
from fields, a discovery
about what the world
1555
02:18:41,828 -->
02:18:45,670
is made of and not a
revelation that it's fake.
1556
02:18:47,230 -->
02:18:51,643
In Chalmers' view
virtual reality is genuine
1557
02:18:51,693 -->
02:18:55,850
reality and a life lived
there counts as a life.
1558
02:18:58,330 -->
02:19:05,790
Outside the lecture halls the idea took on
a looser, stranger form and people started
1559
02:19:05,964 -->
02:19:07,030
looking for cracks.
1560
02:19:08,029 -->
02:19:11,070
The best known is called the Mandela
Effect.
1561
02:19:12,950 -->
02:19:20,950
In 2009 a writer named Fiona Broom noticed
that she and a surprising number of other
1562
02:19:23,019 -->
02:19:27,630
people clearly remembered
Nelson Mandela dying in
1563
02:19:27,631 -->
02:19:32,170
prison in the 1980s with
news coverage and a funeral.
1564
02:19:33,830 -->
02:19:41,830
In fact he lived until 2013 Then came the
children's books about a family of bears.
1565
02:19:43,309 -->
02:19:49,890
Many people are certain the series is
spelled Berenstein Bears with an E and I
1566
02:19:50,214 -->
02:19:53,530
and are startled to find that the covers
say Berenstein.
1567
02:19:56,290 -->
02:20:00,495
Psychologists explain such
cases as shared false memory,
1568
02:20:00,496 -->
02:20:04,090
the mind filling gaps with
the most natural pattern.
1569
02:20:07,569 -->
02:20:13,970
Online many people prefer a different
answer the program was edited and some of
1570
02:20:14,119 -->
02:20:15,830
us kept the old version.
1571
02:20:18,550 -->
02:20:23,950
Around 2018 another piece of gaming
language slipped into everyday talk.
1572
02:20:24,850 -->
02:20:30,637
An NPC, a non-player
character, is a figure in a video
1573
02:20:30,638 -->
02:20:35,350
game who repeats the same
lines and follows a fixed script.
1574
02:20:36,995 -->
02:20:40,810
As slang it came to mean a person who
seems to do the same.
1575
02:20:42,044 -->
02:20:49,330
You've seen the joke someone behaves
predictably and a stranger online says
1576
02:20:49,331 -->
02:20:54,730
they must be running a program it's
insulting and playful at once.
1577
02:20:55,790 -->
02:21:01,710
And it only works because the idea of a
scripted person is now familiar.
1578
02:21:03,965 -->
02:21:05,810
And then there's the black cat.
1579
02:21:07,830 -->
02:21:12,135
In The Matrix Neo notices a
cat walk past a doorway and
1580
02:21:12,136 -->
02:21:16,450
then the same cat walk
past again, exactly the same.
1581
02:21:18,390 -->
02:21:21,580
A character explains
that deja vu is what
1582
02:21:21,581 -->
02:21:24,710
you feel when the
program changes something.
1583
02:21:25,315 -->
02:21:26,590
It's Philip K.
1584
02:21:26,714 -->
02:21:31,730
Dick's claim from Mets, delivered as a
movie line two decades later.
1585
02:21:33,839 -->
02:21:35,870
Now try it in your own pocket.
1586
02:21:37,250 -->
02:21:39,890
You open a message from someone you know.
1587
02:21:41,260 -->
02:21:46,050
The words are fine the tone is friendly
and a small doubt flickers.
1588
02:21:47,115 -->
02:21:49,050
Did a person write this?
1589
02:21:49,495 -->
02:21:51,510
Or did a machine write it for them?
1590
02:21:52,140 -->
02:21:54,450
You can't tell from the text alone.
1591
02:21:55,759 -->
02:22:01,510
Turing's question has come back and it
arrives every morning with the mail.
1592
02:22:04,279 -->
02:22:10,530
Now let's talk about the problem that sits
under this whole idea the one Bostrom's
1593
02:22:10,679 -->
02:22:14,510
argument quietly leans on and that is
consciousness.
1594
02:22:17,525 -->
02:22:25,450
To see why it's so stubborn, go back to
1714 to a German philosopher named
1595
02:22:25,799 -->
02:22:29,887
Gottfried Wilhelm Leibniz
who was living in Hanover
1596
02:22:29,888 -->
02:22:33,370
and writing a short book
called The Monodology.
1597
02:22:36,325 -->
02:22:39,952
Leibniz was one of the
great mathematicians of
1598
02:22:39,953 -->
02:22:42,690
his age and he had a
clear head for machines.
1599
02:22:43,470 -->
02:22:50,650
In one passage he asks you to imagine a
machine built to think feel and perceive.
1600
02:22:54,459 -->
02:23:00,500
Now suppose it's enlarged, he says,
until it's as big as a mill so that you
1601
02:23:00,501 -->
02:23:05,500
can walk right inside it the way you'd
walk through a working flour mill.
1602
02:23:07,189 -->
02:23:08,560
What would you find?
1603
02:23:09,820 -->
02:23:16,980
You'd walk past wheels turning, levers
pushing and gears meshing with other gears.
1604
02:23:18,279 -->
02:23:22,190
You could examine every
part and each part would
1605
02:23:22,191 -->
02:23:25,980
be doing nothing except
pushing on another part.
1606
02:23:27,605 -->
02:23:30,400
Nowhere on the tour would you come across
a perception.
1607
02:23:31,960 -->
02:23:35,420
You'd see motion but you'd never see the
seeing.
1608
02:23:37,640 -->
02:23:43,500
Leibniz thought this showed that perception
can't be explained by machinery alone.
1609
02:23:46,209 -->
02:23:50,180
Three centuries later the mill has become
a computer.
1610
02:23:51,429 -->
02:23:57,180
Open the case and you find circuits and
under a microscope you find switches
1611
02:23:57,454 -->
02:23:59,440
flipping between two states.
1612
02:24:00,380 -->
02:24:05,400
Open a skull and you find cells passing
chemical signals.
1613
02:24:08,580 -->
02:24:10,870
The tour comes out the same.
1614
02:24:11,950 -->
02:24:18,290
Everything you can point to is a part
pushing another part and the one thing you
1615
02:24:18,291 -->
02:24:23,690
were looking for, the feeling of being
someone never shows up on the tour.
1616
02:24:27,310 -->
02:24:33,630
In 1974 a philosopher at New York
University named Thomas Nagel gave the
1617
02:24:33,631 -->
02:24:40,390
puzzle a famous shape with an essay titled
What is it like to be a bat?
1618
02:24:43,409 -->
02:24:46,511
A bat finds its way
through the dark by sending
1619
02:24:46,512 -->
02:24:49,650
out high pitched cries
and reading the echoes.
1620
02:24:51,050 -->
02:24:54,033
Scientists have mapped
how this works in
1621
02:24:54,034 -->
02:24:57,370
great detail down to
the nerve cells involved.
1622
02:25:00,410 -->
02:25:06,690
Yet Nagel's point was that you could learn
every one of those details and still not
1623
02:25:06,691 -->
02:25:11,691
know what it's like from
the inside to be a bat,
1624
02:25:11,692 -->
02:25:15,690
to sense a moth as a
pattern of returning sound.
1625
02:25:16,970 -->
02:25:22,590
He suggested that a creature is conscious
when there's something it is like to be
1626
02:25:22,814 -->
02:25:29,110
that creature and that no description from
outside can capture it.
1627
02:25:32,670 -->
02:25:38,630
Twenty years later in 1994 a young
Australian philosopher named David
1628
02:25:38,631 -->
02:25:46,130
Chalmers stood up at a conference on
consciousness in Tucson, Arizona and drew
1629
02:25:46,131 -->
02:25:50,890
a line that has organised the debate ever
since.
1630
02:25:52,869 -->
02:25:57,070
He split the questions about the mind into
two groups.
1631
02:25:58,369 -->
02:26:03,340
The first he called the easy problems and
he didn't mean they were simple.
1632
02:26:06,649 -->
02:26:11,890
They're the questions about what the brain
does, how it tells red from green,
1633
02:26:12,630 -->
02:26:19,690
how it focuses attention, how it stores a
memory, how it reports what it sees,
1634
02:26:20,170 -->
02:26:22,550
how it falls asleep and wakes up.
1635
02:26:24,889 -->
02:26:31,430
These are enormously hard to answer in
practice, but they all have the same form.
1636
02:26:32,689 -->
02:26:39,330
They ask how a system performs a task and
a scientist knows how to go looking for
1637
02:26:39,529 -->
02:26:40,590
that kind of answer.
1638
02:26:42,870 -->
02:26:49,530
The second group has just one member and
Chalmers named it the hard problem.
1639
02:26:51,429 -->
02:26:56,630
It asks why any of that activity comes
with experience at all.
1640
02:26:57,550 -->
02:27:03,150
Why does the brain's processing of light
at a certain wavelength feel like red
1641
02:27:03,699 -->
02:27:07,870
instead of simply happening in the dark
with no one home?
1642
02:27:10,489 -->
02:27:17,990
You could explain every step of how the
eye and brain handle that wavelength and
1643
02:27:18,089 -->
02:27:24,670
the question of why it feels like anything
would still be standing there untouched.
1644
02:27:26,839 -->
02:27:30,868
To sharpen the point, Chalmers
used a figure philosophers
1645
02:27:30,869 -->
02:27:34,930
had been playing with for
years, the philosophical zombie.
1646
02:27:36,109 -->
02:27:39,150
This isn't the staggering monster from
films.
1647
02:27:40,739 -->
02:27:45,284
It's a being that looks
exactly like you down
1648
02:27:45,285 -->
02:27:49,490
to every atom and
behaves exactly like you.
1649
02:27:49,810 -->
02:27:56,990
It laughs at jokes, winces when it stubs a
toe and says it's enjoying the sunset.
1650
02:27:59,134 -->
02:28:01,030
But inside there is nothing.
1651
02:28:02,190 -->
02:28:05,632
No sunset is seen,
no pain is felt because
1652
02:28:05,633 -->
02:28:10,810
for the zombie there's
no inner life at all.
1653
02:28:11,750 -->
02:28:17,570
Chalmers argued that if you can even
coherently imagine such a being then
1654
02:28:17,769 -->
02:28:21,910
experience is something over and above the
physical machinery.
1655
02:28:24,044 -->
02:28:28,952
And you'll notice that the
zombie is the perfect NPC, a figure
1656
02:28:28,953 -->
02:28:33,790
that does everything a person
does while no one is inside.
1657
02:28:35,715 -->
02:28:38,430
You can feel the problem in your own
kitchen.
1658
02:28:39,590 -->
02:28:44,170
Try describing the taste of coffee to
someone who has never had any.
1659
02:28:45,970 -->
02:28:53,870
You can say it's bitter, hot, a little
roasted, a little like smoke and you can
1660
02:28:53,871 -->
02:28:58,270
hand them the chemistry, the temperature,
even the colour.
1661
02:28:58,945 -->
02:29:02,930
Every word of it stays on the outside of
the cup.
1662
02:29:04,530 -->
02:29:08,212
The one thing they're
missing is the taste itself
1663
02:29:08,213 -->
02:29:11,750
and no sentence you can
build will carry it across.
1664
02:29:14,990 -->
02:29:19,702
In 1998, at the end of
a conference in Bremen,
1665
02:29:19,703 -->
02:29:23,350
Germany, two men
made a bet over a drink.
1666
02:29:24,590 -->
02:29:31,750
One was Christoph Koch, a neuroscientist
who spent his days hunting for the brain
1667
02:29:31,849 -->
02:29:35,510
activity that goes with conscious
experience.
1668
02:29:37,490 -->
02:29:41,817
The other was David Chalmers,
the philosopher who had
1669
02:29:41,818 -->
02:29:45,610
drawn the line between the
easy problems and the hard one.
1670
02:29:47,919 -->
02:29:50,670
Koch was sure that science would crack it.
1671
02:29:52,370 -->
02:29:57,990
He wagered that within 25 years,
researchers would find the particular
1672
02:29:57,991 -->
02:30:02,430
pattern of brain cell activity that
produces consciousness.
1673
02:30:04,525 -->
02:30:06,370
Chalmers took the other side.
1674
02:30:07,310 -->
02:30:09,950
The steak was a case of fine wine.
1675
02:30:12,095 -->
02:30:14,110
25 years went by.
1676
02:30:16,344 -->
02:30:23,090
In June 2023, at another conference,
Koch walked to the front of the room and
1677
02:30:23,890 -->
02:30:24,890
conceded.
1678
02:30:26,900 -->
02:30:33,400
Brain science had found a great deal about
which areas light up when a person sees or
1679
02:30:33,401 -->
02:30:40,220
feels something, but it hadn't found the
thing Koch had promised, a mechanism that
1680
02:30:40,221 -->
02:30:43,040
explains why any of it feels like
anything.
1681
02:30:45,369 -->
02:30:48,000
He paid up with a case of Portuguese wine.
1682
02:30:50,070 -->
02:30:53,660
And the question stayed exactly as open as
it was before.
1683
02:30:56,409 -->
02:30:58,660
So where does that leave us?
1684
02:31:00,080 -->
02:31:06,220
Over the centuries, thinkers have settled
on four main answers and each one points
1685
02:31:06,269 -->
02:31:09,320
somewhere different for the simulation
idea.
1686
02:31:11,639 -->
02:31:13,660
The first is materialism.
1687
02:31:15,054 -->
02:31:20,580
It says that consciousness is what certain
physical processes are, nothing more.
1688
02:31:23,159 -->
02:31:27,960
When the right pattern runs in a brain,
that pattern is experience.
1689
02:31:28,989 -->
02:31:32,220
The philosopher Daniel Dennett pushed this
furthest.
1690
02:31:35,779 -->
02:31:41,830
He argued that the hard problem is partly
an illusion, a trick of how we think about
1691
02:31:41,979 -->
02:31:47,050
ourselves and that once science explains
everything the brain does, there's nothing
1692
02:31:47,249 -->
02:31:48,670
left over to explain.
1693
02:31:51,489 -->
02:31:58,630
If materialism is right, a computer running
the right pattern would be conscious too.
1694
02:31:59,655 -->
02:32:02,350
And Bostrom's argument stands.
1695
02:32:04,660 -->
02:32:10,350
The second is dualism, which we met with
Descartes.
1696
02:32:10,990 -->
02:32:16,690
Mind and matter are two different kinds of
thing, and the mind isn't made of the
1697
02:32:16,889 -->
02:32:18,210
stuff that physics studies.
1698
02:32:20,130 -->
02:32:26,970
On this view, a machine could copy a
brain's behaviour perfectly and still be a
1699
02:32:26,971 -->
02:32:30,410
zombie because the mind would be something
else.
1700
02:32:32,560 -->
02:32:34,570
The third is panpsychism.
1701
02:32:35,544 -->
02:32:41,850
The claim that experience is a basic
feature of the world, present in tiny
1702
02:32:41,851 -->
02:32:47,230
amounts, even in the smallest particles,
the way mass and charge are.
1703
02:32:48,115 -->
02:32:50,650
Brains don't create consciousness.
1704
02:32:52,429 -->
02:32:55,650
They gather it into larger, richer forms.
1705
02:32:57,250 -->
02:33:03,910
It sounds odd, but it has serious
defenders, because it dodges the question
1706
02:33:03,911 -->
02:33:07,490
of how mindless matter could ever produce
a mind.
1707
02:33:09,904 -->
02:33:15,110
The fourth is idealism, and by now you
know its first great champion.
1708
02:33:16,890 -->
02:33:20,237
Berkeley said that
mind is all there is, and
1709
02:33:20,238 -->
02:33:23,550
that matter is how minds
appear to one another.
1710
02:33:24,795 -->
02:33:27,870
Versions of that view are alive again
today.
1711
02:33:29,530 -->
02:33:34,690
Now notice how the two roads of this story
split at exactly this point.
1712
02:33:36,070 -->
02:33:40,470
Follow Bostrom, and you exist only inside
the simulation.
1713
02:33:42,105 -->
02:33:44,950
You're a pattern in a
machine, with no other
1714
02:33:44,951 -->
02:33:48,770
home, and when the
program stops, so do you.
1715
02:33:50,150 -->
02:33:56,450
Follow the matrix, and you exist outside
it, but as a body, a human form in a pod.
1716
02:33:57,615 -->
02:34:03,330
A lump of flesh fed through tubes,
while a false world plays on your senses.
1717
02:34:04,739 -->
02:34:09,210
The deceiver has an outside to be found,
and it's made of matter.
1718
02:34:12,220 -->
02:34:18,220
The hard problem leaves the choice open,
because nobody can say whether a program
1719
02:34:18,269 -->
02:34:23,017
can really feel, but
it also hints at a third
1720
02:34:23,018 -->
02:34:27,180
possibility, one neither
of those pictures allows.
1721
02:34:29,659 -->
02:34:35,500
If consciousness is not produced by matter
or code, but is the basic thing itself,
1722
02:34:36,960 -->
02:34:40,204
then you're not a
character inside a simulation,
1723
02:34:40,205 -->
02:34:43,160
and you're not a
body strapped into one.
1724
02:34:45,249 -->
02:34:50,060
You're something that exists outside it,
as awareness looking in.
1725
02:34:51,519 -->
02:34:55,169
That's the other road,
and a physicist named
1726
02:34:55,170 -->
02:34:59,060
Tom Campbell has
spent his life walking it.
1727
02:35:00,900 -->
02:35:05,920
Let's go to the early 1970s, to a quiet
corner of Virginia.
1728
02:35:07,520 -->
02:35:14,840
Campbell was a physicist, and for most of
his working life, he held jobs that sound
1729
02:35:15,039 -->
02:35:16,440
like they belong in a thriller.
1730
02:35:18,630 -->
02:35:24,880
He worked on defense projects,
including missile defense, where the work
1731
02:35:24,881 -->
02:35:32,860
meant careful measurement, hard numbers,
and results that either held up or didn't.
1732
02:35:33,939 -->
02:35:37,480
He was trained to distrust anything he
couldn't test.
1733
02:35:39,840 -->
02:35:45,640
And yet, in those same early years,
he spent his evenings and weekends
1734
02:35:45,641 -->
02:35:50,880
somewhere very different, outside the town
of Faber, Virginia.
1735
02:35:53,319 -->
02:35:58,820
A former radio broadcaster named Robert
Monroe ran a small laboratory.
1736
02:36:00,440 -->
02:36:05,960
Monroe had spent years having a strange
experience, a sensation of floating out of
1737
02:36:05,961 -->
02:36:09,578
his own body, and he wanted
to find out whether sound
1738
02:36:09,579 -->
02:36:15,420
could help people reach
states like it, on purpose.
1739
02:36:19,319 -->
02:36:23,620
He built a place to study the
question, and he needed people
1740
02:36:23,621 -->
02:36:27,720
who could build equipment
and people willing to be tested.
1741
02:36:29,635 -->
02:36:31,320
Campbell was both.
1742
02:36:33,760 -->
02:36:39,540
Along with a colleague named Dennis
Mennerich, he helped build the electronics
1743
02:36:39,664 -->
02:36:43,599
the lab used, the machines
that played carefully
1744
02:36:43,699 -->
02:36:47,360
designed patterns of
sound into a person's ears.
1745
02:36:48,660 -->
02:36:51,020
Then he lay down in the booth himself.
1746
02:36:53,310 -->
02:37:00,100
He served as one of Monroe's test
subjects, learning to leave the body under
1747
02:37:00,101 -->
02:37:06,760
laboratory conditions, with instruments
recording the session and a scientist's
1748
02:37:06,761 -->
02:37:10,160
habit of writing down exactly what
happened.
1749
02:37:11,759 -->
02:37:13,800
He kept at it for years.
1750
02:37:15,740 -->
02:37:22,880
And he kept his day job in physics the
whole time, which meant he was looking at
1751
02:37:22,881 -->
02:37:28,860
those experiences with the eyes of someone
who built measuring devices for a living.
1752
02:37:31,529 -->
02:37:33,920
That is the odd thing about his story.
1753
02:37:34,880 -->
02:37:39,900
Most people who report such experiences
come them as believers.
1754
02:37:41,310 -->
02:37:46,200
Campbell came to them as an engineer,
with a toolbox of questions.
1755
02:37:47,895 -->
02:37:49,460
What is the structure here?
1756
02:37:49,965 -->
02:37:51,240
What are the rules?
1757
02:37:52,365 -->
02:37:56,600
And what would a model have to look like
to explain all of it?
1758
02:37:58,339 -->
02:38:04,540
He spent three decades turning those
questions over before he wrote anything down.
1759
02:38:07,424 -->
02:38:11,577
In 2003, he published
The Answer, a three volume
1760
02:38:11,578 -->
02:38:15,360
work with a title that is
half joke and half boast.
1761
02:38:16,940 -->
02:38:18,620
My Big Toe.
1762
02:38:18,755 -->
02:38:21,300
The Toe stands for Theory of Everything.
1763
02:38:22,560 -->
02:38:27,061
The name physicists
give to the long sort set of
1764
02:38:27,062 -->
02:38:31,240
equations that would
unite all the forces of nature.
1765
02:38:32,295 -->
02:38:35,460
Campbell's version is not written in
equations.
1766
02:38:37,169 -->
02:38:42,177
It's a plain language model
of what reality is and why
1767
02:38:42,178 -->
02:38:45,860
it exists, set out across
roughly a thousand pages.
1768
02:38:47,325 -->
02:38:48,620
Notice the date.
1769
02:38:50,259 -->
02:38:54,860
It's the same year that Nick Bostrom
published his paper from Oxford.
1770
02:38:56,650 -->
02:39:01,480
Two men who had never met, one a
philosopher working from logic,
1771
02:39:02,560 -->
02:39:06,123
and the other a physicist
working from experience,
1772
02:39:06,124 -->
02:39:10,180
each opened a door into
the same room in 2003.
1773
02:39:12,070 -->
02:39:14,380
They went in opposite directions.
1774
02:39:18,014 -->
02:39:20,854
Bostrom starts with
matter and computation
1775
02:39:20,855 -->
02:39:23,790
and asks whether minds
could arise from them.
1776
02:39:25,155 -->
02:39:27,190
Campbell starts at the other end.
1777
02:39:28,095 -->
02:39:31,170
In his model, consciousness comes first.
1778
02:39:32,510 -->
02:39:38,770
Before there's any physical universe,
there is a simple, undeveloped awareness
1779
02:39:39,569 -->
02:39:42,730
and this awareness has one remarkable
property.
1780
02:39:44,170 -->
02:39:45,570
It can change itself.
1781
02:39:47,890 -->
02:39:53,310
It can notice a difference between one
state and another, and it can organize
1782
02:39:53,534 -->
02:39:57,470
itself to become more ordered and more
capable.
1783
02:40:00,010 -->
02:40:01,830
That is the whole beginning.
1784
02:40:02,925 -->
02:40:07,130
Everything else is what happens when such
a thing keeps going.
1785
02:40:09,239 -->
02:40:14,110
Campbell calls the full result the larger
consciousness system.
1786
02:40:15,570 -->
02:40:19,322
He describes it as an
information system that
1787
02:40:19,323 -->
02:40:22,710
evolves in the way a
living thing evolves.
1788
02:40:24,685 -->
02:40:31,270
By trying arrangements and keeping what
works, it has a direction built into it.
1789
02:40:31,585 -->
02:40:34,670
Its basic drive is to lower its own
entropy.
1790
02:40:35,720 -->
02:40:41,530
Entropy is a physicist's word for
disorder, for the way a tidy room turns
1791
02:40:41,779 -->
02:40:45,130
messy and a hot cup cools into the air.
1792
02:40:47,710 -->
02:40:51,658
Lowering entropy means
becoming more organized,
1793
02:40:51,659 -->
02:40:55,670
more coherent, more
efficient at being what it is.
1794
02:40:56,579 -->
02:41:03,050
The system, in Campbell's account, exists
to grow into a better version of itself.
1795
02:41:04,969 -->
02:41:06,110
Where do we fit?
1796
02:41:07,679 -->
02:41:09,310
We are pieces of it.
1797
02:41:11,130 -->
02:41:17,670
Campbell calls each of us an individuated
unit of consciousness, a part of the
1798
02:41:17,671 -->
02:41:21,090
larger awareness that has been given a
separate point of view.
1799
02:41:22,340 -->
02:41:25,945
He holds that each unit
has genuine free will,
1800
02:41:25,946 -->
02:41:29,430
and that matters more
than it first sounds.
1801
02:41:32,660 -->
02:41:38,520
Without real choices there would be
nothing to learn, and a system built to
1802
02:41:38,521 -->
02:41:43,800
evolve needs parts that can try different
things and find out what happens.
1803
02:41:46,080 -->
02:41:49,700
In his picture, you are not a character
following a script.
1804
02:41:50,980 -->
02:41:54,560
You are a small piece of a great awareness
choosing.
1805
02:41:57,720 -->
02:42:04,280
Now, let's look at what that awareness has
built, because this is where Campbell's
1806
02:42:04,281 -->
02:42:07,640
model begins to sound like the rest of
what we've covered.
1807
02:42:09,520 -->
02:42:15,972
In his account, the physical
universe is a virtual reality created
1808
02:42:15,973 -->
02:42:20,440
inside the larger consciousness
system as a place to learn.
1809
02:42:22,130 -->
02:42:28,740
He compares it to a multiplayer online
game, and the comparison is meant literally.
1810
02:42:29,819 -->
02:42:34,825
Many players log in at once,
they share a single world,
1811
02:42:34,826 -->
02:42:38,860
and what one does can be
seen and felt by the others.
1812
02:42:41,305 -->
02:42:46,200
Every game needs rules, and a game with no
rules teaches nothing.
1813
02:42:47,739 -->
02:42:54,300
If the ground sometimes held you up,
and sometimes didn't, your choices would
1814
02:42:54,301 -->
02:42:58,710
carry no consequences, and nobody could
learn from them.
1815
02:42:59,199 -->
02:43:06,590
So the system runs the world on a fixed
ruleset, and that ruleset is what we call
1816
02:43:06,739 -->
02:43:08,330
the laws of physics.
1817
02:43:10,025 -->
02:43:12,850
Gravity pulls the same way every day.
1818
02:43:14,290 -->
02:43:16,270
Fire burns every time.
1819
02:43:17,025 -->
02:43:19,330
Ice melts at the same temperature.
1820
02:43:21,990 -->
02:43:27,050
Campbell's point is that these laws are
consistent, because a game has to be
1821
02:43:27,074 -->
02:43:30,166
consistent, and the
consistency is the reason
1822
02:43:30,167 -->
02:43:33,990
we trust the world
enough to plan inside it.
1823
02:43:38,080 -->
02:43:41,302
Under this picture, your
body is an avatar, the
1824
02:43:41,377 -->
02:43:44,340
thing we followed from
Vishnu to the game designers.
1825
02:43:47,209 -->
02:43:52,800
It's the form you use to move around in
the shared world, and it's built to fit
1826
02:43:52,801 -->
02:43:59,240
the rules, with a nervous system that reads
the environment and muscles that act on it.
1827
02:44:00,835 -->
02:44:03,560
The player is the one who stands behind
it.
1828
02:44:05,980 -->
02:44:11,540
Campbell goes a step further, and says the
ruleset explains one of physics's
1829
02:44:12,080 -->
02:44:15,000
strangest facts, the speed of light.
1830
02:44:17,139 -->
02:44:20,500
Nothing in our universe can travel faster
than light.
1831
02:44:21,500 -->
02:44:27,080
Not a spaceship, not a signal, not a
thought passing between two machines.
1832
02:44:29,599 -->
02:44:34,860
To Campbell, that cap looks like what a
programmer would build.
1833
02:44:37,380 -->
02:44:42,880
A maximum speed written into the system,
so the computing load stays manageable,
1834
02:44:43,360 -->
02:44:47,560
and no player can leap across the whole
world in an instant.
1835
02:44:50,359 -->
02:44:55,260
Then comes the part that links straight
back to Bostrom's cheap trick,
1836
02:44:55,580 -->
02:44:57,060
and to Burtvy's bishop.
1837
02:44:58,520 -->
02:45:04,220
Campbell holds that the system does not
draw the entire world at all times.
1838
02:45:08,330 -->
02:45:14,590
What nobody is observing stays as a set of
possibilities, and the system fills in the
1839
02:45:14,714 -->
02:45:19,470
detail only when information about it
becomes available to an observer.
1840
02:45:22,769 -->
02:45:26,107
He ties this to the most
famous odd result in
1841
02:45:26,157 -->
02:45:29,390
quantum physics, the
double-slit experiment.
1842
02:45:31,110 -->
02:45:37,290
Fire single particles such as electrons at
a barrier with two narrow openings.
1843
02:45:39,750 -->
02:45:44,910
If nobody checks which opening each
particle goes through, they land on the
1844
02:45:44,911 -->
02:45:49,710
screen behind in a striped pattern,
the kind that waves make.
1845
02:45:52,229 -->
02:45:58,190
But when a detector records which opening
each one used, the stripes vanish,
1846
02:45:58,924 -->
02:46:04,210
and the particles land in two plain bands,
as if they were tiny bullets.
1847
02:46:05,750 -->
02:46:07,670
Looking changes what happens.
1848
02:46:09,245 -->
02:46:12,190
Campbell reads this as the rendering at
work.
1849
02:46:13,859 -->
02:46:19,610
The system settles the particle's path
when the information is there to be used,
1850
02:46:19,975 -->
02:46:21,390
and not before.
1851
02:46:23,115 -->
02:46:24,870
Notice who has just returned.
1852
02:46:27,290 -->
02:46:32,630
Berkeley said the unseen world goes on
existing because God perceives it.
1853
02:46:33,945 -->
02:46:37,270
Campbell keeps the structure and swaps the
name.
1854
02:46:38,290 -->
02:46:41,914
The thing that holds
the world in being is the
1855
02:46:41,915 -->
02:46:45,330
system itself, and it
renders what is observed.
1856
02:46:47,480 -->
02:46:51,605
In 2017, he took the
step that separates a
1857
02:46:51,654 -->
02:46:56,270
model from a mood and
tried to make it testable.
1858
02:46:58,419 -->
02:47:05,230
With three colleagues, Campbell
co-authored a paper called On Testing the
1859
02:47:05,231 -->
02:47:11,450
Simulation Theory, published in the
International Journal of Quantum Foundations.
1860
02:47:13,950 -->
02:47:21,950
The authors proposed variations on the
double-slit experiment, arranged so that
1861
02:47:22,000 -->
02:47:26,378
information about the
particle's path is recorded, and
1862
02:47:26,379 -->
02:47:30,210
then destroyed, before
any conscious being sees it.
1863
02:47:33,769 -->
02:47:39,230
If the stripes returned, it would suggest
that the result depends on whether a mind
1864
02:47:39,279 -->
02:47:44,950
could access the information, and not
merely on the recording.
1865
02:47:46,410 -->
02:47:51,790
Campbell has pushed for these experiments
to be carried out ever since.
1866
02:47:53,745 -->
02:47:56,910
His model also reaches past the physical
world.
1867
02:47:59,234 -->
02:48:05,130
If everything is information, then the
physical game is only one environment
1868
02:48:05,131 -->
02:48:11,410
inside a larger system, and other
environments exist alongside it.
1869
02:48:12,619 -->
02:48:17,690
That's how he explains the experiences he
had in Monroe's laboratory.
1870
02:48:20,665 -->
02:48:25,540
An out-of-body experience in his account
is not a trip through space.
1871
02:48:27,680 -->
02:48:31,825
Consciousness shifts its
attention from the data stream
1872
02:48:31,826 -->
02:48:35,620
that builds the physical
world to a different one.
1873
02:48:36,730 -->
02:48:39,260
The same logic covers remote viewing.
1874
02:48:41,074 -->
02:48:46,689
Where a person describes a
distant place they've never seen,
1875
02:48:46,690 -->
02:48:50,660
and telepathy where one mind
receives another's thoughts.
1876
02:48:52,135 -->
02:48:54,300
These are not powers of the body.
1877
02:48:56,620 -->
02:48:59,639
They are the player
reading from other data
1878
02:48:59,640 -->
02:49:02,940
streams, ones the avatar
was never built to receive.
1879
02:49:05,139 -->
02:49:06,520
So what is the game for?
1880
02:49:07,909 -->
02:49:12,220
Campbell's answer comes back to that
single drive toward lower entropy.
1881
02:49:13,310 -->
02:49:15,360
And he gives it a human face.
1882
02:49:16,560 -->
02:49:19,340
Fear in his model is high entropy.
1883
02:49:20,200 -->
02:49:22,460
A frightened mind is a disordered one.
1884
02:49:22,940 -->
02:49:27,612
It defends, hoards,
lashes out, and spends its
1885
02:49:27,613 -->
02:49:32,060
energy keeping itself
separate from everyone else.
1886
02:49:33,939 -->
02:49:35,440
Love is low entropy.
1887
02:49:36,515 -->
02:49:39,000
A loving mind is orderly and open.
1888
02:49:39,935 -->
02:49:45,880
And it cooperates because it treats other
players as parts of the same system and
1889
02:49:46,029 -->
02:49:47,029
not as threats.
1890
02:49:48,640 -->
02:49:52,145
Every choice you make in
the physical world nudges
1891
02:49:52,146 -->
02:49:55,020
your own consciousness
one way or the other.
1892
02:49:56,060 -->
02:50:01,500
The world is built so that you can feel
the difference.
1893
02:50:02,545 -->
02:50:07,440
And the quality of the awareness you end
up with is what you carry out of the game.
1894
02:50:09,840 -->
02:50:11,820
That makes it a learning program.
1895
02:50:13,359 -->
02:50:15,460
Nothing about it is a punishment.
1896
02:50:16,745 -->
02:50:18,660
And nothing about it is a prison.
1897
02:50:20,874 -->
02:50:24,335
Then the question of death
comes up and Campbell's
1898
02:50:24,336 -->
02:50:26,900
answer is the obvious
part of the model.
1899
02:50:28,520 -->
02:50:34,000
The avatar is a tool and when it wears
out, the player puts it down.
1900
02:50:34,845 -->
02:50:36,620
Death is logging off.
1901
02:50:39,520 -->
02:50:46,040
The awareness that was steering the body
returns to the larger system, keeps what
1902
02:50:46,041 -->
02:50:52,208
it learned, and may log in
again later with a new avatar,
1903
02:50:52,209 -->
02:50:56,820
a new set of circumstances,
and a new set of lessons.
1904
02:50:58,400 -->
02:51:04,080
That's his account of reincarnation,
put in the language of games, and it
1905
02:51:04,081 -->
02:51:09,420
carries the same weight the old traditions
gave it, only without a temple.
1906
02:51:11,699 -->
02:51:16,520
If that sounds familiar, it should,
because the circle has just closed.
1907
02:51:18,180 -->
02:51:24,120
Remember, Lila, the world as the play of
the absolute, joyful and free,
1908
02:51:24,880 -->
02:51:28,380
a being delighting in becoming many
things.
1909
02:51:30,660 -->
02:51:36,780
And remember Narada, who walked off to
fetch a cup of water, married,
1910
02:51:37,440 -->
02:51:44,060
raised children, lost them all in a flood,
and then heard Vishnu's voice asking where
1911
02:51:44,209 -->
02:51:47,760
his water was, with barely a moment gone
by.
1912
02:51:50,454 -->
02:51:54,536
Narada was a player who
lived a whole life inside the
1913
02:51:54,537 -->
02:51:59,060
game, and the grief was
entirely real while he was in it.
1914
02:52:00,100 -->
02:52:05,400
Then somebody tapped him on the shoulder,
and he was himself again.
1915
02:52:06,600 -->
02:52:11,800
Campbell has rebuilt that story with a
different vocabulary, a larger
1916
02:52:11,801 -->
02:52:16,400
consciousness, a rule set, an avatar,
a log off.
1917
02:52:17,789 -->
02:52:24,500
The structure is the same one that was told
in India more than a thousand years ago.
1918
02:52:26,540 -->
02:52:30,360
You've seen this yourself without any
theory.
1919
02:52:31,980 -->
02:52:38,080
Think of a child on the living room floor,
building a castle out of blankets,
1920
02:52:38,929 -->
02:52:40,580
completely gone into it.
1921
02:52:42,179 -->
02:52:45,110
The castle has a king,
and there's a dragon
1922
02:52:45,111 -->
02:52:47,900
under the sofa, and
the stakes are enormous.
1923
02:52:49,050 -->
02:52:52,480
A voice calls from the kitchen that supper
is ready.
1924
02:52:54,150 -->
02:52:56,760
For a moment the child doesn't hear.
1925
02:52:58,595 -->
02:53:01,020
Then the world rearranges itself.
1926
02:53:02,280 -->
02:53:07,800
The blankets are only blankets,
the dragon is a cushion, and the child
1927
02:53:07,801 -->
02:53:13,680
looks up a little dazed, remembering who
they are and what room they're in.
1928
02:53:14,559 -->
02:53:20,080
They get up, they go to the table,
and the game will be there tomorrow.
1929
02:53:21,820 -->
02:53:25,400
Go back now to the night we started with.
1930
02:53:27,545 -->
02:53:30,180
Somewhere a person has put on a headset.
1931
02:53:31,200 -->
02:53:34,452
It's late, the house is
quiet, and the world
1932
02:53:34,502 -->
02:53:37,720
they're steering through
isn't the one around them.
1933
02:53:39,909 -->
02:53:43,620
They turn their head, and the sky turns
with it.
1934
02:53:44,899 -->
02:53:49,252
They reach out a hand, and
a hand that looks like theirs
1935
02:53:49,253 -->
02:53:53,140
reaches out inside a valley,
someone else designed.
1936
02:53:55,400 -->
02:54:03,400
Every rock, every river, every shifting
patch of light was built by people they've
1937
02:54:03,401 -->
02:54:09,500
never met, and it holds together so well
that for long stretches they forget
1938
02:54:09,799 -->
02:54:11,240
there's anything else.
1939
02:54:13,359 -->
02:54:19,500
Now pull back, one layer at a time,
the way we've been doing this whole time.
1940
02:54:21,509 -->
02:54:26,180
The first layer is the avatar,
the figure walking through the valley.
1941
02:54:27,499 -->
02:54:31,960
It has a body, a set of controls,
and a point of view.
1942
02:54:33,369 -->
02:54:38,620
It feels like the self, because it's where
the self is looking out from.
1943
02:54:40,095 -->
02:54:42,920
Behind the avatar is the player.
1944
02:54:44,544 -->
02:54:50,040
The player's hands are gripping the
controllers, and the player's mind is the
1945
02:54:50,041 -->
02:54:56,720
one deciding where to go, what to fear,
and what to try next.
1946
02:54:57,390 -->
02:55:02,700
Without the player, the avatar would
simply stand there, as still as a painting.
1947
02:55:04,600 -->
02:55:06,460
Behind the player is the room.
1948
02:55:07,809 -->
02:55:13,320
The headset sits on a face, the face on a
body, and the body in a chair,
1949
02:55:13,520 -->
02:55:17,280
with a desk side it, and a cup of tea gone
cold.
1950
02:55:19,369 -->
02:55:22,972
The room has walls, and
a window, and a floor, and
1951
02:55:22,973 -->
02:55:26,740
all of it is quietly ignored
while the valley is on.
1952
02:55:28,740 -->
02:55:34,700
Behind the room is the house, with its
sleeping people, its humming refrigerator,
1953
02:55:35,759 -->
02:55:41,220
its pipes ticking as they cool,
and behind the house is the night itself,
1954
02:55:42,360 -->
02:55:50,360
a dark street, a few lit windows,
and a sky of stars so far away that their
1955
02:55:50,361 -->
02:55:53,420
light left them before anyone alive was
born.
1956
02:55:55,159 -->
02:56:01,440
At every step, the thing that seemed like
the whole world turned out to be a layer,
1957
02:56:02,539 -->
02:56:08,340
and at every step, whoever stood in the
layer was sure it was the last one.
1958
02:56:09,860 -->
02:56:16,360
The avatar thinks the valley is
everything, the player thinks the room is,
1959
02:56:17,429 -->
02:56:23,060
each is right about what it can see,
and each is missing what's behind it.
1960
02:56:24,849 -->
02:56:30,140
That's the oldest question in
this story, and everyone who
1961
02:56:30,141 -->
02:56:34,340
has asked it has been standing
where that person stands.
1962
02:56:35,620 -->
02:56:41,760
Plato's prisoner looked at shadows,
and Narada looked at a flooded village,
1963
02:56:42,800 -->
02:56:49,880
Descartes sat by a stove, and Berkeley
looked at an apple, Bostrom looked at a
1964
02:56:49,881 -->
02:56:55,480
planet-sized machine, and Campbell lay
down in a booth in Virginia.
1965
02:56:57,299 -->
02:57:03,420
Each of them asked whether the layer they
could see was the last, and none of them
1966
02:57:03,619 -->
02:57:06,660
could step far enough back to be certain.
1967
02:57:09,319 -->
02:57:13,160
So we come back to a man lying under a
tree in ancient China.
1968
02:57:14,529 -->
02:57:20,100
He has just woken up, the butterfly is
gone, and the sun is on his hands,
1969
02:57:20,699 -->
02:57:24,700
and for a moment, he doesn't know which of
them is the real one.
1970
02:57:26,789 -->
02:57:33,240
Is he Joe, who dreamed of a butterfly,
or is he a butterfly now dreaming of Joe?
1971
02:57:34,260 -->
02:57:36,900
He lies there, and does not settle it.
1972
02:57:38,300 -->
02:57:42,251
He doesn't reach for an
argument, or a proof, and
1973
02:57:42,252 -->
02:57:45,720
he doesn't need a
machine to explain it to him.
1974
02:57:47,680 -->
02:57:51,178
What he notices
instead is that the two are
1975
02:57:51,179 -->
02:57:54,820
different, and yet one
has passed into the other.
1976
02:57:55,860 -->
02:58:03,840
A butterfly became a man, and a man might
become a butterfly, and nothing in between
1977
02:58:03,841 -->
02:58:06,860
could say where one ended and the other
began.
1978
02:58:08,170 -->
02:58:14,800
The old text gives that crossing a name,
and the name is the last thing it says.
1979
02:58:16,439 -->
02:58:18,600
The transformation of things.
