All language subtitles for Through the Wormhole S04E08 Is Reality Real [pseudo]

Freeman:
Do we live in the real world?

[ Alarm clock beeps ]

Or is it all in our minds?

Do we see the universe as it is?

Or do our senses deceive us?

Scientific observation reveals
hidden realities.

The judgment of our senses
cannot be trusted.

[ Engine revs ]

And our basic assumptions
about life and the universe

may be false.

Is existence an illusion?

Is reality real?

Space, time, life itself.

The secrets of the cosmos
lie through the wormhole.

Subtital By RA_One

What is real?

We assume it's everything we
encounter in our daily lives.

But how can we be certain

the universe we see around us
actually exists?

And how can we know

that the world we see matches
what anyone else experiences?

Our senses certainly make
reality seem real enough.

These things are solid.

But...

What if they actually aren't?

Our reality may be
a fragile tissue of illusions

illusions about ourselves,
our society,

and even the whole
of the natural world.

When I was young,
a magician came to town.

He was pretty good.

Watching him made me doubt
the reliability of my own eyes.

No matter how hard I looked,
I couldn't see how he did it.

What was I missing?

And why was I missing it?

Lawrence rosenblum
is a Professor

of perceptual psychology

at the university of California,
riverside.

He also dabbles in magic.

More than most,

Larry understands the mechanisms
magicians use to warp reality.

Man: Ladies and gentlemen,
the amazing Larry!

Rosenblum: Good evening,
ladies and gentlemen.

Tonight, I'd like to teach you
a little bit about perception.

How did that trick work?

Well, as I was throwing
the ball up,

you were following my eyes
with your attention.

And that continued
through the last throw,

which was not a real throw.

That technique of misdirection
is just one

of the many techniques
that professional magicians use.

Freeman:
Illusionists like David gabbay
perform tricks

that fool us again and again,
no matter how closely we watch.

They take advantage
of our brain's eagerness

to make sense of the world.

Rosenblum: David's not helping
our brains create a reality

as much as guiding our attention
of the perceptual information

in different ways.

And in that way, I think that
David has a lot to teach us.

Freeman: David's trick exploits
a mental shortcut

called amodal completion.

Here is how it works.

Let's say you see a rabbit.

Then your view of the rabbit
is partially blocked.

Is the rabbit still there?

Of course.

You know that
because your brain matches it up

with a three-dimensional model
of a rabbit

you have filed in your memory.

Your brain fills in
the missing piece.

Voilà!

Freeman:
We have millions of these models
stored in our minds.

We use them to assemble

a seemingly continuous picture
of the world

what we think of as reality.

Our sense of reality is
profoundly affected

by the way
our senses work together.

For instance...

Bah, bah, bah, bah...

Freeman: What do you hear?

Bah, bah, bah...

Larry seems to be saying,
"Bah, bah, bah."

but here's what happens when the
picture is changed just a bit.

Fah, fah, fah, fah...

Freeman: Now it sounds like
he is saying, "Fah, fah, fah."

but close your eyes and listen.

The sound hasn't changed.

Larry is still saying,
"Bah," With a "B."

bah, bah, bah.

In the case with an auditory
"Bah" And a visual "Vah,"

what happens is
the visual information ends up

overriding
the auditory information

because it's so salient.

It is so easy to see.

Bah, bah, bah.

And the perceptual brain,
in this case,

mostly the auditory brain
ends up using that information

to kind of push the "Bah"
To sound more like a "Vah,"

and that's what people
end up believing

they're actually hearing.

Freeman: Many different sensory
systems interact within our brains.

Our minds take this information
and tell a story about it.

We call it reality.

We're perceiving a lot more
than we realize.

And what I mean by that is

that there are entire channels
of information

that are getting to the brain

underneath our level
of awareness.

But at any one time,

not only are you
seeing something

and attending
to what you're seeing,

but what you're not attending to
is affecting you as well,

and that isn't just
from information

you get through your eyes,

but information
you get through your ears

and through your nose
and through your skin.

And all of that is happening
as we're sitting there

experiencing what we think is
a visual reality.

The other senses
are affecting it all.

Freeman:
But for all we perceive,
there is much we miss.

Most of us share
the same set of senses.

Yet some of us see things
very differently than others.

Can any of us perceive the world
as it truly is?

Professor Charles Falco is
one of the few who can.

He explores the invisible world
the reality we can't see.

[ Camera shutter clicking ]

The human vision system only
captures a really tiny fraction

of the light that's available.

If we look at a bust like this,

we see it looks red
to the naked eye.

But if we image this
in the ultraviolet,

possibly,
this bust will fluoresce

because of some of the chemical
composition that's in it.

Infrared typically penetrates
fairly far through red pigment.

So we'll be able to see
what's underneath the pigment,

if there's something
between the pigment

and the plaster bust itself.

Freeman: In his laboratory
at the university of Arizona,

Charles had exotic instruments
that can examine objects

at resolutions across all ranges

of visible
and invisible light

x-rays, ultraviolet, infrared,

and machines that see
millions of times sharper

than human eyes.

This electron microscope can
read the rough molecular surface

of the bust's
seemingly smooth red paint.

The crown jewel
of his collection

is a machine that reads
the space between atoms,

giving physicists
a completely different way

of looking at how molecules
are constructed.

Falco:
If you only have your eyes,

you look at something,
you think you understand it.

Turns out that the more tools
you have to look at something,

it reveals
much more information.

So reality is
a much more complex thing

than we think about.

The more ways we have
studying of reality,

the more we realize reality is
a bigger picture

than we could possibly
have understood before.

Freeman: There is no
evolutionary pressure

to create an animal that sees
reality as it really is.

We have evolved to see
the reality we need to see.

When we see something,
how our brain interprets it

isn't usually what exactly
is imprinted on our eyeball.

We're not a camera.

We have a brain
behind our retinas.

And the brain processes
the information

and tells us
what it wants us to see.

There is so much
visual information

in the world around us
that it turns out

our brain gives us a limited
spotlight of attention,

where we focus our attention on
exactly what's in front of us,

ignoring things
that go on everywhere else.

Freeman: When your attention's
attracted by something,

neurons enhance the sensitivity

of the central region
of your field of vision

and suppress the sensitivity
of the surrounding regions.

And this is how we see
the world through binoculars.

We see only a tiny fraction

of the reality
that's in front of us.

There is so much
sensory information,

so much visual information

that, in fact, it's impossible
to process it all.

So everyone's brain,
every animal's brain

has been programmed by evolution
to accept

only a small fraction of
the information and process it.

Otherwise,
there'd be total overload.

Freeman:
But reality isn't defined solely
by how you or I see the world

it's something we share.

We check our observations

against the observations
of others.

If we didn't agree
on what is real and what is not,

society couldn't function.

But this man believes

our shared reality
is the greatest illusion of all.

I am not real.

You are looking at thousands
of glowing, colored dots

on a screen.

The pattern of these dots
changes

once every 30th of a second,

creating the illusion
of movement.

And I'm not saying these words
right now.

This is a captured impression

of something I said
in the recent past.

Or is it?

What if I did this?

You've been conditioned

to believe that,
when something says "Live,"

it's really happening right now.

Our society is tied together
by these shared beliefs.

But how much of it is real?

And how much is
just an elaborate fantasy?

For much of his life,

scientist and philosopher
Jim baggott has been haunted

by a simple question
what is reality?

All reality is a fantasy
created in our own heads.

We are locked in the prison
of our own minds,

and as a consequence,
we have to create for ourselves

an understanding
of what reality is like

on the basis
of what we can absorb,

what we can learn,
what we can see.

[ Door creaks ]

So when we see with our eyes,

what we perceive, of course,
is not reality as such.

Our brains are, after all,
just clumps of tissue

weighing about 3½ pounds, with
a consistency of cold porridge.

It's only when we interpret
the electrical signals

generated by our brain
in our conscious mind

do we create
our individual reality.

That begs the question

what happens when those
electrical signals are shut off?

Well, I'm about to find out.

Freeman:
Jim's going to have his hearing
and vision blocked out

for 15 minutes.

This simple form
of sensory deprivation

sends him
into an alternate reality.

He loses track of time...

[ Alarm clock rings ]

...and experiences
vivid hallucinations.

In the absence of sensory input,

Jim's world-making machinery
manufactures a reality

with no connection
to the world outside his body.

Baggott: Deprived of two
of my most important senses,

what happens is
the brain scrambles for inputs

from other senses.

So you become very conscious
of the taste in your mouth

and the hardness of this bed
that I'm lying on.

I began to drift
into some dreamlike states.

But then I became aware

that me eyes are,
in fact, wide open,

and I'm fully awake
and conscious.

Freeman:
When your senses are shut off,

your brain makes up
its own version of reality.

But according to Jim, we all
live in a false reality

a hyperreality created
by society,

filled with illusions
that have become more real to us

than the physical world
around us.

We are all part
of a community of minds,

a world created by billions
of brains working in concert

over thousands of years.

The modern consumer society

is the latest twist
our mass mind has evolved

to advance the species.

Money lies at the heart
of this society.

But in many ways,

it is the most hyperreal
of all of our creations.

Baggott: I have here a $50 bill
and a 50£ note.

Current currency-conversion
rates tells us that the pound

is about 1½ times greater
in value than the dollar.

And these little pieces of paper
hold such a spell

over our lives.

They tell us whether
almost

who is gonna live,
who is gonna die.

But, really, value is something

that's part of the hyperreality
that we've created,

and I don't know what the real
value of a piece of paper

made of three parts cotton fiber
and one part linen really is,

but I can tell you
it's a lot less than $50 or 50£.

Freeman:
Money would be valueless
if we didn't all believe in it.

Our shared reality is
an illusion

we have to struggle to maintain.

And if we fail
to strictly observe its rules,

reality can crumble.

Baggott: Once these structures
are out there, as it were,

they develop,
you know, laws of their own.

They develop
a life of their own almost.

And that misinterpreting
those rules

and distorting those rules
and changing those rules

we do that at our peril.

Freeman: There is perhaps
no greater example

than the recent near collapse
of the global financial system.

[ Atm beeping ]

Baggott: The global
banking crisis of 2008

resulted from bankers playing
with the rules of the game.

And as a consequence,

the value of money, literally
overnight, was destroyed.

[ Bell ringing ]

Woman: Wall street is a panic
after a record drop.

Freeman: For a brief moment,
people became conscious

that money is essentially
an illusion.

But if we stop believing
in the global monetary system,

society could collapse.

So we choose
to keep on believing.

Civilization was brought
almost to its knees.

But the fact that civilization
didn't disappear

perhaps tells us
that hyperreality,

despite the fact that it exists
only in our minds,

is still too tough to kill.

Freeman:
Why is it so easy for us
to live in a fantasy world?

What is it about being human

that compels us
to create a hyperreality?

Is it social pressure?

[ Baby crying ]

Or is it born into us?

This neuroscientist believes
the answer is buried

deep in our brains

and our denial of reality
may be essential

to the survival of our species.

The human brain is
a storyteller.

It tells us tales
about the way things are,

and it allows us to imagine
the way things could be.

But what if the stories
we tell ourselves aren't true?

How would we know?

What if all our brains are wired
to lie about reality

and our place in it?

This man is about to ride
his motorcycle

through the traffic-clogged
streets of London.

When he does, he will enter
an alternate reality.

[ Engine turns over ]

[ Engine revs ]

Motorcyclists make up
less than one percent

of vehicle traffic in britain.

But they suffer 14% of total
deaths and serious injuries.

Bikers in the U.S. are
about 37 times more likely

to die in a crash
than people in a car.

[ Siren wails ]

But in this man's reality,
those numbers don't apply,

at least not to him.

Despite knowing
the grim statistics,

he, like millions
of other bikers,

continues
to ride his motorcycle.

Why do so many people
consistently disregard risk?

At university college London,

neuroscientist tali sharot
has discovered

there's a reality-distortion
mechanism

built into the human brain.

She wrote a book about it
called "The optimism bias."

so the optimism bias

is our tendency to overestimate
the positive things in our lives

and underestimate the likelihood
of negative things in our lives.

So, for example,

people overestimate
their success professionally,

their longevity.

They underestimate
their likelihood

of suffering from cancer,
of getting divorced.

We are more optimistic
than realistic,

but most of us are oblivious
to the fact.

We're not aware of it.

Freeman:
Nearly 80% of the population
is affected by this bias.

It's easy to see it in action,

as tali demonstrates
with a random group of students.

So, I'm gonna give you a list of
abilities and characteristics,

and I want you to think,
for each of these abilities,

where you stand relative
to the rest of the population.

So, the first one is
getting along well with others.

Who believes they are
at the bottom 25%?

Okay. No one. [ Chuckles ]

Who thinks
they are at the top 50%?

Okay. So that's most people.

So, what we find is

that most people rate themselves
above average on most abilities.

And that's, of course,
statistically impossible,

'cause we can't all be
better than everyone else.

Who here thinks that they will
have talented kids?

That's most of us here.

And who here thinks
they will be successful

in their professional life?

Freeman:
It's commonly believed

that, when your expectations
are not met,

you alter your expectations.

Yet tali's experiments show
that most people,

despite all evidence
to the contrary,

remain optimistic
in the face of reality.

She decided to find out why.

Using a brain scanner,

tali monitors
what happens in our heads

when we process information.

Today, this man will learn

if he's out of touch
with the real world.

Sharot: Okay, so you're gonna
see the negative life events,

such as cancer,

and what you need to do is
estimate your likelihood

of experiencing this event
in your lifetime.

Then you will see
the average likelihood

of someone like you
experiencing that event.

Freeman: Nick the biker will be
asked to calculate his chances

of experiencing 80 different
negative events in the future.

Nick thinks his chances
of getting lung cancer

are about 10%.

Actually, it's 30% for a man
of his age and lifestyle.

Now he's presented
with more negative events.

With each new scenario,

he gives a prediction before
finding out the real statistic.

When Nick hears good news,

his brain scans show plenty of
activity in the frontal lobes.

But when he hears bad news,
there is much less activity.

Now Nick will
take the test again

to see whether these facts
have changed his beliefs.

Sharot: What we usually find,
again and again,

is that people change
their estimates quite a lot

in the second session for items
where they got information

that was better
than their own estimates.

So, for example, if Nick says

that his likelihood of suffering
from Alzheimer's is about 30%,

and we tell him,

well, the average likelihood
of Alzheimer's is only 10%,

we find that most people
change their estimates

the second time around.

They would say, "Well,
maybe my average likelihood

of Alzheimer's
is only about 12%."

and we see,
in the frontal lobes,

enhanced activity
when people get information

that's better
than what they expected.

Freeman:
But when people get information
that's worse than expected,

it doesn't sink in.

Despite being told he has a 30%
chance of dying of lung cancer,

Nick barely changes his estimate
from 10% to 13%.

Our brains seem
to resist negative information,

but only when it applies to us.

Sharot: So we're mostly
optimistic about ourselves,

and we're optimistic about
our kids, about our families,

but we're not optimistic
about other people.

So people tend to be
even slightly pessimistic

about the future of the country
and the future of the world.

People do have
quite pessimistic expectations

of where the economy is going,
for example,

but they tend to think
that they will be okay.

Freeman:
And this is why the warnings on
cigarette packages go unheeded.

Yes, smoking kills
six million people a year.

But smokers believe
that it kills the other guy.

They are unique.
They will survive.

[ Inhales deeply ]

Freeman: That's the downside
of living in a false reality.

But there is a strong
positive aspect to it, as well.

So, optimism changes
the way we see the world.

Man: Nelson mandela!

Sharot: But it also changes
objective reality.

And it does so because it acts
as a self-fulfilling prophecy.

So positive expectations changes
our actions and our interactions

with the people around us,
with the world,

and that actually changes
the world around us.

Freeman:
And this reality-distortion
field, tali believes,

is essential to the survival and
advancement of the human race.

Hope may not always be
realistic,

but it makes the world
a better place.

We all live in many realities.

There is the reality
in our minds,

and there is the reality
we share with others.

We now know these realities
can't be entirely trusted.

But what about
the physical world

that exists
outside of our minds?

Surely,

in the rock-solid cause-
and-effect world of nature,

we can rely on things
to be indisputably real.

Maybe not.

In many ways, we are blind
to the true nature of reality.

Our perceptions are limited.

Our brains distort the truth.

So can we ever know
what is real?

That's the mission of science

to probe deep into the massive
puzzle box of nature

to find its ultimate truths.

But how successful have we been?

What if we are blind to an
entire extra dimension of space?

There are two kinds
of physicists

theoreticians,
who make informed guesses

as to why the world works
the way it does,

and experimentalists,

who break things apart
to see what's inside.

Steve nahn is
an experimentalist.

I absolutely believe
that reality is a real thing,

but that does not mean that we
completely understand it.

When you look at the first maps
of the world,

what you notice immediately is
there are major pieces missing.

But as we explored more,

our accuracy on the maps got
much, much better,

and we discovered continents,

like the americas
or Antarctica or Australia.

Today, thanks to satellites, our
maps are incredibly accurate.

But when it comes
to the deeper levels of reality,

we're kind of like
those first maps here.

We don't know
everything that's out there.

Freeman: Physicists map
the subatomic levels of reality

using the large hadron collider
in Geneva.

The lhc is the biggest
microscope in the world.

It smashes together protons

at 99.999999 percent
of the speed of light.

Steve was one of the small army
of scientists

who found the signature traces
of the higgs field in July 2012.

The higgs field is responsible
for the existence of matter

in the universe.

But this remarkable discovery
may be just the beginning.

Many more strange things
could emerge from the lhc...

Perhaps even gateways
to unseen new realities.

Huh?

There may be dimensions
of space and time

beyond the ones we know,

dimensions that could explain
one of the greatest mysteries

of physics.

There are
four fundamental forces

that drive everything we know.

There is
the electromagnetic force,

there is the strong force
and the weak force,

and then there's the one
that we know the least about,

and that's gravity.

Gravity is a trillion, trillion,
trillion times weaker

than the scale
of those other forces.

So what's going on with gravity?

Why is it so much weaker?

That's one of the questions we'd
like to be answer at the lhc.

Freeman: Many physicists suspect
the three dimensions we know

are slices
of a much larger universe.

In other, as yet undetected,
dimensions,

gravity may be as strong
as the other three forces.

The proof would be
discovering high-energy clones

of familiar particles.

Nahn: Suppose that you found
some new particles

that were
sort of kissing cousins

to the particles
you love and know,

only at higher mass.

So for each electron,

you have another electron
that's at much higher mass.

And for each quark, you have
another quark at higher mass.

And that would be a signature
for extra dimensions,

and it would actually provide,
possibly, a clue

for what's going on
with gravity.

Because some particles can
travel in this extra dimension,

and some particles cannot.

But if you could go off
in that extra dimension

somewhere further away,

gravity becomes just as strong
as the other forces.

Freeman:
Things would be very different
in this hidden reality.

For one thing,
they would be much heavier.

Nahn: Take this basketball.

Let's pretend
that it is a particle

that can travel
in the extra dimension.

If it's here where we are,
in that extra dimension,

and I drop it,
gravity pulls it to the ground,

and the floor is strong enough

to push it
back up into my hands.

But suppose that it then moves

somewhere else
in this extra dimension,

where gravity grows
exponentially stronger.

If I drop it over there,

the floor wouldn't be
strong enough at all...

...and the ball would go
straight through the ground,

crashing through
the building below us.

Freeman: Back at the large
hadron collider in Geneva,

the beams will soon be smashing
together with enough force

to prove whether or not

this gravity-heavy dimension
actually exists.

The lhc may shake up
the orthodoxy

by proving these theories
right or wrong.

I myself do not take sides.

My job is to find out
what is really there

and what is really not there.

There are
many different possibilities.

Like the mapmakers of old,
we are exploring terra incognita

and trying to draw new maps
of the true nature of reality.

Freeman: The universe may have
more dimensions

than the ones we know.

But there is another
even more radical possibility.

What if there are fewer
dimensions than we think?

What if there is less to reality
than there appears to be?

We live in a world
of cause and effect.

The universe appears to behave
in predictable ways.

But down deep,
at the subatomic level,

reality shifts and changes.

The world we know gives way
to quantum strangeness,

where all realities happen
at once,

and the outcome of any event
is unknowable.

Can an object be in two places
at once?

Can things appear
out of thin air?

Not in the reality we live in.

But nature has many layers.

And the closer we look,

the more we find reality
as we know it breaks down

and magic is real.

Okay, guys.
An amazing sleight of hand.

Just follow the coin,
guess the hand.

You ready?

Do this one again to see...

Freeman: David tong is not
a professional magician.

He's a theoretical physicist

at Cambridge university centre
for mathematical sciences,

where he studies
the magic of the quantum world.

[ Coin drops ]

[ Chuckles ]

Okay, in my defense,
I could argue

that this is just an example
of quantum uncertainty.

For particles like electrons,

you never know
where they're gonna be

from one minute to the next.

In fact,

by the time you go down to the
fundamental level of reality,

it looks like everything is
something of an illusion.

Freeman:
In the subatomic world, at the
smallest known level of reality,

particles like electrons don't
obey the laws of common sense.

They obey the laws
of quantum mechanics.

In the quantum world,

the properties
that a particle seems to have

depends
on the experiment you do.

You can measure
the position of a particle

with as much accuracy
as you like,

or you can measure its speed,

but you can't measure both
at the same time.

Similarly, an electron can
appear as a particle or a wave,

but never as both
at the same time.

Quantum objects are fuzzy,
like the edges of shadows.

It doesn't make sense, but this
really is the way nature works

at the most fundamental level.

Tong:
Quantum mechanics is simply
the best scientific theory

that we've ever developed.

It underpins everything we
understand about the universe.

It's never been found
to be wrong.

But where does this leave us?

What is the true reality?

Freeman: The prevailing theory
of quantum mechanics

suggests we will never know

because we can never measure
all of the properties

of quantum objects
with absolute certainty.

It's like the story
of Plato's cave.

2,000 years ago, the Greek
philosopher Plato suggested

that we could never understand
the true meaning of reality.

He said we were
a little like prisoners,

chained in a cave and forced
to look at the back wall.

Behind the prisoners,

there is a distant fire
which throws shadows over them,

shadows of the life that's
going on behind the prisoners.

But they never get to see
that life.

All they see are the shadows.

And after a while,

they think reality is some
two-dimensional dancing image.

They've got no way
of ever turning around

and seeing this beautiful,
colorful three-dimensional world

behind them.

Now, this is a little bit
like quantum mechanics.

We can never understand
everything

about the quantum wave.

We can never measure
all of the information

which is contained in it.

All we can see are projections,

like the shadows
of the true reality.

Freeman:
But David says the truth may be
even stranger than that.

The shadows on the wall may be
the true reality.

This is the contention
of the holographic principle.

Mathematicians attempted
to calculate

the amount of information
you can cram into a black hole.

They realized
the amount is proportional

to its surface area,
not to its volume.

And if this is true
for a black hole,

they reasoned, it's probably
true for any region in space.

Right now, we could all be
inside a huge black hole

and not even know it.

Reality may actually be
two-dimensional.

Think of everything in the
universe as bits of information,

like the information stored
in the books on this wall.

When the books lie flat
like this,

they appear two-dimensional.

But, of course,
when I pull them out,

we see that the books are
three-dimensional at heart.

The information is
three-dimensional.

The holographic principle says
that this is an illusion

not just this, but you, me,
the earth, the stars,

even space itself

everything
that's three-dimensional

is actually an illusion.

The true reality is
the books lining the wall.

The true reality lives
in two dimensions.

Freeman:
And this explains why quantum
objects look fuzzy to us.

They are projections

that don't actually exist
in three-dimensional space.

Tong: And what we think of
as this three-dimensional world

is just a holographic projection

from a surface
somewhere in the universe

to create the space we see.

It's as if Plato's prisoners
had it right all along.

The shadows are real.

What's behind them was
the illusion.

Freeman: Right now,
there is no way to prove

whether
the holographic principle

is the genuine description
of reality

or the shared delusion
of theoretical physicists.

But there may be
another explanation

for quantum weirdness.

What if reality gets blurry

because it was never there
to begin with?

Some scientists say

our reality could be
a deliberately created illusion.

Using the tools of science,

we catch glimpses of
the vast structure of creation.

There is so much we cannot see.

Why is the truth
so hard to find?

Perhaps it's because
the universe we live in

is just a small part
of a larger reality...

And we are all just living
in a world of dreams.

[ Alarm blaring ]

[ Alarm beeps, blaring stops ]

Have you ever had
a recursive dream...

[ Alarm blaring ]

[ Alarm beeps, blaring stops ]

...a dream with a dream
within a dream?

[ Alarm blaring ]

[ Alarm beeps, blaring stops ]

Jan westerhoff has.

And for all he knows,
he might still be dreaming.

Or you might be dreaming this.

Westerhoff: How do you know
whether waking up this morning

was actually a real awakening?

Perhaps you just woke up
into another dream.

The reason why
you should worry about this

is that there is actually
a significant chance

that we are dreaming right now.

Let's do the numbers.

Freeman: According to jan,

most people spend 8 hours asleep
and 16 hours awake every day.

About 20% of sleep is spent
in the r.E.M. State,

when you dream.

20% of 8 is 1.6, which means...

Westerhoff: We know
that, at this very moment,

you have a 1 in 10 chance
of dreaming right now,

which is actually
quite a significant probability.

Freeman:
Jan doesn't actually believe
he lives in a dreamworld,

but as a philosopher at the
university of durham in england,

his job is to question how and
why things are the way they are.

And despite
what the numbers say,

logic tells you
you are probably not asleep.

If this was a dreamworld,

why would it be bound
by the laws of causality?

Why don't fire-breathing dragons
go rampaging through London,

destroying the city?

Well, they don't.

What you saw was
just an illusion.

Reality follows
a strict set of rules,

even though it gets a little
blurry at the quantum level.

What might explain that?

Well, perhaps we are living
in a simulation

made by a higher-order reality.

Freeman: In other words,
reality may not be a dream,

but it could be
a computer simulation.

Imagine a time,
perhaps centuries from now,

when our descendants have
the power

to model fully functional
human brains in computers.

These simulated minds
could be placed

in computer-simulated worlds,

perhaps even re-creations
of the past.

They would never know
they weren't real.

What if this
has already happened?

Westerhoff: How do we know that
the present year we are in here

is actually the original
rather than some sort of rerun

where some weird event
in the past had been changed

just to see what kind
of ramifications it had?

Freeman: Believe it or not,

there is a chance we are all
part of a giant simulation.

Imagine, for example,
that I buy a dalí print.

I get really excited about this

because I just love
melting clocks.

Now the problem here is
that, according to experts,

about 90% of all dalí prints
on the market are fake.

So the chance that I've got
a fake here is 0.9.

Huh?

Freeman: What are the odds
that our world is a fake?

Huh?

Huh?

Some say as high as 1 in 20.

But jan says
the percentage isn't important.

If there is any chance at all
that you are simulated,

then you can't dismiss
the possibility

that you are simulated.

But here is the thing

even if this is all a dream,
does it really matter?

Even if this is
just a dream cake

and I paid for it with dream
money, it still tastes great.

So presupposing
this all continues,

does it really matter whether
it's a dream or a simulation?

I can still plan my life,
causes will have effects,

and actions will have
consequences.

Is reality real?

It certainly seems real to us.

But we now know
the reality we perceive

is just a small slice
of what really is.

And, perhaps, in the long run,
that doesn't matter.

What matters most to us is
the reality we know.

As the philosopher-king
Marcus aurelius wrote

2,000 years ago,
"The universe is change.

Our life is
what our thoughts make it."