Original subtitles

Did you do this? I didn't do that.

You realize it's $400. No.

Dude, it wasn't me. Come in. Come on.

You ever tell a lie... Even a little one?

[ Cellphone chimes ]

Is technology making it easier for us to lie?

Or maybe nothing ever changes,

and dishonesty is just a timeless part of human nature.

Dion. Oh.

What are you doing? Who is that?

Could society function in a world

without lying or secrets?

No, I do not have another girlfriend.

[ Buzzer ]

Mm.

Well, you're a liar.

Dishonesty might be so widespread

because we're so easily fooled,

and our memories are fallible.

Can we ever see the true nature of reality?

Or is truth just a lie?

Space, time, life itself.

The secrets of the cosmos lie through the wormhole.

Captions by vitac www.Vitac.Com

captions paid for by discovery communications

I'm going to let you in on a little secret.

I have never told a lie.

Not once in my long career has an untruth crossed my lips,

honest.

[ Chuckles ]

We all agree that lying is shameful,

yet we still deliberately deceive each other all the time.

Perhaps we lie because we just can't help it.

When did you tell your first lie?

Perhaps it was soon after you were first lied to.

I told my son if he didn't eat his broccoli,

he would be under 4 feet the rest of his life.

I told my son his blanket would protect him from monsters

in the closet.

I told my daughter if she didn't keep her room clean,

she would never find a man that would want to marry her.

Freeman: Kang Lee is a developmental psychologist

at the university of Toronto.

As a father, he understands why we lie to our kids.

Sometimes, you have exhausted all the other better methods,

and the lying sometimes becomes the only way

you can deal with the situation on hand.

Freeman: In fact, Kang is as guilty as the rest of us.

I used to drive my son Nathan to his school every morning.

[ Indistinct shouting ]

And sometimes, in the backseat,

and he would be acting up and screaming, yelling,

and I pointed to the hazard light

and I said, "that actually is an eject button.

If I push that button, your car seat

is going to blow off and go through the roof,

and you're going to fly out of the car."

And immediately, he became very quiet.

Freeman: Would children remain honest and pure

if we grown ups didn't corrupt them with our lies?

Kang believes something deeper is going on.

He and his colleagues have run an experiment

with thousands of kids of various ages.

[ Barking ]

What do you think it is?

A dog. A dog.

Come around. Yes, it is a dog.

Doggy.

[ Chuckles ]

It starts as a game...

Guess the animal from just the sound it makes.

[ Neighing ]

A horse? Yes.

Turn around. Take a look.

Yeah.

Kids are promised a prize

if they can guess the third animal correctly.

Turn around.

Then, the grown ups leave the room.

And I'm gonna play the sound...

All right. So I'll be right back, okay?

[ Door opens, closes ]

[ Door closes ]

You can guess how well that worked.

Hidden cameras revealed

that for many children, the temptation was too great.

[ Door opens, closes ]

Sorry.

You can turn around now.

When I was gone,

did you turn around to peek to see what it is?

No? Okay.

Now, what do you think it is?

Cow.

It's a cow?

If they later identified the animal without ever hearing it,

the experimenters knew those children lied.

Lee: That's basically the procedure

we have been using with kids in the U.S., in Canada,

in China, in Africa.

And it works very, very well with kids all over the world.

Freeman: Researchers used to believe

that children start lying around age 5,

after more exposure to the adult world.

But Kang has shown that lying starts much earlier.

What do you think it is?

Cow.

[ Laughing ] It's a cow. Okay.

How do you know it's a cow?

Kids actually start to tell lies at 2 years of age,

so that is very surprising.

At 2 years of age,

about 30% of kids would tell lies,

and at 3 years of age,

about 50% of the kids would tell a lie.

By 7 and 8 years of age, 100% of kids will lie.

Did you turn around to peek?

No.

Freeman: Kang's revelation is enough to send worried parents

into a tizzy,

except there is a bright side to early lying.

Lee: Those kids who lie earlier than the other kids

are actually those kids

who have better cognitive development abilities.

So they seem to be more advanced

than those kids who are telling the truth,

which is totally surprising to us.

Freeman: A good lie requires forethought and self control.

Lee: You have to be able to plan ahead what you are going to say

and how you are going to say it.

Freeman: In other words, the onset of lying

is an important stage in brain development.

But why do we start lying as soon as our brains are able to?

Would we be better off always telling the truth?

Lee: Some of them are actually very good... prosocial lies.

The reason we tell white lies is because

we do not want to hurt other people's feelings.

Imagine I'm playing cards with my friends.

At the same time, I really want to watch my favorite TV show.

What do I do?

One way I can do it is do it bluntly.

My favorite TV show just came on and, uh, so I have to go.

Uh, thank... Thank you, guys.

Bye bye.

Nobody's gonna like you.

Or you can do it differently.

You basically tell a white lie by saying, "oh, you know,

I don't feel very good. I have to lie down."

Sorry, guys.

I suddenly don't feel very well.

I probably have to go in and lie down.

Uh... Oh, do you need water?

So you really have to be able to know when is the time

to tell the truth

and when is not a good time to tell the truth.

A little white lie doesn't hurt anyone.

But some people can't stop twisting the truth, no matter

how damaging the consequences to others or themselves.

For them, dishonesty is a disease.

What separates these pathological liars

from the rest of us?

Charles Ponzi began lying to his investment clients

in the early 1900s, and he couldn't stop,

even after he'd been to prison three times for fraud.

18th century journalist Daniel defoe

invented as many facts as he reported

and did time for slander.

What drives some liars to reach pathological levels of deceit?

That's what Yaling Yang, a psychologist

at children's hospital Los Angeles, wants to find out.

We start to spot inconsistency between their statement.

Even when they know that we have other data,

including official criminal records,

they still lie.

Freeman: Yaling and her colleagues

wondered if there might be physical differences

between the brains of pathological liars

and the brains of average people.

The brain stores our memories and knowledge

in gray matter cells,

but another type of neuron, the white matter cell,

creates connections between all that information.

Whenever we tell a story, whether it's true or not,

we have to gather details from gray matter cells

in different parts of the brain.

It's like gleaning information from a series of books.

The books are the gray matter, filled with the knowledge

that you need to fit together into a compelling narrative.

The aisles that lead from book to book are the white matter.

Imagine going to a bookstore to get 10 different books

that are scattered

across different areas of the bookstore.

Having multiple pathways that lead you to the books

will help you get to the books more easily and quickly.

The human brain works in a very similar fashion.

When you have more connections

between various parts of the brain, that will make it

easier for you to retrieve important information.

Freeman: For example, let's say a friend

asks Yaling what she had for dinner yesterday.

To tell the truth,

she only has to gather a few pieces of information.

She ate spaghetti and a salad at home.

But lying is harder.

Yaling would have to ignore the truth

and cook up a story about a five star restaurant

and a six course meal,

a special occasion and expensive champagne.

If she hesitates at any point, her lie will be discovered.

She needs good pathways so she can race from topic to topic,

grabbing the information she needs.

Since lying requires a lot more information gathering

than telling the truth,

Yaling and her colleagues conjectured that the brains

of pathological liars might have more white matter pathways.

Brain scans proved them right.

Liars have about 25% increase in white matter

compared to healthy individuals.

So having more white matter allows all this information

to be retrieved and be used in a much faster way.

Freeman: Yaling also found that pathological liars

have 14% less gray matter than average people.

Gray matter stores our memories,

but it also has another function...

It controls our reckless impulses.

Yang: Gray matter plays a very important role

in impulse control.

So this kind of reduction in gray matter

is likely to contribute to the lack of impulse control

in pathological liars.

Freeman: Pathological liars can easily ruin their own lives,

as well as others'.

Perhaps now that we know more about what makes them lie,

we can develop therapies to help them stop.

Yang: Without that information,

it will be very difficult to develop any kind

of intervention or treatment for this very damaging behavior.

Freeman: But isn't technology

making it easier for us to deceive one another?

Is there a way to tell what's true

and what's not online?

This information scientist has developed a way to find out.

Our modern devices appear to make lying easier than ever.

After all, no one can see us behind a screen.

Today's technology has ushered in a new breed of lie.

It's called digital deception.

Is the information age really the disinformation age?

[ Keypad clicking ]

Information scientist Jeff Hancock at Cornell university

is examining the differences between high tech lies

and the old standbys.

If I wanted to call in sick, in the old days,

I'd need to psych myself up and get my sick voice on.

[ Telephone rings ]

Yeah, hi. [ Coughs ]

I'm really sorry. [ Coughs ]

I'm... I'm too sick to come in today.

Yeah. [ Coughs ]

Nowadays, we can type a message about feeling sick,

no voice, no vocal cues, no nonverbal cues.

Hit send, and my lie's done.

Freeman: Some digital deceptions have become so common

that Jeff and his team gave them names.

Hancock: One of the things we saw on text messages

all the time was a lie we call the Butler lie.

[ Doorbell rings ]

We used to have people that would act as that buffer,

and they would provide that physical buffer

between you and the world trying to get in and talk to you.

[ Cellphone chimes ]

Freeman: Now we all have digital butlers.

Hancock: People say, "well, I'm on my way," when, in fact,

they're not, or, "my battery was dead," because what we realized

is they're providing a buffer between that person

and the fact that the world can contact them pretty much 24/7.

Freeman: Even though it makes us easier to reach,

the online world also offers unprecedented anonymity.

A new identity is just a few keystrokes away.

This leads to a digital deception

known as the sock puppet lie.

Hancock: Sock puppet is identity deception,

where you have an alter ego

that can say things on your behalf

without appearing like you.

You're not Jeff Hancock, are you?

No. Not me.

Perfect, because I've got this new book coming out,

and I really need a positive review.

Could you help me out?

Yeah. Great, thanks.

Freeman: It's no wonder we have a hard time

deciding what to believe of all that we read online.

Is it possible to sort truth from lie?

That's what Jeff decided to find out.

He started by looking at something

we've all wondered about...

Those consumer reviews we see when we shop online.

Who writes those, and can we trust them?

The stakes are huge.

Together, we spend trillions of dollars worldwide

on online sales every year.

Jeff examined the hotel reviews we use to plan our vacations.

Should we really be relying on the opinions of strangers?

We had people write fake reviews for us,

and we paid for them.

We knew they were fake.

We compared them to ones that were real.

So we took them from the verified sites,

and we looked at linguistic patterns and how they differed.

Freeman: If he'd actually been there,

Jeff would write about the hotel in a certain way.

He would know about every detail of the room.

Hancock: A real reviewer will have a sense

of what the beds are like and the bathroom.

Is it clean, is the shower small or not?

That sort of thing, since they've experienced the space,

their bodies moved through it.

Freeman: But if Jeff had never been to the hotel...

He wouldn't know if there was mold in the shower

or if the Internet service was slow.

So he'd have to write about something else,

something made up.

Hancock: Now, me writing a fake review here in my home with my computer

is completely different.

When a fake reviewer has to write about something,

they're going into storytelling.

We were on business.

So they'll tell stories about who they were with,

what they were supposed to be doing.

They're trying to convince people.

Freeman: Jeff and his team compared the fake reviews

they had paid for with the verified truthful ones.

Then, they developed a truth or lie algorithm

that zeroes in on telltale words and phrases.

Hancock: See here that ones that are true

are things like, "rooms were large,"

and, "they were more expensive," whereas,

over on the deceptive one,

we can see people talking about themselves.

"I had a reservation."

Lot of instances of "i."

Freeman: Jeff has developed

keyword algorithms for other products and services

and discovered some surprising results.

People tend to think most reviews are fake,

and our estimation is that it's much lower than that.

Like, maybe 5% to 10% are fake.

Freeman: So online reviews are pretty reliable.

What about digital communications in general?

Do we use our gadgets to lie more or less

than in old fashioned face to face talks?

Things like e mail,

there's actually a lot less lying than people expect.

The main reason, I think, is that there's a record.

We evolved to talk and have it disappear,

and now we're in a radically new era.

If I write you an e mail,

not only have I created a record for myself,

I've given you a record.

That record can be copied.

It can be searched. It can be shared.

And so telling a lie in a digital format

comes with substantial risks that we've never,

as a set of communicators, ever had to worry about before.

Freeman: Jeff found a little more lying in texting,

which we use for more informal communication than e mail.

And as soon as the written words disappear,

more lies reappear.

What we find is that it's the phone

where people lie a lot.

That's... every study,

it's always on the phone where you see the most lies.

Freeman: According to Jeff,

we lie the most when we ditch our gadgets altogether

and talk to each other face to face.

Why?

Perhaps because we are really bad at spotting lies.

But a new device may help us catch a liar every time.

Think you can spot a liar?

Oh, you may look for certain tells,

facial expression, unusual tone of voice, awkward body language.

But let's not kid ourselves, folks.

It can be hard to tell if someone is lying.

Could technology restore truth to the expression,

"the eyes are the window to the soul"?

This university of Utah student is looking to swipe some money

from a campus office.

And he just found his chance.

He's not worried about throwing away his future

for a measly 20 bucks...

...because it's all part of a "mission: Impossible" experiment

dreamed up by psychophysiologist John Kircher.

John has spent the last 30 years studying lies,

and this experiment is designed to test a device

that may one day make lying impossible.

Today, there are two test subjects.

John doesn't know if one,

both, or neither of them will steal any money.

The subject receives secret agent style instructions,

a mysterious envelope,

and directions from a computerized voice.

You are an innocent participant in this experiment.

Please wait outside the building for 20 minutes

before returning to the lab.

The other student receives a diabolical assignment.

You must steal $20 from the purse.

You must have an alibi prepared.

You will not receive full credit if you are caught.

They get instructions to go to a different building,

to go to a secretary's office

and ask her where Dr. Mitchell's office is,

and she'll reply that there's no Dr. Mitchell

or that they should check with the Dean's office.

Freeman: The secretary is in on the caper.

She's been instructed to leave her office unattended

for a few minutes

after the student asks for Dr. Mitchell.

Kircher: We tried to set this up like a "mission: Impossible"

scenario to get the subject engaged

and apprehensive about what they're doing.

Those effects reproduce the kinds of things that we see

in field situations with actual criminal suspects.

Take a seat right over here.

Freeman: Now for the moment of truth or lies.

The ocular deception test begins.

The subjects answer

identical true or false questions about general topics

and about the crime.

Below the screen is John's device...

An infrared eye tracker able to spot microscopic dilations

and contractions of the pupils.

The changes that we're seeing in the size of the pupil

are very tiny.

They're less than 1/10 of a millimeter,

but with a computer, we can get a clear indication

that the pupil is dilating when a person is deceptive.

The subject looks like they didn't have a difficult time

answering these questions,

and the pupil data

look like we would expect from a truthful individual.

Freeman: Did the thief's pupils dilate

when answering the same questions?

Kircher: They're showing stronger reactions

to the questions about the $20,

so I'd say there's a good chance the subject's in a guilty group.

Freeman: Sure enough, John is right.

The female subject was innocent

and the male subject had to give back the 20 bucks.

But how did pupil dilation help John catch the thief?

John knows that when our brains

go into overdrive with mental effort,

our pupils dilate involuntarily.

And since deception

is more complicated than telling the truth,

the male student's brain had to work harder.

He couldn't hide his lying eyes.

John's ocular deception device is already 85% accurate.

That's as good as the best polygraph results.

But while people can be trained to beat polygraph tests,

pupil dilation is involuntary.

And as technology improves,

the accuracy of John's lie detector will, too.

Kircher: With better eye tracking technology,

we'll get better measures of pupil change.

Freeman: That means the accuracy of John's device

could one day reach 100%.

Imagine a future where a person with a cellphone

or smart eyewear could use a miniaturized version

of John's device on anyone they're talking to...

Husband and wife, parent and child,

worker and boss.

Would the whole truth and nothing but the truth

bring us closer together or tear us apart?

According to this cognitive scientist,

knowing the real truth about the world around us

would simply blow our minds.

What we think of as reality is just a series of illusions.

Why are our brains and senses so easily fooled?

Wow.

We rely on our senses to make sense of our world.

That's why it's so unsettling when they fail us.

We can't trust our ability to see the truth.

And even if we could...

[ Telephone rings ]

...could we handle it?

Hello?

Hello?

Hello?

I'm Don Hoffman... As far as I can tell.

Freeman: UC Irvine cognitive scientist Don Hoffman

thinks that anyone who believes our senses

are designed to show what's the truth has got it all wrong.

He enjoys proving his point

by finding new ways to fool the senses.

I'm about to eat this very tart lemon,

which normally doesn't sound like a good idea,

but before I do, I'm going to first eat this miracle berry

from west Africa.

It releases something called miraculin,

a chemical that binds to the sweet receptors on my tongue.

And what it's supposed to do is, when the acid from the lemon

binds to the miraculin, it triggers my sweet receptors

to give me an illusion of a sweet taste.

Let's see it really works.

So I'll take the berry out, and we'll cut this lemon.

And the moment of truth.

Wow.

That does taste sweet.

I've never tasted a lemon like that before.

That is really good. [ Chuckles ]

Freeman: don has identified plenty of ways our senses

and brains misconstrue the world around us.

Surely, we think, our sense of touch could never be wrong.

With touch, we feel like we're in direct contact with reality

as it really is.

Well, if you tap the shoulder and then tap the elbow

and then tap the wrist and you do the timing just right,

what a person will feel is tapping between.

So you feel a tap here and a tap here, tap there, a tap there.

And it'll feel like there's some animal running down your arm.

The brain is saying, "what is the best story

about the world that I could come up with?"

And the best story that it comes up with is, "well,

there's probably something crawling down my arm."

Freeman: With such limited senses,

the unfiltered truth of the world

never reaches our brains, so we're forced to use stories

or preconceived rules about how reality should be.

But once you're constructing reality based on rules,

if something doesn't match your assumptions,

we construct things that aren't really there.

Freeman: Each of our eyes can only take in a 2 d image.

It's our brains that create a 3 d view of the world.

There's gradients and shading,

so as you go from light to dark and dark to light,

the visual system automatically interprets that

in terms of three dimensional shapes.

As you see things like railroad tracks

converging in the distance,

you'll actually give a depth interpretation to that.

Ah!

Freeman: don's radical conclusion is that our senses

aren't intended to see the truth of reality.

Our senses do just enough to help us find mates, find food,

and avoid becoming someone else's food.

Hoffman: It's the perceptual systems

that allow you to stay alive long enough to reproduce.

Those are the ones whose genes get passed on

to the next generation.

So, in that sense, it's quite clear.

Perception and evolution of perception

is about having kids, not about the truth.

Freeman: Every creature on earth develops only the senses

it needs to survive and reproduce.

This region used to be a much bigger wetland

with millions of frogs.

Freeman: This is how researchers believe the world looks to a frog.

If things aren't moving,

the frog pretty much either doesn't see them

or is programmed to ignore them.

Freeman: Luckily for the frog, it's great at detecting small objects

flying around close enough to its tongue

to become a tasty meal.

We can see stationary objects that a frog can't,

but we don't see all the colors that a butterfly does,

and we can't hear every frequency of sound

that a bat can,

which begs the question, what is the world really like?

What are we not seeing?

Imagine a color you've never experienced before.

Nothing happens.

If we can't even do that,

just one new color that you've never experienced before,

we're really in the dark

about what the full complexity of objective reality might be.

So our senses are this wonderful window on the world,

but they're also a prison that we really can't see outside of.

We can't necessarily trust our senses,

but even if we only grasp a simplified version of reality,

surely, our memories

can keep track of where and when things happen.

Or that's what we thought.

New research suggests

that our brains trick us into misremembering the truth.

We can't possibly remember every single thing

that happens to us,

but we trust the memories we do retain.

We remember every detail about the birth of a child.

We know where we had a special meal and whom we were with.

But what if some of those memories aren't real?

What if we invented them?

Or... Someone else implanted them?

This is Susumu Tonegawa's favorite spot

to enjoy a cup of coffee.

And sitting here also reminds the M.I.T. scientist of the time

two cars slammed into each other just a few feet away.

He mentions the accident to his friend,

but his friend remembers it differently.

I had an argument with my friend,

that he said, "no, no, no.

Actually, car accident happened in front of our lab."

[ Crash ]

Freeman: Susumu thought, "no, that can't be right."

But I insisted accident happened in front of coffee shop.

Freeman: And then, he realized his mistake.

I was thinking of the conversation

I was having with my friend, drinking a coffee,

when actually, car accident happened in front of our lab.

[ Crash ]

Freeman: He and his friend were in front of the lab

when the cars collided,

but his mind was on one of their previous conversations

at the coffee shop.

Susumu's brain mistakenly combined the two locations

and created a new memory that is actually false.

As a Nobel laureate and a scientist

who's devoted three decades to understanding memory,

Susumu wanted to know how this could happen.

He and his team decided to look for physical evidence

of false memories being formed.

In the brain, the area called the hippocampus

plays a very crucial role in these types of memory.

If you have impairment in the hippocampus,

then you cannot form memory of episode very well.

Freeman: Susumu's research centers on the physical changes

in the hippocampus when an episodic memory forms.

When we experience something, like witnessing a car accident,

it biochemically changes a small group of neurons

in the hippocampus.

Neuroscientists call that changed group an engram.

It is a physical trace of the stored memory.

That stored memory is sometimes triggered when we see something

that's new but similar.

A lone, majestic pine tree may remind us of our first glimpse

of the Eiffel Tower during a vacation years ago.

Susumu found that when old memories

are activated by new experiences,

both can become confused.

Sometimes, the neurons of the old memory engram

become physically linked to the recently formed engram.

The result is a false memory

that mistakenly combines two events.

That got Susumu and his colleagues wondering,

is it possible to intentionally create false memories?

They devised an experiment with a mouse and two chambers.

Freeman: The mouse forms separate memories for each location.

For example, chamber b has a wire floor,

and chamber a does not.

Susumu then sets about locating each memory

in the mouse's brain.

The mouse has a series

of tiny wires monitoring activity in its brain.

When he places the mouse in chamber a,

Susumu can pinpoint the location of the chamber a memory.

But the wires can also stimulate neurons

to respond by emitting small pulses of light.

So whenever Susumu shines a light on those same neurons,

he can activate the mouse's memory of being in chamber a.

Once the mouse has formed a memory of chamber a,

it's placed in the wire floored chamber b.

Susumu is ready to create the false memory.

The shock is harmless but startling.

Since the chamber a memory

is activated while the mouse receives the shock in chamber b,

it creates an association between chamber a and the shock.

And sure enough,

when Susumu places the mouse back in chamber a,

it suddenly freezes in fear.

Even with no wire floor,

the mouse acts like it might get a shock.

It now possesses a false memory

of being shocked in the chamber where no shock ever happened.

Susumu and his colleagues

have successfully inserted false memories into mice.

Does this mean the same thing could be done to people?

What is science fiction today

may not be science fiction in 50 years.

Human brain much bigger than mouse brain,

but theoretically, it's possible.

Freeman: So if we can't trust our memories, our senses,

or each other,

is there any such thing as an ultimate truth?

This physicist is looking for answers in the quantum world.

He is finding that the notion of truth keeps getting curiouser

and curiouser.

Truth is hard to find in the human world.

Our brains are wired for lying.

We remember events that never happened.

And our senses

don't perceive the reality of the world around us.

But surely if we use the tools of science

to examine the fundamental nature of reality,

we can see the ultimate truth.

Unless the universe itself lies to us.

I am Jeff Tollaksen, and that's the truth.

Freeman: Jeff Tollaksen, a physicist

at Chapman university in Southern California,

has taken many trips into the quantum world.

There are a million, million, billion atoms

in each individual grain of sand.

But when we are talking about the quantum world,

we mean even smaller pieces of matter that make up the atoms.

The protons, the neutrons, and the electrons...

They make up everything in the entire universe,

including us.

Freeman: Jeff knows that the basic building blocks of existence

don't follow basic rules.

Tollaksen: Take, for instance, the electron.

The laws of the quantum world

suggest that things can be at many different places

at the same time.

They also forbid us from knowing everything about the electron.

It's a bit like looking at a hummingbird.

Its wings are moving so fast that they appear as just a blur.

But if I take a photo of the hummingbird,

I can learn one of two things.

If I set it to a high shutter speed...

...i can clearly see the location of the wings,

but I can't tell anything about velocity.

So now I'll set it to a low shutter speed.

And now it's just a blur.

I can't tell anything about the location of the wings,

but I can clearly see that they have a velocity.

Freeman: Similarly, we can never know the true position

and velocity of an electron.

So the notion of truth at the quantum level

is very different from our usual human understanding of truth.

Freeman: But as strange as these particles are,

we still know they are bits of matter

and they have certain defining properties,

such as spin direction and electrical charge.

Matter and its properties go together like rock and hard.

You can't have one without the other.

Or can you?

The more Jeff and his colleagues

study the building blocks of the universe,

the curiouser and curiouser it all becomes.

Tollaksen: If you've ever read Lewis carroll's "Alice in wonderland,"

you know that there is a cheshire cat.

Now, the cheshire cat has a grin.

And it's a remarkable grin.

So you can't have the cheshire cat without the grin.

The grin belongs to the cat.

But one day, Alice is having a conversation with the cat,

and suddenly, the body disappears,

leaving just the grin.

To which Alice said,

"well, I've often seen a cat without a grin.

But a grin without a cat?

It's the most curious thing I've ever seen."

Now, it seems physically impossible,

even in your wildest dreams, that such a thing could happen.

But what's remarkable is we've predicted how you could do this,

namely separate properties from matter.

Freeman: In July 2014,

Jeff and colleagues at the Vienna institute of technology

put that prediction to the test.

Could they actually create a quantum cheshire cat?

They split a stream of neutrons into two beams.

Then, they used magnetic fields to give the neutrons

in each beam opposite spin direction.

Using other magnetic fields and filters,

they manipulated the system

until something very curious happened.

The mass of the neutrons went entirely through the upper beam,

while the neutrons' spin properties

traveled exclusively through the lower beam.

Like a cat and its grin,

matter and its properties were separated.

If it's possible to separate an object

from the properties that we use to describe it,

is truth itself

just another property that can be stripped away?

Are we closer to finding the truth about the universe,

or closer to dismissing it as nothing more than a phantom?

Tollaksen: Every time we peel back a little bit more of that veil,

we discover incredibly beautiful and awe inspiring new truths.

Whether or not scientists will ever be able to discover

absolute truth, deep nature of everything,

we don't know.

But it is in the spirit of science to keep trying.

Will we continue to peel back layer after layer

of new truths forever?

Could we even comprehend the truth with our limited senses

and our faulty, selective memories?

There's only one thing we can be sure of...

Anyone who claims to know the ultimate truth...

...is probably just telling you another lie.

[ Chuckles ]

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