All language subtitles for Spark.Mind-Blowing.Facts.About.Our.Reality.The.Secrets.of.Quantum.Physics..x264.AAC2.0.1080p.en

[Music]

beneath the complexities of everyday life

the rules of our universe seem

reassuringly simple

this solid bridge supports my weight the

water flowing underneath always goes

downhill and when I throw this stone

it always flies through the air

following a predictable path

but as scientists peered deep into the

tiny building blocks of matter

all such certainty vanished

they found the weird world of quantum

mechanics deep down inside everything we

see around us we found a universe

completely unlike our own to paraphrase

one of the founders of quantum mechanics

everything we call real is made up of

things that cannot be themselves

regarded as real

years ago some of the world's greatest

scientists began a journey down the

rabbit hole into the strange and the bizzare

they found that in the realm of the very

small things could be in two places at once

that their fates are dictated by chance

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and that reality itself defies all

common sense

and at stake that everything we thought

we knew about the world might turn out

to be completely wrong

the story of our descent into scientific

Madness begins with the most unlikely object

Berlin 1890

Germany is a new country recently

unified and hungry to industrialize

in this newly unified Germany a number

of new engineering companies were

founded they had spent millions buying

the European patent for Edison's new

invention the light bulb

the light bulb was the epitome of modern technology

a great optimistic symbol of progress

engineering companies quickly realized

there were fortunes to be made building

street lights for the new German Empire

but what they didn't realize was that

they would also unleash a scientific revolution

strangely enough this humble object is

responsible for the birth of the most

important theory in the whole of science

quantum mechanics a theory that I've

spent my life studying

and that's because back in 1900 the

light bulb presented a rather strange problem

Engineers knew that if you heated the

filament with electricity it glowed

the physics that underpinned this though

was completely unknown

that something as basic as the

relationship between the temperature of

the filament and the color of light it

produces was still a complete mystery

a mystery they were obviously been to solve

and with the help of the new German

state they saw how to steal a march on

their competitors

in 1887 the German government invested

millions in a new technical research

Institute here in Berlin the physicalist

technician Russian starts or PTR then in

1900 they enlisted a bright if somewhat

straight-less scientist to help work

here his name was Max Planck

Planck took on a deceptively simple

problem why the color of the light

changes as the filament gets hotter

forget a sense of the puzzle facing

Plank I'm going to ride this bicycle

with an old-fashioned lamp powered by an

old-fashioned dynamo

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um

obviously the faster I go the brighter

the light the more I pedal the more

electricity the dynamo produces the

hotter the filament in the lamp and the

brighter the light

but the light the bulb makes isn't just

getting brighter it's changing color too

as I speed up the color shifts from red

to orange to yellow

right now I'm going to really belt it

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now the bulbs filament is

but although it certainly gets brighter

the color seems to stay the same yellow white

why doesn't the light get any bluer

to investigate Planck and his colleagues

built this a black body radiator

it's a special tube they could heat to a

very precise temperature and a way to

measure the color or frequency of the

light It produced

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nowadays over a hundred years later the

PTR still do exactly this kind of

measurement just much more accurately

the temperature inside here is 841

degrees centigrade

feel the heat coming off

and it's glowing with a lovely orangey red color

it's about the same color as my bike

light when I'm cycling slowly

I want to see something hotter still the

temperature inside here is about 2000

degrees centigrade

and it's glowing with a much brighter

whiter colored light

produce light of this intensity and

color requires a power of about 40

kilowatts now that's equivalent to about

400 meters on a bike cycling very fast

or the combined output of the entire

Tour de France

although the light is whiter it's red

white there's very little blue

why is blue so much harder to make than red

and further up the spectrum beyond blue

the so-called ultraviolet is hardly

produced at all even when we look at

things as hot as the Sun

even the Sun at a temperature of five

and a half thousand degrees centigrade

produces mostly white visible light and

makes remarkably little ultraviolet

light given how hot it is

why is this why is ultraviolet light so to make

remarkable failure of common sense so

perplexed scientists of the late 19th

century that they gave it a very

dramatic name they called it the

ultraviolet catastrophe

Plank took a crucial first step to

solving this he found the precise

mathematical link between the color of

light its frequency and its energy but

he didn't understand the connection

however it was another weird anomaly

that would really put the cat amongst the pigeons

in the late 19th century scientists were

studying that their newly discovered

radio waves and how they were

transmitted and to do that they were

building experimental rigs very similar to this one

basically by spinning this disc that

could generate huge voltages that caused

sparks to jump across the gap between

the two metal spheres

but in doing so they discovered

something very unexpected to do with light

they found that by shining a powerful

light source on the spheres they could

make the sparks jump across more easily

this suggested a mysterious and

unexplained connection between light and electricity

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to understand what was happening

scientists use this it's called a gold

leaf electroscope it's basically a more

sensitive version of the spark gap

apparatus now first of all I have to charge it up

what I'm doing is adding an excess of

electrons that are pushing the two gold

leaves apart

first I take red light and shine it on

the metal surface

and nothing happens even if I increase

the brightness of the light still the

gold leaves aren't affected

now I'll try this special blue light

rich in ultraviolet

immediately the gold leaves collapse

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light can clearly remove static electric

charge from the leaves it can somehow

knock out the electrons I added to them

but why is ultraviolet light so much

better at doing this than red light

this new puzzle became known as the

photoelectric effect

the ultraviolet catastrophe and the

photoelectric effect were big problems

for physicists

because neither could be understood

using the best science of the time

science that said quite unequivocally

that light was a wave

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all around us we see light behaving in a

perfectly common sense wavy way look at

the shadow of my hand it's fuzzy around the edges

we understand this as the light hitting

the sides of my hand and bending and

smearing out slightly just like water

waves around an obstruction

perfectly common sense wave-like behavior

and here's something else something

rather beautiful

look at these soap bubbles shine a light

on them and gorgeous colored patterns

emerge from nowhere and this was easily

explained if you accept that light was a

wave reflecting off the outer and inner

layers of the thin soap film and

breaking up into the colors of the rainbow

rather like ripples on the surface of water

light was simply ripples of energy

spreading through space

and this was as firmly accepted as the

fact that the Earth was round

but although this wave theory worked

perfectly well for shadows and bubbles

when it came to the ultraviolet

catastrophe and the photoelectric effect

the wheels started coming off the

problem was this how could light do this

to truly grasp how absurd this

phenomenon was it might be useful to

consider how waves in water behave all right

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this is the wave tank at the Renlise

headquarters in Dorset it's used to

train lifeboat teams to deal with a

range of different kinds of water waves

first small waves just 30 centimeters high

these waves don't have much energy

hardly enough energy to knock this top

hand off the other

but when the waves grow to over a meter

and a half

is a very different proposition

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it's clear what water waves are telling us

bigger more intense waves have more power

they easily knocked me and the cans around

so if light was a wave more intensity

should knock out more electrons

that's not what happened

remember no matter how intense the red

light was it still didn't budge

electrons from the metal

but weirdly weak ultraviolet worked

within seconds

so thinking of light as a wave just

wasn't adding up okay

to resolve this someone needed to think

the unthinkable and in 1905 someone did

you may well have heard of him his name

was Albert Einstein

[Music]

this is the Archenhold Sternvark

observatory in Berlin

perched on top is a strange huge iron

and steel construction

but it's not a gun it's actually a telescope

built in 1896 the telescope was one of

the largest of its kind in the world and

made the observatory the go-to place to

engage and astound the public in new science

Albert Einstein gave a very famous

public lecture here on his theory of

relativity which is of course what he's

most famous for but it's not the work

that won him the Nobel Prize

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in 1905 he'd also come up with a new

theory to explain the photoelectric effect

what he suggested was revolutionary and

even heretical

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he argued that we have to forget all

about the idea that light is a wave and

think of it instead as a stream of tiny

bullet-like particles

the term he used to describe a particle

of light was a Quantum

to Einstein a Quantum was a tiny lump of

energy and although in 1905 the word

wasn't new the idea that light could be

a Quantum seemed crazy

following Einstein's heretical line of

thought to its logical conclusion solved

all the problems with light at a single stroke

I'll try to explain how this helps using

a rough analogy of course like all

analogies it's far from perfect but

hopefully it'll give you a sense of the

physics to help you understand why

thinking of light as a stream of

particles solves the mystery of the

photoelectric effect

in this analogy these red balls

represent Einstein's light quanta

and those cans over there are the

electricity held in the metal now in the

original experiment they made

electricity flow from the surface of the

metal by shining light on it in my

analogy I'm going to try and knock those

tin cans over using these red balls

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absolutely no effect

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that's just like red light

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according to Einstein each particle of

red light carries very little energy

because red light has a low frequency

so even a very bright red light with

many red light particles can't dislodge

any electrons from the metal plate

just like the red balls

now I'm going to use heavier balls like

these blue golf balls and I'm going to

try and knock off the tin cans with these

lights in the experiment

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now each individual light particle

carries more energy

because ultraviolet light is higher frequency

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just a few of them like a dim

ultraviolet light are enough to knock

the electrons out of the metal plate and

collapse the gold leaf

so Einstein's idea that light is made up

of tiny particles or quanta is a

wonderful explanation of the

photoelectric effect I remember when I

first learned about this being blown

away by sheer elegance and simplicity

but what's more Einstein's nifty idea

all to help solve Planck's mystery of

the light bulb

there was more red than ultraviolet

because ultraviolet quanta took so much

more energy to make

about a hundred times more energy no

wonder there are so few of them

that moment at the beginning of the 20th

century signaled a genuine revolution

because it demonstrated that the kind of

physical science of people were doing

right back to Newton and LaPlace and

people like that that you needed a

completely new approach

physics has never recovered from that

moment in the sense that it's built on

that moment that's where modern physics

really began

but Einstein's theory also left

physicists with a dizzying paradox

defying all common sense

light was definitely a wave which

explained shadows and bubbles

and now it was definitely a particle too

Einstein's quanta explaining the

photoelectric effect and the ultraviolet catastrophe

then just a few years after Einstein's

brilliant crazy idea the paradox got a

lot deeper and a whole lot weirder

because what seemed to be a curious

mystery about light was about to become a battleground

but the nature of reality itself

1922 the Western world is in the grip of

a revolution a cultural revolution

James Joyce's Ulysses is published

Stravinsky is at the height of his

powers and Chaplin has just released his

first serious movie the Ottoman Empire collapses

Europe is still recovering from the war

to end or wars in which millions of men

lost their lives Russia is newly

communist meanwhile America is exporting

jazz to the world

thank you

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in arts politics literature economics

there was an insatiable appetite for

change this was the birth of modernism

you got a heart that there's no way of knowing

you can see where you are but can't see

where you're going and I'm stuck here

still I'm tangled up with you

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this whole world can be so unsaid

but and I might get into trouble for

saying this I would argue that the

upheaval that took place in physics at

this time would eclipse them all and

have far longer lasting consequences it

had begun with the discovery of the

weird and contradictory wave particle

nature of light

they ended up as an epic battle fought

between the greatest minds and science

for the highest possible stakes the

nature of reality itself

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on one side a new wave of modernist

revolutionary scientists and their

leader the brilliant Danish physicist

Niels Bohr

on the other side the voice of reason

Albert Einstein at the height of his

powers are now world famous a formidable adversary

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the battle raged for decades actually in

some ways it still does it was fought

across the world in universities at

conferences in bars and cafes it would

reduce grown men to tears and it began

with a deceptively simple experiment

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but weirdly it was an experiment that

wasn't even about light

was about the particles that make

electricity

in the mid-1920s an experiment was

carried out at Bell Laboratories in New

Jersey in America which uncovered

something entirely unexpected about

electrons

now at the time it was accepted without

question that electrons were these tiny

lumps of matter small but solid

particles like miniature billiard balls

in the experiment they fired a beam of

electrons at a crystal and watched how

they scattered

now that's entirely equivalent to taking

a beam of electrons say from an electron

gun and firing it at a screen with two

slits in it so that the electrons pass

through the slits and hit another screen

at the back

what the Bell science has found shocked

the physics world to the core

to understand why consider a similar

experiment with water waves

I've set up a simple experiment I have a

water ripple tank placed on top of an

overhead projector I have a generator

producing waves that pass through two

narrow gaps the projector beams the

image of the waves onto the back wall

you can see as the waves come in from

the left and squeeze through the two

gaps they spread out on the other side

and interfere with each other

what this means is that when you get the

crest from one wave meeting the crest

from another they add up to make a

higher wave but when the crest from one

meets a trough they cancel out

this gives rise to these characteristic

lines leading to the signature wave

pattern

bands of light and dark

whenever you see these light and dark

bands the signature wave pattern you

know without doubt that you've got

wave-like behavior

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so guess what they saw in New Jersey now

it seemed that firing electrons tiny

solid particles through the two gaps

produced exactly the same kind of

pattern bands of light and dark

first light for a long time believed to

be a wave was found to sometimes behave

like particles and now electrons for a

long time believed to be particles were

behaving like waves

but it was actually stranger than that

the wave pattern wasn't merely some

result of the entire beam of electrons

more recently this experiment has been

repeated in labs around the world by

firing one electron at a time through

the slits onto the screen

at first each electron seems to land

randomly on the screen

a signature wave pattern

let me be quite clear about just how

weird this is remember from the wave

tank experiment where the signature wave

pattern only exists because each wave

passes through both slits and then it's

two pieces interfere with each other

but here every individual electron each

single particle is passing alone through

the slits before it hits the screen

and yet each single electron is still

contributing to the signature wave

pattern

each electron

can be behaving like a wave

to explain this strange result Niels

Bohr and his colleagues created quantum

mechanics the crazy theory of light and

matter that embraced contradiction and

didn't care that it was almost

impossible to understand as Niels Bohr

himself said anyone who isn't shocked by

quantum theory hasn't understood it so

viewers I'm going to take our tiny

electron and use it to delve deep into

the heart of reality

and yes prepare to be shocked because

this is the only way to explain what we

observe when a single electron travels

through the slits and hits the screen

quantum mechanics says this

we can't describe what's traveling as a

physical object

all we can talk about are the chances of

where the electron might be

this wave of chance somehow travels

through both slits producing

interference just like the water wave

then when it hits the screen what was

just the ghostly possibility of an

electron mysteriously becomes real

let me try and capture just how weird

this is with an analogy if I spin this

coin

then all the time is spinning it's a

blur I can't tell if it's heads or tails

but if I stop it I force it to decide

and its heads so before it was sort of

not heads or tails but a mixture of both

but as soon as I've stopped it I've

forced it to make up its mind this is

what boar and his supporters claimed was

happening with our electrons

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in a sense as it spins the coin is both

heads and tails

similarly the electrons wave of chance

passes through both slits two paths at

the same time

our coin then stops at heads

the ethereal wave of probability hits

the screen and only then becomes a

particle

the quantum world was unlike anything

ever seen before

it's hard to overstate just how crazy

this is ball was effectively claiming

that one can never know where the

electron actually is at all

until you measure it and it's not just

that you don't know where the electron

is it's weirdly as though the electron

itself is everywhere at once

bear in mind that electrons are among

the commonest and most basic building

blocks of reality

and yet here's Bohr saying that only by

looking do we actually conjure their

position into existence

it's like there's a curtain between us

and the quantum world and behind it

there is no solid reality

just the potential for reality

things only become real when we pull

back the curtain and look and this you

ladies and gentlemen became known as The

Copenhagen interpretation

[Applause]

persuasive as it might seem many people

couldn't stomach Niels balls outlandish

ideas and they found a natural leader in

the most powerful man in science

Albert Einstein hated this

interpretation with every fiber of his

being he famously said does the moon

cease to exist when I don't look at it

he was very unhappy because it gave

limits to knowledge that he didn't think

should be final he thought there should

be a better underlying theory

over the next 10 years Einstein and Bohr

would argue passionately about whether

quantum mechanics meant giving up on

reality or not

then with two other scientists Nathan

Rosen and Boris Podolski Einstein

thought they'd found a way to win the

argument

he was convinced he'd found a fatal flaw

in the Copenhagen interpretation and its

claim that reality was summoned into

existence by the act of looking at it at

the heart of Einstein's argument was an

aspect of quantum mechanics called

entanglement now entanglement is this

special incredibly close relationship

between a pair of quantum particles

whose fates are intertwined for example

if they were created in the same event

they try and explain this by imagining

the two particles are spinning coins

imagine

are two electrons created from the same

event and then moved apart from each

other quantum mechanics says that

because they're created together they're

entangled and now many of their

properties are forever linked wherever

they are

remember the Copenhagen interpretation

says that until you measure one of the

coins neither of them is heads or tails

in fact heads and tails don't even exist

and here's where entanglement makes this

weird situation even weirder

when we stop the first coin and it

becomes heads

because the coins are linked through

entanglement the second coin will

simultaneously become tails

and here's the crucial thing I can't

predict what the outcome of my

measurement will be only that they will

always be opposite Einstein seized on

this

[Applause]

because it meant that something was

happening between the two coins the

almost too crazy to imagine

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it's as if the two coins are secretly

communicating communicating

instantaneously across space and time

even if the first column was on earth

and the other was on Pluto

Einstein refused to believe this

instantaneous faster than light

communication his theory of relativity

said that nothing could travel that fast

not even information

so how could one coin instantaneously

know how the other would land

he disparagingly called it spooky action

at a distance and claimed it was a fatal

flaw in the Copenhagen interpretation

what's more he had a better idea

Einstein believed there was a simpler

interpretation that somehow the destiny

of the two coins whether or not they

ended up heads or tails was already

fixed long before we observed them

[Applause]

he said that although it seemed the coin

was deciding to be say heads at the

moment of observation actually that

decision was taken long before

it was just hidden from us

in Einstein's mind Quantum particles

were nothing like spinning coins they

were more like say a pair of gloves left

and right separated into boxes

we don't know which box contains which

glove until we open one but when we do

and find say a right-handed glove then

immediately we know that the other box

contains the left-handed glove but

crucially this requires no spooky action

at a distance neither glove has been

altered by the act of observation both

of them were either left or right-handed

glove from the beginning and the only

thing that has changed is our knowledge

so which is the true description of

reality

Boar's coins which only become real when

we look at them

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and then magically communicate to each

other

or Einstein's gloves which are hidden

from us but are definitely left or right

from the beginning in other words is

there an objective reality as Einstein

believed or not as Bohr maintained

in the late 1930s as the world plunged

into war there was no way to answer this

question the battle to understand the

nature of reality was deadlocked

the war rolled across Europe and many of

the leading scientists fled to the

United States

then as the second world war led

inexorably to the Cold War

American Science backed by dollar bills

and a new vision of the future boomed

remember after the war visitors came

back raring to go and try to apply the

ideas of quantum theory to uh to atoms

the interaction between electrons and

light and what have you you didn't need

to worry about the philosophical side of

things to make progress with that so as

you say it really took a back seat

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quantum mechanics led to a profound

understanding of semiconductors which

helped create the modern electronic age

It produced lasers revolutionizing

Communications breathtaking new medical

advances

breakthroughs in nuclear power

quantum mechanics was so successful that

most working physicists deliberately

chose to ignore Einstein's objections

it simply didn't matter to them because

it worked they even coined a phrase for

it shut up and calculate

and the price for this success was that

Boren Einstein's debate on the reality

of the quantum world was simply brushed

under the carpet

[Music]

and amidst all this success and

pragmatism there were few who still

worried what it all meant

but as the 50s rolled headlong into the

60s one lone dissenter worked out how to

settle the argument once and for all

John Bell I think is fair to say isn't

well known to the general public

but to physicists like me he's well a

hero

he was an original thinker with real

courage in his convictions and the story

of his rise to become one of the greats

of physics is made even more remarkable

when you consider how he started

he was born in Belfast in the 1920s into

a poor working-class family his father

was a horse dealer

and they really struggled to get him

into Queen's University Belfast to study

Physics

in fact he was the only one in his

family to even finish school

this I believe made him insatiably

curious fiery and stubborn

I remember meeting John Bell in 1989 a

year before he died we were both at a

conference in America and we happened to

be sharing a lift just after both

attending a talk on quantum mechanics

Keen to say something to the great John

Bell I said I thought the the speaker's

conclusions were completely crazy

he he stared at me with his piercing

blue eyes and for a moment I thought my

fledgling physics career was going down

the drain

but as the lift doors opened and he was

about to leave he said yes I completely

agree with you haven't they heard of the

helium problem

to this day I'm not quite sure what the

helium problem is but I was just so

relieved that John Bell and I agreed

for many years he worked here at

Britain's Atomic Energy Research Center

at Harwell who built this early

experimental nuclear reactor called Dido

it was here that he started pondering

the deep and worrying questions that

quantum mechanics raised

did the quantum world only exist when it

was observed or was there a deeper truth

out there waiting to be discovered

in fact he was so troubled he began to

wonder if there was a problem at the

heart of quantum mechanics

he famously said I hesitate to think it

might be wrong but I know it is rotten

and so in the early 1960s Bell decided

to try and resolve the crisis at the

heart of quantum physics it was an epic

challenge after all how do you check if

something is real if something is or

isn't there all without looking

how do you look behind the curtain

without pulling it open

John Bell came up with a brilliant way

of doing exactly that

[Music]

I think this is one of the most

ingenious ideas in the whole of physics

is certainly one of the most difficult

to understand and explain but I'm going

to try and have a go and yes I'm afraid

I'm going to use another analogy this

time I'm going to play a game of cards

but it's one for the highest possible

Stakes the nature of reality itself

the card game is against a mysterious

Quantum dealer

the cards he deals represent any

subatomic particles or even quanta of

light photons

and the game we'll play will ultimately

tell us whether Einstein or ball was

right

now the rules of the game are

deceptively simple the dealer is going

to deal two cards face down if they're

the same color I win

if they're different colors I lose

so I have a red so I need another red to

win that's black I lose

again opposite colors I've lost both

those

that's four in a row

[Music]

that's six pairs in a row that I've lost

okay I think I know what the deal is

doing here clearly the deck has been

rigged in advance so that every pair

come out as opposite colors

but there's a simple way to catch the

dealer out

so what we can do now is change the

rules of the game

this time if they are the opposite color

I win

[Music]

but once again every time my evil

Quantum opponent beats me

but again I can see what the karate

dealer could have done maybe while I

wasn't looking he's switched the pack

and and rigged it so that it always

lands in his favor now if repair is the

same color

rigged decks remember were what Einstein

thought was really happening in the

entanglement experiment

he said that just like the gloves were

already placed in the box so the evil

dealer stacked the cards before we

played

but Neil's Boar's idea was very

different he said red and black don't

even exist until you turn them over

Belle's genius was that he came up with

a way of deciding once and for all who

was right Einstein or boar

this is how he did it I'm now not going

to tell the dealer which game I want to

play same color wins or different color

wins until after he's dealt the cards

[Music]

now because he can never predict which

rules I'm going to play by

he can never stack the deck correctly

now he can't win

can he

so now the rules are

different wins

the same okay

same color wins

this gets to the very heart of Belle's

idea

if we now start playing and I win as

many as I lose then Einstein was right

the dealer is just a trickster with a

gift for sleight of hand

reality may be tricky but it does have

an objective existence

what if I lose well then I'm forced to

admit

that there is no sensible explanation

card must be sending secret signals to

the other across space and time in

defiance of everything we know

I'm forced to accept that at the

fundamental Quantum level reality is

truly unknowable

[Music]

Bell reduced this idea into a single

mathematical equation that tells us once

and for all what seemed unanswerable

how reality really is

John Bell published his idea in 1964 and

the extraordinary thing is at the time

the entire physics Community ignored him

total radio silence it seems the world

simply wasn't ready

perhaps it was because his equation

seemed untestable or just because nobody

thought it was worth investigating

but that was about to change

and the change would come from a very

unexpected place

[Music]

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America was in crisis over Vietnam

Watergate feminism the Black Panthers

and while all this was going on a small

group of hippie physicists were working

at the University of Berkeley in

California they did all the hippie

things they smoked dope they popped LSD

they debated things like Buddhism and

telepathy

[Music]

and they loved quantum mechanics in its

weird version of reality they saw

parallels with their own esoteric

beliefs

[Music]

style physics also caught the attention

of the public who read their crazy

hippie books that mixed quantum

mechanics with Eastern mysticism books

like the tower of physics

the dancing Woolly Masters and my

personal favorite space-time and beyond

towards an explanation of the

unexplainable

but more importantly for our story the

story of quantum mechanics these hippie

physicists also turn their attention to

Einstein's now famous thought experiment

and what it told us about the nature of

reality

they saw Niels Bohr's secret signaling

as proof that physics supported their

own ideas

because if two particles could spookily

communicate across space then ESP

telepathy and clairvoyance were probably

true as well

only they could prove it really existed

then in 1972 they realized that with a

bit of mathematical sleight of hand they

could take Bell's equation and

experimentally test it

one of their group John Clauser borrowed

some equipment from the lab he was

working in and set up the first genuine

and ultimate test of quantum mechanics

this is a picture of that first

experiment built of leftovers and stolen

equipment

over the next few years it was improved

by a team led by Alan Aspect in Paris

making its results more reliable

over 10 years after Bell first proposed

his equation

finally it could be put to the test

this is a modern version of the

experiment first carried out by John

Clauser and then Alan Aspect

here a crystal converts laser lights

into pairs of entangled light quanta

photons making two very precise beams

these photons are passed round and bent

back again until they pass through these

detectors the two photons are like the

two cards the evil dealer places in

front of me

we'll measure a property of the photons

called polarization which is equivalent

to the color of the playing cards in my

game

so for instance winning with two

matching red cards might be the same as

two photons with matching polarization

but because this is quantum mechanics

it's more complicated than my simple

card game and these dials here allow me

to measure a second property of the

photons as well now that's equivalent to

me not only trying to guess the color of

the face of the cards but also trying to

guess the color of the back of the cards

okay so we're now going to switch on the

laser and start the experiment

so this number here gives me the number

of photon pairs coming through the

experiment that's equivalent to the

pairs of cards in my game

the graph here dropping down gives me

the probability that I can win that I'm

guessing right

the more photons the more accurate it

becomes I'll stop at an uncertainty of

about one percent

and the final answer is 0.56 so if I

put that into my equation I now need to

run The Experiment three more times

corresponding to the four different

settings of these dials

each run is now like a different set of

rules for the quantum dealer

and when I add them up and get the

answer if it's less than two then

Einstein was right if it's greater than

2 then ball was right okay so now for

the second setting

just remember what the experiment will

show

if the numbers come out less than two

then it's proof the dealer has been

stacking the deck this was Einstein's

view okay so the number I get this time

is 0.82

now reset for run three

but if the result is greater than two

then the deck cannot be stacked and

something else is at work okay so the

Run 3 result is minus 0.59 and finally

run 4.

this last number will finally reveal if

the world follows common sense

something much more bizarre okay so our

final result is in and it's 0.56 so if

we turn the laser off

right I better just work out the answer

and there we have it 2.53

it's a number greater than two absolute

proof that Albert Einstein was wrong and

Neil's Bohr was right

the significance of this result is

simply enormous just remember what it

means Einstein's version of reality

cannot be true no amount of clever

jiggery pokery with our experiment can

cheat nature the two entangled photons

properties couldn't have been set from

the beginning but are summoned into

existence only when we measure them

something strange is linking them across

space something we can't explain or even

imagine other than by using mathematics

and weirder

futons do only become real when we

observe them

in some strange sense it really does

suggest the moon doesn't exist when

we're not looking

it truly defies common sense

no wonder towards the end of his life

Einstein wrote all these 50 years of

conscious brooding have brought me no

nearer to the question what are like

quanta every Tom Dick and Harry thinks

he knows it that he is mistaken

the experiment only confirms this

whatever is happening we just don't

understand it

but it doesn't mean we should stop

looking

while it's true that Einstein's dream of

finding a reasonable common sense

explanation was shattered for good my

own personal view is that this doesn't

necessarily banish physical reality

like Einstein I still believe there

might be a more palatable explanation

underlying the weird results of quantum

mechanics but one thing is clear whether

there are physical spooky connections

whether there are parallel universes

whether we bring reality into existence

by looking

whatever the truth is the weirdness of

the quantum world won't go away

it'll rear its ugly head somewhere

120 years ago the greatest Scientific

Revolution ever was brought about by a

light bulb

and scientists are still using powerful

light sources like x-rays to unlock

nature's mysteries

this is the diamond light source it's

Britain's single larger science facility

the X-rays produced here are 10 billion

times more powerful than a Hospital

X-ray with that sort of power scientists

can slice into matter and glimpse those

quantum secrets inside

researchers here are using this powerful

light beam to investigate new materials

which may have the potential to bring

about an electronics breakthrough as

great as any before

just as the quantum pioneers of the 20s

and 30s ended up bringing about a

scientific and technological revolution

so this generation of physicists are set

to usher in a new quantum era

[Music]

an era where Einstein's hated quantum

entanglement now produces unbreakable

computer security

new kinds of communication systems super

fast computers and other advances we

can't yet even imagine

and this is why quantum mechanics

thrills and frustrates me it's

capricious it's counter-intuitive it

even sometimes feels just plain wrong

and yet it still surprises us every day

and I for one believe that our knowledge

of the quantum world is still far from

complete that there are greater truths

about nature yet to be discovered

and that's still what keeps me awake at

night

this week join me as my journey into the

quantum world gets even more

I investigate how its weird rules are

crucial for life and how the bizarre

behavior of subatomic particles might

even influence evolution itself

welcome to a new and very strange World

of Nature

taken over by the weird subatomic

particles of quantum physics

as a physicist I've spent my working

life studying how these particles behave

in the laboratory

but now I'm heading out into the natural

world I'm on a mission to prove that

quantum physics can solve the greatest

mysteries in biology this is a real

adventure for me I'm very much out of my

comfort zone trying to apply the very

careful ideas I'm familiar with in a

Physics laboratory to the messy world of

living things

[Music]

I believe that quantum physics could

hold many of life's secrets

that deep in the cells of animals

particles glide through walls like

ghosts

[Music]

that when plants capture sunlight

their cells are invaded by shimmering

waves that can be everywhere at the same

time

[Music]

and that even our human senses are

tuning into strange quantum vibrations

[Music]

in the fantastic world of quantum

biology

life is a game of chance

played by quantum rules

this is what I hope to convince you of

to show you that quantum mechanics is

essential in explaining many of the

important processes in life and

potentially that quantum mechanics may

even underpin the very existence of life

itself

begins with one of the most majestic

sights in nature

migration

every winter Barnacle geese arrive right

on cue at the same Scottish River

the end of an epic 2000 mile voyage from

Svalbard high above the Arctic Circle

of course many birds head south for

winter then back home for summer

but for decades exactly how birds

navigated with such a

CK was one of the greatest mysteries in

biology

[Music]

so the most recent discovery has caused

a sensation

yeah

in the past few years one species of

bird has helped create a scientific

revolution I was one of many physicists

who were shocked to discover that it

navigates using one of the strangest

tricks in the whole of science

it utilizes a quirk of quantum mechanics

one Bamboozled even the greatest of

physicists from Richard Feynman to

Albert Einstein himself

so you might be surprised to discover

the identity of this mysterious creature

say hello to the quantum Robin

[Music]

this is the European Robin

every year she migrates from northern

Europe to the tip of Spain and back

in this laboratory in the woods

biologist Henrik Morrison is trying to

solve the mystery of how she does it

but he's found himself in my world the

strange world of quantum mechanics

quantum mechanics describes the very

weird behavior of subatomic particles

down in this realm of the very small we

have to abandon common sense and

intuition

Instead this is a world where objects

can spread out like waves

quantum particles can be in many places

at once and send each other mysterious

Communications

I set out to understand how the bird

finds it�s way but it just turned out

that the data

more and more pointed towards this as

the only explanation that could bring

all the different results together

it's investigating a long-standing

theory

that Robins navigate by the Earth's

magnetic field

his laboratory is an ingenious magnetic

bird cage

and these plastic cones lined with

scratch sensitive paper provide the key

measurements

[Music]

Hendrick's artificial magnetic field is

like the earth except that he can point

it in any direction he likes

[Music]

inside their cones the Robins always

respond to the field leaving scratches

in a single direction

the big mystery is how

the Earth's magnetic field is incredibly

weak far too weak for any living

creature to detect

but Henrik has found an intriguing clue

by giving the quantum Robin a mask

we have a little leather hood similar to

what you put on a falcon you know but

just for Robin and you have then a hole

in front of one eye or a hole in front

of the other eye but what we can see is

that if you cover up the right eye you

turn off their magnetic compass

processing in the left part of the brain

If you cover up this eye you turn the

compass off in this part of the brain

The Robin's magnetic compass seemed to

be in her eyes

I can show you what's going on using my

own eye now we use our eyes for vision

but we also have a second light

detecting mechanism if I shine this

torch into my eye

you can see that my pupil closes down

it's basically a defense mechanism to

protect my eyes

my eye is responding to particles of

light or photons

the energy provided by the photons is

clearly enough to activate chemical

reactions after all that's what controls

my eye muscles

light must be causing similar chemical

reactions in the Robin's eyes

in fact it's the power supply for a

unique form of magnetic compass

inside her cells

in the weird world of subatomic

particles

a place where only quantum physics can

explain what's going on

to see why imagine the chemical

reactions in the Robin's eye taking

place in mountains and valleys of energy

to get a reaction to start you have to

push molecules to the top of a mountain

thanks to henrik's experiments we now

know that light does most of the hard

work

when it reaches the free peak the

molecule becomes incredibly sensitive to

the slightest touch

the key point here is that the Robin's

chemical compass is now balanced on an

energy peak between two valleys going

one way produces one set of chemical

products the other a different set

now even a tiny change in the earth

magnetic field can the molecule over the

top but the way this happens defies

common sense the final piece of the

puzzle depends on one of the truly

mind-boggling ideas in physics

but don't worry if you find it hard to

understand even Albert Einstein called

it spooky

the idea is called quantum entanglement

it involves particles that seem to

communicate faster than the speed of

light

in 1935 Einstein published a famous

paper arguing that it was impossible

but Einstein was wrong

in recent years extremely delicate

experiments have shown that subatomic

particles really are entangled

it means they can subtly and

instantaneously influence each other

across space

now it seems the same thing is going on

inside the Robin's eye

when a photon enters the Robin's eye it

creates what's called an entangled pair

of electrons

here's how it works each electron has

two possible states for simplicity I'm

choosing to call them red and green

now here's the weird thing until I

measure it it's neither one nor the

other but both at the same time

think of the electrons like spinning

their simultaneously red and green

but by firing a dart

I can force the first electron to do one

or the other

so far it's just a game of chance

I don't know what I'll get until I try

it

so I know my first electron is red

suppose I now measure the second

electron you'd think I'd have a 50 50

chance of getting red or green after all

that's what you'd expect in the normal

everyday world but you'd be wrong

in quantum entanglement the electrons

are mysteriously linked

link for example if I get red on the

first

I always get red on the second

it's not a game of chance anymore

it's as if the first electron is telling

the second one what to do

that's why Einstein called it spooky

the electrons seem to know that they

should both have the same color no

matter how far apart they are

the really important part

is that the two electrons needn't be the

same color

they can be entangled in a different way

so that if the first electron is red

the second one is always green

seems that this mysterious connection is

the ultimate secrets of the quantum

Robin's compass

because the direction of the Earth's

magnetic field can influence the outcome

near the equator they may be more likely

to be red red but near the pole they may

be more likely to be red green

and that's the vital factor that finally

tips the balance of the Robin's chemical

compass

variations in the Earth's magnetic field

change the way electrons in the Robin's

eye are entangled

and that's just enough to trigger her

compass

now finally we can see how something is

weak as the Earth's magnetic field can

tip that balance one way or the other

no no no no

no no no no no

If the message changes the chemical

reaction tips a different way

changing the Robin's compass reading

suddenly it looks like it's a

fundamentally quantum mechanical

phenomenon in Birds it would be one of

the first if not the first in biology

biologists better get used to the

weirdness of physics

the Robin is navigating by spooky

quantum entanglements

to see subtle Quantum effects even in a

controlled austere environment of a

physics lab is really difficult and yet

here's the robin doing it with ease

these experiments are real and

verifiable and yet even though I'm

seeing them with my own eyes I still

find it hard to believe

[Music]

thank you bird navigation has brought

physics and nature together as the

science of quantum biology

there's a whole new world to explore

but its pioneers have found that it

doesn't just affect birds

[Music]

affects every single one of us

because the latest experiments say

you're doing quantum physics right now

and believe it or not you're doing it

with your nose

our sense of smell is remarkable and

quite different from our other senses of

sights and hearing among the thousands

of scents that we can recognize many of

them may well trigger very powerful

memories and emotions it's as though our

sense of smell is wired directly to our

inner consciousness

it's also different in another way the

other senses of sight and hearing rely

on us detecting waves light and sound

but our sense of smell involves

detecting particles chemical molecules

recently scientists have begun to

realize that when it comes to our sense

of smell something very mysterious is

going on

for decades biologists thought they knew

exactly how our noses sniffed out

different chemicals

but physicists like Jenny Brooks think

there could be a new ingredient in the

mix

and it smells like quantum mechanics

a lot of people think of the sense of

smell and of function and the science of

affection as being a problem that's been

solved and we know all about it and we

do know a lot about it we know about the

ingredients we know about the equipment

that we use to smell but I would argue

that there's a little bit more to

understand

[Music]

to understand more I need someone to

help me with a smell test

and Jim is going to sniff him out

[Music]

gives off a cocktail of chemicals

Jen's nose could detect a single gram of

it dissolved over an entire city

[Music]

so she has no trouble finding the man

I'm looking for

meet Colin the gardener a man who's used

to smelling the flowers

[Music]

right then Colin I'm going to put your

sniffing skills to the test cool I've

got a selection of chemicals here and I

want you to tell me what what they

remind you of okay

I'll start yours easily

like a minty

minty vapor rub it is yes

Menthol yeah but it's that that essence

right here's the next one

ah you should be able to recognize this

one

speaking with my daughter

um

icing sugar vanilla vanilla yeah

when our noses detect a chemical they

fire a nerve signal to our brains

but different chemicals create

different Sensations

standard explanation for this is to do

with the shape of the molecules

a conventional theory that goes back to

the 1950s says that the scent molecule

has a particular shape that allows it to

fit in to the receptor molecules in our

nose

[Music]

if it has the right shape it's like a

hand in a glove or a key in a lock in

fact it's called the lock and key

mechanism with the wrong shape it won't

fit into the receptor but with the right

shape it fits into the receptor

triggering that unique smell sensation

[Music]

different receptors are wired to

different parts of our brains

so when a menthol molecule locks into

its specific receptor it triggers that

minty fresh sensation

[Music]

but the lock and key theory has always

had a problem

and Colin's next test will show you why

okay how about

this one

quite strong smell

oh that's

yeah what does it remind you of what

does it conjure up what memories

I think Christmas

cake yeah

yeah that's it yep very yeah

Colin identified the smell of marzipan

or almonds in fact it's due to a scent

molecule called benzaldehyde

what I didn't give him to smell was this

other chemical cyanide both benzaldehyde

and cyanide have the same smell they

both smell of almonds but these

molecules are both very different shapes

so the lock and key mechanism as an

explanation for how we smell can't be

the whole story

so why would two molecules with

different shapes smell the same

Quantum biology has a head-spinning

explanation

says our noses aren't smelling chemical

molecules

[Music]

they're listening to them

it's not just the shape of a scent

molecule that matters

let's take a closer look at this model

of a cyanide molecule the white ball

here is a hydrogen atom and the gray

sticks are the bonds that hold it

together with the carbon and nitrogen

but the reality isn't as simple as that

I can give you a better sense of what's

going on if we look at this larger white

ball you see atoms don't just sit still

the bonds that hold them together are

like vibrating strings

and that gives us a whole new way of

thinking about smell

the bizarre new quantum theory of smell

is all about vibrating bonds

[Music]

chemical molecules are playing music for

our noses

imagine a receptor molecule in my nose

is like my guitar before it can make a

sound a scent molecule has to enter my

nose and when that scent molecule is in

place its chemical bonds provide the

strings and it's ready to be played

the receptor molecules contain quantum

particles electrons

as they leap from one atom to another

they vibrate the bonds of the scent

molecule like my fingers plucking a

guitar string

[Music]

what's remarkable about this theory is

that it tells us our sense of smell is

about the vibrations of molecules or

wave-like behavior and not so much about

the shape of a particular scent molecule

our sense of smell may be much more like

our sense of hearing

[Music]

a particular molecule say that of grass

will vibrate at a particular frequency

[Music]

but a different molecule say that of

mint will vibrate at a different

frequency

[Music]

[Music]

this would explain why cyanide smells

like almonds

the two molecules have different shapes

but their chemical bonds just happen to

vibrate at the same frequency

the constant vibration in the Adrian is

almost literally like a particle of

sound so yeah we're saying that the

process of smell could be exactly like

an acoustic resonance event it could be

very analogous to

um hearing and seeing actually

but can we really be listening with our

noses

[Music]

a bizarre theory needs a bizarre

experiment to test it

here's how it works

scientists used a molecule that smells

fruity like orange blossom

but if the theory is right then I should

be able to change its smell by changing

its vibrations

the molecule contains lots of hydrogen

atoms like this bonded to carbon atoms

what if I were to replace all these

atoms with a different form of hydrogen

called deuterium

now it won't change the shape of the

molecule but it will change the way it

vibrates

and here's why deuterium is twice as

heavy as normal hydrogen and so it

vibrates more slowly

now different vibrations mean different

smells so if I were to make a new form

of this chemical all packed with

deuterium atoms instead of normal

hydrogen it should smell different

Quantum biologists found a unique way to

carry out this experiment

[Music]

a smell comparison using the real

experts in fruity aromas

fruit flies

first the flies were trained to avoid

the modified version of the fruity

molecule

[Music]

to be honest I haven't got a clue how

you go about training a fruit fly but

apparently you can

in the laboratory the flies had to pass

through a kind of maze

they were then given a choice

[Music]

go right for the nice fruity smell

or left for the nasty modified version

[Music]

there could definitely smell the

difference

[Music]

they always preferred the original and

turned right

fly experiment gives hard evidence that

Quantum smell theory really works

but ultimately it works in harmony with

the lock and key theory

first the scent molecule fits into the

receptor

then those molecular vibrations take

over

incredible as it seems flies humans and

dogs may be smelling the sound of

quantum biology

our sense of smell is fascinating and

mysterious as it is but to think that

when I encounter a particular scent and

that sets off a whole wave of memories

and emotions in my mind that is

underpinned that it's triggered by

quantum mechanics I think makes it even

more remarkable

the mysterious influence of quantum

physics reaches into every corner of the

natural world

in fact it inhabits the walls of every

living cell on Earth

because the latest experiments suggest a

magical solution to one of the greatest

mysteries of nature

the miracle of metamorphosis

[Music]

the transformation of a tadpole into a

frog has never been fully explained

in little more than six weeks the

tadpole breaks down then reassembles in

its adult form

but the big mystery is how it happens so

fast

when you think about it there's nothing

more extraordinary than a tadpole

turning into a frog

take its tail for example over a period

or several weeks it gets reabsorbed into

the body and the proteins and fibers

that make up the flesh get recycled to

form the Frog's new limbs

but for this to happen trillions and

trillions of chemical reactions work

together breaking molecules forming new

ones in a carefully orchestrated dance

but the fibers that hold flesh together

are very very strong they're a bit like

these ropes holding my raft together in

order to dismantle the raft I'd have to

undo these very tight knots

you can think of it like this

pole is held together by long ropes of

proteins knotted together by chemical

bonds

the bonds are so strong that they should

last for years much longer than the

tadpole's entire lifespan

so how can it turn into a frog in just a

few weeks

the explanation involves one of the most

important molecules of life

tiny widgets in all our cells called

enzymes

for the enzymes are the actual machinery

of the cell they're actually the

little machines inside cells that do the

chemical transformations that are

involved in everyday life they're

absolutely crucial and the reason

they're so crucial is because what

they're able to do is to accelerate

chemical reactions by enormous amounts

let me show you just how quickly enzymes

get to work

inside this bottle is a substance called

hydrogen peroxide you're probably most

familiar with it as the chemical used to

bleach hair in fact I obtained this

sample from my local hairdressers

hydrogen peroxide is also produced in

the body and it's the job of the liver

to get rid of it now the way it does

that is using an enzyme which breaks

down hydrogen peroxide into water and

oxygen now to show you just how quickly

this enzyme works I'm going to do a

quick demonstration I've got some liver

here which I've chopped up in order to

release the enzyme

now watch what happens when I add this

liver mixture containing the enzyme to

the hydrogen peroxide

watch how quickly the oxygen is released

just a hundred grams of liver fired my

rocket nearly 20 feet

liver enzymes make the breakdown of

hydrogen peroxide incredibly efficient

it happens a trillion times faster

that's a million million times faster

than it would otherwise

in metamorphosis it's enzymes that

dismantle the tadpole's tail

and that means breaking down an

incredibly tough protein called collagen

collagen is one of the most important

proteins for the biological world it's

the protein which actually gives that

resilience that elasticity to tendons to

cartilage and of course to to our skin

as well and in the tail of the tadpole

it provides the kind of scaffold right

that's that supports that structure now

when the tadpole is transformed into the

frog what you need to do is to

essentially have an enzyme collagenase

which will literally snip the collagen

down into small pieces and thereby take

that scaffold apart

but how do enzymes break chemical bonds

apart so incredibly fast

let me show you why it's a problem only

Quantum biology can solve

think of it this way all these different

parts of the knot are like subatomic

particles electrons protons that hold

the different parts of the molecule

together now to untie the knot enzymes

have to move protons about but as you

can see this takes quite a bit of effort

and a lot of time if there are many many

knots to unpick

physicists have a fancy way of saying

put in effort to get something done they

say you have to overcome an energy

barrier

[Music]

okay here's my energy barrier

and here's my proton

to break up on the part it needs enough

energy to get over the barrier

the trouble is when we work out how long

this would take it's much too slow to

break down a tadpole's tail

but this is where protons turn into

ghosts

I wouldn't blame you for thinking that

this is an idea that's a clever

theoretician has come up with that it's

just mere speculation something that we

have no proof of but we do it takes

place all the time

[Music]

in the quantum world protons don't have

to go over barriers

they can tunnel

straight through

tunneling strikes at the very heart of

what is most strange about quantum

mechanics it's like nothing we see in

our everyday world

Quantum particle can tunnel from one

place to another even if it has to pass

through an impenetrable barrier

they're not solid objects like balls in

our everyday world they have spread out

fuzzy wave-like behavior that allows

them to leak through an energy barrier a

particle can disappear on one side of

the barrier and instantaneously reappear

on the other

in nuclear physics this effect is a

proven fact

without Quantum tunneling the sun simply

wouldn't shine

but I never thought I'd see it

in a tadpole

it's hard to stress just how weird this

process is is as though I would approach

a solid brick wall and like a phantom

disappear from one side and reappear on

the other

the most important advantage of

tunneling is its speed

much faster than if protons go over the

barrier

as a nuclear physicist Quantum tunneling

is my bread and butter subatomic

particles like protons do it all the

time

but what has this got to do with biology

the answer is that without Quantum

ghosts the metamorphosis of a tadpole

would be impossible

remember chemical bonds are basically

knots

tunneling unties them fast

have a look at these two knots now on

the face of it they look identical

but there's a subtle difference

this knot has the two short ends of the

Rope on the same side

whereas this one has the two short ends

on opposite sides

now you think that wouldn't make a

difference but it does

you see this knot

is very hard to break

whereas this one

is easy

Quantum tunneling

turns strong knots into weak ones

so in a tadpole the entire collagen

scaffold breaks apart easily

and finally other enzymes rebuild it in

the shape of a frog

the quantum tunneling of particles is

one of those weird features of the

subatomic world that a physicist like me

is very familiar with after all it's

responsible for radioactive decay and it

goes on inside the sun it's the reason

why the Sun and all stars shine but to

discover that it's going on inside every

cell of every living organism on the

planet because every cell contains

enzymes now that I find truly amazing

[Music]

Quantum biology casts its spell over

every living creature

[Music]

we've seen that birds mammals insects

and amphibians are governed by the

strangest laws in science

but the most dramatic recent

breakthrough concerns the single vital

process on which all these forms of life

depend

conversion of air and sunlight into

plants

this fine specimen is a laryx decidua or

european Larch it's about a hundred feet

high and right at this moment passing

just this side of the planet Venus is a

bullet with this tree's name on it

[Music]

the bullet is a photon nearing the end

of its long journey from the Sun

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its ultimate destiny is to kick start a

series of chemical reactions that

underpins all life on Earth

photosynthesis

every second of every day sixteen

thousand tons of new plant life are

created on Earth

and for me it's incredible to think that

our existence on this planet depends on

what happens in the next trillionth of a

second

The crucial first stage of

photosynthesis is the capture of energy

from the Sun

it's nearly a hundred percent efficient

vast is superior to any human technology

but the way that every plant on Earth

achieves this is one of the great

puzzles in biology

when it turned out that Quantum

weirdness might hold the answer

physicists could hardly believe it

was like a revelation it was very

exciting because I was used to work on

problems that were quite abstract

experiments it was I'm a theoretician

but I always related my theory to

experiments that were very clean in the

lab things that you can control but now

finding out that the things that I knew

can help me to understand better how

nature works really

I don't know scientifically it was like

a an inspiration to My Life as a

scientist so I I really as I would say I

fell in love with this field

textbook biology says the color of green

plants comes from chlorophyll molecules

inside the living cells they absorb

light from the sun

this energy is then transferred

incredibly quickly to the food making

factory at the heart of the cell

the entire event takes just a millionth

of a millionth of a second when the

photon hits the cell it knocks an

electron out of the middle of a

chlorophyll molecule this creates a tiny

packet of energy called an exiton the

exoton then bounces its way through a

forest of chlorophyll molecules until it

reaches what's called the reaction

center now that's where its energy is

used to drive chemical processes that

create the all-important biomolecules of

life

the problem is the exiton needs to find

its way to the reaction center in the

first place

or biology can't explain how the exiton

does this

because of course it doesn't know where

it's going

it just bounces around like a pinball in

a process called a random walk

sooner or later it'll pass through every

single part of the cell

but this isn't the most efficient way to

get around

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because when the exiton eventually does

reach the reaction center

it's by pure charms

if the exoton just blindly and randomly

hops between the chlorophyll molecules

it would take too long to reach the

reaction Center and would have lost its

energy as waste heat but it doesn't

something very different must be going

on

the vital clue comes from recent

experiments that stunned the world of

science

chemists fired lasers at plant cells to

simulate the capture of light from the

sun

they confirmed the exoton wasn't

bouncing along a haphazard route through

the cell

this original understanding didn't

explain what we were observing in the

lab so the mystery realizing okay so

then what is the explanation for what we

are observing in the lab

the solution is that plants obey the

most famous law in all of quantum

mechanics

the uncertainty principle

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it says you can never be certain that

the exiton is in one specific place

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instead it behaves like a Quantum wave

smearing itself out across the cell

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the exiton doesn't simply move from A

to B

in a bizarre but very real sense it's

heading in every direction at the same

time

it's spreading itself out as a wave so

that it can explore all possible Roots

simultaneously

this strikes at the very heart of what's

so strange about quantum mechanics the

exoton wave isn't just going this way or

that way it's following all paths at the

same time that's what gives it such

incredible efficiency

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if the exiton is trying every route to

the reaction center at once

bound to find the fastest possible way

to deliver its energy

it's hard to express how incredible this

discovery seems to physicists like me

biological cells are full of the random

jiggling of billions of atoms and

molecules

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that somehow exitons maintain their form

as beautiful perfect Quantum waves

waves transporting the energy that

guarantees life on Earth

it opened a whole new

scientific path for me and I I really

enjoy the fact that to be able to

understand fully what is happening there

or in the plants you have to interact

with scientists that have completely

different approaches like biologists and

chemists but we all have to come

together to actually understand what is

the relevance of this the relevance of

this so for me this is one of the most

exciting parts of this field

real scientific experiments leave no

doubt

strange hand of quantum mechanics has

shaped the entire living world

it's not a surprise that you should find

Quantum tricks being used in biological

systems the reason is because they're

better

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quantum entanglement is normally seen in

the tightly controlled conditions of the

physics lab

but now we know that Robins use it to

navigate with extraordinary precision

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Quantum vibrations mean our noses listen

to chemicals

enhancing our perception of the world

around us

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the living cells of all animals depend

vanish and reappear like ghosts

beating up the vital processes of life

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the synthesis reveals the big picture

a shimmering world where Quantum waves

capture the sun's energy in an instant

sometimes people say ah but physicists

have been looking for this for decades

well biology has had millions of years

the ultra modern science of quantum

mechanics is an ancient fact of life

for the end of my journey I want to take

these ideas to their logical conclusion

of course as a scientist any

speculations I have have to be backed up

by careful experiments so I want to

concoct a thought experiment that helps

me to answer the biggest biological

question I can think of

does quantum physics play any role in

the mechanism of evolution itself

in 1859 Charles Darwin stunned the world

with his theory of evolution by natural

selection

he went on to explain the differences

between humans and other Apes

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150 years later there's no doubt that

Darwin's theory accounts for every

living organism on land and sea

but I'd like to explore the latest

extraordinary interpretation of his

ideas

could there be a quantum theory of

evolution

the snails I'm used to seeing in my back

Garden tend to have rather Bland boring

shells so have a look at this beauty

the patterns on its shell very perfectly

match the lines on the stem

it's called a banded snail sepia

numeralis

and the pattern isn't there by accident

come and have a look at this

less well adapted snails are more likely

to be found here

this stone is called a thrush's anvil

the song thrush is the snail's main

predator it catches a snail and smashes

its shell against the stone to get to

the snail now what I can see here is

that there aren't many banded snail

shells suggesting that its colors

camouflage it very well hiding it from

the bird

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Darwin's theory says that evolution

depends on variation within a species

snails with camouflage are more likely

to survive and reproduce

passing on their shells to the next

generation so that the species as a

whole becomes better adapted

so variation the random differences

between snails is the driving force

behind their evolution

now all species evolve and adapt to

their environment

but the question I'd like to explore is

whether quantum mechanics plays a role

in this

the only way to find out is by

scientific experiments

so my adventures in Quantum biology

finally bring me home

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to the university of Surrey

here in the laboratories I'm planning a

new analysis of the most celebrated

molecule in science

deoxyribonucleic acid or DNA

stubble helix holds the genetic code for

every living organism

it's a remarkable fact that Darwin

himself had no idea what created

variation in the species

the structure of DNA wasn't discovered

until 1953 by Francis Crick and James

Watson

the most famous feature of DNA is of

course its beautiful double helix

structure

but that's just scaffolding the real

genetic secret lies in between

the four different colored molecules are

called bases

color code on one side say blue red blue

forms a gene the parents pass on to

their offspring a gene is a bit like a

jigsaw puzzle it fits together like this

a full strand of the double helix forms

a colored pattern

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but the other strand always pairs up the

same way

a blue base always goes with yellow and

green always goes with red

because only those colors have the right

shape to fit together what Crick and

Watson realized was that this provides a

mechanism for passing on the genetic

code

when cells reproduce the two strands of

DNA separate ready to be copied

but red still goes with green

and yellow still goes with blue

so bit by bit the cell creates two new

strands

two perfect copies of the entire genetic

code

so far there's no genetic variation this

new copy is identical to the original

but here's the interesting bit during

the copying process something very

important can happen

sometimes mistakes creep in

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they're called mutations

let's have a look at these two bases

here

the two prongs that hold them together

are subatomic particles they're protons

they're basically the bonds between the

strands of DNA

these protons can jump across to the

other side

if the strands split when the protons

have jumped across they find themselves

in the wrong position

now this red base will no longer bind to

a green base instead it has to bond to a

Yellow base

slotting this back in

we see that now this copy is no longer

identical to the original because I have

a yellow base here instead of a green

one we've brought in a genetic mutation

jumping protons would change the snail's

DNA

it could make a new gene for camouflaged

shells

the question is how do protons jump

it's my belief that Quantum spookiness

can take over

now for these mutations to take place

the protons have to overcome an energy

barrier and if you remember what

happened with enzymes well you can

probably guess what's coming next

protons can behave as if barriers don't

exist

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the tunnel straight through

but does this ghostly effect really

happen

my colleagues in biology are already

looking for the very first evidence of

quantum mutations

didn't really even know about quantum

mechanics so when you tell them that you

know particles can be in two places at

once they can't say well not in my cells

they can't

our experiments involves samples of

bacteria

the first sample is prepared in normal

water containing hydrogen nuclei or

protons

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when the bacteria reproduce we simply

count the mutations

but if our theory is correct then we

should be able to change the rate at

which mutations occur

remember how we tested the quantum

theory of smell what if I replace the

proton with its big brother the deuteron

this is the nucleus of an atom of

deuterium now crucially a deuteron is

twice as heavy as a proton and this

should influence how easy it is for the

deuteron to Quantum tunnel

quantum mechanics is full of surprises

protons tunnel easily

deuterons don't

these heavier particles are much more

likely to bounce straight back

so the second sample of bacteria is

prepared in heavy water which is full of

deuterons

our theory says you should get far fewer

mutations

and so far the results are extremely

encouraging the preliminary experiments

that we've done gives us a hint that the

mutation rate is indeed depressed and

deuterated water we find that it is

lowered so my hunches that were right

but we'll have to wait a little while

before we're sure

final proof lies in the future

even if we're right Quantum tunneling is

a rare form of mutation

but our results promise hard evidence

for a new explanation of one of the most

fundamental processes of life

even the nearest possibility of a new

Quantum mechanism for evolution itself

is tremendously exciting in fact the

story of quantum biology is only just

beginning what the frog the Robin the

fruit fly and the tree have shown us is

that real Quantum effects are going on

in nature all the time

and if there's anything we've learned

from the history of quantum mechanics

it's this we can never be certain where

new discoveries will take us next

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Quantum biology is a revolution in

science

but it's time I got back to the physics

department

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thank you

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thank you

I know I deserve you I know you're my

savior but when I observe you you change

your behavior so I'm stuck