Nova (1974–…): Season 38, Episode 18 - Quantum Leap - full transcript
Lying jusf beneath
everyday reality
is c: breathtaking world,
where much of whcn' we perceive
about The universe is wrong.
Physicist and besf-selling
author Bricm Greene fakes you
on c: journey fhcn' bends The
rules of human experience.
BRIAN GREENE: Why don"r we ever see
events unfold in reverse order?
According To The laws
of physics, this can happen.
H's c: world
fhcn' comes To light
as we probe The most extreme
realms of The cosmos,
from black holes
To The Big Bang.
To The very hecm'
of maffer itself.
I'm going To have
what he's having.
Here, our universe may be one
of numerous parallel recllilies.
The Three-dimensional world
may be jusf cm illusion,
cmci There's no ciisfinciion
befween pasf, presem'
and fufure.
GREENE: Bu'r how could This be?
How could we be so wrong
about something so familiar?
Does it bother us?
Absolutely.
There's no principle
built inio The laws of n
Th(JTS(JyTh(JTTl'1€OI'€TiCC1l
physicists have To be happy.
H's c: game-changing
perspective
fhcn' opens up Ci new world
of possibilities.
Coming up...
The realm of Tiny aloms ancl
particles: The auanlum realm.
The laws here seem impossible.
There's
don'? Like To be Tied down
'ro jus'r one locofion.
Yef They're vifal
To everything in The universe.
There's no disagreement
between quantum mechanics
and any experiment
'rh
Whcn' do They reveal
ClbOUT The ncn'ure of reality?
Take c: "Qucmfum Leap" on
"The Fabric of The Cosmos,"
righf now on NOVA.
Major funding for NOVA is
provided by the following:
And...
And by The Corporofion
for Public Broodcosfing
and by contributions
To your PBS s'r
Major funding
for "The Fabric of The Cosmos"
is provided by
the Noiionol Science Foundoiion.
And...
Supporting original research
and public unaersianaing
of science, Technology,
engineering and mathematics.
Additional funding
is provided by...
And the George D. Smith Fund.
GREENE: For Thousands of years,
we've been Trying To unlock
the mysteries of how
the universe works.
And we've done prefiy well,
coming up with
that describes The clear
and certain motion
of galaxies and s'rars
and planets.
Bu'r now we know,
GT
things are
because we've discovered
that have completely Transformed
our picture of the universe.
From outer space, To The heart
of New York City,
to the microscopic realm,
our view of The world
has shifted,
thanks to These strange
and mysterious laws
that are redefining our
understanding of reality.
They are the laws
of quantum mechanics.
Quantum mechanics rules over
every atom and Tiny particle
in every piece of matter.
In stars and planets,
in rocks and buildings,
and in you and me.
We don'? Notice the strangeness
of quantum mechanics
in everyday life,
bu'r I'r's always There,
if you know where To look.
You jus'r have To change
your perspective
and get down
to the tiniest of scales,
lo the level of aloms
and the particles inside Them.
Down at The quantum level, The
laws that govern This Tiny realm
appear complefely ciifferenf
from fhe familiar laws
that govern big,
everyday objects.
And once you catch
you never look at the world
in quite the same way.
L'r's almost impossible To
picture how weird Things can gei
down at the smallest of scales.
But what if you could visit
where the quantum laws
were obvious,
where people and objecls behave
like liny atoms and parlicles?
You'd be in for quite
Here, objects do Things
that seem crazy.
I mean, in the quantum world,
'rhere's
don'? Like To be Tied down
'ro jus'r one locofion,
or to follow jus'r one path.
L'r's almost as if Things were in
more than one place GT
And what I do here can have an
immediate effect somewhere else,
even if 'rhere's no one There.
And here's one of The strangest
things of all:
İf people behaved like the
particles inside The atom,
then most of the time,
you wouldn"r know exactly
where they were.
Instead, they could be
almost anywhere,
until you look for Them.
H€Y...
I'm going To have
what he's having.
So why do we believe
These bizarre laws?
Well, for over 75 years,
we've been using Them
to make predictions
for how atoms and particles
should behave.
And in experiment
The quanium laws
have always been right.
L'r's the best theory we have.
There are literally
billions of pieces
of confirming evidence
for quantum mechanics.
L'r has passed so many 'res'rs
of so many bizarre predictions.
There's no disagreement
between quantum mechanics
and any experiment
'rh
The quanium laws
become most obvious
when you get down
to tiny scales, like atoms,
but consider this:
I'm made of atoms.
So are you.
So is everything else we see
in the world around us.
So I'r must be The case
that these weird quantum laws
are not just telling us
about small things.
They're Telling us
C1bOUTI'6C1liTy.
So how did we discover them,
these strange laws
that seem To contradict
much of what we Thought
we knew C1bOUTTl'1€ universe?
Not long ago, we Though? We had
it pretty much figured out.
The rules that govern
how planets orbit The Sun.
How
How ripples move across
the surface of
These laws were all spelled oul
in
called classical mechanics,
and they allowed us To predict
the behavior of things
with certainty.
ITC1II seemed To be making
perfect sense.
UHTilC1bOUTC1 hundred years ago,
when scien'ris'rs were
struggling To explain
some unusual properties
of light.
In particular, The kind of light
that glowed from gases
when they were heated
in
When scieniisis observed
This light Through
they saw something
'rhey'd never expected.
PETER GALISON: If you heated up some gas
and looked at I'r Through
it formed lines.
Not the continuous spectrum
'rho'r you see projected
by
on your Table,
but very distinct lines.
DAVID KAISER:
L'r wouldn't give out
kind of complete rainbow
of light.
Ii would give out
sori of pencil beams of light
at very specific colors.
GALISON: And I'r was
something of
how to understand
what was going on.
GREENE: An explanation for The
mysterious lines of color
would come from
of radical scientists.
WhO, C1TTl'1€ beginning
of the 2O'rh century,
were grappling with The
fundamental nature
of The physical world.
And some of the most
startling insights
came from the mind
of Niels Bohr,
new ideas over ping-pong.
Bohr wos convinced
'rho'r The solution 'ro The mystery
lay at the heart of matter,
in the structure of the atom.
He Thought that atoms resemble
tiny solar systems,
with even tinier particles
called electrons
orbiting around
much the way the planets
orbit around The Sun.
Bu'r unlike The solor system,
Bohr proposed 'rho'r electrons
could not move
in jus'r any orbit.
Instead, only certain orbits
were allowed.
GALISON:
And he had
and completely
counterphysical idea,
which was that There
were definite sioies,
fixed orbits that These
electrons could hove,
and only those orbits.
GREENE: Bohr said that
when an atom was heated,
its electrons would
become agitated
and leap from one fixed orbit
To another.
Each downward leap would emit
energy in The form of light
in very specific wavelengths,
ond 'rho'r's why otoms produce
very specific colors.
This is where we get
the phrase "quantum leap."
JIM GATES: If I'r weren"r
for the quantum leap,
you would hove this smeor
of color coming out from on otom
as I'r go'r excited or de-excited.
BUTThC1T'S not what we see
in the laboratory.
You see very sharp reds
and very sharp greens.
L'r's the quantum leap.
Th(JT'S The origin and The author
of that sharp color.
GREENE: What made The
quantum leap so surprising
was that the electron goes
directly from here To There,
seemingly without moving
through the space in between.
L'r was C1SifMC1I'S suddenly
popped from its own orbit
out To Jupiter.
Bohr argued 'rha'r The auan'rum
leap arises from a fundamental,
and fundamentally weird,
property of electrons in atoms,
Th(JT1'h€il' energy comes
in discrete chunks
'rhd'r CGHHOT be subdivided,
specific minimum quantities
CC1II€CI "qUC1fiTC1."
And Th(JT'S why There are only
discrete, specific orbits.
ThC1T€l€CTI'OfiS can occupy.
KAISER: An electron had
To be here or There,
and simply nowhere in between.
And Th(JT'S like nothing
we experience in everyday life.
Think of your daily life.
When you eo'r food, you think
your food is quonfized?
Do you think
that you have To Take
of minimum food?
Food is not quantized.
But the energy of electrons
in an atom are quantized.
Thai is very mysterious,
why that is.
GREENE:
As mysterious as I'r might be
for Tiny particles
in an atom To act this way,
the evidence quickly mounted,
showing that Bohr was right.
In more and more experiments,
eleclrons followed
o clifferenl sel of rules
than planets or ping-pong balls.
Bohr's discovery
was
And with This new picture of The
atom, Bohr and his colleagues
found themselves
on
with the accepted laws
of physics.
The quantum leap
WC1SjUST The beginning.
Soon, Bohr's radical views
would bring him heod-'ro-heod
with one of the greatest
physicists in history.
Albert Einstein was no'r
afraid of new ideas.
Bu'r during The 19205,
the world of quantum mechanics
begdn To veer in d direction
Einstein did noi wdni to go,
d direction
ihdi sharply diverged
from the Qbsoluie,
definitive predictions
lhal were The hallmark
of classical physics.
TEGMARK: If you asked Einstein
or other physicists at The time
what ii was
that distinguished physics
from all kind of flaky
speculation,
they would have said,
"l'r's ThC1TW€ can predict
Things with cer'r
And quantum mechanics
seemed To pull the rug out
from under 'rh
GREENE:
One 'res'r in particular,
which would come To be known
C1STl'1€ double-sli'r experiment
exposed quantum mysteries
like no other.
If you were looking
for
based on certainty, your
expectations would be shafiered.
We can ge'r
for the double-slit experiment
and how dramatically ll allers
our piclure of realily,
by carrying ou'r
not on the scale
of tiny particles
but on the scale
of more ordinary objects,
like those you'd find here
in
But first I need To make
to the lane.
You'd expect that if I roll
down the lane,
They'll either be stopped
by The barrier
or pass Through one
or The other sli'r
and hit the screen GT The back.
And in f
Th(J1"SjUSTWhC11' happens.
Those balls 'rha'r make I'r Through
always hit the screen
directly behind either The lef'r
sli'r or The right sli'r.
The double sli'r experiment
was much like this,
except instead of bowling balls,
you use eleclrons, which are
billions of limes smaller.
You can picture Them like this.
Le'r's see what happens if I
Throw
When electrons are hurled
at the two slits,
something very different happens
on the other side.
Instead of hitting
jus'r two areas,
the electrons land allover
the detector screen,
creating
including some right between
the two slits,
the very place you'd think
would be blocked.
So WhC11"S going on?
Well, To physicists,
even in The 1920s,
this pattern could mean
only one Thing:
WGVGS.
Waves do all kinds
of interesting Things,
Things that bowling balls
would never do.
They can split.
They can combine.
If I sent
Through The double sli'rs,
it would split in two,
and then the two sets of waves
would intersect.
Their peaks and valleys
would combine,
getting bigger in some places,
smaller in others,
and sometimes
They'd cancel each other out.
With The height of The water
corresponding to brightness
on The screen,
the peaks and valleys
would create
in WhC11"S known as
an interference pattern.
So how could electrons,
which are particles,
form that pattern?
How could d single eleclron end
up in pldces d wove would go?
Particles are particles.
WGVGS GT9 WGVGS.
How can
Unless you give up The idea
Th(J1'iT'S
And Think, "Aha!"
"This Thing 'rha'r I Thought was
a particle was actually a wave."
A wove in an ocean,
'rh
The ocean is made
ou'r of particles,
but the waves in the ocean
are not particles.
And rocks are not waves,
rocks are rocks.
So
of
an ocean wave is an example
of an ocean wove,
and now somebody's Telling you
What?
Back in The 19205,
when
experiment was first clone,
scientists struggled to
understdnd this wdvy behdvior.
Some wondered if o single
electron, while in motion,
might spread out in'ro
And the physicist
Erwin Schrédinger
came up with an equation
that seemed To describe I'r.
STEVEN WEINBERG: Schrédinger
Thought Th(JT1'hiS wave
wds d description
of dn extended electron,
that somehow an electron
got smeared out
and I'r was no longer
bu'r was like
There was
C1bOUT€XC1CTly what
this represented.
GREENE: Finally,
physicist named Max Born
came up with
and revolutionary idea
for WhC1TTh€ wave equation
described.
Born said that The wave
is not
or anything else previously
encountered in science.
Instedd, he declared
I'r's something
'rha'r's really peculiar:
A probability wave.
[That is, Born argued that the
size of the wave (JTC1I'1ylOC(]TiOH
predicts The likelihood of The
electron being found There.
WEINBERG:
Where The wave is big,
'rh
of The electron is,
'rh
is most likely To be.
And 'rh
very strange, right?
So The electron on I'rs own seems
To be
PETER FISHER:
You're not allowed To ask,
"Where is The electron
right now?"
You ore allowed lo osk,
"lf I look for The eleclron
"in This li'r'rle particular
part of space,
what is The likelihood
I will find I'r There?"
I mean, that bugs
anyone anytime.
As weird as I'r sounds,
this new way of describing how
particles like elecirons move
is actually right.
When I Throw
I can never predict
where I'r will land,
but if I use
Schrédingefs equation
to find the elec'rron's
probability wove,
I can predict
with great certainty
that if I Throw
enough electrons,
Then, say, 33.1%
would end up "here,"
7.9% would end up "There,"
and so on.
These kinds of predictions
have been confirmed
again and again by experiments.
And so, The equations
of quantum mechanics
turn out To be amazingly
accurate and precise,
so long as you can accept
Th(J1'iT'S all about probability.
If you Think
that probability means
you're reduced To guessing,
the casinos of Las Vegas
are ready To prove you wrong.
Try your hand GT any one
of these games of chance,
and you can see
the power of probability.
Le'r's say I place
here at The roulefie Table.
The house doesn"r know
whether I'll win on This spin
or The next or The next.
One.
Bul il cloes know The probability
that I'll win.
In this game, I'r's one in 38.
21.
(bell rings)
WOMAN: 29.
So even though I may win
now and Then, in The long run,
the house always Takes in
more than it loses.
The point is, The house doesn"r
hove 'ro know the outcome
of any single card game,
roll of The dice,
or spin of the roulette wheel.
Casinos can s'rill be confident
that over The course
of Thousands of spins, deals,
and rolls, they will win,
and they can predict
with exquisiie accuracy
exactly how often.
According To quantum mechanics,
the world itself is
of chance much like this.
All the matter in the universe
is made of atoms
and subatomic particles
that are ruled by probability,
not certainty.
EDWARD FARHI:
AT base, nature is described
by an inherently
probabilistic Theory.
And that is highly
counterintuitive,
and something which many people
would find difficulty accepting.
GREENE: One person who found
if difficulf was Einsfein.
Einsiein could noi believe
Thai The fundamental nature
of redli'ry, d'r the deepest
level, wds determined by chdnce.
And This is what Einstein
could not accept.
Einstein said,
"God does not Throw dice."
He didn't like the idea that we
couldn't with certainty say,
"This happens or that happens."
GREENE:
Bu'r
weren"r so put off
by probability,
because The equations
of quantum mechanics
gave Them The power
to predict The behavior
of groups of atoms
and tiny particles
with astounding precision.
Before long,
that power would lead.
To some very big inventions.
Lasers, Transistors,
the integrated circuit
the entire field of electronics.
MAX TEGMARK: If quantum mechanics
suddenly went on strike,
every single machine
that we have in The US, almost
would stop functioning.
GREENE: The equations
of quantum mechanics
would help engineers design
microscopic swiiches
that direct The flow
of tiny electrons
ond control virtually
every one of 'rodoy's computers,
digital cameras,
and telephones.
ADAMS: All the devices 'rhd'r we live
on, diodes, 'rrdnsis'rors, jus'r...
that form the basis of
information Technology,
the basis of daily life in all
sorls of ways, they work.
And why do they work?
They work because
of quantum mechanics.
WEINBERG: I'm tempted To SC1yThC1T
without quantum mechanics,
we'd be back in The dark ages,
but I guess more accurately,
without quantum mechanics we'd
be back in the 19'rh century.
Steam engines,
Telegraph signals.
TEGMARK: Quantum mechanics is
the most successful theory
that we physicists
have ever discovered.
And yet, we're s'rill arguing
about what it means,
WhC1TiTT€llS us about
the nature of reality.
GREENE:
In spite of all of its Triumphs,
quantum mechanics remains
deeply mysterious.
L'r makes all This stuff run,
bu'r we s'rill haven'? Answered
basic quesiions
raised by Alberi Einstein.
C1llTl'1€ way back
in The 1920s and '30s,
quesiions involving probability
and measurement
the act of observation.
For Niels Bohr, measurement
changes everything.
He believed 'rhd'r before you
measured or observed d pdrricle,
its characteristics
were uncertain.
For example, an electron
in the double-sli'r experiment.
Before the detector ot the book
pinpoints its locotion,
it could be almost anywhere,
with
of possibilities.
Until The moment you observe I'r,
and only at that point
will the loc
uncertainty disappear.
According to Bohr's approach
To quantum mechanics,
when you measure
the (JCT of measurement forces
The particle To relinquish
all of the possible places
il could have been
onci select one definite locotion
where you find it.
The act of measurement
is what forces The particle
to make that choice.
Niels Bohr accepted
that the nature of reality
was inherently fuzzy.
Bu'r not Einstein.
He believed in certainty,
not jus'r when something
is measured or looked GT,
bUTC1ll The Time.
As Einstein said, "l like
To Think The moon is There"
even when I'm not
looking at I'r."
ThC1T'S what Einstein
was so upset about.
Do we really Think The realily
of the universe resls on
whether or not we happen
To open our eyes?
ThC1T'S jus'r bizarre.
GREENE: Einsiein was convinced something
was missing from quonium Theory,
something that would describe
all the aetailea features of
particles, like their locations,
even when you were
not looking at Them.
But at the time, few physicists
shared his concern.
KAISER: And Einstein just
Thought I'r was giving up
on the job of the physicist.
L'r w
iTjUSTWC1STOTC1llyiHCOI'T1lDl€T€.
ThC1T'S Einstein's refrain.
Quantum mechanics is not
incorrect, I'r's as far as...
in so far as it goes,
bu'r I'r's incomplete.
L'r doesn"r capture
all of The Things
that can be said or predicted
with certainty.
GREENE: Despite Eins'rein's argumenis,
Niels Bohr remained unmoved.
When Einstein repeated that
"God does no'r play dice,"
Bohr responded,
"Stop telling God what To do."
Bu'r in 1935, Einstein
Thought he'd finally found.
The Achilles' Heel
of quantum mechanics.
(screaming)
Something so strange,
so counler lo all logical views
of The universe,
he Thought I'r held The key.
To proving The Theory
was incomplete.
L'r's called "en'r
LEWIN: The most bizarre,
the most absurd, The most crazy,
the most ridiculous prediction
that quantum mechanics makes
is entanglement.
GREENE: Entanglement is
that comes from The equations
of quantum mechanics.
Two particles
can become entangled
if they're close Together and
their properties become linked.
Remarkably,
quantum mechanics says
that even if you separated
those particles,
sending Them
in opposite directions,
they could remain entangled,
inextricably connected.
To understand how profoundly
weird This is,
consider
called "spin."
(screaming)
Unlike
an elec'rron's spin,
as with other quantum qualifies,
is generally completely
fuzzy and uncertain
until the momen'r you measure I'r.
And when you do, you'll find
I'r's either spinning clockwise
or counterclockwise.
L'r's kind of like This wheel.
When it stops Turning,
ll will randomly land
on eilher recl or blue.
Now imagine
If lnese lwo wheels behaved
like lwo enlanglecl electrons,
Then every time one landed red,
the other is guaranteed
to land on blue.
And vice-verse.
Now, since the wheels
are not connected,
'rh
But the quantum mechanics
embraced by Niels Bohr
and his colleagues
went even further,
predicting that if one
of the pair were far away,
even on the moon, with no wires
or Transmitters connecting Them,
still, if you look o'r one
ond find red,
the other is sure To be blue.
In other words, if you measured
not only would you affect I'r,
but your measurement would also
affect its entangled partner,
no matter how distant.
For Einstein, that kind of weird
long-range connection
be'rween spinning wheels
or particles was so ludicrous,
he called I'r spooky:
"spooky action at
WhC1T'S surprising is Thai
when you make
of one particle, you affect
the state of the other particle.
You change I'rs STGTG.
There's no forces or pulleys
or, you know, Telephone wires.
There's nothing connecting
Those Things, right.
How could my choice To (JCT here
have anything to do
with what happens over There?
So 'rhere's no way they can
communicate with each other.
So I'r is completely bizarre.
GREENE: Einstein just could not
accept entanglement worked this way,
convincing himself that only
The math was weird, no'r reality.
He agreea that entangled
particles could exis'r,
bu'r he Thought that There was
for why they were linked
that did not involve
connection.
Instead, he insisted
that entangled particles
were more like
Imogine someone seporoies
The Two gloves,
putting each in
Then that person delivers
one of Those cases to me,
and sends the other case
to Antarctica.
Thanks.
Before I look inside my cose,
I know 'rho'r it hos
either
or
And when I open my case,
if I find
Then at that ins'r
I know The case in Antarctica
mus? Contain
even though no one
hos looked inside.
There's nothing mysterious
about this.
Obviously, by looking
inside The case,
I've not affected ei'rher glove.
This case has always
had
and the one in Antarctica
has always had
That was se'r from The moment
the gloves were separated
and packed away.
Now, Einstein Thought
that exactly the same idea
applies lo enlanglea parlicles.
Whatever configuration
the electrons are in
must have been fully determined
from The moment
that they flew apart.
So who was right?
Bohr, who championed
the equations ThC1TSC1id
that particles were like
spinning wheels
that could immediately link
their random resulis
even across great distances?
Or Einsiein, who believed There
wos no spooky connection,
but ins'redd, everything
wds decided
well before you looked?
Well, the big challenge
in figuring oul who was righl,
Bohr or Einstein,
is that Einstein is saying
spin before you measure I'r.
"How do you check 'rh
you say To Einstein.
He says, "Well, measure it"
and you'll find
The definite spin."
Bohr would say, "But I'r's
the act of measurement"
that brought that spin
To
No one knew how to resolve
the problem,
so 'rhe whole question come
'ro be considered philosophy,
not science.
In 1955, Einsiein died, s'rill
convinced that quantum mechanics
offered, at best, an incomplete
picture of reality.
In 1967, GT Columbia University,
Einstein's mission To challenge
quantum mechanics
was Taken up
by an unlikely recruit.
John Clauser was on The verge of
earning
The only Thing
standing in his way
was his grade
in quantum mechanics.
JOHN CLAUSER: When I was still
graduate s'ruden'r, Try as I might
I could no'r understand
quantum mechanics.
GREENE: Clauser was wondering
if Einstein might be right
when he made
L'r was an obscure paper
by
physicist named John Bell.
Amazingly, Bell seemed
lo have found
to break The deadlock
be'rween Einstein and Bohr,
and show, once and for all,
who was right
about the universe.
CLAUSER: I was convinced that
the quantum mechanical view
was probably wrong.
GREENE: Reading the paper,
Clduser sdw 'rhd'r Bell
hdd discovered
how To 'rell
if entangled particles
were really communicating
through spooky action,
like matching spinning wheels,
or if There was
nothing spooky C1TC1II
and the particles were already
se'r in their ways,
like
WhC1T'S more, with some
clever mathematics,
Bell showed that if spooky
action were not C11'WOI'l
then quantum mechanics
w
as Einstein thought:
İt was wrong.
I came to The conclusion 'rh
"My God,
this is one of the mos'r profound
results I've ever seen."
GREENE: Bell was
But his pdper showed 'rhd'r
the question could be decided
if you could build
that created and compared many
pairs of entangled particles.
Bell lurnecl The queslion
inlo an experimental queslion.
L'r w
To be about philosophy
or trading pieces of paper.
And The experiment that he
envisioned could be done.
You could really se'r up
an actual experiment
to force The issue.
GREENE: Clauser se'r about
constructing
that would finally
settle the debate.
Now, I WC1SjUST This punk
graduate student at the time.
This really seemed like, "Wow."
There's always the slim chance
that you will find
that will shake The world.
GREENE:
CIC1US€I"S machine could measure
thousands of pairs
of entangled particles
and compare their spins
in many different directions.
As the results
started coming in,
Clauser was surprised,
and not happy.
[I kept asking myself,
"Wh(]ThC1V€ldOfi€ wrong?
What mistakes
have I made in This?"
GREENE: Clauser repeated
his experiments, and soon,
French physicist Alain Aspect
started doing similar 'res'rs.
Aspect go'r The same results.
GREENE: CIC1US€I"S and Aspec'r's
results are truly shocking.
Even Though they defy
our intuition,
they prove that The math
of quantum mechanics is right.
Entanglement is real.
Quantum particles
can be linked across space.
Measuring one thing can,
in f
instantly affect
its distant partner,
as if The space between Them
didn"r even exis'r.
The one Thing that Einstein
Thought was impossible,
spooky action GT
actually happens.
I wds dgdin very saddened
that I had no'r overthrown
quantum mechanics,
because I still had
and, to this day,
s'rill have great difficulty
in understanding I'r.
That is The mos? Bizarre Thing
of quantum mechanics.
L'r is impossible
To even comprehend.
Don"r even ask me why.
DOH'TC1Sl< me, which you're
going 'ro, how I'r works,
because I'r's
an illegal queslion.
All we can say
is that is apparently
the way the world ticks.
GREENE:
So, if we accept that The world
really does Tick
in This bizarre way,
could we ever harness
the long-distance spooky action
of entanglement.
To do something useful?
Well, one dream has been.
To somehow transport
people and things
from one place To another
without crossing The space
in between.
In other words: 'relepor'r
"Beam me aboard!"
"Energize."
"Energizing!"
GREENE: Star Trek has always
made "beaming," or teleporfing,
look pretty convenient.
Ii seems like pure
science fiction,
but could entanglement
make it possible?
Remarkably, 'res'rs
are already underway
here on The Canary Islands,
off the coast of Africa.
ANTON ZEILINGER: We do the experiments
here on the Canary Islands
because you hove
two observotories.
And
I'r's
GREENE: Anton Zeilinger is
long way from Teleporfing himself
or any other human,
but he is trying to use
qu
To ielepori Tiny individual
particles,
in this case, photons,
particles of light.
He starts by generating
in
of L0 Palma.
One entangled photon
stays on L0 Palma,
while the other is sent by laser
to the island of Tenerife,
89 miles away.
Now, Zeilinger brings in
o third photon,
the one he wants to 'relepor'r,
and has I'r interact with The
entangled photon on L0 Palma.
The Team studies
the interaction,
comparing the quantum STGTGS
of the two particles.
And here's The amazing part:
Because of spooky action,
Zeilinger is C1bl€TO use
that comparison.
To Transform The entangled
photon on The distant island
into on iclenficol copy
of 'rho'r Third photon.
L'r's as if The Third photon
has Teleporfed across the sea,
without traversing The space
between the islands.
We sort of ex'rroc'r
The informofion
carried by the original
and make
GREENE: Using This Technique,
Zeilinger has successfully
Teleporfed dozens of particles.
Bu'r could This go even further?
Since we're made of particles,
could This process moke humon
'relepor'ro'rion possible one doy?
ATTENDANT:
Welcome to New York City.
Le'r's say I want to get
To Paris for
Well, in Theory,
entanglement might someday
make that possible.
Here's WhC1Tl'Cl need:
of particles here in New York
that's entangled with another
chamber of particles in Paris.
Right this way, Mr. Greene.
GREENE:
I would step in'ro
that acts sor'r of like
or
While 'rhe device scans 'rhe huge
number of particles in my body...
more particles
than There are stars
in the observable universe...
it's jointly scanning the
particles in the other chamber,
and I'r creates
compares The quantum STGTG
of the two sets of particles.
And here's where entanglement
comes in:
Because of spooky action
a'r a distance,
lhal lisl also reveals how the
original s'ra're of my parlicles
is related To The STGTG
of The particles in Paris.
Next, the operator
sends that list to Paris.
There, They use The data
to reconstruct
the exact quantum state
of every single one
of my particles,
and
L'r's not that The particles
Traveled from New York To Paris.
L'r's that entanglement
allows my quantum slale
to be extracted in New York
and reconstituted in Paris,
down To The l(JSTIOC1I'TiCl€.
(French music plays)
Bonjour, Mr. Greene.
Hi There.
So here I om in Paris,
an exact replica of myself.
And I'd be'r'rer be, because
measuring the quantum STGTG
of all my particles in New York
has aeslroyea the original me.
FARHI: l'r is obsolufely required in
the quontum 'relepor'ro'rion protocol
that The Thing
1'hC1TiS teleporfed
is destroyed in the process.
And you know, that does
make you
I guess you would just
end up being
of neutrons, protons,
ond electrons.
You wouldn"r look 'roo good.
Now, we are
from human T€l€lOOI'TC1TiOH Today,
bui The possibility
raises
İs the Brian Greene
who arrives in Paris really me?
Well, There should be
no difference
between the old me in New York
and the new me here in Paris.
And The reason is 'rh
according to quantum mechanics,
I'r's not the physical particles
that make me "me,"
I'r's The information
those particles contain.
And that information
has been Teleporfed exactly
for all The lrillions
of lrillions of particles
that make up my body.
ZEILINGER: Ii is o very deep
philosophical question,
whether what arrives
at The receiving s'r
is The original or not.
My position is 'rh
we mean something which has all
The properlies of The original.
ATTENDANT:
Welcome to New York City.
ZEILINGER: And if this is the
case, Then I'r is The original.
I wouldn't
step into that machine.
Uaughfl.
Whether or not
human T€l€lOOI'T(JTiOH
ever becomes
The fuzzy uncertainty
of quantum mechanics
has all sorts of other
potential applications.
Here at MIT, Seth Lloyd
is one of many researchers
trying to harness quantum
mechanics in powerful new ways.
LLOYD:
Quantum mechanics is weird.
ThC1T'S just The way I'r is.
So you know, life is dealing us
weird lemons,
can we make some weird lemonade
from This?
GREENE: Lloyd's weird lemonode comes
in the form of o quontum computer.
LLOYD: These are The guts
of
GREENE:
This gold ond bross con'rrop'rion
might not look onyihing
like your familiar lopiop,
but a'r its heart, it speaks
the same language: binary code,
in zeros and ones, callecl bils.
LLOYD: So The smallest chunk
of information is
And whai
simply busis up The information
into the smallest chunks,
and Then flips Them really,
really, really rapidly.
GREENE: This quantum
computer speaks in bits,
bu'r unlike
which at any moment can be
either zero or one,
is much more flexible.
You know, something here
can be
Here is zero, There is one.
ThC1T'S
So if you can have something
'rh
GT The same Time, Then you have
GREENE: Just as an electron
can be
of spinning clockwise
ond counterclockwise,
can be
of being
LLOYD: Then it meons you
con do computations
in ways
that our classical brains
could not hdve dreamed of.
GREENE: In Theory, quantum bits
could be made from anything
that acts in
like an electron or an atom.
The qubi'rs GT 'rhe heart
of this computer
are tiny
super-conducting circuits
built with nonotechnology
that can run
in two directions GT once.
Since quantum bits are so good
at multi-tasking,
if we can figure out
how to get qubifs to work
together To solve problems,
our computing power could
explode exponentially.
To gel o feel for why o quonlum
compuler would be so powerful,
imagine being Ti'C1lDIO€d
in the middle of d hedge mdze.
What you'd wont is To find
The problem is,
There are so many options.
And ljus'r have To Try Them out
one at
That means I'm going To hit
lo'rs of dead ends,
go clown lols of blind alleys,
and make lo'rs of wrong Turns
before I finally get lucky
and find The exi'r.
And Th(JT'S pretty much
how Today's computers
solve problems.
Though They do I'r very quickly,
they only carry out
one Task GT
jusi like I can only invesiigaie
one path oi
Bul if I could lry all
of the possibililies cl once,
it would be
And Th(JT'S kind of how
quonium computing works.
Since particles can, in
be in many places GT once,
the computer could investigate
or solutions at The same time,
and find the correct one
in
Now,
only has
of routes To explore,
so o convenfionol computer
could find the way out
pretty quickly.
But imagine
with millions or billions
of variables,
like predicting The weather
far in advance.
We might be able To forecast
natural disasters
like earthquakes or Tornadoes.
Solving Thai kind of problem
right now would be impossible,
because I'r would Take
but
could get The job done
with just
And so The brain
of that computer...
it would be smaller
than
There's no doubt we're getting
be'r'rer and better
at harnessing The power
of the quantum world,
and who knows where that
could Take us?
Bu'r we can'? Forget that
at The heart of This Theory,
which has given us so much,
There is s'rill
All the weirdness down
at The quantum level...
at The scale of atoms
and lDC1I'TiCl€S...
where does The weirdness go?
Why can Things
in The quanium world
hover in
seemingly being portly here
and portly There,
wiih so many possibilities,
while you and I...
WhO, C1fl'€I' C1II, C1I'€ made
of atoms and lDC1I'TiCl€S...
seem To always be stuck
in
We are always
either here or There.
Niels Bohr offered
no real explanation
for why all the weird fuzziness
of The quantum world
seems To vanish
as Things increase in size.
As powerful and accurate
as quantum mechanics
has proven to be,
scien'ris'rs are s'rill struggling
to figure this out.
Some believe that There is
some detail missing
in the equations
of quantum mechanics.
Ancl so, even though lhere are
multiple possibilities
in The Tiny world, The missing
details would C1CljUSTTl'1€ numbers
on our way up from atoms
To objects in the big world
so that I'r would become clear
lhal all but one of Those
possibililies disappear,
resulting in
certain outcome.
Other physicisls believe
Thai all The possibililies
that exist in The quonium world,
they never do go away.
Instead, each and every possible
outcome actually happens,
only most of Them happen
in other universes
parallel lo our own.
L'r's
but reoli'ry could go beyond
the one universe we oll see
and be constantly branching off,
creating new,
alternative worlds,
where every possibility
geis played oui.
This is The frontier
of quantum mechanics,
and no one knows
where I'r will lead.
The very fact 'rh
is much grander than we Thought
much more strange and mysterious
than we Thought,
is to me also very beautiful
and awe-inspiring.
The beauly of science is that
il allows you lo learn things
which go beyond
your wildest dreams.
And quantum mechanics
is The epitome of 'rh
After you learn
quantum mechanics,
you're never really
the same again.
GREENE: As strange as
quantum mechanics may be,
WhC11"S now clear
is that there's no boundary
between the worlds
of the tiny and the big.
Instead, These laws
apply everywhere,
and iT'SjUSTTh(JTTl'1€il' weird
features are most apparent
when things are small.
And so The discovery
of quantum mechanics
has revealed a realily,
our realily,
'rh
and thrilling,
bringing us that much closer
to fully understanding
the fabric of The cosmos.
Major funding for NOVA
is provided by:
And...
And by The Corporofion
for Public Broodcosfing
and by contributions
To your PBS s'r
Major funding
for "The Fabric of The Cosmos"
is provided by
the Noiionol Science Foundoiion.
And...
Supporting original research
and public unaersianaing
of science, Technology,
engineering and mathematics.
Additional funding
is provided by...
And the George D. Smith Fund.
everyday reality
is c: breathtaking world,
where much of whcn' we perceive
about The universe is wrong.
Physicist and besf-selling
author Bricm Greene fakes you
on c: journey fhcn' bends The
rules of human experience.
BRIAN GREENE: Why don"r we ever see
events unfold in reverse order?
According To The laws
of physics, this can happen.
H's c: world
fhcn' comes To light
as we probe The most extreme
realms of The cosmos,
from black holes
To The Big Bang.
To The very hecm'
of maffer itself.
I'm going To have
what he's having.
Here, our universe may be one
of numerous parallel recllilies.
The Three-dimensional world
may be jusf cm illusion,
cmci There's no ciisfinciion
befween pasf, presem'
and fufure.
GREENE: Bu'r how could This be?
How could we be so wrong
about something so familiar?
Does it bother us?
Absolutely.
There's no principle
built inio The laws of n
Th(JTS(JyTh(JTTl'1€OI'€TiCC1l
physicists have To be happy.
H's c: game-changing
perspective
fhcn' opens up Ci new world
of possibilities.
Coming up...
The realm of Tiny aloms ancl
particles: The auanlum realm.
The laws here seem impossible.
There's
don'? Like To be Tied down
'ro jus'r one locofion.
Yef They're vifal
To everything in The universe.
There's no disagreement
between quantum mechanics
and any experiment
'rh
Whcn' do They reveal
ClbOUT The ncn'ure of reality?
Take c: "Qucmfum Leap" on
"The Fabric of The Cosmos,"
righf now on NOVA.
Major funding for NOVA is
provided by the following:
And...
And by The Corporofion
for Public Broodcosfing
and by contributions
To your PBS s'r
Major funding
for "The Fabric of The Cosmos"
is provided by
the Noiionol Science Foundoiion.
And...
Supporting original research
and public unaersianaing
of science, Technology,
engineering and mathematics.
Additional funding
is provided by...
And the George D. Smith Fund.
GREENE: For Thousands of years,
we've been Trying To unlock
the mysteries of how
the universe works.
And we've done prefiy well,
coming up with
that describes The clear
and certain motion
of galaxies and s'rars
and planets.
Bu'r now we know,
GT
things are
because we've discovered
that have completely Transformed
our picture of the universe.
From outer space, To The heart
of New York City,
to the microscopic realm,
our view of The world
has shifted,
thanks to These strange
and mysterious laws
that are redefining our
understanding of reality.
They are the laws
of quantum mechanics.
Quantum mechanics rules over
every atom and Tiny particle
in every piece of matter.
In stars and planets,
in rocks and buildings,
and in you and me.
We don'? Notice the strangeness
of quantum mechanics
in everyday life,
bu'r I'r's always There,
if you know where To look.
You jus'r have To change
your perspective
and get down
to the tiniest of scales,
lo the level of aloms
and the particles inside Them.
Down at The quantum level, The
laws that govern This Tiny realm
appear complefely ciifferenf
from fhe familiar laws
that govern big,
everyday objects.
And once you catch
you never look at the world
in quite the same way.
L'r's almost impossible To
picture how weird Things can gei
down at the smallest of scales.
But what if you could visit
where the quantum laws
were obvious,
where people and objecls behave
like liny atoms and parlicles?
You'd be in for quite
Here, objects do Things
that seem crazy.
I mean, in the quantum world,
'rhere's
don'? Like To be Tied down
'ro jus'r one locofion,
or to follow jus'r one path.
L'r's almost as if Things were in
more than one place GT
And what I do here can have an
immediate effect somewhere else,
even if 'rhere's no one There.
And here's one of The strangest
things of all:
İf people behaved like the
particles inside The atom,
then most of the time,
you wouldn"r know exactly
where they were.
Instead, they could be
almost anywhere,
until you look for Them.
H€Y...
I'm going To have
what he's having.
So why do we believe
These bizarre laws?
Well, for over 75 years,
we've been using Them
to make predictions
for how atoms and particles
should behave.
And in experiment
The quanium laws
have always been right.
L'r's the best theory we have.
There are literally
billions of pieces
of confirming evidence
for quantum mechanics.
L'r has passed so many 'res'rs
of so many bizarre predictions.
There's no disagreement
between quantum mechanics
and any experiment
'rh
The quanium laws
become most obvious
when you get down
to tiny scales, like atoms,
but consider this:
I'm made of atoms.
So are you.
So is everything else we see
in the world around us.
So I'r must be The case
that these weird quantum laws
are not just telling us
about small things.
They're Telling us
C1bOUTI'6C1liTy.
So how did we discover them,
these strange laws
that seem To contradict
much of what we Thought
we knew C1bOUTTl'1€ universe?
Not long ago, we Though? We had
it pretty much figured out.
The rules that govern
how planets orbit The Sun.
How
How ripples move across
the surface of
These laws were all spelled oul
in
called classical mechanics,
and they allowed us To predict
the behavior of things
with certainty.
ITC1II seemed To be making
perfect sense.
UHTilC1bOUTC1 hundred years ago,
when scien'ris'rs were
struggling To explain
some unusual properties
of light.
In particular, The kind of light
that glowed from gases
when they were heated
in
When scieniisis observed
This light Through
they saw something
'rhey'd never expected.
PETER GALISON: If you heated up some gas
and looked at I'r Through
it formed lines.
Not the continuous spectrum
'rho'r you see projected
by
on your Table,
but very distinct lines.
DAVID KAISER:
L'r wouldn't give out
kind of complete rainbow
of light.
Ii would give out
sori of pencil beams of light
at very specific colors.
GALISON: And I'r was
something of
how to understand
what was going on.
GREENE: An explanation for The
mysterious lines of color
would come from
of radical scientists.
WhO, C1TTl'1€ beginning
of the 2O'rh century,
were grappling with The
fundamental nature
of The physical world.
And some of the most
startling insights
came from the mind
of Niels Bohr,
new ideas over ping-pong.
Bohr wos convinced
'rho'r The solution 'ro The mystery
lay at the heart of matter,
in the structure of the atom.
He Thought that atoms resemble
tiny solar systems,
with even tinier particles
called electrons
orbiting around
much the way the planets
orbit around The Sun.
Bu'r unlike The solor system,
Bohr proposed 'rho'r electrons
could not move
in jus'r any orbit.
Instead, only certain orbits
were allowed.
GALISON:
And he had
and completely
counterphysical idea,
which was that There
were definite sioies,
fixed orbits that These
electrons could hove,
and only those orbits.
GREENE: Bohr said that
when an atom was heated,
its electrons would
become agitated
and leap from one fixed orbit
To another.
Each downward leap would emit
energy in The form of light
in very specific wavelengths,
ond 'rho'r's why otoms produce
very specific colors.
This is where we get
the phrase "quantum leap."
JIM GATES: If I'r weren"r
for the quantum leap,
you would hove this smeor
of color coming out from on otom
as I'r go'r excited or de-excited.
BUTThC1T'S not what we see
in the laboratory.
You see very sharp reds
and very sharp greens.
L'r's the quantum leap.
Th(JT'S The origin and The author
of that sharp color.
GREENE: What made The
quantum leap so surprising
was that the electron goes
directly from here To There,
seemingly without moving
through the space in between.
L'r was C1SifMC1I'S suddenly
popped from its own orbit
out To Jupiter.
Bohr argued 'rha'r The auan'rum
leap arises from a fundamental,
and fundamentally weird,
property of electrons in atoms,
Th(JT1'h€il' energy comes
in discrete chunks
'rhd'r CGHHOT be subdivided,
specific minimum quantities
CC1II€CI "qUC1fiTC1."
And Th(JT'S why There are only
discrete, specific orbits.
ThC1T€l€CTI'OfiS can occupy.
KAISER: An electron had
To be here or There,
and simply nowhere in between.
And Th(JT'S like nothing
we experience in everyday life.
Think of your daily life.
When you eo'r food, you think
your food is quonfized?
Do you think
that you have To Take
of minimum food?
Food is not quantized.
But the energy of electrons
in an atom are quantized.
Thai is very mysterious,
why that is.
GREENE:
As mysterious as I'r might be
for Tiny particles
in an atom To act this way,
the evidence quickly mounted,
showing that Bohr was right.
In more and more experiments,
eleclrons followed
o clifferenl sel of rules
than planets or ping-pong balls.
Bohr's discovery
was
And with This new picture of The
atom, Bohr and his colleagues
found themselves
on
with the accepted laws
of physics.
The quantum leap
WC1SjUST The beginning.
Soon, Bohr's radical views
would bring him heod-'ro-heod
with one of the greatest
physicists in history.
Albert Einstein was no'r
afraid of new ideas.
Bu'r during The 19205,
the world of quantum mechanics
begdn To veer in d direction
Einstein did noi wdni to go,
d direction
ihdi sharply diverged
from the Qbsoluie,
definitive predictions
lhal were The hallmark
of classical physics.
TEGMARK: If you asked Einstein
or other physicists at The time
what ii was
that distinguished physics
from all kind of flaky
speculation,
they would have said,
"l'r's ThC1TW€ can predict
Things with cer'r
And quantum mechanics
seemed To pull the rug out
from under 'rh
GREENE:
One 'res'r in particular,
which would come To be known
C1STl'1€ double-sli'r experiment
exposed quantum mysteries
like no other.
If you were looking
for
based on certainty, your
expectations would be shafiered.
We can ge'r
for the double-slit experiment
and how dramatically ll allers
our piclure of realily,
by carrying ou'r
not on the scale
of tiny particles
but on the scale
of more ordinary objects,
like those you'd find here
in
But first I need To make
to the lane.
You'd expect that if I roll
down the lane,
They'll either be stopped
by The barrier
or pass Through one
or The other sli'r
and hit the screen GT The back.
And in f
Th(J1"SjUSTWhC11' happens.
Those balls 'rha'r make I'r Through
always hit the screen
directly behind either The lef'r
sli'r or The right sli'r.
The double sli'r experiment
was much like this,
except instead of bowling balls,
you use eleclrons, which are
billions of limes smaller.
You can picture Them like this.
Le'r's see what happens if I
Throw
When electrons are hurled
at the two slits,
something very different happens
on the other side.
Instead of hitting
jus'r two areas,
the electrons land allover
the detector screen,
creating
including some right between
the two slits,
the very place you'd think
would be blocked.
So WhC11"S going on?
Well, To physicists,
even in The 1920s,
this pattern could mean
only one Thing:
WGVGS.
Waves do all kinds
of interesting Things,
Things that bowling balls
would never do.
They can split.
They can combine.
If I sent
Through The double sli'rs,
it would split in two,
and then the two sets of waves
would intersect.
Their peaks and valleys
would combine,
getting bigger in some places,
smaller in others,
and sometimes
They'd cancel each other out.
With The height of The water
corresponding to brightness
on The screen,
the peaks and valleys
would create
in WhC11"S known as
an interference pattern.
So how could electrons,
which are particles,
form that pattern?
How could d single eleclron end
up in pldces d wove would go?
Particles are particles.
WGVGS GT9 WGVGS.
How can
Unless you give up The idea
Th(J1'iT'S
And Think, "Aha!"
"This Thing 'rha'r I Thought was
a particle was actually a wave."
A wove in an ocean,
'rh
The ocean is made
ou'r of particles,
but the waves in the ocean
are not particles.
And rocks are not waves,
rocks are rocks.
So
of
an ocean wave is an example
of an ocean wove,
and now somebody's Telling you
What?
Back in The 19205,
when
experiment was first clone,
scientists struggled to
understdnd this wdvy behdvior.
Some wondered if o single
electron, while in motion,
might spread out in'ro
And the physicist
Erwin Schrédinger
came up with an equation
that seemed To describe I'r.
STEVEN WEINBERG: Schrédinger
Thought Th(JT1'hiS wave
wds d description
of dn extended electron,
that somehow an electron
got smeared out
and I'r was no longer
bu'r was like
There was
C1bOUT€XC1CTly what
this represented.
GREENE: Finally,
physicist named Max Born
came up with
and revolutionary idea
for WhC1TTh€ wave equation
described.
Born said that The wave
is not
or anything else previously
encountered in science.
Instedd, he declared
I'r's something
'rha'r's really peculiar:
A probability wave.
[That is, Born argued that the
size of the wave (JTC1I'1ylOC(]TiOH
predicts The likelihood of The
electron being found There.
WEINBERG:
Where The wave is big,
'rh
of The electron is,
'rh
is most likely To be.
And 'rh
very strange, right?
So The electron on I'rs own seems
To be
PETER FISHER:
You're not allowed To ask,
"Where is The electron
right now?"
You ore allowed lo osk,
"lf I look for The eleclron
"in This li'r'rle particular
part of space,
what is The likelihood
I will find I'r There?"
I mean, that bugs
anyone anytime.
As weird as I'r sounds,
this new way of describing how
particles like elecirons move
is actually right.
When I Throw
I can never predict
where I'r will land,
but if I use
Schrédingefs equation
to find the elec'rron's
probability wove,
I can predict
with great certainty
that if I Throw
enough electrons,
Then, say, 33.1%
would end up "here,"
7.9% would end up "There,"
and so on.
These kinds of predictions
have been confirmed
again and again by experiments.
And so, The equations
of quantum mechanics
turn out To be amazingly
accurate and precise,
so long as you can accept
Th(J1'iT'S all about probability.
If you Think
that probability means
you're reduced To guessing,
the casinos of Las Vegas
are ready To prove you wrong.
Try your hand GT any one
of these games of chance,
and you can see
the power of probability.
Le'r's say I place
here at The roulefie Table.
The house doesn"r know
whether I'll win on This spin
or The next or The next.
One.
Bul il cloes know The probability
that I'll win.
In this game, I'r's one in 38.
21.
(bell rings)
WOMAN: 29.
So even though I may win
now and Then, in The long run,
the house always Takes in
more than it loses.
The point is, The house doesn"r
hove 'ro know the outcome
of any single card game,
roll of The dice,
or spin of the roulette wheel.
Casinos can s'rill be confident
that over The course
of Thousands of spins, deals,
and rolls, they will win,
and they can predict
with exquisiie accuracy
exactly how often.
According To quantum mechanics,
the world itself is
of chance much like this.
All the matter in the universe
is made of atoms
and subatomic particles
that are ruled by probability,
not certainty.
EDWARD FARHI:
AT base, nature is described
by an inherently
probabilistic Theory.
And that is highly
counterintuitive,
and something which many people
would find difficulty accepting.
GREENE: One person who found
if difficulf was Einsfein.
Einsiein could noi believe
Thai The fundamental nature
of redli'ry, d'r the deepest
level, wds determined by chdnce.
And This is what Einstein
could not accept.
Einstein said,
"God does not Throw dice."
He didn't like the idea that we
couldn't with certainty say,
"This happens or that happens."
GREENE:
Bu'r
weren"r so put off
by probability,
because The equations
of quantum mechanics
gave Them The power
to predict The behavior
of groups of atoms
and tiny particles
with astounding precision.
Before long,
that power would lead.
To some very big inventions.
Lasers, Transistors,
the integrated circuit
the entire field of electronics.
MAX TEGMARK: If quantum mechanics
suddenly went on strike,
every single machine
that we have in The US, almost
would stop functioning.
GREENE: The equations
of quantum mechanics
would help engineers design
microscopic swiiches
that direct The flow
of tiny electrons
ond control virtually
every one of 'rodoy's computers,
digital cameras,
and telephones.
ADAMS: All the devices 'rhd'r we live
on, diodes, 'rrdnsis'rors, jus'r...
that form the basis of
information Technology,
the basis of daily life in all
sorls of ways, they work.
And why do they work?
They work because
of quantum mechanics.
WEINBERG: I'm tempted To SC1yThC1T
without quantum mechanics,
we'd be back in The dark ages,
but I guess more accurately,
without quantum mechanics we'd
be back in the 19'rh century.
Steam engines,
Telegraph signals.
TEGMARK: Quantum mechanics is
the most successful theory
that we physicists
have ever discovered.
And yet, we're s'rill arguing
about what it means,
WhC1TiTT€llS us about
the nature of reality.
GREENE:
In spite of all of its Triumphs,
quantum mechanics remains
deeply mysterious.
L'r makes all This stuff run,
bu'r we s'rill haven'? Answered
basic quesiions
raised by Alberi Einstein.
C1llTl'1€ way back
in The 1920s and '30s,
quesiions involving probability
and measurement
the act of observation.
For Niels Bohr, measurement
changes everything.
He believed 'rhd'r before you
measured or observed d pdrricle,
its characteristics
were uncertain.
For example, an electron
in the double-sli'r experiment.
Before the detector ot the book
pinpoints its locotion,
it could be almost anywhere,
with
of possibilities.
Until The moment you observe I'r,
and only at that point
will the loc
uncertainty disappear.
According to Bohr's approach
To quantum mechanics,
when you measure
the (JCT of measurement forces
The particle To relinquish
all of the possible places
il could have been
onci select one definite locotion
where you find it.
The act of measurement
is what forces The particle
to make that choice.
Niels Bohr accepted
that the nature of reality
was inherently fuzzy.
Bu'r not Einstein.
He believed in certainty,
not jus'r when something
is measured or looked GT,
bUTC1ll The Time.
As Einstein said, "l like
To Think The moon is There"
even when I'm not
looking at I'r."
ThC1T'S what Einstein
was so upset about.
Do we really Think The realily
of the universe resls on
whether or not we happen
To open our eyes?
ThC1T'S jus'r bizarre.
GREENE: Einsiein was convinced something
was missing from quonium Theory,
something that would describe
all the aetailea features of
particles, like their locations,
even when you were
not looking at Them.
But at the time, few physicists
shared his concern.
KAISER: And Einstein just
Thought I'r was giving up
on the job of the physicist.
L'r w
iTjUSTWC1STOTC1llyiHCOI'T1lDl€T€.
ThC1T'S Einstein's refrain.
Quantum mechanics is not
incorrect, I'r's as far as...
in so far as it goes,
bu'r I'r's incomplete.
L'r doesn"r capture
all of The Things
that can be said or predicted
with certainty.
GREENE: Despite Eins'rein's argumenis,
Niels Bohr remained unmoved.
When Einstein repeated that
"God does no'r play dice,"
Bohr responded,
"Stop telling God what To do."
Bu'r in 1935, Einstein
Thought he'd finally found.
The Achilles' Heel
of quantum mechanics.
(screaming)
Something so strange,
so counler lo all logical views
of The universe,
he Thought I'r held The key.
To proving The Theory
was incomplete.
L'r's called "en'r
LEWIN: The most bizarre,
the most absurd, The most crazy,
the most ridiculous prediction
that quantum mechanics makes
is entanglement.
GREENE: Entanglement is
that comes from The equations
of quantum mechanics.
Two particles
can become entangled
if they're close Together and
their properties become linked.
Remarkably,
quantum mechanics says
that even if you separated
those particles,
sending Them
in opposite directions,
they could remain entangled,
inextricably connected.
To understand how profoundly
weird This is,
consider
called "spin."
(screaming)
Unlike
an elec'rron's spin,
as with other quantum qualifies,
is generally completely
fuzzy and uncertain
until the momen'r you measure I'r.
And when you do, you'll find
I'r's either spinning clockwise
or counterclockwise.
L'r's kind of like This wheel.
When it stops Turning,
ll will randomly land
on eilher recl or blue.
Now imagine
If lnese lwo wheels behaved
like lwo enlanglecl electrons,
Then every time one landed red,
the other is guaranteed
to land on blue.
And vice-verse.
Now, since the wheels
are not connected,
'rh
But the quantum mechanics
embraced by Niels Bohr
and his colleagues
went even further,
predicting that if one
of the pair were far away,
even on the moon, with no wires
or Transmitters connecting Them,
still, if you look o'r one
ond find red,
the other is sure To be blue.
In other words, if you measured
not only would you affect I'r,
but your measurement would also
affect its entangled partner,
no matter how distant.
For Einstein, that kind of weird
long-range connection
be'rween spinning wheels
or particles was so ludicrous,
he called I'r spooky:
"spooky action at
WhC1T'S surprising is Thai
when you make
of one particle, you affect
the state of the other particle.
You change I'rs STGTG.
There's no forces or pulleys
or, you know, Telephone wires.
There's nothing connecting
Those Things, right.
How could my choice To (JCT here
have anything to do
with what happens over There?
So 'rhere's no way they can
communicate with each other.
So I'r is completely bizarre.
GREENE: Einstein just could not
accept entanglement worked this way,
convincing himself that only
The math was weird, no'r reality.
He agreea that entangled
particles could exis'r,
bu'r he Thought that There was
for why they were linked
that did not involve
connection.
Instead, he insisted
that entangled particles
were more like
Imogine someone seporoies
The Two gloves,
putting each in
Then that person delivers
one of Those cases to me,
and sends the other case
to Antarctica.
Thanks.
Before I look inside my cose,
I know 'rho'r it hos
either
or
And when I open my case,
if I find
Then at that ins'r
I know The case in Antarctica
mus? Contain
even though no one
hos looked inside.
There's nothing mysterious
about this.
Obviously, by looking
inside The case,
I've not affected ei'rher glove.
This case has always
had
and the one in Antarctica
has always had
That was se'r from The moment
the gloves were separated
and packed away.
Now, Einstein Thought
that exactly the same idea
applies lo enlanglea parlicles.
Whatever configuration
the electrons are in
must have been fully determined
from The moment
that they flew apart.
So who was right?
Bohr, who championed
the equations ThC1TSC1id
that particles were like
spinning wheels
that could immediately link
their random resulis
even across great distances?
Or Einsiein, who believed There
wos no spooky connection,
but ins'redd, everything
wds decided
well before you looked?
Well, the big challenge
in figuring oul who was righl,
Bohr or Einstein,
is that Einstein is saying
spin before you measure I'r.
"How do you check 'rh
you say To Einstein.
He says, "Well, measure it"
and you'll find
The definite spin."
Bohr would say, "But I'r's
the act of measurement"
that brought that spin
To
No one knew how to resolve
the problem,
so 'rhe whole question come
'ro be considered philosophy,
not science.
In 1955, Einsiein died, s'rill
convinced that quantum mechanics
offered, at best, an incomplete
picture of reality.
In 1967, GT Columbia University,
Einstein's mission To challenge
quantum mechanics
was Taken up
by an unlikely recruit.
John Clauser was on The verge of
earning
The only Thing
standing in his way
was his grade
in quantum mechanics.
JOHN CLAUSER: When I was still
graduate s'ruden'r, Try as I might
I could no'r understand
quantum mechanics.
GREENE: Clauser was wondering
if Einstein might be right
when he made
L'r was an obscure paper
by
physicist named John Bell.
Amazingly, Bell seemed
lo have found
to break The deadlock
be'rween Einstein and Bohr,
and show, once and for all,
who was right
about the universe.
CLAUSER: I was convinced that
the quantum mechanical view
was probably wrong.
GREENE: Reading the paper,
Clduser sdw 'rhd'r Bell
hdd discovered
how To 'rell
if entangled particles
were really communicating
through spooky action,
like matching spinning wheels,
or if There was
nothing spooky C1TC1II
and the particles were already
se'r in their ways,
like
WhC1T'S more, with some
clever mathematics,
Bell showed that if spooky
action were not C11'WOI'l
then quantum mechanics
w
as Einstein thought:
İt was wrong.
I came to The conclusion 'rh
"My God,
this is one of the mos'r profound
results I've ever seen."
GREENE: Bell was
But his pdper showed 'rhd'r
the question could be decided
if you could build
that created and compared many
pairs of entangled particles.
Bell lurnecl The queslion
inlo an experimental queslion.
L'r w
To be about philosophy
or trading pieces of paper.
And The experiment that he
envisioned could be done.
You could really se'r up
an actual experiment
to force The issue.
GREENE: Clauser se'r about
constructing
that would finally
settle the debate.
Now, I WC1SjUST This punk
graduate student at the time.
This really seemed like, "Wow."
There's always the slim chance
that you will find
that will shake The world.
GREENE:
CIC1US€I"S machine could measure
thousands of pairs
of entangled particles
and compare their spins
in many different directions.
As the results
started coming in,
Clauser was surprised,
and not happy.
[I kept asking myself,
"Wh(]ThC1V€ldOfi€ wrong?
What mistakes
have I made in This?"
GREENE: Clauser repeated
his experiments, and soon,
French physicist Alain Aspect
started doing similar 'res'rs.
Aspect go'r The same results.
GREENE: CIC1US€I"S and Aspec'r's
results are truly shocking.
Even Though they defy
our intuition,
they prove that The math
of quantum mechanics is right.
Entanglement is real.
Quantum particles
can be linked across space.
Measuring one thing can,
in f
instantly affect
its distant partner,
as if The space between Them
didn"r even exis'r.
The one Thing that Einstein
Thought was impossible,
spooky action GT
actually happens.
I wds dgdin very saddened
that I had no'r overthrown
quantum mechanics,
because I still had
and, to this day,
s'rill have great difficulty
in understanding I'r.
That is The mos? Bizarre Thing
of quantum mechanics.
L'r is impossible
To even comprehend.
Don"r even ask me why.
DOH'TC1Sl< me, which you're
going 'ro, how I'r works,
because I'r's
an illegal queslion.
All we can say
is that is apparently
the way the world ticks.
GREENE:
So, if we accept that The world
really does Tick
in This bizarre way,
could we ever harness
the long-distance spooky action
of entanglement.
To do something useful?
Well, one dream has been.
To somehow transport
people and things
from one place To another
without crossing The space
in between.
In other words: 'relepor'r
"Beam me aboard!"
"Energize."
"Energizing!"
GREENE: Star Trek has always
made "beaming," or teleporfing,
look pretty convenient.
Ii seems like pure
science fiction,
but could entanglement
make it possible?
Remarkably, 'res'rs
are already underway
here on The Canary Islands,
off the coast of Africa.
ANTON ZEILINGER: We do the experiments
here on the Canary Islands
because you hove
two observotories.
And
I'r's
GREENE: Anton Zeilinger is
long way from Teleporfing himself
or any other human,
but he is trying to use
qu
To ielepori Tiny individual
particles,
in this case, photons,
particles of light.
He starts by generating
in
of L0 Palma.
One entangled photon
stays on L0 Palma,
while the other is sent by laser
to the island of Tenerife,
89 miles away.
Now, Zeilinger brings in
o third photon,
the one he wants to 'relepor'r,
and has I'r interact with The
entangled photon on L0 Palma.
The Team studies
the interaction,
comparing the quantum STGTGS
of the two particles.
And here's The amazing part:
Because of spooky action,
Zeilinger is C1bl€TO use
that comparison.
To Transform The entangled
photon on The distant island
into on iclenficol copy
of 'rho'r Third photon.
L'r's as if The Third photon
has Teleporfed across the sea,
without traversing The space
between the islands.
We sort of ex'rroc'r
The informofion
carried by the original
and make
GREENE: Using This Technique,
Zeilinger has successfully
Teleporfed dozens of particles.
Bu'r could This go even further?
Since we're made of particles,
could This process moke humon
'relepor'ro'rion possible one doy?
ATTENDANT:
Welcome to New York City.
Le'r's say I want to get
To Paris for
Well, in Theory,
entanglement might someday
make that possible.
Here's WhC1Tl'Cl need:
of particles here in New York
that's entangled with another
chamber of particles in Paris.
Right this way, Mr. Greene.
GREENE:
I would step in'ro
that acts sor'r of like
or
While 'rhe device scans 'rhe huge
number of particles in my body...
more particles
than There are stars
in the observable universe...
it's jointly scanning the
particles in the other chamber,
and I'r creates
compares The quantum STGTG
of the two sets of particles.
And here's where entanglement
comes in:
Because of spooky action
a'r a distance,
lhal lisl also reveals how the
original s'ra're of my parlicles
is related To The STGTG
of The particles in Paris.
Next, the operator
sends that list to Paris.
There, They use The data
to reconstruct
the exact quantum state
of every single one
of my particles,
and
L'r's not that The particles
Traveled from New York To Paris.
L'r's that entanglement
allows my quantum slale
to be extracted in New York
and reconstituted in Paris,
down To The l(JSTIOC1I'TiCl€.
(French music plays)
Bonjour, Mr. Greene.
Hi There.
So here I om in Paris,
an exact replica of myself.
And I'd be'r'rer be, because
measuring the quantum STGTG
of all my particles in New York
has aeslroyea the original me.
FARHI: l'r is obsolufely required in
the quontum 'relepor'ro'rion protocol
that The Thing
1'hC1TiS teleporfed
is destroyed in the process.
And you know, that does
make you
I guess you would just
end up being
of neutrons, protons,
ond electrons.
You wouldn"r look 'roo good.
Now, we are
from human T€l€lOOI'TC1TiOH Today,
bui The possibility
raises
İs the Brian Greene
who arrives in Paris really me?
Well, There should be
no difference
between the old me in New York
and the new me here in Paris.
And The reason is 'rh
according to quantum mechanics,
I'r's not the physical particles
that make me "me,"
I'r's The information
those particles contain.
And that information
has been Teleporfed exactly
for all The lrillions
of lrillions of particles
that make up my body.
ZEILINGER: Ii is o very deep
philosophical question,
whether what arrives
at The receiving s'r
is The original or not.
My position is 'rh
we mean something which has all
The properlies of The original.
ATTENDANT:
Welcome to New York City.
ZEILINGER: And if this is the
case, Then I'r is The original.
I wouldn't
step into that machine.
Uaughfl.
Whether or not
human T€l€lOOI'T(JTiOH
ever becomes
The fuzzy uncertainty
of quantum mechanics
has all sorts of other
potential applications.
Here at MIT, Seth Lloyd
is one of many researchers
trying to harness quantum
mechanics in powerful new ways.
LLOYD:
Quantum mechanics is weird.
ThC1T'S just The way I'r is.
So you know, life is dealing us
weird lemons,
can we make some weird lemonade
from This?
GREENE: Lloyd's weird lemonode comes
in the form of o quontum computer.
LLOYD: These are The guts
of
GREENE:
This gold ond bross con'rrop'rion
might not look onyihing
like your familiar lopiop,
but a'r its heart, it speaks
the same language: binary code,
in zeros and ones, callecl bils.
LLOYD: So The smallest chunk
of information is
And whai
simply busis up The information
into the smallest chunks,
and Then flips Them really,
really, really rapidly.
GREENE: This quantum
computer speaks in bits,
bu'r unlike
which at any moment can be
either zero or one,
is much more flexible.
You know, something here
can be
Here is zero, There is one.
ThC1T'S
So if you can have something
'rh
GT The same Time, Then you have
GREENE: Just as an electron
can be
of spinning clockwise
ond counterclockwise,
can be
of being
LLOYD: Then it meons you
con do computations
in ways
that our classical brains
could not hdve dreamed of.
GREENE: In Theory, quantum bits
could be made from anything
that acts in
like an electron or an atom.
The qubi'rs GT 'rhe heart
of this computer
are tiny
super-conducting circuits
built with nonotechnology
that can run
in two directions GT once.
Since quantum bits are so good
at multi-tasking,
if we can figure out
how to get qubifs to work
together To solve problems,
our computing power could
explode exponentially.
To gel o feel for why o quonlum
compuler would be so powerful,
imagine being Ti'C1lDIO€d
in the middle of d hedge mdze.
What you'd wont is To find
The problem is,
There are so many options.
And ljus'r have To Try Them out
one at
That means I'm going To hit
lo'rs of dead ends,
go clown lols of blind alleys,
and make lo'rs of wrong Turns
before I finally get lucky
and find The exi'r.
And Th(JT'S pretty much
how Today's computers
solve problems.
Though They do I'r very quickly,
they only carry out
one Task GT
jusi like I can only invesiigaie
one path oi
Bul if I could lry all
of the possibililies cl once,
it would be
And Th(JT'S kind of how
quonium computing works.
Since particles can, in
be in many places GT once,
the computer could investigate
or solutions at The same time,
and find the correct one
in
Now,
only has
of routes To explore,
so o convenfionol computer
could find the way out
pretty quickly.
But imagine
with millions or billions
of variables,
like predicting The weather
far in advance.
We might be able To forecast
natural disasters
like earthquakes or Tornadoes.
Solving Thai kind of problem
right now would be impossible,
because I'r would Take
but
could get The job done
with just
And so The brain
of that computer...
it would be smaller
than
There's no doubt we're getting
be'r'rer and better
at harnessing The power
of the quantum world,
and who knows where that
could Take us?
Bu'r we can'? Forget that
at The heart of This Theory,
which has given us so much,
There is s'rill
All the weirdness down
at The quantum level...
at The scale of atoms
and lDC1I'TiCl€S...
where does The weirdness go?
Why can Things
in The quanium world
hover in
seemingly being portly here
and portly There,
wiih so many possibilities,
while you and I...
WhO, C1fl'€I' C1II, C1I'€ made
of atoms and lDC1I'TiCl€S...
seem To always be stuck
in
We are always
either here or There.
Niels Bohr offered
no real explanation
for why all the weird fuzziness
of The quantum world
seems To vanish
as Things increase in size.
As powerful and accurate
as quantum mechanics
has proven to be,
scien'ris'rs are s'rill struggling
to figure this out.
Some believe that There is
some detail missing
in the equations
of quantum mechanics.
Ancl so, even though lhere are
multiple possibilities
in The Tiny world, The missing
details would C1CljUSTTl'1€ numbers
on our way up from atoms
To objects in the big world
so that I'r would become clear
lhal all but one of Those
possibililies disappear,
resulting in
certain outcome.
Other physicisls believe
Thai all The possibililies
that exist in The quonium world,
they never do go away.
Instead, each and every possible
outcome actually happens,
only most of Them happen
in other universes
parallel lo our own.
L'r's
but reoli'ry could go beyond
the one universe we oll see
and be constantly branching off,
creating new,
alternative worlds,
where every possibility
geis played oui.
This is The frontier
of quantum mechanics,
and no one knows
where I'r will lead.
The very fact 'rh
is much grander than we Thought
much more strange and mysterious
than we Thought,
is to me also very beautiful
and awe-inspiring.
The beauly of science is that
il allows you lo learn things
which go beyond
your wildest dreams.
And quantum mechanics
is The epitome of 'rh
After you learn
quantum mechanics,
you're never really
the same again.
GREENE: As strange as
quantum mechanics may be,
WhC11"S now clear
is that there's no boundary
between the worlds
of the tiny and the big.
Instead, These laws
apply everywhere,
and iT'SjUSTTh(JTTl'1€il' weird
features are most apparent
when things are small.
And so The discovery
of quantum mechanics
has revealed a realily,
our realily,
'rh
and thrilling,
bringing us that much closer
to fully understanding
the fabric of The cosmos.
Major funding for NOVA
is provided by:
And...
And by The Corporofion
for Public Broodcosfing
and by contributions
To your PBS s'r
Major funding
for "The Fabric of The Cosmos"
is provided by
the Noiionol Science Foundoiion.
And...
Supporting original research
and public unaersianaing
of science, Technology,
engineering and mathematics.
Additional funding
is provided by...
And the George D. Smith Fund.