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♪ ♪

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ANNOUNCER:
The following "NOVA" program
contains scenes

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of quantum physics,
which is known to cause

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confusion, anxiety,
and even heartbreak.

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Please see your physicist

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if symptoms persist.

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NARRATOR:
Quantum physics.

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It's the science
of the very small,

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but it punches
far above its weight.

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Quantum physics has not just
been important,

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it's been revolutionary.

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NARRATOR:
It's the most successful
scientific theory

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of the last 100 years.

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Quantum mechanics already
permeates everything we do.

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NARRATOR:
Everything from your computer
or cellphone

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to how we keep time

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depends on our understanding
of the quantum world.

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DAVID KAISER:
We can say now that
we live in a quantum age.

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NARRATOR:
And it's behind one of
the greatest discoveries

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in the history of science:

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gravitational waves,

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tiny ripples in the fabric
of space-time itself.

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SEAN CARROLL:
Gravitational waves
give us a whole new way

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to look at the universe.

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NARRATOR:
And yet, beyond the mathematics,

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quantum physics
makes a shocking claim:

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that at its deepest level,

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reality plays like a game
of chance...

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ELBA ALONSO-MONSALVE:
Probabilities are not

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a measure of what we don't know.

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They're just intrinsic
to the quantum theory.

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NARRATOR:
...with mind-boggling behaviors
like superposition

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and entanglement.

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This is weird-- it's strange.

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NARRATOR:
What quantum physics
really means

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remains deeply mysterious.

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But it's created
the world we live in today.

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Quantum physics actually
governs everything around us.

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TARA FORTIER:
It's not some weird outpost
of physics that's far away.

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It's completely changed

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the way we used to live
into the way we live now.

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NARRATOR:
"Decoding the Universe:
Quantum."

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Right now, on "NOVA."

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♪ ♪

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NARRATOR:
December 12, 1970.

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NASA launches a Scout B rocket

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from a former oil-drilling
platform off Kenya's coast.

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♪ ♪

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Its payload is a small satellite
named Uhuru,

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a Swahili word
meaning "freedom."

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Uhuru is the first space
telescope

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dedicated to observing X-rays,

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high-energy light waves
invisible to our eyes.

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Powerful sources of X-rays
constantly bombard Earth,

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but our atmosphere blocks them.

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With this
groundbreaking telescope,

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a new vista for exploration
opens.

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But buried in the data collected
from Uhuru

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is something ominous.

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In 1971,

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scientists reveal
that the constellation Cygnus,

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the Swan,

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contains what until then

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was more of a
mythical mathematical beast.

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A black hole.

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ALONSO-MONSALVE:
Black holes are

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the most mysterious objects
in the universe.

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Also the most violent.

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JANNA LEVIN:
Even Einstein didn't think
nature would allow

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such a crazy object.

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NARRATOR:
Black holes are
fearsome monsters,

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capable of devouring
whole planets...

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...whole stars...

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...and even each other.

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A black hole is created
when gravitational forces

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bring together enough mass

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to put a rip into the fabric
of space-time.

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KAISER:
Some of them are genuinely
monstrous.

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I mean, millions, billions,

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maybe even ten billion times

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the mass of our own sun.

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ALONSO-MONSALVE:
We don't actually have

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laws of physics to predict

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what's going to happen to us
when we go in.

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Hopefully, none of us will
experience it anytime soon.
(laughs)

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NARRATOR:
In the decades
since the first sighting,

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science has learned a lot about

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these menacing and mysterious
objects of destruction.

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They aren't that rare.

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Supermassive black holes
sit at the center

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of most large galaxies.

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We have one in ours.

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But it turns out
these cosmic behemoths

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also may have an Achilles' heel.

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First predicted by
Stephen Hawking in 1974,

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scientists thought
of a black hole

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as a one-way trip to oblivion.

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That past its event horizon,
nothing could escape.

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But Hawking disagreed.

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He theorized something did
escape from these mighty giants:

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radiation.

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Ironically, the end result
of physics

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at the tiniest of scales:
quantum physics.

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♪ ♪

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Clifford Johnson
is a nonfiction graphic author

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and also a theoretical
physicist.

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JOHNSON:
One of the key things

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that was discovered in quantum
physics

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is that empty space itself
is not empty.

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It's seething with possibility.

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Instead of having empty space
here,

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a particle and its antiparticle
can appear,

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dance around a little bit,

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and then annihilate
back into empty space.

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Now, imagine that happening
near a black hole horizon,

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which we're told
is a one-way door.

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What if one of those particles
falls in?

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And now the partner doesn't have
anything to annihilate with.

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So it will actually fly off,

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and a distant observer
will see that particle

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as radiation
coming from the black hole.

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NARRATOR:
Without consuming more matter,
if it emits radiation,

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it will gradually shrink
in size.

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The black hole actually begins
to evaporate.

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Now, this is a completely
stunning revelation.

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NARRATOR:
Known as Hawking Radiation,

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its existence
is still only a theory.

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But perhaps, given enough time--

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and it is a very,
very, very long time...

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For many black holes,

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longer than the current age
of the universe.

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NARRATOR:
...even a supermassive
black hole,

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like the one at the heart
of the Milky Way,

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may evaporate and disappear,

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vanquished by the quantum world

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and the physics
of the very small.

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♪ ♪

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The quantum world is often cast
as weird,

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and it sure can look that way
in the movies.

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JANET VAN DYNE:
You're sending a signal

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down to the Quantum Realm.

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(woman yelps)

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Cassie!

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♪ ♪

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(whispers):
Where are we?

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NARRATOR:
But what is quantum physics?

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It arose as the solution
to a problem.

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Science during the 19th century
had investigated

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smaller and smaller amounts
of matter and energy.

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But by the first two decades
of the 20th century,

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the existing line
between the physics of particles

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and the physics of waves

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had grown murky,

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especially
when trying to understand

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the fundamental nature of light.

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KAISER:
Sometimes it really is important
to describe light

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as a wave, as an extended object
that sort of waves in space

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and travels over time,

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analogously to an ocean wave
in the water.

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Other times, as people
like Albert Einstein and others

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began to, to find, they really,
really had to describe

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aspects of light as if
it was a collection of particles

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that traveled almost
like miniature billiard balls.

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NARRATOR:
Ultimately, the answer was
a new kind of physics,

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quantum mechanics,

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which included
an amalgam of ideas

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about both particles and waves.

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Its earliest formulation
dates back roughly 100 years.

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This 1927 conference in Brussels

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is where the world's leading
physicists met

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to discuss
the newly formed theory.

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(people talking in background)

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NARRATOR:
And there was a lot to discuss.

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Because quantum mechanics
represented a radical departure

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from the previous paradigm
of physics--

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what we call today
"classical physics."

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CARROLL:
In classical physics,

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handed down by Newton,
we had determinism.

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We had the clockwork universe.

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So if you throw a ball-- that's
a classical object--

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with the same force,
the same speed,

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the same angle,

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it's always going to go
to the same place, right?

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In principle,
if you knew exactly the state

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of the whole world all at once,

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and you knew the laws
of physics,

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you could exactly predict
what everything was going to do

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arbitrarily far in the future
and into the past.

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NARRATOR:
In classical physics,

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even events that we think of
as random aren't, really.

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HAKEEM OLUSEYI:
There are things

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that appear random in our
everyday lives,

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like rolling dice.

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It looks random, right?

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But actually, it's a
deterministic

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set of events which leads to

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whatever outcome the dice shows.

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If I told you exactly how
I was going to roll the dice...

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OLUSEYI:
...you could predict,
based on that initial throw,

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what the final outcome
is going to be.

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It's a very hard
mathematical problem,

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but it's not intractable.

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Quantum mechanically,
that's not the case.

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NARRATOR:
Quantum mechanics
tossed out the certainty

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of the classical
clockwork universe

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for one that only allowed
for probabilistic predictions

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about potential observations.

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Probability in quantum physics
is different.

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Because even if we have

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the most complete description

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that the laws of physics will
allow us to have,

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typically,
we're unable to predict

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precisely what we'll see when
we observe a quantum system.

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CARROLL:
Quantum mechanics says we can
know everything there is to know

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about the setup right now.

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And still, when we want to make
a measurement of it

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in the future,
the best we can do is say,

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"There's a 50% chance
of getting this outcome,

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30% chance of that,
20% chance of that."

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In the quantum theory,

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probabilities are not
a measure of what we don't know.

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They're just intrinsic
to the quantum theory.

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We cannot get around them.

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That is impossible.

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NARRATOR:
Some physicists,
raised on determinism,

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had trouble accepting
this new probabilistic view.

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Albert Einstein famously said
that he didn't believe

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God plays dice
with the universe.

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But there is another related,
even stranger aspect

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to quantum mechanics.

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In classical physics,

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external reality
is independent of the observer.

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Looking at the moon
doesn't change the moon.

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And if you look away,

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the deterministic laws
of physics

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continue to guide the moon
on its path.

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But in quantum mechanics,
things are weirder.

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CARROLL:
The basic idea
of quantum mechanics,

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the thing that we really
struggle with

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to get our heads around,
even as professional physicists,

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is that unlike any other version
of physics,

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quantum mechanics separates
what happens in a system

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when we're not observing it

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from what we see
when we measure it.

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NARRATOR:
A few rare exceptions aside,

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quantum mechanics says
that we can't know

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the position of a particle
like an electron

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when we're not observing it.

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At best, it can only
be described mathematically

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as a wave,

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its exact position
given in probabilities.

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But at the moment
that the particle is observed,

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the probabilistic wave function
collapses

254
00:14:02,466 --> 00:14:06,100
to one specific location.

255
00:14:07,500 --> 00:14:11,133
To the observer, who never
sees this wave-like quality,

256
00:14:11,133 --> 00:14:17,533
it is like the particle
was a particle all along.

257
00:14:17,533 --> 00:14:19,866
That opens up a whole world
of questions, you know?

258
00:14:19,866 --> 00:14:23,433
What happens to the
observational outcomes

259
00:14:23,433 --> 00:14:25,100
that are not observed?

260
00:14:25,100 --> 00:14:27,600
What picks out which outcome
is going to happen?

261
00:14:27,600 --> 00:14:30,300
This is still what
we're thinking about today.

262
00:14:31,366 --> 00:14:33,666
NARRATOR:
During that mysterious period,

263
00:14:33,666 --> 00:14:36,900
when the particle is considered
neither here nor there,

264
00:14:36,900 --> 00:14:41,700
it is said to be
in superposition--

265
00:14:41,700 --> 00:14:47,666
in a sense, a combination
of all the possible outcomes.

266
00:14:47,666 --> 00:14:50,500
But what does that really mean?

267
00:14:50,500 --> 00:14:52,933
Is the electron everywhere
at the same time?

268
00:14:52,933 --> 00:14:54,633
Is it nowhere at all?

269
00:14:54,633 --> 00:14:57,666
Is it at one particular place
and we just don't know?

270
00:14:57,666 --> 00:15:00,600
All of those questions
are actually outside

271
00:15:00,600 --> 00:15:03,866
of what quantum theory itself
actually can answer.

272
00:15:03,866 --> 00:15:05,700
It's not part of the theory
at all.

273
00:15:05,700 --> 00:15:07,633
So if you ask me,
your guess is as good as mine.

274
00:15:07,633 --> 00:15:11,166
(chuckles): Unfortunately,
that's the best I can do.

275
00:15:11,166 --> 00:15:13,833
♪ ♪

276
00:15:13,833 --> 00:15:16,633
NARRATOR:
For most people,
quantum mechanics remains

277
00:15:16,633 --> 00:15:19,666
deeply unintuitive.

278
00:15:19,666 --> 00:15:24,333
And yet it has proven itself
again and again

279
00:15:24,333 --> 00:15:27,133
by making predictions
with uncanny accuracy.

280
00:15:27,133 --> 00:15:29,433
In practical terms,

281
00:15:29,433 --> 00:15:34,133
it is the most successful theory
science has ever produced,

282
00:15:34,133 --> 00:15:37,333
and it has shaped
our modern life.

283
00:15:37,333 --> 00:15:39,366
♪ ♪

284
00:15:39,366 --> 00:15:41,666
OLUSEYI:
Quantum physics has not just

285
00:15:41,666 --> 00:15:43,566
been important,
it's been revolutionary.

286
00:15:43,566 --> 00:15:44,933
It's completely changed

287
00:15:44,933 --> 00:15:47,300
the way we used to live
into the way we live now.

288
00:15:47,300 --> 00:15:50,100
♪ ♪

289
00:15:50,100 --> 00:15:53,600
NARRATOR:
Take our sense of time.

290
00:15:53,600 --> 00:15:58,233
(tango music playing)

291
00:15:58,233 --> 00:16:02,200
Perhaps there is no better
illustration

292
00:16:02,200 --> 00:16:03,666
of our intimate relationship
with it

293
00:16:03,666 --> 00:16:05,166
than music and dance.

294
00:16:05,166 --> 00:16:09,300
♪ ♪

295
00:16:09,300 --> 00:16:11,800
FORTIER:
The underlying movement of tango

296
00:16:11,800 --> 00:16:15,200
is reliant on the beat, which is
reliant on timing,

297
00:16:15,200 --> 00:16:17,000
which creates synchronization.

298
00:16:17,000 --> 00:16:20,533
To create a truly smooth dance,

299
00:16:20,533 --> 00:16:23,666
it's not enough to just be
synchronized on the beat.

300
00:16:23,666 --> 00:16:25,933
It's also the synchronicity

301
00:16:25,933 --> 00:16:27,800
between the beats
that's important.

302
00:16:27,800 --> 00:16:29,566
That's the real beauty in it,

303
00:16:29,566 --> 00:16:31,766
in finding that connection
through,

304
00:16:31,766 --> 00:16:34,200
stretching out that second.

305
00:16:34,200 --> 00:16:37,400
♪ ♪

306
00:16:41,500 --> 00:16:45,100
NARRATOR:
Tara Fortier
is a tango professional

307
00:16:45,100 --> 00:16:48,766
and a physicist deeply involved

308
00:16:48,766 --> 00:16:51,400
in the science of time.

309
00:16:51,400 --> 00:16:53,300
So, we have a number of systems
in this lab.

310
00:16:53,300 --> 00:16:54,300
NARRATOR:
She works here...

311
00:16:54,300 --> 00:16:55,666
These systems are used

312
00:16:55,666 --> 00:16:57,433
to characterize atomic clocks,

313
00:16:57,433 --> 00:16:59,133
and also compare
atomic clocks.

314
00:16:59,133 --> 00:17:02,333
NARRATOR:
...at the Boulder, Colorado,
laboratories

315
00:17:02,333 --> 00:17:05,633
of the National Institute
of Standards and Technology,

316
00:17:05,633 --> 00:17:08,033
or NIST,

317
00:17:08,033 --> 00:17:10,433
home to some
of the atomic clocks

318
00:17:10,433 --> 00:17:14,700
that help set the official time
for the country.

319
00:17:16,633 --> 00:17:17,933
Over the centuries,

320
00:17:17,933 --> 00:17:20,466
we've tracked time
a variety of ways:

321
00:17:20,466 --> 00:17:22,733
by the sun's movement,

322
00:17:22,733 --> 00:17:25,566
the swing of pendulums,

323
00:17:25,566 --> 00:17:27,933
the oscillations of springs,

324
00:17:27,933 --> 00:17:29,800
and, in the 20th century,

325
00:17:29,800 --> 00:17:33,300
the vibrations
of quartz crystals.

326
00:17:33,300 --> 00:17:36,133
But since the 1960s,

327
00:17:36,133 --> 00:17:38,933
time has been officially
determined

328
00:17:38,933 --> 00:17:41,800
using atomic clocks

329
00:17:41,800 --> 00:17:45,166
and the quantum characteristics
of atoms.

330
00:17:45,166 --> 00:17:48,000
And the idea is that the laws
of physics are unchanging,

331
00:17:48,000 --> 00:17:50,300
unlike something like
the rotation of the Earth.

332
00:17:50,300 --> 00:17:52,433
The rotation of the Earth itself
can change

333
00:17:52,433 --> 00:17:53,833
because of plate tectonics,

334
00:17:53,833 --> 00:17:56,466
because the moon is moving away
from the Earth.

335
00:17:56,466 --> 00:17:58,800
Its physics
is not truly fundamental.

336
00:17:58,800 --> 00:18:02,266
JUN YE:
The reason why we love
atomic clock,

337
00:18:02,266 --> 00:18:04,366
it's a universally defined time.

338
00:18:04,366 --> 00:18:06,133
No matter who does
the experiment,

339
00:18:06,133 --> 00:18:08,200
no matter
where you do the experiment,

340
00:18:08,200 --> 00:18:09,800
you know, in principle, once
you've corrected

341
00:18:09,800 --> 00:18:11,833
for all the systematic effects,

342
00:18:11,833 --> 00:18:14,933
you should produce the same time
no matter where.

343
00:18:17,466 --> 00:18:20,900
NARRATOR:
The consistency
of atomic clocks arises

344
00:18:20,900 --> 00:18:24,633
from the very nature of atoms.

345
00:18:24,633 --> 00:18:27,400
Atomic clocks depend crucially

346
00:18:27,400 --> 00:18:29,266
on the quantum physics of atoms.

347
00:18:29,266 --> 00:18:33,533
You have a nucleus,

348
00:18:33,533 --> 00:18:35,900
around which there are electrons

349
00:18:35,900 --> 00:18:38,366
in certain energy levels.

350
00:18:38,366 --> 00:18:41,400
And these energy levels
are possible energy states

351
00:18:41,400 --> 00:18:44,966
that the electron can have
inside the atom.

352
00:18:44,966 --> 00:18:49,300
NARRATOR:
Since an electron can only be
at certain energy levels

353
00:18:49,300 --> 00:18:53,433
and not in between,
to get to a higher level,

354
00:18:53,433 --> 00:18:57,300
it needs to encounter
a very specific helping hand,

355
00:18:57,300 --> 00:19:01,300
such as a particular photon.

356
00:19:03,266 --> 00:19:05,900
If it were to absorb
an incoming photon,

357
00:19:05,900 --> 00:19:08,500
it would have to be
of just the right energy

358
00:19:08,500 --> 00:19:12,500
to jump from one level
to a higher level.

359
00:19:12,500 --> 00:19:14,400
NARRATOR:
That special relationship

360
00:19:14,400 --> 00:19:17,266
between the electrons
of a particular atom

361
00:19:17,266 --> 00:19:20,266
and a photon
of a specific energy level

362
00:19:20,266 --> 00:19:23,766
is a unique signature
for that atom.

363
00:19:23,766 --> 00:19:27,033
It's called
a "resonant frequency."

364
00:19:28,833 --> 00:19:31,500
JOHNSON:
So this characteristic signature
of this atom

365
00:19:31,500 --> 00:19:34,333
gives us a very specific
frequency standard

366
00:19:34,333 --> 00:19:38,566
that we can use to build
a time-keeping device.

367
00:19:39,733 --> 00:19:42,666
NARRATOR:
Atomic clocks
work in different ways,

368
00:19:42,666 --> 00:19:45,766
but they all use
a specific type of atom

369
00:19:45,766 --> 00:19:49,133
or molecule
as a reference to lock in

370
00:19:49,133 --> 00:19:52,400
the frequency
of an electromagnetic wave,

371
00:19:52,400 --> 00:19:56,800
whose oscillations provide
the "ticking" of the clock.

372
00:20:00,133 --> 00:20:03,733
Today, a second
is officially defined

373
00:20:03,733 --> 00:20:06,166
by counting the oscillations

374
00:20:06,166 --> 00:20:08,666
of the primary
resonant frequency

375
00:20:08,666 --> 00:20:11,633
of a cesium-133 atom.

376
00:20:13,500 --> 00:20:18,033
That's over nine billion
oscillations per second.

377
00:20:19,733 --> 00:20:22,633
And you interact
with that time reference

378
00:20:22,633 --> 00:20:24,433
more than you might think.

379
00:20:24,433 --> 00:20:28,833
For example, through
the Global Positioning System:

380
00:20:28,833 --> 00:20:30,933
GPS.

381
00:20:30,933 --> 00:20:33,733
♪ ♪

382
00:20:33,733 --> 00:20:34,900
GPS:
Turn left.

383
00:20:34,900 --> 00:20:36,500
FORTIER:
I think that GPS

384
00:20:36,500 --> 00:20:38,500
is actually kind of crazy,
when you think about it.

385
00:20:38,500 --> 00:20:40,966
How did we do anything
before GPS?

386
00:20:42,233 --> 00:20:45,333
NARRATOR:
The U.S.-based GPS system

387
00:20:45,333 --> 00:20:48,466
uses over 30 dedicated
orbiting satellites,

388
00:20:48,466 --> 00:20:52,200
each with
multiple atomic clocks.

389
00:20:52,200 --> 00:20:54,433
When you use the GPS
on your cell phone,

390
00:20:54,433 --> 00:20:57,966
its receiver checks the signals

391
00:20:57,966 --> 00:21:01,000
from four or more satellites.

392
00:21:01,000 --> 00:21:03,766
The signal contains information

393
00:21:03,766 --> 00:21:08,666
about the satellite's position
and the time it sent the signal.

394
00:21:08,666 --> 00:21:11,500
That time stamp is critical.

395
00:21:11,500 --> 00:21:15,233
Your phone uses it to calculate
how long it took

396
00:21:15,233 --> 00:21:17,966
to receive the signal,
and from that,

397
00:21:17,966 --> 00:21:20,966
knows the distance
to the satellite.

398
00:21:20,966 --> 00:21:24,733
With that information
from multiple satellites,

399
00:21:24,733 --> 00:21:27,833
it is possible to triangulate
the phone's position

400
00:21:27,833 --> 00:21:30,200
within a few yards.

401
00:21:31,800 --> 00:21:36,733
But the whole system depends
on knowing the time.

402
00:21:36,733 --> 00:21:39,433
FORTIER:
In the end, I find it amazing,

403
00:21:39,433 --> 00:21:42,566
how strongly we're committed
and tied to atomic clocks

404
00:21:42,566 --> 00:21:44,566
and how much we take it
for granted.

405
00:21:44,566 --> 00:21:46,400
Even though I build
atomic clocks,

406
00:21:46,400 --> 00:21:47,766
but when I'm driving,

407
00:21:47,766 --> 00:21:49,166
being guided
by this GPS service,

408
00:21:49,166 --> 00:21:51,866
you don't really become aware

409
00:21:51,866 --> 00:21:54,466
of how much atomic clock
technology has permeated

410
00:21:54,466 --> 00:21:57,000
everywhere in modern life.

411
00:21:59,466 --> 00:22:04,033
♪ ♪

412
00:22:04,033 --> 00:22:05,633
Have you had a chance to look

413
00:22:05,633 --> 00:22:08,233
at more systematically
varying the V-Z?

414
00:22:08,233 --> 00:22:11,600
NARRATOR:
Jun Ye is a physicist
with joint appointments:

415
00:22:11,600 --> 00:22:14,366
with NIST,

416
00:22:14,366 --> 00:22:16,166
the University of Colorado-
Boulder,

417
00:22:16,166 --> 00:22:19,166
and their joint institute, JILA.

418
00:22:19,166 --> 00:22:21,466
What if you locked exactly
on top of each other

419
00:22:21,466 --> 00:22:23,900
and see whether
that peak disappears completely?

420
00:22:23,900 --> 00:22:28,000
NARRATOR:
He works on the new generation
of atomic clocks,

421
00:22:28,000 --> 00:22:32,000
known as optical atomic clocks.

422
00:22:32,000 --> 00:22:33,600
While cesium clocks

423
00:22:33,600 --> 00:22:34,866
use microwaves,

424
00:22:34,866 --> 00:22:37,033
optical clocks use lasers,

425
00:22:37,033 --> 00:22:40,766
which run at higher frequencies.

426
00:22:40,766 --> 00:22:44,633
That also means
using a different atom.

427
00:22:44,633 --> 00:22:49,900
Instead of cesium, Jun's work
mostly uses strontium atoms,

428
00:22:49,900 --> 00:22:52,566
along with a laser
carefully tuned

429
00:22:52,566 --> 00:22:56,600
to one of strontium's
resonant frequencies.

430
00:22:56,600 --> 00:23:02,033
It puts one of the strontium
electrons into superposition,

431
00:23:02,033 --> 00:23:07,433
so it is both excited
and unexcited at the same time,

432
00:23:07,433 --> 00:23:12,600
creating what Jun calls
a quantum pendulum.

433
00:23:12,600 --> 00:23:15,933
This pendulum
is swinging at a speed

434
00:23:15,933 --> 00:23:19,100
of nearly one million
billion cycles per second.

435
00:23:19,100 --> 00:23:21,966
It's going back and forth,
back and forth.

436
00:23:21,966 --> 00:23:25,400
And this superposition
creates this quantum pendulum.

437
00:23:25,400 --> 00:23:27,966
NARRATOR:
And when it comes
to accuracy,

438
00:23:27,966 --> 00:23:31,166
more swings or higher frequency

439
00:23:31,166 --> 00:23:33,566
equals more precision.

440
00:23:33,566 --> 00:23:37,500
If you think of swings
as marks on a ruler,

441
00:23:37,500 --> 00:23:42,400
the more marks you have, the
more exactly you can measure.

442
00:23:42,400 --> 00:23:46,866
So, compared to a cesium clock,
Jun's strontium clock

443
00:23:46,866 --> 00:23:51,700
is around 100,000 times
more precise.

444
00:23:53,066 --> 00:23:56,866
And that much sensitivity makes
all the more apparent

445
00:23:56,866 --> 00:23:59,833
some of the stranger aspects
of time,

446
00:23:59,833 --> 00:24:04,466
including one first predicted
by Einstein:

447
00:24:04,466 --> 00:24:07,800
gravitational time dilation.

448
00:24:07,800 --> 00:24:10,333
In the movie "Interstellar,"

449
00:24:10,333 --> 00:24:13,133
part of the crew of a spaceship

450
00:24:13,133 --> 00:24:15,666
descends in a shuttle
to a planet

451
00:24:15,666 --> 00:24:19,566
orbiting
a supermassive black hole.

452
00:24:22,433 --> 00:24:23,766
When the shuttle returns,

453
00:24:23,766 --> 00:24:25,400
those on the mission feel

454
00:24:25,400 --> 00:24:27,633
they've only been gone for three
hours,

455
00:24:27,633 --> 00:24:30,800
but not the crew member who
remained in orbit.

456
00:24:30,800 --> 00:24:32,266
Hello, Rom.

457
00:24:32,266 --> 00:24:34,233
I've waited years.

458
00:24:34,233 --> 00:24:38,066
CASE: 23 years, four months,
eight days.

459
00:24:38,066 --> 00:24:40,500
NARRATOR: The difference in time
is another effect

460
00:24:40,500 --> 00:24:45,166
 
of the black hole's warping
of the fabric of space-time.

461
00:24:45,166 --> 00:24:48,600
The warping not only means
gravity gets stronger

462
00:24:48,600 --> 00:24:53,866
closer to the black hole,
but time gets slower, too.

463
00:24:53,866 --> 00:24:57,933
And you don't need a black hole
to be able to measure it.

464
00:24:57,933 --> 00:25:02,066
Even on Earth, gravity varies,

465
00:25:02,066 --> 00:25:05,200
and so does time,
based on the distance

466
00:25:05,200 --> 00:25:07,733
from the planet's center.

467
00:25:07,733 --> 00:25:12,100
So a person at the top
of the Empire State Building

468
00:25:12,100 --> 00:25:14,766
experiences weaker gravity

469
00:25:14,766 --> 00:25:16,933
and time going faster

470
00:25:16,933 --> 00:25:19,000
than a person at street level,

471
00:25:19,000 --> 00:25:21,600
where gravity is stronger.

472
00:25:21,600 --> 00:25:25,100
But all that happens
imperceptibly.

473
00:25:25,100 --> 00:25:28,200
Our wristwatches
just aren't accurate enough

474
00:25:28,200 --> 00:25:30,966
to show the difference.

475
00:25:32,000 --> 00:25:35,633
But Jun's optical clocks
are so accurate

476
00:25:35,633 --> 00:25:40,566
that even a small difference
in elevation between two clocks

477
00:25:40,566 --> 00:25:46,633
will reveal a discrepancy
in the passage of time.

478
00:25:46,633 --> 00:25:49,200
When the clock changes elevation
by a few hundred microns,

479
00:25:49,200 --> 00:25:52,100
basically size of a human hair,

480
00:25:52,100 --> 00:25:53,866
you will start to be able to see

481
00:25:53,866 --> 00:25:55,366
that time is actually running
differently.

482
00:25:55,366 --> 00:25:58,300
♪ ♪

483
00:25:58,300 --> 00:26:02,533
NARRATOR:
With that much accuracy,
a clock transforms

484
00:26:02,533 --> 00:26:04,166
into something more
than a timepiece.

485
00:26:04,166 --> 00:26:09,700
It becomes a new window
into the nature of the universe.

486
00:26:09,700 --> 00:26:11,966
♪ ♪

487
00:26:11,966 --> 00:26:15,566
YE:
Making a clock is much more
than just a piece to keep time.

488
00:26:15,566 --> 00:26:19,033
It is a sensor to explore
fundamental physics,

489
00:26:19,033 --> 00:26:22,000
to expand our curiosity,

490
00:26:22,000 --> 00:26:24,933
to build new technologies
that can connect

491
00:26:24,933 --> 00:26:27,666
to quantum computing,
quantum information processing,

492
00:26:27,666 --> 00:26:29,500
and communication.

493
00:26:35,333 --> 00:26:37,433
♪ ♪

494
00:26:37,433 --> 00:26:41,666
NARRATOR:
Central to making Jun's
precision atomic clocks work

495
00:26:41,666 --> 00:26:45,900
are ultra-stable lasers,

496
00:26:45,900 --> 00:26:50,733
which themselves are also
a quantum technology.

497
00:26:50,733 --> 00:26:53,533
They date back to the 1960s.

498
00:26:53,533 --> 00:26:56,400
GOLDFINGER:
You are looking
at an industrial laser,

499
00:26:56,400 --> 00:26:58,333
which emits
an extraordinary light

500
00:26:58,333 --> 00:26:59,533
not to be found in nature.

501
00:26:59,533 --> 00:27:00,966
I will show you.

502
00:27:00,966 --> 00:27:02,933
(laser cracks)

503
00:27:02,933 --> 00:27:05,300
NARRATOR:
This scene from 1964's
"Goldfinger"

504
00:27:05,300 --> 00:27:09,000
is said to be one of the first
popular depictions

505
00:27:09,000 --> 00:27:11,966
of this new, cutting-edge tech.

506
00:27:11,966 --> 00:27:13,700
I think you've made your point,
Goldfinger.

507
00:27:13,700 --> 00:27:14,966
Thank you for the demonstration.

508
00:27:16,133 --> 00:27:20,700
♪ ♪

509
00:27:20,700 --> 00:27:25,200
NARRATOR:
Today, lasers are everywhere.

510
00:27:27,600 --> 00:27:30,566
There are medical lasers
to correct vision,

511
00:27:30,566 --> 00:27:33,433
lasers at the checkout counter,

512
00:27:33,433 --> 00:27:36,133
lasers for cutting,

513
00:27:36,133 --> 00:27:37,466
communicating,

514
00:27:37,466 --> 00:27:39,333
entertaining cats,

515
00:27:39,333 --> 00:27:43,366
and, of course, for light shows.

516
00:27:43,366 --> 00:27:46,033
(crowd cheering)

517
00:27:46,033 --> 00:27:49,500
NARRATOR:
Which encourage us all
to trip the light fantastic.

518
00:27:49,500 --> 00:27:54,566
(band playing)

519
00:27:59,866 --> 00:28:01,866
(cheering)

520
00:28:01,866 --> 00:28:04,766
(plays note)

521
00:28:06,166 --> 00:28:07,633
(note stops)

522
00:28:07,633 --> 00:28:09,266
NARRATOR:
Which may be why...

523
00:28:09,266 --> 00:28:11,233
♪ ♪

524
00:28:11,233 --> 00:28:14,166
...experimental physicist
Rana Adhikari

525
00:28:14,166 --> 00:28:18,566
is laser-focused on lasers.

526
00:28:18,566 --> 00:28:19,866
When I talk about how,

527
00:28:19,866 --> 00:28:21,533
how beautiful a laser
is as a instrument,

528
00:28:21,533 --> 00:28:23,400
I don't want to gush about
it too much.

529
00:28:23,400 --> 00:28:24,933
Like, I'm in love with lasers,
I don't know.

530
00:28:24,933 --> 00:28:26,166
I feel like a weirdo fanatic

531
00:28:26,166 --> 00:28:27,966
or something like that, but...

532
00:28:27,966 --> 00:28:29,266
They're just,
there's something about them.

533
00:28:30,566 --> 00:28:34,166
NARRATOR:
To understand what makes
laser light so special,

534
00:28:34,166 --> 00:28:38,766
it makes sense to look
at an ordinary light bulb--

535
00:28:38,766 --> 00:28:41,800
the old-fashioned kind,
with a tungsten filament.

536
00:28:41,800 --> 00:28:46,700
It produces light through
thermal radiation--

537
00:28:46,700 --> 00:28:49,700
an electric current
passing through the filament

538
00:28:49,700 --> 00:28:51,266
heats it up.

539
00:28:51,266 --> 00:28:54,633
Its tungsten atoms
become excited

540
00:28:54,633 --> 00:28:57,300
and vibrate at different speeds,

541
00:28:57,300 --> 00:28:59,666
which causes them
to emit photons

542
00:28:59,666 --> 00:29:04,866
in all directions,
across a variety of wavelengths.

543
00:29:04,866 --> 00:29:10,800
Compared to a laser,
this is chaos.

544
00:29:10,800 --> 00:29:12,866
ADHIKARI:
The way you should think
about a light bulb

545
00:29:12,866 --> 00:29:13,866
is something like,

546
00:29:13,866 --> 00:29:15,333
they're just a mob of people,

547
00:29:15,333 --> 00:29:17,100
all singing at different pitch,

548
00:29:17,100 --> 00:29:18,833
so it's like
a rock concert audience.

549
00:29:18,833 --> 00:29:22,133
CROWD (singing):
♪ We will, we will rock you ♪

550
00:29:22,133 --> 00:29:24,600
But a laser,
a laser is more like

551
00:29:24,600 --> 00:29:27,900
if you go to Juilliard
or Berklee School of Music

552
00:29:27,900 --> 00:29:29,933
and you go to a concert.

553
00:29:29,933 --> 00:29:33,500
(singing on one pitch)

554
00:29:33,500 --> 00:29:35,366
ADHIKARI:
It's like a choir of people

555
00:29:35,366 --> 00:29:36,766
who have got perfect pitch,

556
00:29:36,766 --> 00:29:38,000
but it's a choir
of something like

557
00:29:38,000 --> 00:29:40,000
a million trillion people

558
00:29:40,000 --> 00:29:41,933
singing at the same time,
the same tone.

559
00:29:43,133 --> 00:29:45,000
NARRATOR: That's because

560
00:29:45,000 --> 00:29:46,600
laser light is generated

561
00:29:46,600 --> 00:29:48,566
in an entirely different way,

562
00:29:48,566 --> 00:29:50,800
a fact hidden in its name:

563
00:29:50,800 --> 00:29:53,466
stimulated emission.

564
00:29:53,466 --> 00:29:55,700
Let's say we have,
inside an atom,

565
00:29:55,700 --> 00:29:59,033
an electron that's
at some excited state,

566
00:29:59,033 --> 00:30:01,333
some higher energy level,

567
00:30:01,333 --> 00:30:03,133
and now a photon of
just the right frequency

568
00:30:03,133 --> 00:30:06,200
passes by the atom.

569
00:30:06,200 --> 00:30:09,966
It triggers the atom
to do something interesting.

570
00:30:09,966 --> 00:30:15,066
The electron loses energy
and goes to a lower energy,

571
00:30:15,066 --> 00:30:20,333
and emits a photon of
precisely the same frequency

572
00:30:20,333 --> 00:30:21,933
as the one that came in.

573
00:30:21,933 --> 00:30:24,666
It's going in the same direction
and it has the same phase.

574
00:30:24,666 --> 00:30:26,766
So what we have there is

575
00:30:26,766 --> 00:30:28,633
a quantum mechanical
amplification process.

576
00:30:28,633 --> 00:30:33,200
NARRATOR:
If we place a group of
those same excited atoms

577
00:30:33,200 --> 00:30:36,900
inside a chamber
with mirrors at both ends,

578
00:30:36,900 --> 00:30:41,833
the emitted photons
will bounce back and forth,

579
00:30:41,833 --> 00:30:46,666
continuing to stimulate
the emission of more photons,

580
00:30:46,666 --> 00:30:51,766
which in turn stimulate
even more photons.

581
00:30:51,766 --> 00:30:55,733
One of the mirrors is only
partially reflective.

582
00:30:55,733 --> 00:31:00,233
It allows some of the light
to escape.

583
00:31:00,233 --> 00:31:02,100
Now, that light's very special.

584
00:31:02,100 --> 00:31:04,433
It's composed of photons

585
00:31:04,433 --> 00:31:06,266
that are all
the same frequency--

586
00:31:06,266 --> 00:31:10,033
so, the same color--
and they're all the same phase,

587
00:31:10,033 --> 00:31:11,800
and all going in
the same direction.

588
00:31:11,800 --> 00:31:14,166
So you have this intense
pure beam of light,

589
00:31:14,166 --> 00:31:15,833
and that's the laser.

590
00:31:15,833 --> 00:31:18,533
♪ ♪

591
00:31:18,533 --> 00:31:22,566
NARRATOR:
Lasers have proven to be
an extremely versatile tool,

592
00:31:22,566 --> 00:31:25,933
including for
measuring distance.

593
00:31:27,933 --> 00:31:30,400
Rana's work with
stable high-frequency lasers

594
00:31:30,400 --> 00:31:33,200
takes that to an extreme.

595
00:31:33,200 --> 00:31:35,300
When you use them,

596
00:31:35,300 --> 00:31:37,500
you're in a whole different
realm of measurement

597
00:31:37,500 --> 00:31:38,966
than anything else
that has to do with rulers

598
00:31:38,966 --> 00:31:40,266
and any of that other stuff.

599
00:31:40,266 --> 00:31:42,733
Anybody who is, like, a real pro

600
00:31:42,733 --> 00:31:45,200
knows that the only thing
that you ever measure

601
00:31:45,200 --> 00:31:46,333
is frequency.

602
00:31:46,333 --> 00:31:47,666
If you're measuring
anything else,

603
00:31:47,666 --> 00:31:49,033
you're kind of an amateur.

604
00:31:51,966 --> 00:31:53,833
NARRATOR:
Thanks to the fixed speed
of light,

605
00:31:53,833 --> 00:31:56,100
the beam
of a high-frequency laser

606
00:31:56,100 --> 00:31:59,200
has an incredibly short
wavelength,

607
00:31:59,200 --> 00:32:04,433
perfect for measuring extremely
small changes in distance.

608
00:32:05,800 --> 00:32:09,400
Since 1996, Rana has been part
of a project

609
00:32:09,400 --> 00:32:11,500
that uses laser light

610
00:32:11,500 --> 00:32:16,200
to measure something incredibly,
unimaginably small--

611
00:32:16,200 --> 00:32:17,433
and weird:

612
00:32:17,433 --> 00:32:20,100
tiny fluctuations

613
00:32:20,100 --> 00:32:24,400
in the fabric of space and time
itself.

614
00:32:24,400 --> 00:32:26,866
Space and time ripple.

615
00:32:26,866 --> 00:32:29,233
They're not fixed things,
and so,

616
00:32:29,233 --> 00:32:31,266
the distance
between my two hands

617
00:32:31,266 --> 00:32:33,000
is not always going to be this
if I hold them steady.

618
00:32:34,500 --> 00:32:36,566
NARRATOR:
The idea, like so many,

619
00:32:36,566 --> 00:32:38,700
goes back to Einstein.

620
00:32:39,800 --> 00:32:42,800
In the early 20th century,
his work led

621
00:32:42,800 --> 00:32:46,733
to the merging of space and time
into one concept:

622
00:32:46,733 --> 00:32:48,700
space-time.

623
00:32:48,700 --> 00:32:51,866
And he theorized that gravity

624
00:32:51,866 --> 00:32:54,500
was the warping
of that space-time fabric

625
00:32:54,500 --> 00:32:57,666
by the mass of objects.

626
00:32:57,666 --> 00:33:02,066
But that carried
a startling implication,

627
00:33:02,066 --> 00:33:05,033
that the acceleration
of objects with mass

628
00:33:05,033 --> 00:33:08,466
would create ripples
in space-time

629
00:33:08,466 --> 00:33:11,600
that spread
at the speed of light:

630
00:33:11,600 --> 00:33:15,233
gravitational waves.

631
00:33:15,233 --> 00:33:16,733
TIFFANY NICHOLS:
Gravitational waves

632
00:33:16,733 --> 00:33:18,300
were first predicted
by Einstein,

633
00:33:18,300 --> 00:33:20,766
and he didn't believe it
at first.

634
00:33:20,766 --> 00:33:22,233
So he went back and forth

635
00:33:22,233 --> 00:33:24,833
through, I believe,
the mid-'30s.

636
00:33:24,833 --> 00:33:26,366
But his first prediction was

637
00:33:26,366 --> 00:33:29,666
they were too minute
to ever be detected.

638
00:33:29,666 --> 00:33:31,966
♪ ♪

639
00:33:31,966 --> 00:33:36,033
NARRATOR:
By the 1980s, that
sentiment had changed,

640
00:33:36,033 --> 00:33:39,100
and LIGO--
the Laser Interferometer

641
00:33:39,100 --> 00:33:41,766
Gravitational Wave
Observatory--

642
00:33:41,766 --> 00:33:46,266
was founded as a joint
Caltech and M.I.T. project.

643
00:33:48,666 --> 00:33:52,366
Part of Rana's work at Caltech
has been

644
00:33:52,366 --> 00:33:55,200
to continuously improve
the essential art of LIGO:

645
00:33:55,200 --> 00:33:57,933
laser interferometry.

646
00:34:00,433 --> 00:34:03,133
This is the,
where it all begins.

647
00:34:03,133 --> 00:34:04,533
I'm going to show you

648
00:34:04,533 --> 00:34:06,600
the whole laser interferometer
in here

649
00:34:06,600 --> 00:34:08,333
that's a prototype
of the LIGO system.

650
00:34:08,333 --> 00:34:12,933
NARRATOR:
The basic design
is easy to understand.

651
00:34:12,933 --> 00:34:15,966
The LIGO interferometer
has two arms

652
00:34:15,966 --> 00:34:18,033
at right angles
to each other.

653
00:34:18,033 --> 00:34:20,266
A very stable infrared laser

654
00:34:20,266 --> 00:34:22,533
feeds into a beam splitter,

655
00:34:22,533 --> 00:34:25,566
which directs half the beam
down each arm.

656
00:34:25,566 --> 00:34:28,633
ADHIKARI:
Half of the light goes one way
and half goes the other way.

657
00:34:28,633 --> 00:34:31,166
And then you have mirrors
at the ends,

658
00:34:31,166 --> 00:34:33,400
and they reflect the light back.

659
00:34:33,400 --> 00:34:36,133
NARRATOR:
The phase of one arm
of the laser

660
00:34:36,133 --> 00:34:38,000
is the reverse of the other.

661
00:34:38,000 --> 00:34:39,433
If all is normal,

662
00:34:39,433 --> 00:34:43,033
when recombined,
they will cancel each other out,

663
00:34:43,033 --> 00:34:46,166
resulting in no signal.

664
00:34:46,166 --> 00:34:50,033
But if a gravitational wave
passes through,

665
00:34:50,033 --> 00:34:52,100
distorting space-time,

666
00:34:52,100 --> 00:34:55,566
the length of each arm
will change,

667
00:34:55,566 --> 00:34:59,200
shifting the phase
of the two beams.

668
00:34:59,200 --> 00:35:01,533
For a brief moment,

669
00:35:01,533 --> 00:35:04,266
the equipment will register
a signal.

670
00:35:05,933 --> 00:35:08,000
Instead of having exact
cancellation

671
00:35:08,000 --> 00:35:09,700
and destructive interference,

672
00:35:09,700 --> 00:35:11,833
you have a little bit of light
leaking out.

673
00:35:11,833 --> 00:35:13,166
And that little bit of light

674
00:35:13,166 --> 00:35:14,566
that leaks out
is what we detect.

675
00:35:16,066 --> 00:35:17,700
NARRATOR:
But there is a key difference

676
00:35:17,700 --> 00:35:19,866
between Rana's working testbed

677
00:35:19,866 --> 00:35:21,966
and the real deal:

678
00:35:21,966 --> 00:35:25,000
size.

679
00:35:25,000 --> 00:35:27,833
This is one of
two LIGO installations

680
00:35:27,833 --> 00:35:29,500
in the United States.

681
00:35:29,500 --> 00:35:32,533
While the arms of
the Caltech instrument

682
00:35:32,533 --> 00:35:35,100
are about 44 yards long,

683
00:35:35,100 --> 00:35:40,800
the ones here cover about
two-and-a-half miles each.

684
00:35:42,233 --> 00:35:45,000
Costing hundreds
of millions of dollars,

685
00:35:45,000 --> 00:35:49,933
LIGO was a huge gamble
on an unproven idea...

686
00:35:51,233 --> 00:35:53,300
...that paid off.

687
00:35:53,300 --> 00:35:55,733
♪ ♪

688
00:35:55,733 --> 00:35:59,166
In 2015, a signal was detected.

689
00:36:01,366 --> 00:36:04,933
And it was a doozy.

690
00:36:04,933 --> 00:36:08,000
LEVIN:
The first event
that LIGO detected

691
00:36:08,000 --> 00:36:11,900
was the most powerful event
human beings had recorded

692
00:36:11,900 --> 00:36:14,033
since the Big Bang itself.

693
00:36:14,033 --> 00:36:15,666
More power came out

694
00:36:15,666 --> 00:36:17,066
of that collision
of those two black holes

695
00:36:17,066 --> 00:36:19,366
than was emanated by

696
00:36:19,366 --> 00:36:21,966
all the stars in the universe
combined.

697
00:36:21,966 --> 00:36:24,600
All of that power came out

698
00:36:24,600 --> 00:36:26,600
in the ringing of the drum
of space time.

699
00:36:26,600 --> 00:36:29,300
NARRATOR:
Since the original event,

700
00:36:29,300 --> 00:36:31,866
LIGO has confirmed the detection

701
00:36:31,866 --> 00:36:35,566
of more than 80 others.

702
00:36:35,566 --> 00:36:37,300
It is hard to overstate

703
00:36:37,300 --> 00:36:40,266
the significance
of the discovery.

704
00:36:40,266 --> 00:36:45,100
♪ ♪

705
00:36:45,100 --> 00:36:46,133
LIGO is massive.

706
00:36:46,133 --> 00:36:47,966
Albert Einstein predicted

707
00:36:47,966 --> 00:36:49,133
that gravitational waves
should exist,

708
00:36:49,133 --> 00:36:50,533
and now we measure them.

709
00:36:50,533 --> 00:36:52,933
This is the most
direct observation

710
00:36:52,933 --> 00:36:54,400
of black holes
that we've ever had.

711
00:36:54,400 --> 00:36:57,566
This is a complete revolution
in science.

712
00:36:59,666 --> 00:37:01,700
NARRATOR:
And it's all possible

713
00:37:01,700 --> 00:37:03,866
because of that
quantum technology

714
00:37:03,866 --> 00:37:07,600
that has become completely
embedded in our lives:

715
00:37:07,600 --> 00:37:09,633
the laser.

716
00:37:09,633 --> 00:37:11,800
The more stable your laser is,

717
00:37:11,800 --> 00:37:13,866
the more things in the universe
you can measure.

718
00:37:13,866 --> 00:37:16,033
And there's no limit to it.

719
00:37:16,033 --> 00:37:17,533
So every year, when we get
lasers

720
00:37:17,533 --> 00:37:18,866
better and better, we'll be able
to see

721
00:37:18,866 --> 00:37:20,566
further out into the universe

722
00:37:20,566 --> 00:37:22,333
and see tinier things

723
00:37:22,333 --> 00:37:25,300
in the microscopic nature
of reality, matter,

724
00:37:25,300 --> 00:37:27,400
space and time--
anything like that.

725
00:37:27,400 --> 00:37:29,400
You just have to keep working
on this one tool

726
00:37:29,400 --> 00:37:31,066
and make it better and better.

727
00:37:31,066 --> 00:37:33,133
♪ ♪

728
00:37:33,133 --> 00:37:36,900
NARRATOR:
Arguably, the most important
change in quantum physics

729
00:37:36,900 --> 00:37:40,066
in recent decades
is a deeper understanding

730
00:37:40,066 --> 00:37:44,166
of a special kind
of shared state

731
00:37:44,166 --> 00:37:47,100
called quantum entanglement.

732
00:37:47,100 --> 00:37:52,766
Imagine a machine that spits out
pairs of coins,

733
00:37:52,766 --> 00:37:56,000
which, on the surface,
look like ordinary coins.

734
00:37:56,000 --> 00:37:59,600
If you flip one,
it comes up heads or tails

735
00:37:59,600 --> 00:38:01,866
about 50% of the time.

736
00:38:01,866 --> 00:38:04,466
Nothing strange there.

737
00:38:04,466 --> 00:38:08,433
But using a pair of coins
fresh out of the machine,

738
00:38:08,433 --> 00:38:11,266
you flip one, it comes up heads.

739
00:38:11,266 --> 00:38:13,266
And then the other,

740
00:38:13,266 --> 00:38:15,533
it also comes up heads.

741
00:38:15,533 --> 00:38:17,166
That could just be luck.

742
00:38:17,166 --> 00:38:18,800
(machine chirping,
crowd cheering)

743
00:38:18,800 --> 00:38:21,966
NARRATOR:
So then you do the same thing
with another fresh pair.

744
00:38:21,966 --> 00:38:25,033
This time,
the first coin is tails,

745
00:38:25,033 --> 00:38:26,900
and so is the second--

746
00:38:26,900 --> 00:38:29,166
agreement again.

747
00:38:29,166 --> 00:38:32,066
So you flip another pair,

748
00:38:32,066 --> 00:38:34,200
and then another,

749
00:38:34,200 --> 00:38:36,666
and another,

750
00:38:36,666 --> 00:38:39,033
and another.

751
00:38:39,033 --> 00:38:40,966
 
Pair after pair,

752
00:38:40,966 --> 00:38:45,133
the two coins always agree
on the first flip.

753
00:38:45,133 --> 00:38:47,600
What's going on?

754
00:38:49,066 --> 00:38:51,333
Maybe the first flipped coin,

755
00:38:51,333 --> 00:38:53,266
once it comes up heads or tails,

756
00:38:53,266 --> 00:38:56,766
is somehow telling
the other coin how to behave.

757
00:38:57,866 --> 00:38:59,900
To make sure that can't happen,

758
00:38:59,900 --> 00:39:03,966
you separate the coins
by flying one to the moon

759
00:39:03,966 --> 00:39:06,600
and flip them at the same time,

760
00:39:06,600 --> 00:39:10,766
so no message could possibly
travel between them.

761
00:39:10,766 --> 00:39:14,466
Still, they come up
in agreement.

762
00:39:14,466 --> 00:39:16,700
♪ ♪

763
00:39:16,700 --> 00:39:20,366
It all sounds too strange
to be true,

764
00:39:20,366 --> 00:39:25,700
but particles really can behave
like those coins.

765
00:39:25,700 --> 00:39:30,066
In quantum physics,
it's called "entanglement."

766
00:39:30,066 --> 00:39:32,833
KAISER:
Entanglement is really just
a stubborn, stubborn,

767
00:39:32,833 --> 00:39:35,966
exciting and/or frustrating
fact

768
00:39:35,966 --> 00:39:37,633
that takes a long time

769
00:39:37,633 --> 00:39:38,866
to try to get our heads around.

770
00:39:38,866 --> 00:39:40,400
Entanglement is certainly

771
00:39:40,400 --> 00:39:42,500
the most interesting and the
most confusing

772
00:39:42,500 --> 00:39:44,800
aspect of quantum.

773
00:39:44,800 --> 00:39:46,666
It's one of these things
we don't see,

774
00:39:46,666 --> 00:39:48,500
you know, naively
in the world around us,

775
00:39:48,500 --> 00:39:51,433
but it is taking place deep
in the materials

776
00:39:51,433 --> 00:39:52,933
that exist around us
every day.

777
00:39:52,933 --> 00:39:56,266
NARRATOR:
And while you probably
won't come across

778
00:39:56,266 --> 00:40:01,066
a coin entangler anytime soon,

779
00:40:01,066 --> 00:40:04,466
in the lab, scientists
routinely generate

780
00:40:04,466 --> 00:40:07,166
pairs of entangled particles

781
00:40:07,166 --> 00:40:10,200
that share a quantum state
so fully,

782
00:40:10,200 --> 00:40:15,233
they can be thought of
as one quantum object.

783
00:40:15,233 --> 00:40:17,066
You simply can't differentiate
between them.

784
00:40:17,066 --> 00:40:18,966
It's just one pure state.

785
00:40:18,966 --> 00:40:21,433
It's as though
you have a single entity

786
00:40:21,433 --> 00:40:24,500
that's spatially separated
without a physical connection.

787
00:40:24,500 --> 00:40:28,000
NARRATOR:
Entangled particles
remain connected

788
00:40:28,000 --> 00:40:31,166
even when they're separated
by hundreds of miles--

789
00:40:31,166 --> 00:40:34,166
and likely far more.

790
00:40:34,166 --> 00:40:37,466
KAISER:
So does that mean it can
go between here and Andromeda?

791
00:40:37,466 --> 00:40:40,000
Probably-- the equations give us
no reason to think it wouldn't.

792
00:40:40,000 --> 00:40:44,733
NARRATOR:
Entanglement sounds bizarre.

793
00:40:44,733 --> 00:40:47,100
Einstein derided the idea

794
00:40:47,100 --> 00:40:50,233
as "spooky action
at a distance."

795
00:40:50,233 --> 00:40:53,200
But since the 1970s,

796
00:40:53,200 --> 00:40:57,000
experiment after experiment
has confirmed

797
00:40:57,000 --> 00:41:00,833
entanglement is a real
quantum phenomenon.

798
00:41:02,433 --> 00:41:05,200
Now, of course, many,
many decades later,

799
00:41:05,200 --> 00:41:08,166
we know that entanglement is
undeniably a part of the world.

800
00:41:08,166 --> 00:41:10,600
It's how the world works at
the quantum mechanical level.

801
00:41:10,600 --> 00:41:12,433
We better get used to that,

802
00:41:12,433 --> 00:41:13,866
and now see,
what can we do with it?

803
00:41:13,866 --> 00:41:16,500
Because it's powerful,
let's try to use it.

804
00:41:16,500 --> 00:41:18,100
It's become this new tool.

805
00:41:18,100 --> 00:41:20,233
Being able to
create and control it

806
00:41:20,233 --> 00:41:23,100
might be arguably thought of
as one of the biggest

807
00:41:23,100 --> 00:41:24,733
scientific and engineering
developments

808
00:41:24,733 --> 00:41:25,933
of the 21st century.

809
00:41:27,466 --> 00:41:30,633
NARRATOR:
And that's happening
on several fronts.

810
00:41:30,633 --> 00:41:32,466
Entanglement
has been put to work

811
00:41:32,466 --> 00:41:34,700
in quantum cryptography

812
00:41:34,700 --> 00:41:37,400
and quantum communication,

813
00:41:37,400 --> 00:41:39,666
in atomic clocks,

814
00:41:39,666 --> 00:41:43,200
and in continuing improvements
to LIGO,

815
00:41:43,200 --> 00:41:46,566
but perhaps with
the greatest fanfare

816
00:41:46,566 --> 00:41:49,966
in quantum computing.

817
00:41:49,966 --> 00:41:52,633
And that starts with this:

818
00:41:52,633 --> 00:41:55,866
the qubit.

819
00:41:57,966 --> 00:42:00,966
The qubit gets its name
from its cousin

820
00:42:00,966 --> 00:42:04,100
in classical computing,
the binary bit.

821
00:42:04,100 --> 00:42:07,733
♪ ♪

822
00:42:07,733 --> 00:42:09,933
Like its name suggests,

823
00:42:09,933 --> 00:42:14,033
a binary bit can only be set
to zero or one.

824
00:42:14,033 --> 00:42:19,233
But from such humble beginnings,
much has flowed--

825
00:42:19,233 --> 00:42:24,100
more or less all the computing
that makes up the modern world.

826
00:42:24,100 --> 00:42:26,433
All the calculations,
all emails.

827
00:42:26,433 --> 00:42:29,433
Whether you're talking
to your friend

828
00:42:29,433 --> 00:42:31,333
or whether you
are a NASA scientist

829
00:42:31,333 --> 00:42:33,600
doing some rocket calculation,

830
00:42:33,600 --> 00:42:37,133
all of that can boil down
to just zeros and ones

831
00:42:37,133 --> 00:42:39,433
switching inside your computer,

832
00:42:39,433 --> 00:42:41,833
which is kind of amazing,
that it's that universal.

833
00:42:44,066 --> 00:42:46,100
NARRATOR:
Despite its many successes,

834
00:42:46,100 --> 00:42:47,733
the binary bit
is the equivalent

835
00:42:47,733 --> 00:42:49,366
of a light switch--

836
00:42:49,366 --> 00:42:52,033
on or off.

837
00:42:52,033 --> 00:42:55,800
The qubit is far more subtle.

838
00:42:55,800 --> 00:42:57,466
ALONSO-MONSALVE:
The special thing about a qubit

839
00:42:57,466 --> 00:43:01,033
is that it operates by the laws
of quantum mechanics.

840
00:43:01,033 --> 00:43:06,233
It doesn't have to be
just in the zero state

841
00:43:06,233 --> 00:43:08,166
or just in the one state.

842
00:43:08,166 --> 00:43:10,800
It can be in a superposition
of both.

843
00:43:10,800 --> 00:43:14,100
NARRATOR:
That superposition creates

844
00:43:14,100 --> 00:43:15,866
a mathematical space

845
00:43:15,866 --> 00:43:19,666
often represented by a sphere.

846
00:43:19,666 --> 00:43:21,100
SOPHIE HERMANS:
Where a classical bit

847
00:43:21,100 --> 00:43:23,800
can only sit at the South Pole
or the North Pole,

848
00:43:23,800 --> 00:43:25,633
a quantum bit can be anywhere

849
00:43:25,633 --> 00:43:27,300
on the surface of the sphere.

850
00:43:27,300 --> 00:43:30,300
It opens up a whole new array

851
00:43:30,300 --> 00:43:32,933
of possibilities
of mathematical operations.

852
00:43:34,266 --> 00:43:38,900
NARRATOR:
But a single qubit will only
take you so far in computing.

853
00:43:38,900 --> 00:43:41,166
LANES:
One qubit by itself
is not a computer,

854
00:43:41,166 --> 00:43:44,266
or it would be the world's
smallest, most useless computer.

855
00:43:44,266 --> 00:43:45,800
But when you combine them,

856
00:43:45,800 --> 00:43:50,166
it can provide enough
computation and calculations

857
00:43:50,166 --> 00:43:52,733
that you can get something
on the other end.

858
00:43:52,733 --> 00:43:56,033
NARRATOR:
Using several qubits together

859
00:43:56,033 --> 00:43:58,800
opens up the power
of entanglement

860
00:43:58,800 --> 00:44:04,033
and unleashes mind-boggling
levels of complexity.

861
00:44:04,033 --> 00:44:07,233
PRESKILL:
If I wanted to give
a complete description

862
00:44:07,233 --> 00:44:09,233
of what's happening
with just a few hundred qubits,

863
00:44:09,233 --> 00:44:11,133
very highly entangled
with one another,

864
00:44:11,133 --> 00:44:14,500
I would have to write down
more bits

865
00:44:14,500 --> 00:44:17,566
than the number of atoms in the
visible universe.

866
00:44:17,566 --> 00:44:20,466
 
And it's that extravagance
of the quantum language

867
00:44:20,466 --> 00:44:23,600
that we wish to exploit
in a quantum computer.

868
00:44:25,633 --> 00:44:28,433
NARRATOR:
Beyond the work being done
at universities,

869
00:44:28,433 --> 00:44:31,233
there are
about 100 companies

870
00:44:31,233 --> 00:44:32,833
developing qubits

871
00:44:32,833 --> 00:44:36,433
and quantum
computing hardware.

872
00:44:36,433 --> 00:44:39,166
Major players
include Google,

873
00:44:39,166 --> 00:44:40,800
Microsoft,

874
00:44:40,800 --> 00:44:42,233
Amazon,

875
00:44:42,233 --> 00:44:45,233
and IBM.

876
00:44:45,233 --> 00:44:48,833
Its hardware development effort
is centered here,

877
00:44:48,833 --> 00:44:51,966
at the Thomas J. Watson
Research Center

878
00:44:51,966 --> 00:44:55,633
in Yorktown Heights
outside New York City.

879
00:44:55,633 --> 00:44:58,133
Okay, let me introduce you

880
00:44:58,133 --> 00:45:00,000
to our IBM Quantum System Two.

881
00:45:00,000 --> 00:45:03,866
Actually, inside here
is three quantum processors,

882
00:45:03,866 --> 00:45:06,833
and the team is working on how
you investigate algorithms

883
00:45:06,833 --> 00:45:08,866
that use multiple
different processors.

884
00:45:12,500 --> 00:45:18,466
NARRATOR:
IBM's qubits employ small loops
of superconducting metal.

885
00:45:18,466 --> 00:45:20,400
Since superconductors

886
00:45:20,400 --> 00:45:22,733
require cold temperatures
to operate,

887
00:45:22,733 --> 00:45:24,833
the center section
of the computer

888
00:45:24,833 --> 00:45:27,800
is a refrigeration unit.

889
00:45:27,800 --> 00:45:30,466
In fact,

890
00:45:30,466 --> 00:45:32,666
the cooling unit
of a quantum computer

891
00:45:32,666 --> 00:45:34,533
can look so cool,

892
00:45:34,533 --> 00:45:37,900
it's often confused
for the star of the show.

893
00:45:37,900 --> 00:45:39,766
♪ ♪

894
00:45:39,766 --> 00:45:43,266
LANES:
So this is a dilution
refrigerator.

895
00:45:43,266 --> 00:45:46,066
A lot of people think this
entire cool shiny machine here

896
00:45:46,066 --> 00:45:47,866
is a quantum computer,

897
00:45:47,866 --> 00:45:49,133
but that's actually
not the case.

898
00:45:49,133 --> 00:45:50,866
This is not a quantum computer.

899
00:45:50,866 --> 00:45:52,200
This is a quantum computer,

900
00:45:52,200 --> 00:45:54,400
this tiny little chip down here.

901
00:45:54,400 --> 00:45:57,100
(laughing):
This is a freezer, basically.

902
00:45:57,100 --> 00:46:01,733
But you can't deny
that it is amazing-looking.

903
00:46:01,733 --> 00:46:03,833
All of these fancy shiny parts

904
00:46:03,833 --> 00:46:05,833
are just plumbing parts
and cables

905
00:46:05,833 --> 00:46:09,466
designed to keep the quantum
computer insanely cold.

906
00:46:09,466 --> 00:46:11,200
I mean, it's, like,

907
00:46:11,200 --> 00:46:14,133
minus-400-something degrees
Fahrenheit.

908
00:46:14,133 --> 00:46:17,333
Like, there's absolute zero.

909
00:46:17,333 --> 00:46:20,433
We are .015 above that.

910
00:46:20,433 --> 00:46:22,700
It has to be so insanely cold

911
00:46:22,700 --> 00:46:25,300
because we use superconductors
to make our qubits.

912
00:46:25,300 --> 00:46:26,633
And then furthermore,

913
00:46:26,633 --> 00:46:28,800
we want to remove
any type of noise

914
00:46:28,800 --> 00:46:32,700
or thermal excitations,
which can disturb the qubits

915
00:46:32,700 --> 00:46:34,633
and make them behave
in ways that we don't like.

916
00:46:34,633 --> 00:46:36,600
♪ ♪

917
00:46:36,600 --> 00:46:41,166
NARRATOR:
Since 2016, IBM has made
its quantum computers

918
00:46:41,166 --> 00:46:43,933
accessible to the public
over the internet.

919
00:46:43,933 --> 00:46:47,733
Anyone can come up
with a quantum algorithm,

920
00:46:47,733 --> 00:46:50,800
akin to a classical
computer program,

921
00:46:50,800 --> 00:46:53,400
and submit it to be run.

922
00:46:53,400 --> 00:46:55,233
GAMBETTA:
Since we first put it
on the cloud,

923
00:46:55,233 --> 00:46:57,966
people have run
over three trillion jobs

924
00:46:57,966 --> 00:46:59,466
on the quantum computers.

925
00:46:59,466 --> 00:47:03,966
NARRATOR:
Running an algorithm
on a quantum computer

926
00:47:03,966 --> 00:47:07,966
involves setting the initial
state of the qubits,

927
00:47:07,966 --> 00:47:12,333
and then manipulating them
in a series of steps.

928
00:47:12,333 --> 00:47:18,100
To do that, on its systems,
IBM uses microwave pulses.

929
00:47:18,100 --> 00:47:19,700
GAMBETTA:
These microwave pulses

930
00:47:19,700 --> 00:47:21,533
essentially either
flip the qubit,

931
00:47:21,533 --> 00:47:23,033
create it in a superposition,

932
00:47:23,033 --> 00:47:25,100
or measure it.

933
00:47:25,100 --> 00:47:29,366
NARRATOR:
After all the manipulation,
the qubits are read,

934
00:47:29,366 --> 00:47:33,633
collapsing their quantum state
into either a zero or one.

935
00:47:35,033 --> 00:47:37,066
But there's a catch.

936
00:47:37,066 --> 00:47:39,666
LANES:
On a quantum computer,
the chip can

937
00:47:39,666 --> 00:47:41,300
spontaneously decay
from the excited state,

938
00:47:41,300 --> 00:47:43,066
or the one state,
into the zero state

939
00:47:43,066 --> 00:47:44,666
when we don't want it to.

940
00:47:44,666 --> 00:47:46,366
And this can occur, you know,

941
00:47:46,366 --> 00:47:47,833
about every millisecond or so.

942
00:47:47,833 --> 00:47:50,333
These errors
are basically inherent

943
00:47:50,333 --> 00:47:52,200
to the quantum nature
of the device.

944
00:47:52,200 --> 00:47:54,233
NARRATOR:
Correcting these errors

945
00:47:54,233 --> 00:47:55,966
is one of the
built-in challenges

946
00:47:55,966 --> 00:47:57,700
of quantum computing.

947
00:47:57,700 --> 00:48:00,466
The current generation
of quantum computers

948
00:48:00,466 --> 00:48:03,133
are not yet able
to do it themselves.

949
00:48:03,133 --> 00:48:05,933
So there's one final step.

950
00:48:05,933 --> 00:48:08,500
GAMBETTA:
The information
then comes back out.

951
00:48:08,500 --> 00:48:10,633
Then it gets sent over
to a computer

952
00:48:10,633 --> 00:48:12,666
where we do things
like error mitigation,

953
00:48:12,666 --> 00:48:15,466
post-process the results,
correct for any extra noise,

954
00:48:15,466 --> 00:48:17,566
and then we send it back
through the cloud.

955
00:48:17,566 --> 00:48:21,633
♪ ♪

956
00:48:21,633 --> 00:48:24,566
NARRATOR:
It is easy to imagine
that quantum computing

957
00:48:24,566 --> 00:48:27,800
is the next phase
of classical computing.

958
00:48:27,800 --> 00:48:30,433
That soon, you'll see
a box that says

959
00:48:30,433 --> 00:48:34,466
"New Qubitium chip inside!"

960
00:48:34,466 --> 00:48:35,666
The most common question

961
00:48:35,666 --> 00:48:37,700
people always ask me,
which is, like,

962
00:48:37,700 --> 00:48:39,900
"When will I be able
to play 'Minecraft,'

963
00:48:39,900 --> 00:48:42,100
when will I be able to play
'Doom' on my quantum computer?"

964
00:48:42,100 --> 00:48:44,733
Quantum computers
are not good for everything.

965
00:48:44,733 --> 00:48:47,033
In the future, there won't
be quantum PowerPoint,

966
00:48:47,033 --> 00:48:48,833
there won't be quantum Word.

967
00:48:48,833 --> 00:48:50,200
We don't need to do that,

968
00:48:50,200 --> 00:48:52,166
because we have
classical computers

969
00:48:52,166 --> 00:48:54,000
and Xboxes that are
perfectly suitable

970
00:48:54,000 --> 00:48:55,400
for those types of applications.

971
00:48:55,400 --> 00:48:59,900
NARRATOR:
Quantum computers
function very differently

972
00:48:59,900 --> 00:49:04,600
and are aimed
at very different tasks.

973
00:49:04,600 --> 00:49:08,000
Experts see a role
for quantum computers in areas

974
00:49:08,000 --> 00:49:10,533
like simulation
of quantum behaviors

975
00:49:10,533 --> 00:49:13,133
in chemistry and materials,

976
00:49:13,133 --> 00:49:17,133
or optimization
of complex systems

977
00:49:17,133 --> 00:49:19,366
ranging from energy distribution

978
00:49:19,366 --> 00:49:22,366
to database searches.

979
00:49:22,366 --> 00:49:26,800
In any case, the future
of quantum computing

980
00:49:26,800 --> 00:49:30,533
is far from written.

981
00:49:30,533 --> 00:49:34,133
GHOSE:
So because things are really
speeding up all over the world,

982
00:49:34,133 --> 00:49:36,766
I think we're going to
very quickly see

983
00:49:36,766 --> 00:49:38,966
a demonstration of a task

984
00:49:38,966 --> 00:49:41,133
that's been done with
a quantum computer

985
00:49:41,133 --> 00:49:44,366
that just is well,
well outside the capability

986
00:49:44,366 --> 00:49:46,000
of current computers.

987
00:49:46,000 --> 00:49:47,633
And that'll probably
happen within the next

988
00:49:47,633 --> 00:49:49,300
five to ten years,
I would say.

989
00:49:49,300 --> 00:49:50,933
The future of computing

990
00:49:50,933 --> 00:49:54,033
is going to have
classical accelerators,

991
00:49:54,033 --> 00:49:55,566
it's going to have
A.I. accelerators,

992
00:49:55,566 --> 00:49:57,533
and it's going to have
quantum computing accelerators

993
00:49:57,533 --> 00:49:58,966
all working together.

994
00:49:58,966 --> 00:50:01,700
And for me, that's one
of the most exciting things,

995
00:50:01,700 --> 00:50:03,733
is, how do we actually
take advantage

996
00:50:03,733 --> 00:50:05,666
of all these different
accelerators?

997
00:50:05,666 --> 00:50:08,233
CARROLL:
I think that a well-functioning
quantum computer

998
00:50:08,233 --> 00:50:10,866
will be able to do certain
things much, much faster.

999
00:50:10,866 --> 00:50:13,133
But number one, we don't know
for sure.

1000
00:50:13,133 --> 00:50:15,700
And number two, it might
turn out,

1001
00:50:15,700 --> 00:50:17,633
the pessimistic view of this,

1002
00:50:17,633 --> 00:50:19,500
that those problems
are kind of limited,

1003
00:50:19,500 --> 00:50:21,666
that they're very, very
specialized.

1004
00:50:21,666 --> 00:50:24,000
But that's all exciting,
fun work in progress.

1005
00:50:24,000 --> 00:50:25,300
That's what makes it
interesting.

1006
00:50:28,733 --> 00:50:32,200
♪ ♪

1007
00:50:32,200 --> 00:50:35,800
NARRATOR:
The roots of quantum physics
go back 100 years.

1008
00:50:37,400 --> 00:50:39,366
But only in recent decades

1009
00:50:39,366 --> 00:50:42,900
have we started to gain control
over the quantum realm.

1010
00:50:42,900 --> 00:50:47,933
And that has already
transformed the way we live.

1011
00:50:49,300 --> 00:50:51,033
There has been
astonishing change

1012
00:50:51,033 --> 00:50:53,100
in the kinds of quantum systems

1013
00:50:53,100 --> 00:50:54,200
we can build and manipulate.

1014
00:50:54,200 --> 00:50:56,000
Quantum mechanics itself

1015
00:50:56,000 --> 00:50:57,833
already permeates
everything we do.

1016
00:50:57,833 --> 00:51:01,433
They're part of how
we manipulate the world.

1017
00:51:01,433 --> 00:51:03,266
They're part of every transistor
and every computer.

1018
00:51:03,266 --> 00:51:07,466
LANES:
It's about how things interact
on a fundamental level,

1019
00:51:07,466 --> 00:51:10,566
but it turns out we need
to know how things interact

1020
00:51:10,566 --> 00:51:14,166
on a fundamental level
to do big things, as well.

1021
00:51:14,166 --> 00:51:16,366
KAISER:
There are still deep mysteries
to puzzle with.

1022
00:51:16,366 --> 00:51:17,866
That part hasn't gone away.

1023
00:51:17,866 --> 00:51:20,800
What's increased, in a way
that I still find remarkable,

1024
00:51:20,800 --> 00:51:23,400
is that these same curious,

1025
00:51:23,400 --> 00:51:25,533
mind-boggling quantum features

1026
00:51:25,533 --> 00:51:27,000
are now built into how people

1027
00:51:27,000 --> 00:51:28,600
navigate the world
every single day.

1028
00:51:31,000 --> 00:51:32,900
NARRATOR:
But what about the future?

1029
00:51:32,900 --> 00:51:35,833
What will quantum technology
offer

1030
00:51:35,833 --> 00:51:38,600
in the coming decades?

1031
00:51:38,600 --> 00:51:39,900
Just like we can tell
our kids, "Oh, yeah,"

1032
00:51:39,900 --> 00:51:41,933
you know, "I was born
before the internet,

1033
00:51:41,933 --> 00:51:44,200
I was born before
smartphones,"

1034
00:51:44,200 --> 00:51:45,566
50 years from now,

1035
00:51:45,566 --> 00:51:46,933
people are going to be
telling stories

1036
00:51:46,933 --> 00:51:48,833
about technologies
that are normal

1037
00:51:48,833 --> 00:51:51,400
that today we can't even fathom.

1038
00:51:51,400 --> 00:51:53,433
I believe 50 years from now,

1039
00:51:53,433 --> 00:51:56,333
people growing up
won't think twice

1040
00:51:56,333 --> 00:51:58,833
about entanglement,
superposition...

1041
00:51:58,833 --> 00:52:00,833
I think that will be
commonplace.

1042
00:52:00,833 --> 00:52:03,200
One of the things I love
about quantum mechanics

1043
00:52:03,200 --> 00:52:05,633
is that it seems non-intuitive
to us.

1044
00:52:05,633 --> 00:52:07,800
It tells us
that there's something

1045
00:52:07,800 --> 00:52:09,800
beyond just what we think
we understand.

1046
00:52:09,800 --> 00:52:12,166
We can't always rely
on our intuition.

1047
00:52:12,166 --> 00:52:14,233
We have to rely
on our understanding

1048
00:52:14,233 --> 00:52:15,733
to make progress.

1049
00:52:15,733 --> 00:52:19,000
And quantum mechanics
just shows us that so clearly.

1050
00:52:41,100 --> 00:52:43,966
♪ ♪

1051
00:52:44,900 --> 00:52:52,433
♪ ♪

1052
00:52:56,266 --> 00:53:03,866
♪ ♪

1053
00:53:07,700 --> 00:53:15,233
♪ ♪

1054
00:53:16,866 --> 00:53:24,400
♪ ♪

1055
00:53:26,033 --> 00:53:33,566
♪ ♪