[INTRO MUSIC]
What if I told you
were a hologram?
Or maybe I'm getting
ahead of myself.
In my quest to become better
acquainted with reality,
I decided to get the
perspective of someone who
devoted their life to
discovering the true nature
of the universe.
Leonard Susskind is one of
the founders of string theory
and Scientific America's
bad boy of physics.
I'm a professor of physics
at Stanford University.
And I think about physics.
CRAIG: Like many
physicists, Susskind
spends his days
trying to understand
how the universe works.
But physicists
don't always agree.
And about 40 years
ago, a major battle
began in the physics community
that lasted for decades.
And winning the battle
required rethinking
the very nature of reality
CRAIG: There are two
prevailing theories,
the theory of relativity
and then quantum mechanics,
that seem to be at
odds with each other.
Well, Yeah, they do seem to
be at odds with each other,
and always had from the get go.
But they can't be at
odds with each other,
because they're both true.
We've got to make them fit.
We've got to make
them fit together.
CRAIG: So in 1915,
Albert Einstein
published his general
relativity theory,
which explains how gravity
and space-time work.
And quantum mechanics was
developed a few years later
by these people.
LEONARD SUSSKIND: You
know, quantum mechanics
is about very, very
small and light things
which are so delicate that
any way that you touch them
or any way that you
observe them, they change.
Relativity is about gravity.
Gravity is about
very heavy objects.
MATT: So relativity
is great at explaining
the motions of big things,
like stars and planets,
but not so good at tiny
things, like particles.
CRAIG: Yes.
And physicists are always on
the lookout for one theory that
explains everything.
But in the day to day life of
a cosmologist or a particle
physicist, you're usually
dealing with very big things
or very small things.
So for the time being
two theories was OK.
That is, until a young physicist
who was studying black holes
had a brilliant idea that
screwed everything up.
LEONARD SUSSKIND:
Stephen Hawking
put his finger on
a very important,
what's called a paradox.
A paradox means something which
apparently looks contradictory.
What he recognized
is that things
that fall into a black
hole are lost completely.
They're lost, and they
can never come out.
On the other hand,
quantum mechanics says,
and this is one of its very,
very basic ingredients,
that nothing can
ever really be lost.
Information, the
distinctions between things,
can't really be lost.
But what does he
mean by information?
I mean, I lose
information all the time.
I can't remember
where I parked my car,
my dog ate my book report.
That's a little different.
When Susskind talks
about information,
he's referring to
the distinctions
between the fundamental
particles that
make up the atoms in our bodies
and the rest of the universe.
For instance, I could take
this book and burn it.
Hey, I'm not
finished with that.
I'm not going to burn it.
But if I did, you wouldn't
be able to read it,
because it would be a
pile of ash and smoke.
However, from a
physics perspective,
the atoms that make
up the paper and ink
in the letters and
the tragic love story
would still be there and could,
theoretically, be recombined
if we had the right tools.
In fact, I think
of it as more basic
than any of the other
principles of physics.
The most basic
principle of physics
is that distinctions
never disappear.
Now, take that same book,
toss it in a black hole,
and you've got
yourself a problem.
According to Hawking,
all that information
is irretrievably lost.
Why is that, exactly?
Well, it has something to do
with what Hawking discovered
about black holes.
Well, maybe we should explain
what a black hole is first.
Go for it.
A black hole is a
region of space composed
of super densely packed matter.
Because of it's mind-boggling
density, it's pull of gravity
is so strong that nearby planets
and stars can get sucked in.
And nothing, not even
light, can escape
once it's gone beyond the
black hole's event horizon.
So it's a point of
no return, in a sense.
It's a point of no return
in which when anything falls
through it, it simply
cannot get out,
because in a sense space is
moving inward at faster than
the speed of light.
So in 1974.
Stephen Hawking basically said
that all matter and information
that goes into a black
hole is lost forever.
And I guess Susskind
wasn't too happy about this.
No way.
He actually wrote
a book about it.
The Black Hole War, My
Battle with Stephen Hawking
to Make the World Safe
for Quantum Mechanics.
Yeah.
Right.
Could you describe
this battle, and why
it was a war you felt it
was necessary to fight?
Well, as I said, Stephen was
basically a gravity physicist,
a general relativist.
And he believed
in the principles
of general relativity.
Nothing else mattered.
I was always a
quantum physicist.
And when Stephen said that
it looks like black holes,
because they lose
information into them,
violate the principles
of quantum mechanics, I
and a couple of my friends,
in particular a physicist
by the name of Gerard 't Hooft,
a very famous Dutch physicist,
said, no, that can't be right.
And we didn't know
why he was wrong,
but we knew he was wrong.
He held his ground.
We held our ground.
But eventually, we began
to make sense of in what
way Hawking was wrong.
It's a basic
principle of the way
we think of classical
physics, that a thing can only
be in one place.
If it's here, it's not there.
If it's there, it's not here.
What was going on is
that, in some funny sense,
quantum mechanics
was requiring that it
could be in the sense in
two places at the same time.
What?
How is that even possible?
Yeah, what's he talking about?
We begin to get the idea,
in particular, 't Hooft
and myself, that what was
going on on the horizon
of a black hole was
similar to a hologram.
That the surface
of the black hole,
the horizon of the black hole,
was like a photographic film.
And what fell into
the black hole
was like the image created,
a three-dimensional image
created.
CRAIG: So their idea
was that any matter that
falls into a black hole
remains trapped inside.
But at the same
time, an exact copy
is perfectly preserved
on the horizon.
This by itself was a
revolutionary idea.
But Susskind and his
crew soon realized
that the holographic principle
doesn't necessarily only
apply to black holes.
Once we understood
that what was inside
falling into the black
hole, inside the black hole,
was a kind of projection
of the horizon,
we began to understand
the idea was more general,
that the entire three
dimensionality of space
is a projection of a
very distant horizon that
surrounds us.
And not the horizon
of a black hole, it's
the horizon of the universe.
And instead of being
on the outside of it,
like we would be if there
was a black hole here,
we were on the inside of it.
And so you could say that
we on the inside of it
are a projection of this
film-like thing that's
on the boundary of the universe.
So while we stand here
in The Good Stuff studio,
and while you watch this
video at home, or at work,
or in prison awaiting trial,
whatever you're doing,
we are actually projections
of equivalent versions
of ourselves that live on the
outer surface of the universe.
Whatever happens here,
happens there, and vice versa
and vice universa.
So I'm a hologram?
This isn't real?
Oh my god.
Is the real me just
a battery that's
powering a universe-wide
simulation?
No, Matt, you're
not in the Matrix.
There is no spoon.
It's just that you're here,
and you're sort of over there
as well.
Well, if we're here and also
there, are we the projection,
or is the outer
surface the projection?
Which one's reality?
Are we on the inside
of the universe,
or have we actually been in the
outer surface this whole time?
That's your choice.
You decide.
But the mathematics
says they're equivalent.
I feel like I'm here
Yeah, but so does your
image on the boundary.
It's also saying, I
feel like I'm here.
Oh, man.
Right, right.
But the mathematics doesn't care
which way you think about it.
It says there's an equivalence.
That's about all we can say.
Physicists do not
like the word reality.
We may talk about
it all the time.
But when it comes
down to it, we really
don't want to say this is
reality and that's not reality.
There are mathematical
connections between things.
And that's got to be it, because
we don't have insight enough
to be able to tell
which is reality.
That's pretty wild.
It is pretty wild.
And not surprisingly, the idea
of the holographic principle
was initially met with
a bit of skepticism.
This was a wild idea at first.
Nobody really accepted it.
I think for the most part the
reaction of our colleagues
were, those guys used
to be smart guys.
I think they've
lost their marbles.
The world is a hologram?
That's too crazy.
Eventually, the idea got put
into a very, very precise form
by a young Argentinian physicist
by the name of Juan Maldecena.
Juan Maldecena is now one of the
great physicists of the world,
maybe the greatest
physicist of the world.
It's now gone from being
a wild-eyed conjecture
to being an every-day
working tool of physics.
After Juan Maldecena's
mathematical realization
of the holographic principle,
Hawking conceded defeat.
He admitted that he was
wrong about information being
lost in a black hole, calling it
his biggest blunder in science.
So how does Susskind
feel about Hawking
after he admitted he was wrong?
All of these ideas were
put in place as a response
to a very, very deep question
Stephen Hawking asked.
He was incredibly
perceptive to see that there
was this tension there.
And all of the ideas
of modern physics
that are exciting
all of us now trace
right back to his question.
So to say he was just
wrong is a pale reflection
of what really happened.
So does Stephen Hawking
now fully support
the holographic principle?
As far as I can tell
he supports these ideas.
But that's kind of irrelevant,
because the rest of the physics
community does.
You know, we get old.
Steven gets old.
I get old.
At some point it doesn't
matter what he or I think.
OK, so the physics
community generally
accepts this is a
plausible theory.
That's all well and good, Craig.
But how can something so
insane-sounding be true?
Well, maybe you just
don't understand it.
I don't understand it.
Well, why is this stuff
so hard to understand?
When people ask me
about these things,
I always give the same answer.
Our neural wiring, the
thing that we inherited
from our ancestors,
and I don't mean
our ancestors our
grandparents, I mean, you know,
the worms in the muck.
Through evolution, the neural
wiring that we inherited
was not built for
quantum mechanics.
It was not built for
higher dimensions.
It was not built for thinking
about curved space-time.
It was built for
classical physics.
It was built for
rocks and stones
and all the ordinary objects.
And it was built for
three dimensional space.
And that's not quite
good enough for us
to be able to visualize
and internalize
the ideas of quantum mechanics
and general relativity
and so forth.
So instead, what do we do?
We use mathematics.
Eventually, in time we
develop intuitions out
of the abstract mathematics.
We get better at it.
And we begin to think that way.
But that can be
extremely frustrating
when trying to explain
to the outside world.
The outside world
by and large has not
had that experience of
going through the rewiring
process of converting
their minds
into something that can
deal with 5 dimensions, 10
dimensions, or the quantum
mechanical uncertainty
principle, or whatever
it happens to be.
And so the best we can do is
to use analogies, metaphors.
And the holographic
principle is a metaphor.
The way I've described
it in terms of a hologram
is not precise.
It's not exactly accurate.
It's close.
It captures some of the ideas.
But there is a whole raft
of mathematics behind it
that I can't easily
transfer to you.
Yeah.
I should've paid more
attention in math class.
Well, it wouldn't
have been enough.
Yeah.
I know what you mean.
Like, even learning
about relativity,
just learning about
how time works
and how time is a dimension, it
took me a while to fully grasp.
No, you would get it.
You would get it if you
took a couple years.
I mean, I don't know what your
level of mathematics is, but--
I was good in high school.
That's good enough.
If you were good in
mathematics in high school,
then within a year
or two of effort
these ideas could be conveyed.
Yeah.
But to do so in my living room
here in an hour, all we can do
is try to use metaphors
and analogies.
Right.
So it's possible that
after a few years
of rigorous
mathematical training,
we could potentially
understand these principles.
Still, Susskind admits
that not everyone
will be able to understand,
or even want to.
And that's OK.
In my experience there's
a lot of people out there
who understand that they
can't understand it,
and are very glad
that somebody can.
There's also people
who are very resentful.
They're resentful.
They think there
is a conspiracy,
a conspiracy that the priesthood
of science is hiding something.
Can you tell them no?
Can you tell them?
No, no, no.
We're not hiding anything.
We want more than
anything else that people
should listen to us, and
understand what we're saying.
But we're stuck with this
obstacle of mathematics.
So if you want to
understand the universe
beyond the basic stuff
that we can see and touch,
you gotta learn the math.
Right.
But it's also OK if you don't
know the math, because there
are people out there
who have devoted
their lives and
years of research
to understanding this stuff.
And they're doing
a pretty good job.
Science is a constantly
evolving field.
But there is plenty
that they do know.
And they're getting better and
better at making predictions.
So what did Susskind
think is in store
for the future of physics
and our understanding
of the universe?
Yeah, I think this
holographic idea
is permanent in the
vocabulary of physicists.
It's in the textbooks.
It's going to stay
in the textbooks.
But how the whole story
is going to play out,
the universe, how
quantum mechanics
fits together with
gravity and so forth,
I think there's only one
thing that's certain,
that there will be surprises.
Some of them will
come from experiments.
Some of them will come
from giant telescopes.
And some of them will come from
mathematical and theoretical
thinking about how
things fit together.
And I think one
can be pretty sure
that anybody who thinks that
they have the final answer
now is smokin' something bad.
Or maybe they should be
smoking something better.
Ha-ha-ha.
Don't do drugs, kids.
But I think
there's every reason
to believe that the future
will hold surprises.
So for me to sit here and to
predict how physics will evolve
in the next century or so
is a total waste of time,
because I'll be wrong.
Good answer.
So there's still a
lot to be discovered.
But there's no way to
know how our understanding
of the universe is going
to change in the future.
And, as we've learned
throughout the episode,
it's hard to even know
what's happening right now.
So what are we supposed to do?
Well, I guess we
just have to trust
that there are people out there
who are diligently working
to figure out how our world
works, where we come from,
and where we're going.
And at the same time, we
have to be a little cautious
dealing with people who claim
to have all the answers.
Great summation, Craig.
Thank you.
Pretty nice day out.
Want to go outside and
throw the football around?
That's some classical physics
I can wrap my head around.
Let's go buddy.
Hey, guys, wait for me.
Thanks for watching our Seeing
Isn't Believing playlist.
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Go long, Craig!
Longer.
Even longer.
Don't stop.
It's going to be a bomber.
[MUSIC PLAYING]
