All right, so we've got two papers for you today.
And get this, they're both by Albert Einstein
from 1935, back in 1935. Two months apart. Yeah,
two months apart. And the thing is, Einstein
himself, he didn't actually connect the dots
between them at all. Right. He really thought
they were about. completely different things.
Super worlds of physics, yeah. Exactly. One was
all about quantum mechanics. That's the rule
book for the super tiny, you know, the really,
really small stuff. Right, the microscopic. Yeah,
exactly. And then the other paper was tackling
the huge scale of the universe, like gravity
and space time itself. The realm of general relativity.
Exactly, general relativity. And here's the kicker
for you. And then this is what makes us so exciting.
a bunch of scientists, now they're starting to
think that these two papers, they're actually
deeply connected. And that's kind of mind -blowing,
right? Well, it is. It's really profound because
it's hinting at this fundamental link between
how the smallest bits of reality work and the
grand structure of the entire universe. Yeah,
it's like they're two sides of the same coin.
That's a good way to put it. And that's what
we're going to dive into today in this deep dive,
just for you. Your express route. Exactly. It's
like a shortcut to understanding this cutting
edge area of physics. It really is. And to appreciate
how we got here, it's helpful to think about
the historical context for you. OK. For centuries,
Newtonian physics reigned supreme. Yeah, the
clockwork universe. Yeah, exactly. The idea was
if you knew where everything was and how fast
it was moving, you could predict the entire future.
Like a perfect machine. precisely. And it worked
incredibly well for everyday stuff, you know,
like planets orbiting stars. But then in the
early 20th century, physicists started looking
at the really, really tiny stuff, the microscopic
realm. And that's when things started to break
down. It's like Newton's laws just couldn't keep
up. They just didn't apply anymore, this whole
new ball game. Yeah. And that's where quantum
mechanics comes in, right? Absolutely. It was
this incredible period of intellectual ferment,
and these brilliant minds came together. Yeah,
like Planck, Bohr, Heisenberg. Schrodinger -Bohrn.
Yeah. Yeah, they really revolutionized physics.
And they created this whole new way of understanding
reality, right? They did. And one of the key
things for you to grasp is that there was this
massive shift from certainty to probability.
OK. So instead of saying, this is definitely
going to happen. Quantum mechanics says, here's
the likelihood of this or that outcome. So it's
all about possibilities. Exactly. It's all about
probabilities. It's a very different way of looking
at the world. Yeah, and Einstein, even though
he was a major figure in the early days of quantum
theory, he always felt like it wasn't the whole
story. He had this gut feeling that it was incomplete,
you know? Yeah, like it was a stepping stone
to a deeper understanding. Exactly, and that's
a really important point for you to understand
about Einstein's mindset. Okay. He famously said,
God does not play dice. Yeah, I've heard that
one. And that quote really captures his deep
discomfort with the randomness at the heart of
quantum mechanics, you see. So it wasn't that
he thought quantum mechanics was wrong? No, not
at all. His predictions were and still are amazingly
accurate. It just didn't sit right with him.
Right. He believed that eventually a more fundamental
theory would emerge for you. One that didn't
need probabilities. Yeah, one that would restore
that sense of determinism that Newton had given
us. Okay, so he was kind of hoping to find flaws
in quantum mechanics. He was. He actively tried
to expose inconsistencies within the theory.
And that leads us to the first paper we're looking
at today. The EPR paper. Exactly. Published in
May 1935. Co -authored with Boris Podolsky and
Nathan Rosen. Right, so Einstein, Podolsky, and
Rosen, they thought they'd found a major weakness,
a potential Achilles heel of quantum mechanics.
Through this very strange phenomenon called quantum
entanglement. Entanglement, yeah, I think a lot
of people have heard that word, but let's break
it down for you. Okay. So imagine you're flipping
two coins. Right. In our everyday experience,
each coin is going to land on either heads or
tails completely randomly. Right, they're independent
of each other. Exactly. Now here's where quantum
mechanics gets really weird. Okay. world, before
we look at a particle, it can actually exist
in this blurry state called a superposition.
It's like the coin is both heads and tails at
the same time. Until we actually observe it.
Right. The act of measurement forces it to choose
one state or the other. So imagine now that you
have two particles that are entangled. They've
interacted in a way that links their fates. Okay.
Even if you separate them by a huge distance.
Like across the galaxy. Yeah, potentially even
further. their destinies remain intertwined for
you. So if you measure one particle and find
out, let's say its spin is up... The other particle
instantaneously has to have the opposite spin
down. And that happens no matter how far apart
they are. It's as if they're communicating faster
than the speed of light. Yeah, that's what Einstein
called spooky action at a distance. He really
didn't like that. Yeah, it just seemed to go
against everything he knew about the universe.
It violated his intuition about the independence
of objects that are far apart. And that... no
influence should be able to travel faster than
light. Right. It was as if there was some invisible
thread connecting these distant particles. But
Einstein also had another problem with entanglement
that he found really unsettling. Yeah. He was
also bothered by the fact that in quantum mechanics,
you can know everything about the combined state
of two entangled particles, but know nothing
specific about the individual properties of either
particle until you make a measurement. So it's
like knowing you have two gloves, a left and
a right. But not knowing which glove is which
until you look. Yeah, and that really bothered
him. It struck him as deeply problematic for
you. I can see why that would be confusing. It
is. It's one of those things that really makes
your head spin. And if you're feeling a bit lost
right now, you're not alone. A lot of people
struggle with this. Even physicists. Yeah, we
can use entanglement in technology and we can
predict its effects with incredible accuracy.
Right. But actually understanding what's really
going on. That's a different story. It's like
our intuition just can't quite grasp it. The
key takeaway here is this concept of non -separability.
Okay. Entangled systems are fundamentally linked
in a way that classical physics just doesn't
allow for. So going back to the EPR paper, what
was Einstein really trying to achieve with that?
He wasn't just trying to point out the spookiness
for you. Okay. His real goal was to expose a
contradiction within quantum mechanics itself.
So he was trying to prove it was wrong, somehow.
In a way, yes. He was trying to show that it
was incomplete, that it couldn't be the whole
story. And how did he plan to do that? Through
a thought experiment involving entangled particles.
Okay. They proposed that by carefully choosing
what to measure on one particle, either its momentum
or its position, you could indirectly gain knowledge
about the corresponding property of the other
particle without actually measuring it. Okay,
so because you could choose to measure either
momentum or position on the first particle. It
seemed to imply that the second particle must
have definite values for both momentum and position
all along, even before the measurement. And wouldn't
that violate Heisenberg's uncertainty principle?
Exactly, because the uncertainty principle states
that you can't know both the precise momentum
and position of a particle simultaneously. So
Einstein was basically saying that If a measurement
in one place can tell you something about a particle
far away instantly, then that distant particle
must have already had that property for you.
Like it couldn't have just popped into existence
when you measured it. Right. The measurement
shouldn't magically create that property in a
distant location. And that felt wrong to Einstein.
It just didn't make sense to him. So what happened
with the EPR paper? Did it achieve its goal?
It became incredibly influential, but Einstein
himself wasn't completely satisfied with it.
Why not? Well, Schrödinger wrote to him congratulating
him on the paper. Okay. But Einstein's reply
is quite telling. He felt that his main point
got buried in all the technical details. So it
didn't quite come out the way he wanted. Yeah,
he felt like the paper didn't fully capture his
intended message for you. Interesting. And what
was that message? Well, Lenny Suskin, a very
prominent physicist, has argued that Einstein's
real concern was with the nature of physical
reality itself. What does that even mean? It's
a deep philosophical question about What is real
right what exists independently of our observations?
You know okay, so it was more than just about
the uncertainty principle. It was about the very
foundations of reality for you Okay, so that
was May 1935 now. Let's jump ahead just two months
to July 1935. Another Einstein paper. Yeah, another
one. This time it's just him and Nathan Rosen.
Right. And this one seems completely different.
It's about bridges in space time. Yeah. These
are now known as Einstein, Rosen, bridges or
more popularly wormholes. Wormholes. Yeah, I've
heard of those too. But to understand them, we
need to talk a bit about general relativity.
Absolutely. Einstein's masterpiece from 1915.
Which totally changed our view of gravity, right?
It completely revolutionized our understanding
for you. OK, so before For Einstein, we had Newton's
idea of gravity as this force acting at a distance.
Yeah, like the Earth pulling on the moon. But
Einstein came along and said, no, it's not a
force. It's about the curvature of spacetime
itself. Exactly, caused by mass and energy. OK,
so imagine like a bowling ball on a stretched
rubber sheet. Yeah, that's a good analogy. The
bowling ball creates a dip, and that dip influences
how smaller objects move around it. It's a simplified
picture, but it helps to visualize how gravity
works in Einstein's theory for you. So gravity
is like warping the fabric of space and time.
Precisely. And shortly after Einstein published
his theory, Carl Schwarzschild found this remarkable
solution to his equations. Okay. And his solution
described the space -time around a spherical
object like a star. And that led to a pretty
startling discovery. It did. Schwarzschild showed
that if an object is massive enough and collapses
to a small enough size, the curvature of spacetime
becomes so extreme that it creates a point of
no return. The event horizon. Exactly. Nothing.
Not even light can escape from beyond that horizon.
And we call those black holes, right? We do.
They're regions of spacetime where gravity is
so strong that nothing can escape. So in their
1935 paper, were Einstein and Rosen specifically
talking about black holes? Not explicitly. but
the math they were exploring turned out to have
deep connections to black holes for you. What
did they actually find? They discovered a theoretical
way that two black holes could be connected in
space -time. Connected like how? By a tunnel
or a bridge. Like a shortcut. Yeah, you could
think of it that way. Instead of having to travel
vast cosmic distances through normal space, you
could potentially... pass through this wormhole
and emerge in a totally different location. So
it's like folding that rubber sheet we were talking
about earlier. Yeah, exactly. You fold it so
that two distant points touch, and you create
a shortcut through warp spacetime for you. That's
pretty wild. But at the time, was there any link
between these wormholes and quantum entanglement?
Not at all. They were considered completely separate
areas of physics. But that's where things start
to get really interesting. Yeah. Because in recent
years, there's been this amazing new proposal
that wormholes and entanglement are actually
connected. Exactly. And it's a profound idea
that has huge implications, not just for our
understanding of black holes, but for the very
nature of space and time. So how did this connection
come about? It started in the 1970s with Stephen
Hawking's work on black hole radiation. Contrary
to what we used to think, Hawking showed that
black holes aren't completely black. Wait, so
they don't just suck everything in? They do,
but they also emit a faint thermal radiation
from their event horizon. So they kind of glow
a little bit? In a way, yes. And here's how it
works in the quantum world. Pairs of virtual
particles and antiparticles can just pop into
existence, even in empty space. Out of nothing?
Well, sort of. They borrow energy from the vacuum,
and usually they quickly annihilate each other.
OK. But near the event horizon of a black hole,
something really interesting can happen. What?
One particle of the pair can fall into the black
hole while the other escapes and radiates way
into space. So it's like the black hole is slowly
losing energy. Exactly. And here's the key point
for you. Those pairs of particles, even when
they get separated, they're entangled. So even
though one falls into the black hole and the
other escapes, they're still linked. They are.
They share this spooky connection. And this led
to a big problem, right? The black hole information
paradox. It did because Hawking radiation carries
away energy from the black hole, causing it to
slowly shrink and eventually evaporate completely.
And that creates a problem because one of the
fundamental principles of physics is that information
is never lost. Right, so if something falls into
a black hole, where does the information about
that object go? if the black hole disappears.
That's a good question. It is. And Hawking's
initial calculations suggested that the emitted
radiation was just random thermal radiation.
So it wouldn't carry any information about what
fell in. Right. Which created a conflict with
quantum mechanics, because in quantum mechanics,
time should be reversible and information should
be retrievable. So how do we resolve that paradox?
That's where the holographic principle comes
in. OK. This was a really radical idea, championed
by Leonard Susskind and Gerard Tuft. What did
they propose? They suggested that all the information
contained within a volume of space could actually
be encoded on its two -dimensional boundary.
Like a hologram? Exactly like how a hologram
stores a three -dimensional image on a flat surface.
So all the complexity of the universe could be
encoded on some kind of cosmic boundary? That's
the idea. And Susskind's work in string theory
actually led him to this insight. How so? He
realized that if you probe a fundamental quantum
string with more and more energy, it actually
appears to spread out in space. So it's not really
a point -like particle? No, it's more like a
fuzzy, extended object. Interesting, so the information
isn't localized in the way we usually think.
Right, it's more spread out, maybe even sort
on the boundary of the system for you. Okay,
so the information about something falling into
a black hole could be encoded far away on the
event horizon. Or even further out, potentially.
Okay, but the story doesn't end there, does it?
It doesn't. In 2012, a group of physicists published
a paper that presented a new challenge to our
understanding of black holes. This is the AMPS
paradox, right? It is named after the authors
Harry, Marolf, Pulchinski, and Sully. And what
was their paradox? It focused on the entangled
nature of Hawking radiation. For that outgoing
radiation to carry information about what fell
into the black hole, the early radiation and
the later radiation would also have to be entangled
with each other for you. OK, but I thought you
said entanglement was like a one -to -one connection.
It is. And that's the problem. Quantum mechanics
has this rule called the monogamy of entanglement.
Which means? A quantum system can't be maximally
entangled with two independent other systems
at the same time. So it's like having one phone
line. You can only have one clear conversation
at a time. That's a good analogy, and this created
a crisis for our understanding of black holes.
Because it seemed like the entanglement needed
for information to be preserved was forbidden
by quantum mechanics. Exactly. It was a real
puzzle. So how did they get out of this mess?
This is where the truly mind -blowing proposal
of ER -EPR comes in. OK. This was put forward
by Juan Maldicena and Leonard Susskind. ER equals
EPR. What does that even mean? Well, ER stands
for Einstein -Rosen bridges or wormholes. Right.
And EPR stands for Einstein -Podolsky -Rosen,
the entanglement paper we talked about earlier.
Right. Their radical proposal was that these
two seemingly distinct phenomena are actually
equivalent for you. Equivalent how so? They said
that if two regions of space are entangled at
the quantum level, there must be a wormhole connecting
them. Even if those regions are super far apart.
Even if they're on opposite sides of the universe.
So entanglement creates wormholes. That's the
idea and it's a really profound one because it
completely changes how we think about both entanglement
and wormholes. Okay, so let's go back to the
black hole paradox. How does EREPR solve that?
Remember that the distant Hawking radiation escaping
the black hole is entangled with something inside
the black hole. According to EREPR, that entanglement
implies a wormhole connecting the radiation to
the black hole's interior. So the information
isn't lost, it's traveling through the wormhole.
Exactly. The information is encoded in the entanglement
and that entanglement creates a bridge, a wormhole
connection. So the distant radiation isn't really
that distant after all. Not in this entangled
reality for you. It's amazing that Einstein published
his papers on entanglement and wormholes just
two months apart. It is, and he probably had
no idea that they were connected in this way.
But the story goes even deeper, right? It does.
Mark Van Ramsdonk did some really interesting
work that takes this even further. What did he
do? He used the holographic principle to explore
the relationship between entanglement and the
structure of space -time itself. Okay, so he
was thinking about space -time as a hologram.
Yeah, and he imagined that the underlying quantum
system resided on a boundary. Like the surface
of a sphere. Right. And he asks this fascinating
question. What happens if you theoretically snip
the threads of entanglement between different
parts of that quantum system? Snip them. How?
Just imagine you could somehow remove the entanglement
between those regions. OK. And his calculations
suggested that if you do that, the corresponding
regions of spacetime would literally start to
pull apart. Like the fabric of space is being
torn? In a way, yes. And they could even become
completely disconnected. So entanglement is holding
spacetime together. That's what his work suggests,
and it's a revolutionary idea for you. It is.
It's saying that entanglement isn't just some
weird phenomenon happening within space time.
It's saying that entanglement might be fundamental
to the very fabric of space time itself. So space
itself might emerge from this network of quantum
entanglement. That's the mind blowing implication.
Wow. So where does all this leave us in our quest
to understand the universe? Well, it's challenging
the traditional approach of trying to quantize
gravity. You know, applying the rules of quantum
mechanics to Einstein's general relativity. Exactly.
But this new research is suggesting that maybe
quantum mechanics and gravity are already intertwined
from the get go. Like they're two sides of the
same coin. That's a good way to put it. And it's
possible that quantum mechanics has been knowing
about space and gravity all along in ways we
hadn't realized. So we might have to rethink
everything. We might. And it all ties back to
those two seemingly unrelated papers that Einstein
published in 1935. It's incredible how much those
papers have shaped our understanding of the universe.
They've really opened up entirely new avenues
for exploration. So here's a final thought for
you to ponder. OK. What if space itself, the
very arena in which everything happens. isn't
a pre -existing stage, but rather a manifestation
of quantum entanglement. That's a truly mind
-bending idea. It is. It means that the very
fabric of reality might be woven from these spooky
connections between quantum particles. It all
started with Einstein's papers and the realization
that they're deeply connected in ways he could
never have imagined. So the revolution in our
understanding of the universe continues, and
it's full of surprises. It is, and it's all about
these unexpected connections that are changing.
how we view reality itself for you. And who knows
what other amazing discoveries await us as we
continue to explore the mysteries of quantum
gravity holography and the profound implications
of ER, EPR. It's an exciting time to be a physicist.
That's for sure. And who knows, maybe one day
we'll fully understand the deep connection between
the very small and the very large. I can't wait.
Me neither. This is incredible stuff. It really
is. Thanks for joining us for this deep dive
into Einstein's mind -blowing papers. My pleasure.
It's been a fascinating journey. And until next
time, keep exploring the universe. And keep wondering
about those deep connections. You never know
what you might discover. That's the beauty of
science. Absolutely. Always more to learn. Always
more to uncover. Yeah, it's a never -ending adventure.
And that's what makes it so exciting. Absolutely.
Alright, thanks again and see you next time.
See you then.