Quantum Time: Is the Future Already Written?

<v Speaker 1>Welcome to the quark Side. Quantum Physics podcast, an exploration
<v Speaker 1>of the fundamental structure of reality, where quantum laws govern matter, energy,
<v Speaker 1>and information. Here, uncertainty is a feature, not a flaw,
<v Speaker 1>and understanding begins at the smallest scales.
<v Speaker 2>Okay, I have a request. It's a small one, but
<v Speaker 2>I need you to just commit to it for a moment.
<v Speaker 2>I'm okay to stop whatever you're doing just for a second.
<v Speaker 3>Tune everything else out exactly.
<v Speaker 2>Don't look at your phone. If you're driving, well, okay,
<v Speaker 2>please keep your eyes on the road, but just shift
<v Speaker 2>your mental focus. Try to really look at the.
<v Speaker 3>Now, the present moment.
<v Speaker 2>Right, you can watch the second hand on a clock,
<v Speaker 2>or just you know, feel your own heartbeat, don't. Don't
<v Speaker 2>that sensation right there, that feeling of flow.
<v Speaker 3>It's the most fundamental thing we experienced.
<v Speaker 2>We're obsessed with it. We live our entire lives in
<v Speaker 2>this tiny, razor thin slice of reality. We mourn the
<v Speaker 2>past because it's gone, it's buried in memory, and we
<v Speaker 2>stress about the future because it hasn't happened yet.
<v Speaker 3>Right, it is the universal human condition. We treat the
<v Speaker 3>past as a fixed record. It's done, it's written, and
<v Speaker 3>the future, Well, the future is a void. It's a
<v Speaker 3>blank canvas waiting for paint.
<v Speaker 2>That is the common sense view. I mean, that's how
<v Speaker 2>I live my life. Next Tuesday is a ghost. It
<v Speaker 2>doesn't actually exist, it's it's waiting for me to create it.
<v Speaker 2>But and this is why we're here today. We have
<v Speaker 2>a stack of research sitting right here on the desk
<v Speaker 2>that says, my common sense is what's lying to me.
<v Speaker 3>Lying is a polite way to put it. I mean,
<v Speaker 3>if we take the sources we're analyzing today, and they
<v Speaker 3>range from Einstein's relativity to the absolute latest papers on
<v Speaker 3>quantum gravity, that void of next Tuesday might be just
<v Speaker 3>as solid, just as real, and just as already there
<v Speaker 3>as the chair you're sitting.
<v Speaker 2>In right now, which is frankly a terrifying thought.
<v Speaker 3>It's deeply unsettling.
<v Speaker 2>It implies the script is already written. It implies that
<v Speaker 2>while I feel like I'm improvising my life, you know,
<v Speaker 2>make some choices. Yeah, I might just be reciting lines
<v Speaker 2>that were stamped into the fabric of the universe thirteen
<v Speaker 2>billion years ago.
<v Speaker 3>It does, and the more you dig into the physics
<v Speaker 3>of it, the harder it gets to hold onto that
<v Speaker 3>simple idea that time flows at all. We might be
<v Speaker 3>dealing with a universe that is at its most fundamental
<v Speaker 3>level static frozen, frozen, a block of ice where we
<v Speaker 3>are just well trapped in the middle thinking we're swimming.
<v Speaker 2>Okay, so the mission for this whole exploration today is
<v Speaker 2>to see if we can break that block of ice,
<v Speaker 2>or at least understand it. We're going to start with
<v Speaker 2>it intuitive feeling the arrow of time, crash it head
<v Speaker 2>on into general.
<v Speaker 3>Relative, get completely confused by quantum mechanics.
<v Speaker 2>And see if something like free will can even survive
<v Speaker 2>the laws of physics as we understand them.
<v Speaker 3>It is going to be a messy investigation. We are
<v Speaker 3>going to have to dismantle your intuition piece by piece.
<v Speaker 2>Good. I like messy. So let's start with the most
<v Speaker 2>obvious thing, the arrow me This is the most tangible,
<v Speaker 2>undeniable proof that time exists and that it moves in
<v Speaker 2>one direction. Okay, I drop a coffee mug, It falls,
<v Speaker 2>it hits the floor, and it shatters into a thousand pieces.
<v Speaker 2>I have never not once in my entire life see
<v Speaker 2>a pile of ceramic shards on the floor suddenly jump
<v Speaker 2>up and assemble themselves back into a perfect mug.
<v Speaker 3>Right, you are describing the macroscopic world, the world of
<v Speaker 3>big things, mugs, cars, people, omelets, And in that world
<v Speaker 3>the arrow is absolutely undeniable. Events flow from order to disorder.
<v Speaker 3>We see effects follow their causes.
<v Speaker 2>But the sources we're looking at highlight this massive contradiction
<v Speaker 2>right out of the gate. They claim the fundamental laws
<v Speaker 2>of physics they don't care about that arrow at.
<v Speaker 3>All, And that is the reversibility paradox. This is really
<v Speaker 3>the first major hurdle we have to clear in this
<v Speaker 3>whole discussion. If you zoom in, and I mean way
<v Speaker 3>way into the atoms that are making up that coffee mug.
<v Speaker 3>Let's say you could film two of those out I'm colliding.
<v Speaker 2>Okay, just two particles bouncing off each other.
<v Speaker 3>They bounce off each other. Now play that film backward.
<v Speaker 2>It would look exactly the same. They'd just be coming
<v Speaker 2>from different directions and bounce off each other again.
<v Speaker 3>Precisely, the laws of physics don't care. Newtonian physics, Maxwell's
<v Speaker 3>equations for electromagnetism, even the Schrodinger equation in quantum mechanics, essentially,
<v Speaker 3>all the foundational equations we use to describe reality. They
<v Speaker 3>are time symmetric. They work just as well with a
<v Speaker 3>positive T moving forward or a negative T moving backward.
<v Speaker 2>Waitait, are you actually saying that if I could somehow
<v Speaker 2>reverse the velocity of every single particle in the universe
<v Speaker 2>right now, the mug would unshatter.
<v Speaker 3>In theory, yes, the math allows for it. There is
<v Speaker 3>absolutely nothing in the fundamental laws of motion that forbids
<v Speaker 3>those shards from gathering all their thermal energy, leaping up
<v Speaker 3>and fusing back into a perfect mug. The energy transfer,
<v Speaker 3>the momentum, it all works perfectly in reverse.
<v Speaker 2>That sounds completely insane. I mean, it feels wrong on
<v Speaker 2>a gut level. The the math says the mug can unshatter.
<v Speaker 2>Why doesn't it ever? Is physics just lazy? Why do
<v Speaker 2>we never ever see this happen.
<v Speaker 3>It's not laziness, it's statistics. It's just probability on an
<v Speaker 3>unimaginable scale. And this is where we have to talk
<v Speaker 3>about the physicist Ludwig Boltzmann and his concept of entropy.
<v Speaker 2>The universe tends toward disorder. Yeah, the messy room analogy.
<v Speaker 3>Exactly, But we need to go deeper than just saying
<v Speaker 3>things get messy to really get it. We need to
<v Speaker 3>talk about the difference between micro states and macro states.
<v Speaker 2>Okay, lay that out for us. I've heard the messi
<v Speaker 2>room analogy a thousand times, but give me the technical version.
<v Speaker 2>What's the real engine behind this?
<v Speaker 3>Okay, So think of your coffee mug again. The macro
<v Speaker 3>state is the description whole mug. It looks like a mug.
<v Speaker 3>You can drink from it.
<v Speaker 2>It's a mug, simple enough.
<v Speaker 3>But to achieve that specific shape, that whole mug macro state,
<v Speaker 3>the trillions and trillions of atoms inside it have to
<v Speaker 3>be arranged in a very very specific way. They have
<v Speaker 3>to be bonded here, not there. The handle atoms have
<v Speaker 3>to be with the handle atoms.
<v Speaker 2>So there are very few ways for all those atoms
<v Speaker 2>to be arranged and still be called a mug.
<v Speaker 3>Correct. A relatively low number of posttle micro states correspond
<v Speaker 3>to the macro state. Whole mug. Now, think of the
<v Speaker 3>pile of shards on the floor. That is the macro state,
<v Speaker 3>broken mug, chaos, a mess. But think about the atoms. Now,
<v Speaker 3>you can rearrange those shards in a billion different patterns
<v Speaker 3>on the floor and it still just looks like a
<v Speaker 3>pile of shards. You can move the atoms around within
<v Speaker 3>the shods, you can twist them, scatter them across the
<v Speaker 3>entire room. It's still just a broken mug.
<v Speaker 2>I see where you're going with this. There are vastly
<v Speaker 2>more ways for something to be broken than for.
<v Speaker 3>It to be whole, trillions upon trillions upon trillions more ways.
<v Speaker 3>It's not even close. So as the system evolves over time,
<v Speaker 3>as particles jiggle and move around purely by chance, it
<v Speaker 3>is just overwhelmingly, staggeringly likely to move toward the state
<v Speaker 3>that has more possibilities, more available micro states.
<v Speaker 2>So the arrow of time isn't a force. It's not
<v Speaker 2>some cosmic river pushing us forward.
<v Speaker 3>No, that's the big takeaway. It's just the law of
<v Speaker 3>large numbers playing out. We are drifting from the incredibly
<v Speaker 3>unlikely state, which we call order, to the ridiculously likely stay,
<v Speaker 3>which we call disorder. We perceived the statistical drift as
<v Speaker 3>time flowing, but really it's just things shuffling into more
<v Speaker 3>probable configurations.
<v Speaker 2>That is slightly depressing. So our entire experience of past, present,
<v Speaker 2>and future is just us losing a statistical game against
<v Speaker 2>the universe.
<v Speaker 3>Essentially, Yes, but this realization leads to the biggest, most
<v Speaker 3>profound problem in all of cosmology. If time is just
<v Speaker 3>a one way slide toward disorder, that implies we must
<v Speaker 3>have started at the very top of the slide, the
<v Speaker 3>Big Bang, the Big Bank. The sources call this the
<v Speaker 3>past hypothesis. For the arrow of time to even exist today,
<v Speaker 3>for mugs to break, and for us to remember yesterday,
<v Speaker 3>the universe at the moment of the Big Bang must
<v Speaker 3>have had an entropye so low, so incredibly ordered, that
<v Speaker 3>the odds of it happening by chance are well astronomical
<v Speaker 3>doesn't even begin to cover it.
<v Speaker 2>I saw a number in the notes attributed to the
<v Speaker 2>physicist Roger Penrose. Honestly thought it was a typo.
<v Speaker 3>It wasn't a typo. Pennos calculated the probability of our
<v Speaker 3>universe starting in such a low entropy state by random chance.
<v Speaker 3>The number is one in ten to the power of
<v Speaker 3>ten to the power of one hundred and twenty three.
<v Speaker 2>Can you even visualize a number like that? Is there
<v Speaker 2>an analogy for it?
<v Speaker 3>No, there are not enough particles in the entire known
<v Speaker 3>universe to write the zeros of that number on them.
<v Speaker 3>It is the working definition of a statistical miracle. It
<v Speaker 3>suggests that the beginning was special. It was highly tuned,
<v Speaker 3>incredibly specific.
<v Speaker 2>So the only reason I can remember yesterday, and the
<v Speaker 2>only reason eggs break and never unbreak, is because the
<v Speaker 2>Big Bang was, for some unknown reason, weirdly tidy.
<v Speaker 3>That is what some call the cosmological brute fact. We
<v Speaker 3>are surfing the wave of that initial, unexplained order. But
<v Speaker 3>here's the crucial catch. Entropy explains the direction of time,
<v Speaker 3>why we go from past to future, but it doesn't
<v Speaker 3>explain the existence of time.
<v Speaker 2>Right Okay, just because my room is getting messier doesn't
<v Speaker 2>prove that next Tuesday is already built and waiting for me.
<v Speaker 2>It just means that if I get to next Tuesday,
<v Speaker 2>my room will probably be messier than it is today exactly.
<v Speaker 3>Entropy is a signpost pointing the way, but it isn't
<v Speaker 3>the road itself. To understand the road. To really grapple
<v Speaker 3>with whether the future actually exists right now, we have
<v Speaker 3>to leave thermodynamics behind and bring in the heavy hitter.
<v Speaker 3>We have to bring in Albert Einstein.
<v Speaker 2>The presentism Killer.
<v Speaker 3>A very fitting nickname. Before Einstein, pretty much everyone, including
<v Speaker 3>Isaac Newton, thought time was this absolute universal clock TikTok TikTok,
<v Speaker 3>everywhere in the universe at the same time.
<v Speaker 2>A universal now God's wristwatch. So if it's twelve pointy
<v Speaker 2>zero pm here on Earth, it's twelve point zero pm
<v Speaker 2>on Mars, and it's twelve point zero zero pm in
<v Speaker 2>the Andromeda Galaxy, all at the exact same instant.
<v Speaker 3>Right, That feels deeply intuitive, it feels correct. But special
<v Speaker 3>relativity took that universal wristwatch and just smashed it on
<v Speaker 3>the floor. Einstein showed that now is relative. It actually
<v Speaker 3>depends on how fast you're moving.
<v Speaker 2>I always struggle to visualize this part. I get the
<v Speaker 2>time dilation thing. I travel near the speed of light
<v Speaker 2>in a spaceship. I age slower than someone on Earth.
<v Speaker 2>But this is different. This is about simultaneity that was
<v Speaker 2>happening now it is.
<v Speaker 3>It's a much weirder concept. And the best analogy on
<v Speaker 3>the sources we looked at rely on heavily, is to
<v Speaker 3>think of the universe as a loaf of bread.
<v Speaker 2>Okay, I'm listening, I like bread. How does a bakery
<v Speaker 2>item explain the nature of reality?
<v Speaker 3>Imagine the entire universe, all of space and all of time,
<v Speaker 3>is one giant loaf of sour dough. You have length
<v Speaker 3>with height, and the long way from crust to crust
<v Speaker 3>is time. One end of the loaf is the big Bang.
<v Speaker 3>At the other end is the eventual heat death of
<v Speaker 3>the universe.
<v Speaker 2>Okay, so everything that ever was or ever will be
<v Speaker 2>is already baked into this loaf. My birth, this conversation,
<v Speaker 2>the sun exploding. It's all in there.
<v Speaker 3>It's all in there now. If you and I are
<v Speaker 3>standing still relative to each other, our concept of now
<v Speaker 3>is like taking a knife and making a perfectly straight
<v Speaker 3>slice down through the loaf. Everything contained and that one
<v Speaker 3>thin slice is happening at the same time for us.
<v Speaker 2>Cut it's a single snapshot of the entire universe at
<v Speaker 2>one instant.
<v Speaker 3>But here's where Einstein's math comes in. He showed that
<v Speaker 3>if you start moving, even just walking across the room,
<v Speaker 3>your knife angles. You start to cut the loaf at
<v Speaker 3>a slant.
<v Speaker 2>A slant.
<v Speaker 3>What do you mean, Yes, you're slice of now tilts
<v Speaker 3>in the direction you're moving. Your slice tilts into what
<v Speaker 3>for me is the future part of the loaf, and
<v Speaker 3>behind you it tilts into my past.
<v Speaker 2>But if I'm just walking, the tilt must be I
<v Speaker 2>mean infinitesimally small. I walk it maybe three miles an hour.
<v Speaker 2>That can't make a real difference.
<v Speaker 3>It's microscopically immeasurably tiny. On human scales here on Earth,
<v Speaker 3>you would never ever notice. But and this is the
<v Speaker 3>absolute mind blower. Basic geometry tells us that a tiny,
<v Speaker 3>tiny angle, when extended over a massive distance, creates a huge,
<v Speaker 3>huge gap.
<v Speaker 2>Right the liver effect. If I'm holding a laser pointer
<v Speaker 2>and I tilt my wrist just a millimeter, the dot
<v Speaker 2>on the wall across the room might move ten.
<v Speaker 3>Feet exactly that. Now, replace the wall with a galaxy.
<v Speaker 3>This brings us to a thought experiment called the Andromeda paradox.
<v Speaker 3>The Andromeda galaxy is about two point five million light
<v Speaker 3>years away from us.
<v Speaker 2>It's very far down the loaf of breath.
<v Speaker 3>Very far down the loaf. Now, imagine there's an alien
<v Speaker 3>invasion fleet in Andromeda right now, in my slice of now,
<v Speaker 3>me standing still on Earth. Those aliens are in a
<v Speaker 3>council meeting debating whether or not to launch their attack
<v Speaker 3>on Earth. They haven't decided yet.
<v Speaker 2>Okay, So for you, the fleet is grounded, the war
<v Speaker 2>hasn't started. The future is open.
<v Speaker 3>Now you stand up, and start walking, just a slow
<v Speaker 3>stroll in the direction of the Andromeda galaxy. Because of
<v Speaker 3>that vast two point five million light year distance, your
<v Speaker 3>slice of reality tilts dramatically by the time it reaches
<v Speaker 3>that galaxy.
<v Speaker 2>How much of a difference does just walking make over
<v Speaker 2>that kind of distance.
<v Speaker 3>It can make a difference of days, maybe even weeks.
<v Speaker 3>So in your now, purely because of your slow walking motion,
<v Speaker 3>your slice cuts through the Andromeda part of the loaf
<v Speaker 3>days after their council meeting. For you, the fleet has
<v Speaker 3>already launched. The decision has been made. It is a
<v Speaker 3>historical fact.
<v Speaker 2>Wait. Stop, this is the part that always breaks my brain.
<v Speaker 2>We are standing right next to each other. I take
<v Speaker 2>one step forward, and for me an alien invasion has
<v Speaker 2>already begun. But for you, who's standing still, yeah, there's
<v Speaker 2>still peace.
<v Speaker 3>Correct. And to make it even weirder, if you were
<v Speaker 3>to turn around and walk away from Andromeda, your slice
<v Speaker 3>would tilt the other way into their past. For you,
<v Speaker 3>the council meeting hasn't even been proposed yet, the idea
<v Speaker 3>of invading Earth doesn't exist.
<v Speaker 2>So in this one spot right here, we have three
<v Speaker 2>completely contradictory realities, all existing at the same time the
<v Speaker 2>fleet is launching, the fleet is grounded, and the fleet
<v Speaker 2>isn't even a thought yet. How can that be right?
<v Speaker 3>And that's the trap, that's the part that kills presentism.
<v Speaker 3>If the invasion is a real historical event for you
<v Speaker 3>and we inhabit the same physical universe, it implies that
<v Speaker 3>event is sitting there in space time. It has a coordinate.
<v Speaker 3>You're just viewing it from a different angle. You can
<v Speaker 3>no longer say only the present exists, because your present
<v Speaker 3>is my future and someone else's past.
<v Speaker 2>It's like a statue. I'm looking at the front, you're
<v Speaker 2>looking at the side, but the whole statue is solid,
<v Speaker 2>it's already fully carved.
<v Speaker 3>That is the block universe in a nutshell. If you
<v Speaker 3>accept the core tenets of special relativity, you are almost
<v Speaker 3>forced logically to accept that the future is just as
<v Speaker 3>real and fixed as the past. It's all just geometry.
<v Speaker 2>That makes me feel incredibly claustrophobic. It implies the future
<v Speaker 2>is just a city down the road. We haven't driven
<v Speaker 2>there yet, but the buildings are already built, the stop
<v Speaker 2>lights are already timed, everything is in place precisely.
<v Speaker 3>This philosophical view is called eternalism. The past, the present,
<v Speaker 3>and the future are all equally real, all coexisting in
<v Speaker 3>this four dimensional block. Our feeling of now is just
<v Speaker 3>an illusion of consciousness, like a spotlight moving across the
<v Speaker 3>stage that's already been built and set.
<v Speaker 2>But hold on. If that's true, then my choice to
<v Speaker 2>interrupt you just now wasn't really a choice. It was
<v Speaker 2>It was just a pre written line in the block.
<v Speaker 3>Under a strict intern interpretation of general relativity. Yes, it
<v Speaker 3>was a fixed point in forty space time that was
<v Speaker 3>always going to happen.
<v Speaker 2>Iest I refuse to accept that there has to be
<v Speaker 2>an escape patch. We are just creatures of relativity. We
<v Speaker 2>have quantum mechanics, and quantum mechanics is famous for being
<v Speaker 2>fundamentally weird and random. Doesn't that randomness save us from
<v Speaker 2>the block?
<v Speaker 3>Ah? And this is the quantum wrench in the gears
<v Speaker 3>of the whole machine. Just when relativity convinces us that
<v Speaker 3>the future is fixed and deterministic, quantum mechanics enters the
<v Speaker 3>chat and makes everything fuzzy and uncertain.
<v Speaker 2>Again, because in the quantum world, things aren't fixed until
<v Speaker 2>you look at them, right, That's the basic idea.
<v Speaker 3>Broadly speaking, Yes, on one side, we have the Schrodinger equation,
<v Speaker 3>which describes how a quantum system like an electron in
<v Speaker 3>a cloud of possibility, evolves over time, and interestingly, the
<v Speaker 3>equation itself, the evolution of that wave of possibility is
<v Speaker 3>perfectly deterministic. It's predictable until measurement. The famous collapse of
<v Speaker 3>the wave function when you interact with the system. When
<v Speaker 3>you measure the electron to see where it is, the
<v Speaker 3>entire wave function collapses from a clide of possibilities into
<v Speaker 3>a single, definite state, and this collapse appears to be
<v Speaker 3>completely random, an irreversible.
<v Speaker 2>Okay, So if the fundamental building blocks of reality are
<v Speaker 2>essentially slipping coins every time they interact, how can the
<v Speaker 2>future possibly be fixed? Let's say I have a choice
<v Speaker 2>to eat a burger or a salad for lunch. That
<v Speaker 2>choice ultimately depends on some neuron firing in my brain,
<v Speaker 2>and that neuron firing depends on some quantum event. Isn't
<v Speaker 2>the future genuinely open?
<v Speaker 3>Then that is the great hope for those who want
<v Speaker 3>to save free will in an open future. But and
<v Speaker 3>I hate to be the bearer of bad news again,
<v Speaker 3>it depends entirely on which side of the quantum wars
<v Speaker 3>you're on the interpretation of what quantum mechanics is actually
<v Speaker 3>telling us about reality matters immensely here.
<v Speaker 2>Okay, let's break down the camps, who are the main
<v Speaker 2>combatants in these wars.
<v Speaker 3>Well, first, you have the oldest, and you know, the
<v Speaker 3>standard textbook view. It's called the Cockenhagen interpretation from Bore
<v Speaker 3>and his colleagues. It basically says, the wave function isn't
<v Speaker 3>real reality, it's just a mathematical tool we use for
<v Speaker 3>making predictions. Reality is created in the act of measurement.
<v Speaker 3>So in this view, the future is genuinely open because
<v Speaker 3>nothing is decided until the moment of collapse. The electron
<v Speaker 3>wasn't anywhere until we looked.
<v Speaker 2>Okay, so that's a point for Team free Will. The
<v Speaker 2>bloc universe is cracked, the future is unwritten perhaps.
<v Speaker 3>But then you have the second camp, the hidden variables interpretation,
<v Speaker 3>which was famously championed by physicists like David Boehm. They
<v Speaker 3>looked at that random electron and essentially said Einsteinstein's line,
<v Speaker 3>God does not play.
<v Speaker 2>Dice, meaning that the randomness is just an illusion. It's
<v Speaker 2>fake exactly.
<v Speaker 3>This view says that the particle always had a definite
<v Speaker 3>position and a definite path. We just didn't know the
<v Speaker 3>hidden variables that were guiding it. It's like a complex
<v Speaker 3>magic trick. It looks like magic to the audience because
<v Speaker 3>they can't see that the hidden wires and mirrors, but
<v Speaker 3>the magician knows exactly where the card is going to
<v Speaker 3>end up.
<v Speaker 2>So if the hidden variables interpretation is correct, and all
<v Speaker 2>that quantum weirdness is just a sign of our ignorance,
<v Speaker 2>and we're back to a fully deterministic universe, we are.
<v Speaker 3>Right back in the block universe. The future is fixed
<v Speaker 3>and determined. We just can't predict it because we don't
<v Speaker 3>have access to all the data.
<v Speaker 2>That's deeply disappointing. What about the third one, the one
<v Speaker 2>that science fiction absolutely.
<v Speaker 3>Loves, ah the Many World's interpretation. This one is utterly
<v Speaker 3>fascinating when you think about it in terms of time.
<v Speaker 3>It was proposed by Hugh Everett, and it takes the
<v Speaker 3>Schrodinger equation at its word, as the wave function never collapses.
<v Speaker 2>It keeps going. What happens at the measurement, then it branches.
<v Speaker 3>The entire universe splits. Every single possible outcome of a
<v Speaker 3>quantum measurement actually happens. So in your lunch decision, the
<v Speaker 3>universe splits in two. You eat the burger in one branch,
<v Speaker 3>and an identical copy of you eats the salad in
<v Speaker 3>another branch.
<v Speaker 2>So the universe is constantly infinitely splitting into this massive
<v Speaker 2>fractal of different realities and.
<v Speaker 3>Ever growing branching tree of timeline.
<v Speaker 2>Wait a minute, If the universe splits, then the future
<v Speaker 2>isn't a single line anymore. Correct, So does the future
<v Speaker 2>exist in the mini world's view or is it being created?
<v Speaker 3>All of them exist objectively from a god's eye view
<v Speaker 3>of this multiverse. The entire branching structure is a fixed,
<v Speaker 3>deterministic object Subjectively to you, the future feels open because
<v Speaker 3>you don't know which branch of the tree your consciousness
<v Speaker 3>is going to travel down.
<v Speaker 2>But the whole tree is already there. All the branches
<v Speaker 2>are already mapped out.
<v Speaker 3>The structure is rigid. It's a giant branching crystal that.
<v Speaker 2>Is somehow even worse than the block universe, and that
<v Speaker 2>one at least my choices are singular. This makes my
<v Speaker 2>choice feel meaningless because I end up making every choice anyway.
<v Speaker 3>In a sense, Yes, in the block universe, you play
<v Speaker 3>one pre written role in many worlds, you play every
<v Speaker 3>possible role in every possible play, But in neither interpretation
<v Speaker 3>do you actually get to write the script yourself.
<v Speaker 2>So quantum mechanics, which I thought was our great hope
<v Speaker 2>for freedom, might just be a cage made of infinite mirrors.
<v Speaker 3>It's certainly looking that way. Relativity says it's a block.
<v Speaker 3>Many world says it's a branching block. Hidden variables says
<v Speaker 3>it's a secret deterministic block. The open future of the
<v Speaker 3>Copenhagen interpretation is starting to look like the outlier.
<v Speaker 2>Is there any theory that just gets rid of the
<v Speaker 2>problem entirely, like just kills time itself?
<v Speaker 3>Ironically? Yes, And this is where things get even stranger.
<v Speaker 3>If we try to go to the absolute deepest, most
<v Speaker 3>fundamental level of reality that we can currently probe, which
<v Speaker 3>is trying to combine gravity or general relativity with quantum mechanics,
<v Speaker 3>we get an equation. It's called the Wheeler DeWitt equation.
<v Speaker 2>And this is supposed to be the master equation for
<v Speaker 2>the whole universe, a theory of everything.
<v Speaker 3>It's an attempt at it. Yes, It tries to describe
<v Speaker 3>the quantum state of the entire universe as a single object.
<v Speaker 3>But there is something profoundly strange about this equation. Something
<v Speaker 3>is missing. What's missing the variable for time?
<v Speaker 2>What do you mean it's missing?
<v Speaker 3>I mean the letter T. It just drops out of
<v Speaker 3>the map entirely the equation. It has variables for the
<v Speaker 3>geometry of space, for the matter fields within it, but
<v Speaker 3>there's no variable that corresponds to a clock. The equation
<v Speaker 3>describes the universe as frozen static, a single timeless now
<v Speaker 3>hold on.
<v Speaker 2>So at the most fundamental level of reality we can
<v Speaker 2>describe mathematically, time doesn't exist at all.
<v Speaker 3>That is one very powerful, very influential interpretation. It suggests
<v Speaker 3>that the universe as a whole quantum system just is.
<v Speaker 3>There is no when it's a vast collection of static configurations,
<v Speaker 3>all existing timelessly.
<v Speaker 2>Then why are we having this conversation? Why do things change?
<v Speaker 2>I'm definitely getting older, My coffee is getting colder. I
<v Speaker 2>can feel the passage of time in my bones. If
<v Speaker 2>the math says the universe is frozen, then the math has.
<v Speaker 3>To be wrong or our perception is wrong. This is
<v Speaker 3>what's known as the problem of change. If the fundamental
<v Speaker 3>equation of reality is timeless, how do we get the
<v Speaker 3>vivid experience of a Tuesday turning into a Wednesday. The
<v Speaker 3>leading theory to solve this is called emergence.
<v Speaker 2>Emergence, Okay, that's like how individual water molecules aren't wet,
<v Speaker 2>but if you put enough of them together, the property
<v Speaker 2>of wetness emerges.
<v Speaker 3>That's a great analogy, or closer to the analogy in
<v Speaker 3>the sources heat. An individual molecule isn't hot or cold,
<v Speaker 3>it just has a certain amount of kinetic energy. The
<v Speaker 3>concept of temperature is a statistical average of the motion
<v Speaker 3>of a huge number of molecules. It only makes sense.
<v Speaker 3>It only emerges at a macroscale.
<v Speaker 2>So time is like heat. It's not a real fundamental
<v Speaker 2>thing exactly.
<v Speaker 3>The idea is that at the most fundamental quantum level,
<v Speaker 3>there is no time. But as you zoom out and
<v Speaker 3>look at the relationships between all these different static quantum
<v Speaker 3>states of the universe, a variable emerges that looks and
<v Speaker 3>acts just like time does for us. It implies that
<v Speaker 3>time isn't a fundamental ingredient of the universe. It's a byproduct,
<v Speaker 3>a secondary effect.
<v Speaker 2>That absolutely blows my mind. We spend our entire lives
<v Speaker 2>ruled by the clock, obsessed with saving time or spending time,
<v Speaker 2>but the clock itself might just be a statistical illusion
<v Speaker 2>generated by a timeless reality.
<v Speaker 3>There is even a mention in the research of some
<v Speaker 3>modern ideas from string theory and holography, specifically something called
<v Speaker 3>the ad SCFT correspondence.
<v Speaker 2>I saw that it sounded incredibly technical, and I skipped.
<v Speaker 3>Right over it. It is, but the core idea is beautiful
<v Speaker 3>in this context. It models a universe where gravity exists
<v Speaker 3>in a higher dimensional bulk space. Think of it like
<v Speaker 3>the inside of a soda can, and then quantum fields
<v Speaker 3>exist on the lower dimensional boundary, like the label printed
<v Speaker 3>on the surface of the can.
<v Speaker 2>Okay, I think I can picture that.
<v Speaker 3>In some versions of this theory, time exists on the
<v Speaker 3>boundary on the label, but it emerges from a timeless
<v Speaker 3>bulk from the inside of the can. It just reinforces
<v Speaker 3>this idea that time might be an emergent property that
<v Speaker 3>depends on your perspective or even which dimension you're looking from.
<v Speaker 2>Okay, my brain is officially starting to melt a little bit. Yeah,
<v Speaker 2>we have a universe that's a fixed block, or it's
<v Speaker 2>a timeless, frozen quantum state. But I am sitting here,
<v Speaker 2>my heart is beating I'm feeling the seconds flow by.
<v Speaker 2>Why if physics says the block is real or the
<v Speaker 2>universe is fundamentally timeless, why is my experience so convincingly,
<v Speaker 2>so powerfully different?
<v Speaker 3>And that brings us to the final and maybe the
<v Speaker 3>hardest piece of the puzzle. This is the intersection of
<v Speaker 3>physics and neuroscience. The hard problem of consciousness meets the
<v Speaker 3>hard problem of time. If the universe is a static
<v Speaker 3>movie reel, why do we feel like we were watching
<v Speaker 3>the movie? Why aren't we just a series of static frames?
<v Speaker 2>Exactly? Why do I feel like I'm moving through the
<v Speaker 2>block universe.
<v Speaker 3>There is a concept from neuroscience called the specious present,
<v Speaker 3>and it suggests that what we call now isn't an
<v Speaker 3>infinitely thin, instantaneous point in time. It's actually a window.
<v Speaker 2>A window.
<v Speaker 3>Yes, your brain is constantly integrating sensory inputs over a
<v Speaker 3>short duration fractions of a second to maybe a few seconds.
<v Speaker 3>It takes the sight of my lips moving and the
<v Speaker 3>sound of my voice, which actually arrive at your brain
<v Speaker 3>at slightly different times, and it stitches them together into
<v Speaker 3>one coherent moment.
<v Speaker 2>So now is actually a construct. It's a smeared out delay.
<v Speaker 3>We are always living in a delayed broadcast, a processed,
<v Speaker 3>reconstructed version of reality. We live in a thick present,
<v Speaker 3>not a thin one, and this helps explain that feeling
<v Speaker 3>a flow, we aren't experiencing one static slice. We're experiencing
<v Speaker 3>a blurred integration of many slices at once.
<v Speaker 2>But that still assumes that we are moving from one
<v Speaker 2>set of slices to the next. It brings up that
<v Speaker 2>spotlight idea you mentioned earlier, the spotlight theory.
<v Speaker 3>This is the intuitive idea that our consciousness is like
<v Speaker 3>a spotlight that scans along the timeline of the block universe,
<v Speaker 3>illuminating slice after slice and making it present.
<v Speaker 2>That makes perfect sense to me. The whole movie is
<v Speaker 2>on the real but the bright light of the projector
<v Speaker 2>is what moves and creates the show.
<v Speaker 3>It does feel right, But here is the deep logical
<v Speaker 3>problem with the spotlight theory. What moves the spotlight?
<v Speaker 2>Ah, consciousness moves it. I move it.
<v Speaker 3>But if the spotlight moves, it has to move in time.
<v Speaker 3>You need a second layer of time, a hyper time
<v Speaker 3>for the spotlight to move through the regular time of
<v Speaker 3>the universe. And then what moves the spotlight in that
<v Speaker 3>second time? You need a third time to explain the second,
<v Speaker 3>it just.
<v Speaker 2>Becomes an infinite loop. It's circular logic exactly.
<v Speaker 3>It's a philosophical trap that doesn't actually explain anything.
<v Speaker 2>So if the spotlight doesn't move and the block doesn't change,
<v Speaker 2>and the whole thing is static, why do I feel
<v Speaker 2>like I have agency? Why do I feel like my
<v Speaker 2>choices matter? Why does it feel so powerfully like I
<v Speaker 2>can choose what to do next?
<v Speaker 3>This is where we have to get really careful and
<v Speaker 3>almost redefine what we mean by choice. In a block universe,
<v Speaker 3>your choice to raise your hand is a real event.
<v Speaker 3>It absolutely exists there in the block, and that event
<v Speaker 3>causes the event in the next slice where your hand
<v Speaker 3>is actually up.
<v Speaker 2>Okay, so there's still cause.
<v Speaker 3>And effect, yes, But the choice itself is a fixed,
<v Speaker 3>embedded part of the space time geometry. It's what the
<v Speaker 3>sources call a dependence relationship, not a creative act. The
<v Speaker 3>future slice depends on the present slice, but the present
<v Speaker 3>slice is already sitting there fully formed.
<v Speaker 2>That is a subtle but absolutely huge difference. My choice
<v Speaker 2>matters in that it's part of the causal chain. But
<v Speaker 2>my choice was also written.
<v Speaker 3>Written, or perhaps a better word is embedded. It's part
<v Speaker 3>of the pattern.
<v Speaker 2>But there was an interesting angle on this from information theory.
<v Speaker 2>In the notes, it says the flow of time is
<v Speaker 2>actually the flow of information. What does that mean?
<v Speaker 3>Yes, this is another way of looking at it. Think
<v Speaker 3>about it. Why do we remember the past and not the.
<v Speaker 2>Future because a past already happened?
<v Speaker 3>Or to put it in terms of entropy and information,
<v Speaker 3>the past is low entropy, information that has been organized
<v Speaker 3>and recorded in our brains. The future is high entropy.
<v Speaker 3>It's disordered, unprocessed information. From our perspective, the feeling of
<v Speaker 3>an open future is actually just a feeling of a
<v Speaker 3>profound lack of information.
<v Speaker 2>So when I say the future is open, what I'm
<v Speaker 2>really saying is I don't know what happens next.
<v Speaker 3>Precisely, if you could know the position and velocity of
<v Speaker 3>every particle in the universe, and you have a computer
<v Speaker 3>powerful enough to calculate all their interactions, the future would
<v Speaker 3>look just as rigid and recorded as the past does.
<v Speaker 3>Our powerful sense of free will is, in a very
<v Speaker 3>real way, a direct measure of our own ignorance.
<v Speaker 2>Ignorance is freedom.
<v Speaker 3>In a deterministic universe. It is the only freedom we have.
<v Speaker 2>So Okay, where does that leave us. We've crashed all
<v Speaker 2>these theories into each other. Let's try to synthesize this
<v Speaker 2>whole investigation. What's the final verdict? Do we live in
<v Speaker 2>a block, a branching tree, or just a statistical.
<v Speaker 3>Mess The verdict is that it's profoundly and fundamentally messy.
<v Speaker 3>The evidence is contradictory. You have relativity, which points very
<v Speaker 3>very strongly to the block universe the future exists.
<v Speaker 2>But then you have thermodynamics, which gives us the ero
<v Speaker 2>of time, but it has to rely on this unexplained
<v Speaker 2>miracle at the Big Bang to get started exactly.
<v Speaker 3>Then quantum mechanics comes in and offers this glimmer of
<v Speaker 3>true randomness. But then most of the popular interpretations like
<v Speaker 3>many worlds or hitty variables, snatch it right back toward
<v Speaker 3>a kind of super to terminism.
<v Speaker 2>And finally, quantum gravity, the deepest theory of all, hints
<v Speaker 2>that the whole stage, the whole concept of time, might
<v Speaker 2>just be an illusion of our perspective.
<v Speaker 3>It feels like the more we learn, the less time
<v Speaker 3>looks like that simple ticking clock on the wall. It
<v Speaker 3>feels like we're fish trying to describe water. It's so
<v Speaker 3>fundamental to our existence that we can't step outside of
<v Speaker 3>it to see what it really is.
<v Speaker 2>But there's a human takeaway here right at kind of
<v Speaker 2>silver lining in this source material. It seems to be
<v Speaker 2>that even if the future is absolutely fixed in some
<v Speaker 2>hyperdimensional space time, our experience of it is not.
<v Speaker 3>That's the key, because we can't read the script.
<v Speaker 2>We can't we are.
<v Speaker 3>Embedded inside the movie. We can't skip to the end.
<v Speaker 3>So for us living our lives from our limited perspective,
<v Speaker 3>the future is effectively open. Because we possess absolutely no
<v Speaker 3>information about it, we have no choice but to live
<v Speaker 3>as if it is open.
<v Speaker 2>So the open future might be a trick of perspective,
<v Speaker 2>a necessary illusion, but it's the trick that allows us
<v Speaker 2>to be human. If I don't make the choice to
<v Speaker 2>get out of bed in the morning, nothing happens in
<v Speaker 2>my timeline. The fact that me not getting out of
<v Speaker 2>bed was already written into the block doesn't change the
<v Speaker 2>fact that I am the one who has to go
<v Speaker 2>through the motions exactly.
<v Speaker 3>Your agency, your consciousness, is the mechanism by which the
<v Speaker 3>future becomes the past, even if the whole structure is
<v Speaker 3>static when viewed from the outside. You are the needle
<v Speaker 3>on the record player. The music is already pressed into
<v Speaker 3>the vinyl, but the song only happens because the needle
<v Speaker 3>moves along the groove.
<v Speaker 2>I like that we are the music.
<v Speaker 3>We are the music.
<v Speaker 2>I want to leave our listeners with the one final
<v Speaker 2>slightly provocative thought that came from the deeper end of
<v Speaker 2>the cosmology section we looked at. We talked a lot
<v Speaker 2>about the Big Bang being a brute fact, this incredibly
<v Speaker 2>low entropy, highly ordered start to everything.
<v Speaker 3>Yes, the initial push that got the whole arrow of
<v Speaker 3>time flying, and we.
<v Speaker 2>Talked about how that past event pushes us forward. But
<v Speaker 2>there was a fascinating suggestion in some of the research
<v Speaker 2>that the end of time, the far far future, might
<v Speaker 2>also have special boundary conditions.
<v Speaker 3>That is a wild and fascinating idea. Some cosmological models
<v Speaker 3>suggest the universe isn't just being pushed from the past,
<v Speaker 3>but it's also being pulled toward a very specific future state.
<v Speaker 3>It's like teleology, a purpose in a strange physical way. Yes,
<v Speaker 3>if the universe has to end in a certain configuration
<v Speaker 3>to satisfy the overall equations, maybe it has to settle
<v Speaker 3>into a specific vacuum state. Or end in a big
<v Speaker 3>crunch that mirrors the Big Bang. Then the future is
<v Speaker 3>constraining the present just as much as the past is.
<v Speaker 2>Imagine that for a second. We always always think of
<v Speaker 2>the past pushing us forward, but maybe the future is
<v Speaker 2>pulling us in. Maybe the script for the universe is
<v Speaker 2>written from both ends and we are just living out
<v Speaker 2>the part where they meet in the middle.
<v Speaker 3>It completely turns causality on its head. It would suggest
<v Speaker 3>that the choice you make today might, in some incomprehensible way,
<v Speaker 3>be determined by where the universe needs to be in
<v Speaker 3>a trillion years.
<v Speaker 2>And on that completely mind bending note, I think we
<v Speaker 2>are officially at a time, whether it exists or not,
<v Speaker 2>I suppose we are. This has been a heavy investigation.
<v Speaker 2>We broke the mug, we sliced the loaf of bread,
<v Speaker 2>and we split the universe into infinite copies. Thanks for
<v Speaker 2>listening to us. Try to put it all back together.
<v Speaker 3>And keep questioning the clock.
<v Speaker 2>We'll see you in the future, or I guess we'll
<v Speaker 2>see you the next slice.