Speaker 1: Welcome to the quark Side Quantum Physics podcast, an exploration
Speaker 1: of the fundamental structure of reality where quantum laws govern matter, energy,
Speaker 1: and information. Here, uncertainty is a feature, not a flaw,
Speaker 1: and understanding begins at the smallest scales.
Speaker 2: What if the universe has like a strict built in
Speaker 2: speed limit and I am not talking about the speed
Speaker 2: of light here, or you know, how fast a physical
Speaker 2: object can fly through the vacuum of space. What if
Speaker 2: there is a fundamental, unbreakable speed limit for how fast
Speaker 2: information itself can be shared from one point in reality
Speaker 2: to another.
Speaker 3: Yeah, when you start looking at the fabric of reality
Speaker 3: through that lens, you realize pretty quickly that space and
Speaker 3: time aren't just well, they aren't just an empty stage
Speaker 3: where physics happens.
Speaker 2: Right.
Speaker 3: The universe actively regulates the flow of states and interactions,
Speaker 3: and like any regulating mechanism, it has an absolute maximum
Speaker 3: capacity for how fast it can.
Speaker 2: Evolve, which is just wild to think about. And you know,
Speaker 2: for the longest time this is kind of an open question. Yeah,
Speaker 2: But in twenty twenty six, theoretical physicists Emit Victrm and
Speaker 2: Victor Galitski at the University of Maryland working alongside mathematician
Speaker 2: Laura Show, they published this groundbreaking proof in Physical Review Letters.
Speaker 2: They really did. They mathematically proved that there is a
Speaker 2: universal minimum time required for quantum information to spread through
Speaker 2: a system. So think about it like this. Imagine you
Speaker 2: have a massive crystal clear tank of water, uh huh,
Speaker 2: and you take a single dropper filled with glowing neon
Speaker 2: green dye and you'll let one single drop hit the surface, right, So.
Speaker 3: The physical diffusion of that dye is bound by fluid dynamics.
Speaker 3: You watch the ten rolls of color slowly reach out,
Speaker 3: interacting with the surrounding molecules exactly.
Speaker 2: But the question is what is the absolute minimum time
Speaker 2: it takes for that exact color information, that greenness to
Speaker 2: spread to every single molecule of water in that massive tank.
Speaker 2: But of course, in our conversation today, we aren't talking
Speaker 2: about water and die. We are talking about the quantum
Speaker 2: fabric of the universe itself, like how fast does reality
Speaker 2: scramble and share information at the subatomic level.
Speaker 3: And finding the answer to that question, I mean it
Speaker 3: forces us to rethink everything from the architecture of future
Speaker 3: quantum supercomputers to the deepest origins of chaos. In nature,
Speaker 3: because if you can definitively prove a speed limit on
Speaker 3: how fast quantum information can delocalize, you are essentially establishing
Speaker 3: the hard boundaries of what is physically possible in our universe.
Speaker 2: Okay, so to really wrap our heads around how quantum
Speaker 2: information spreads today, we have to kind of rewind a
Speaker 2: bit and look at the most extreme environments in the
Speaker 2: entire universe. Oh yeah, the places where information gets trapped.
Speaker 2: We need to talk about black holes.
Speaker 3: Yeah, black holes are the perfect starting point. For a
Speaker 3: long time, you know, the classical view of a black
Speaker 3: hole was just a perfect cosmic vacuum cleaner. Nothing escapes,
Speaker 3: not even.
Speaker 2: Light, right, just a bottomless pit exactly.
Speaker 3: But then in nineteen seventy four, Stephen Hawking proposed something radical.
Speaker 3: He demonstrated that black holes actually emit thermal radiation, which
Speaker 3: is what we now call Hawking radiation. In the moment
Speaker 3: you introduce thermal radiation, you introduce thermodynamic properties. They have
Speaker 3: a temperature and crucially.
Speaker 2: They have entropy, right, And in thermodynamics, entropy is usually
Speaker 2: described as a measure of disorder. But when we transition
Speaker 2: into information theory, entropy is effectively a measure of information itself. Yes, precisely,
Speaker 2: the more entropy as system has, the more hidden information
Speaker 2: is required to fully describe its microscopic state. And Hawking
Speaker 2: found that a black hole's entropy is directly proportional to
Speaker 2: its surface area.
Speaker 3: The event horizon. Yeah, the surface of the black hole
Speaker 3: effectively acts like a vast storage medium because entropy measures information,
Speaker 3: that surface area holds a finite quantifiable number of quibbits.
Speaker 2: Wait, let me make sure I'm following you. So a
Speaker 2: black hole is basically a giant cosmic car drive storing
Speaker 2: quibits on its surface, and its temperature dictates how those
Speaker 2: quibits evolve.
Speaker 3: Yes, what's fascinating here is that you really have to
Speaker 3: stop thinking of the event horizon as just a line
Speaker 3: in space. Right in the framework we are discussing, the
Speaker 3: horizon is a dynamic quantum membrane. The information of everything
Speaker 3: that has ever fallen into that black hole doesn't just vanish.
Speaker 3: Its quantum state gets smeared across the surface in the
Speaker 3: form of entangled.
Speaker 2: Quibts smeared across the surface. Okay, Yeah.
Speaker 3: And regarding temperature, well, temperature in any physical system is
Speaker 3: a measure of kinetic energy, right of agitation. Sure, on
Speaker 3: the surface of a black hole, the temperature literally governs
Speaker 3: the thermal jitter of those entangled states. It dictates how
Speaker 3: violently and how quickly those informational bits interact, shuffle, and
Speaker 3: evolve with one another over time.
Speaker 2: So the black hole's heat is basically the engine driving
Speaker 2: the interaction of the data stored on its surface exactly. Well,
Speaker 2: if a black hole is essentially a giant system storing
Speaker 2: and shuffling all this quantum information, the natural next question
Speaker 2: is like, how does that information actually move around? How
Speaker 2: does a change in one single state ripple out to
Speaker 2: the rest of the system. Right, Okay, let's unpack this
Speaker 2: because I like to think about it like a massive,
Speaker 2: highly choreographed dance at a crowded party.
Speaker 3: Oh, I like where you're going to this?
Speaker 2: Yeah, So instead of just whispering a juicy rumor to
Speaker 2: one person, imagine one person in the center of the
Speaker 2: room starts doing a very specific complex dance move. For
Speaker 2: the information or the dance to spread, they have to
Speaker 2: physically lock arms with the people next to them and
Speaker 2: pull them into the.
Speaker 3: Rhythm, right, transferring the state exactly.
Speaker 2: Then those people lock arms with the next group. The
Speaker 2: speed limit we are talking about is the absolute minimum
Speaker 2: amount of time it takes before every single person in
Speaker 2: that massive room is perfectly synchronized in the dance.
Speaker 3: Yes, and in the quantum world. Physicists call this process scrambling. Scrambling, Yeah,
Speaker 3: Scrambling is the process of generating massive multipartit entanglement. You
Speaker 3: take the information from one localized particle and you delocalize it.
Speaker 3: It spreads out across the entire system until you can
Speaker 3: no longer read that original piece of information by just
Speaker 3: looking at the original particle. You would have to measure
Speaker 3: the entire system globally to recover it well.
Speaker 2: And scientist has been trying to figure out the exact
Speaker 2: speed of that delocalization for a long time.
Speaker 3: Oh, absolutely decades.
Speaker 2: Because in two thousand and eight, theoretical physicists Yasuhiro Sakino
Speaker 2: and Leonard Suskind took Hawking's black hole idea further. They
Speaker 2: formulated a conjecture. They did. They proposed that systems of
Speaker 2: quibots at a certain temperature must take a minimum amount
Speaker 2: of time to share information with each other. This time
Speaker 2: delay depends entirely on two things, right, the number of
Speaker 2: particles in the system and the temperature of this system.
Speaker 3: Exactly, Because heat is energy and energy drives interaction. A
Speaker 3: hotter system, like a black hole, with a higher temperature
Speaker 3: has more energy available to drive those quantum interactions.
Speaker 2: So it's scrambled the information faster. Yes, exactly.
Speaker 3: But the problem Sekino and Suskan ran into was that
Speaker 3: this was well merely a conjecture. It was a highly educated,
Speaker 3: mathematically sound guess based on the properties of black holes.
Speaker 3: For years after two thousand and eight, theorists studied the
Speaker 3: scrambling process, but finding a mathematically exact, rigorously proven speed
Speaker 3: limit seemed completely out of reach.
Speaker 2: Just too complicated.
Speaker 3: Yeah, the math governing how these highly entangled systems evolve
Speaker 3: was just too complex to pin down into a universal rule.
Speaker 2: Well, here's where it gets really interesting but also a
Speaker 2: little brain bending. You're saying that just because a system
Speaker 2: has specific energy levels, the universe essentially forces a lag
Speaker 2: time on how fast it can physically change its state.
Speaker 3: Yes, and this is exactly where the twenty twenty six
Speaker 3: breakthrough by Victim and Glitzki comes into play. To finally
Speaker 3: prove this speed limit, they didn't just invent abstract new physics.
Speaker 3: They went back to One of the most famous foundational
Speaker 3: rules in all.
Speaker 2: Of quantum caamare the energy time uncertainty principle.
Speaker 3: Precisely, this is where we get to the core mechanism.
Speaker 3: The energy time uncertainty principle states that the more precisely
Speaker 3: you know a quantum system's energy, the less you can
Speaker 3: know about the exact time it takes for that system
Speaker 3: to evolve into a distinguishably different state.
Speaker 2: But wait, I'm struggling with the mechanism here a bit.
Speaker 2: I understand the statement, But why does knowing the energy
Speaker 2: of a system force a physical lag time on its
Speaker 2: state change? Like why can't a quantum system just instantaneously
Speaker 2: snap from state A to state b? Ah?
Speaker 3: Because quantum states are governed by wave functions, and wave
Speaker 3: functions oscillate. Think of a quantum state like a vibrating
Speaker 3: guitar string. Okay, the energy of that state determines the
Speaker 3: frequency of the vibration. For a quantum system to evolve
Speaker 3: into a completely distinct, non overlapping state, which physicists call
Speaker 3: an orthogonal state, the wave function has to physically shift
Speaker 3: its phase.
Speaker 2: Oh.
Speaker 3: I see, if the energy is fixed and finite, the
Speaker 3: frequency is finite. Therefore, it physically takes a minimum duration
Speaker 3: of time for that wave to oscillate far enough to
Speaker 3: become a newly distinguishable state. The universe simply doesn't have
Speaker 3: the energy available to turn the dial any faster.
Speaker 2: Oh so, it's not like a traffic camera catching you
Speaker 2: going too fast. It's a physical governor on an engine.
Speaker 2: The system's energy strictly caps its maximum RPMs.
Speaker 3: That is a much more accurate metaphor action.
Speaker 2: So, because quantum systems have these well defined energy levels,
Speaker 2: the universe mathematically prevents them from changing faster than that
Speaker 2: wave function could physically shift.
Speaker 3: Exactly, there is an absolute floor to how fast a
Speaker 3: quantum state can evolve. Vikim and Glitski realized that this
Speaker 3: built in wave function lag could be the key to
Speaker 3: understanding the scrambling speed limit makes sense. In twenty twenty four,
Speaker 3: they started applying the energy time uncertainty principle to the
Speaker 3: entire process of quantum scrambling. But they hit a massive roadblock.
Speaker 2: Let me guess, the standard uncertainty principle doesn't account for
Speaker 2: complex thermodynamic environments, right.
Speaker 3: It was missing a crucial ingredient, the temperature. Yes, they
Speaker 3: knew from Sekino and Suskin's black hole theories that temperature
Speaker 3: was the ultimate driving force behind how fast quddits interact
Speaker 3: in a large system. Right, the heat drives the dance exactly,
Speaker 3: but incorporating temperature into the rigid mathematics of the energy
Speaker 3: time uncertainty principle was incredibly difficult. In a thermal system,
Speaker 3: you aren't just dealing with one distinct energy level. You
Speaker 3: are dealing with a thermal density.
Speaker 2: Matrix, which is what exactly.
Speaker 3: It's a statistical mixture of many possible states wildly interacting.
Speaker 3: They needed to find a way to introduce a temperature
Speaker 3: dependence and use rigorous mathematical bounds to translate that chaos
Speaker 3: into a definitive, unbreakable speed limit.
Speaker 2: And that brings us to the final piece of the
Speaker 2: puzzle and the twenty twenty six breakthrough. Vicrum and Glitzky
Speaker 2: teamed up with mathematician Laura Show, and it turns out
Speaker 2: bringing a pure mathematician to a theoretical physics fight is
Speaker 2: exactly what was needed to bridge the gap.
Speaker 3: It really was, Show helped them navigate the mattchmadical complexities
Speaker 3: of that thermal density matrix. Nice Together, they introduced rigorous
Speaker 3: mathematical bounds on the eigenvalues of the system, and the
Speaker 3: Trio successfully proved a clear, indisputable mathematical relationship. They prove
Speaker 3: that the absolute minimum time required to scramble a quantum
Speaker 3: system is proportional to the final entropy of that system
Speaker 3: and inversely proportional to its initial temperature.
Speaker 2: Okay, let's make sure we totally grasp the mechanics of
Speaker 2: that equation. Yeah, inversely proportional to the initial temperature means
Speaker 2: the hotter the system, the shorter the minimum time required.
Speaker 2: The extra thermal energy literally speeds up the wave function
Speaker 2: oscillations we talked about earlier.
Speaker 3: But importantly, it is still a hard limit, it never
Speaker 3: becomes instantaneous, and on the flip side, it is directly
Speaker 3: proportional to the final entropy. Entropy again being the measure
Speaker 3: of hidden information. The larger the amount of information that
Speaker 3: needs to be scrambled, the longer the universe forces the
Speaker 3: system to wait before the process is complete.
Speaker 2: So they basically wrote the exact formula for the universe's
Speaker 2: ultimate engine governor. They did. They proved exactly how fast
Speaker 2: the quantum dance can synchronize based on how hot the
Speaker 2: room is and how much information is being passed around.
Speaker 3: If we connect this to the bigger picture, the magnitude
Speaker 3: of this mathematical proof cannot be overstated. This is a
Speaker 3: massive paradigm shift, really, how so? Previously the scientific expectation
Speaker 3: was that these kinds of strict, mathematically rigorous speed limits
Speaker 3: only existed in highly idealized, small scale systems. Systems where
Speaker 3: you only have a handful of isolated particles interacting in
Speaker 3: a perfectly controlled vacuum.
Speaker 2: Right, the kind of sterile environment you build in a
Speaker 2: multimillion dollar laboratory exactly.
Speaker 3: But what vikrm Glitski and show proved is that this
Speaker 3: exact entropy and temperature dependent speed limit exists in every
Speaker 3: single quantum system. It is a universal law of nature.
Speaker 2: Wow.
Speaker 3: Whether you are looking at a localized laboratory experiment, a
Speaker 3: sprawling commercial quantum computer, or a super massive black hole
Speaker 3: at the center of galaxy, the spreading of information is
Speaker 3: bound by this exact same mathematical limit.
Speaker 2: Okay, so what does this all mean? Like we have
Speaker 2: the math, we know the universe's ultimate quantum speed limit.
Speaker 2: Why does this matter for the future of human technology
Speaker 2: or just for how we understand our own reality?
Speaker 3: The real world implications are staggering, especially for the immediate
Speaker 3: future of human engineering. First, let's look at quantum computing.
Speaker 3: We are currently in a global race to build massive
Speaker 3: error corrected quantum computers.
Speaker 2: Right everyone's trying to build one.
Speaker 3: And these architectures rely on complex networks of millions of
Speaker 3: interacting quivids to make them actually work, to control the
Speaker 3: flow of data without it dissolving into thermal noise. We
Speaker 3: have to deeply understand the emergence of thermal behavior in
Speaker 3: these systems.
Speaker 2: Because a quantum computer isn't just a math machine, it's
Speaker 2: a physical thermal environment.
Speaker 3: Yes, and this universal speed limit gives engineers the exact
Speaker 3: boundary conditions for how fast they can process information within
Speaker 3: that environment. It tells us the hard mathematical sealing of
Speaker 3: computational power in the universe.
Speaker 2: That's incredible.
Speaker 3: Any process related to scrambling fundamentally settles only after this
Speaker 3: minimum time. You cannot engineer a processor faster than the
Speaker 3: laws of physics will allow those wave functions to shift.
Speaker 2: You just cannot beat the clock.
Speaker 3: You really can't. And secondly, this gives us profound new
Speaker 3: tools to explore the origins of chaos. Chaos and physics
Speaker 3: isn't just pure randomness. It is the study of how
Speaker 3: tiny microscopic changes in initial conditions explode into massively different macroscopic.
Speaker 2: Outcomes, the butterfly effect basically right.
Speaker 3: By understanding exactly how fast information spreads and delocalizes at
Speaker 3: the quantum level, we can trace the exact roots of
Speaker 3: chaotic systems as they transition from quantum rules to classical reality.
Speaker 2: And fleshing out those concrete bounds also serveles back to
Speaker 2: where we started black holes.
Speaker 3: Oh, definitely.
Speaker 2: If we can apply this universal math to everything, we
Speaker 2: can finally start to truly decode what is happening on
Speaker 2: this of those cosmic hard drives. Understanding exactly how hawking
Speaker 2: radiation encodes the information of the stars that.
Speaker 3: Collapse to form them absolutely.
Speaker 2: But I want to ask you about something even wilder.
Speaker 2: We've seen headlines for years about scientists teleporting the quantum
Speaker 2: state of a photon from one lab to another using entanglement. Yes,
Speaker 2: does this mean that if we ever master practical quantum
Speaker 2: teleportation on a macroscopic scale, there is a physical lag
Speaker 2: time built into the laws of physics that we can
Speaker 2: never ever bypass.
Speaker 3: It absolutely means that quantum teleportation relies on entanglement, and
Speaker 3: creating that entanglement across the system requires scrambling the actual
Speaker 3: transfer of state. The delocalizing and reassembling of that quantum
Speaker 3: information is permanently bottlenecked by the initial temperature of the
Speaker 3: system and the final entropy. Even if we perfectly untangle
Speaker 3: all the engineering challenges of a teleportation device, there is
Speaker 3: a built in lag that the universe mathematically insists upon
Speaker 3: that is.
Speaker 2: Just mind blowing. It really makes you realize that the
Speaker 2: universe isn't just a physical space containing objects. It's an
Speaker 2: active regulating medium that strictly controls the flow and evolution
Speaker 2: of reality.
Speaker 3: Yeah, the universe has a rhythm and it enforces a
Speaker 3: strict maximum processing capacity on everything inside of it.
Speaker 2: Well, let's bring this all together for everyone listening. We
Speaker 2: started this journey staring into the abyss of a black hole,
Speaker 2: realizing that it isn't empty, but rather its surface acts
Speaker 2: as a storage medium holding information as complex quantum states.
Speaker 2: We looked at how that information scrambles and spreads, requiring
Speaker 2: the physical shifting of wave functions, and we saw how
Speaker 2: a decade's old puzzle was finally solved by applying the
Speaker 2: energy time uncertainty principle to thermal systems, proving that temperature
Speaker 2: and entropy dictate a universal, unbreakable speed limit. Reality literally
Speaker 2: has a maximum speed at which it can physically process changes.
Speaker 3: This raises an important question. We've talked about how the
Speaker 3: speed limit applies to black holes, quantum computers, and modern teleportation,
Speaker 3: but consider the absolute beginning of our universe oho in
Speaker 3: the first fractions of a second during the Big Bang,
Speaker 3: the universe was an infinitely dense, infinitely hot singularity. If
Speaker 3: every quantum system has a fundamental, mathematically proven speed limit
Speaker 3: on how fast its information can scramble, dictated by temperature
Speaker 3: and entropy, how did the entire early universe communicate and
Speaker 3: synchronize its temperature so perfectly before rapid expansion tore it apart.
Speaker 2: That's a huge question.
Speaker 3: Are the echoes of this quantum speed limit stamped directly
Speaker 3: into the cosmic microwave background, hiding the true timeline of
Speaker 3: the dawn of time?
Speaker 2: Now that is a thought that will completely change how
Speaker 2: you look at the night sky the next time you
Speaker 2: drop a little dye into a glass of water and
Speaker 2: watch the color slowly reach out to one another. Just
Speaker 2: remember you're watching the underlying laws of the universe calculate
Speaker 2: the spread of information at the absolute fastest speed it
Speaker 2: physically can. Thank you so much for joining us on
Speaker 2: this exploration of the universe's hidden rules. It has been
Speaker 2: an absolute thrill to unpack the mechanics of reality with you.
Speaker 2: Stay curious, keep questioning the world around you, and we
Speaker 2: will catch you next time.