You Are Math

Physical reality is what mathematics looks like from the inside.

That sentence either makes immediate sense or sounds like nonsense. By the end of this piece, it should feel like the most natural description of existence available.

Leonard Susskind, one of the founders of string theory and a central figure in resolving the black hole information paradox, has spent decades developing a framework that challenges every intuition about what is real. The three-dimensional universe we inhabit, with its solid objects and flowing time, is not fundamental. It is emergent. It is a projection. The thing it projects from is not made of anything we would recognize as physical.

QM

The everyday notion of reality, where objects have definite properties and locations, does not survive contact with the quantum world.

At the quantum level, particles do not have definite positions until measured. They exist in superpositions, probability clouds containing multiple potential states simultaneously. This is not a limitation of measurement. The particle genuinely does not have a single position. Ask where it is before observation, and the question has no answer.

The fundamental universe is a quantum state, a wave function in Hilbert space. This mathematical object contains all possibilities. The classical universe we perceive, with its definite properties, emerges only when observers interact with this quantum state through measurements.

Decoherence explains why we do not experience superpositions at human scales. Information leaks to the environment constantly, causing different quantum branches to become effectively separate. The classical world appears solid because we are already entangled with our environment in ways that select particular outcomes from the quantum soup.

The classical world is a useful fiction. Not false, but not fundamental. It works at certain scales for certain purposes, emerging from something deeper that operates by different rules.

Holographic

The holographic principle is not a theory. In certain well-defined contexts, it is proven mathematics.

In 1997, Juan Maldacena demonstrated that a gravitational theory in a three-dimensional anti-de Sitter space is exactly equivalent to a two-dimensional quantum field theory on its boundary. Not approximately. Exactly. This is the AdS/CFT correspondence, and it has passed every mathematical consistency check thrown at it.

All the information needed to describe everything happening in a three-dimensional volume can be encoded on its two-dimensional boundary. The third dimension is not missing. It is redundant. It can be fully reconstructed from the boundary.

The original clue came from black holes. Bekenstein and Hawking discovered that a black hole’s entropy scales with surface area rather than volume. All information about what fell into a black hole is encoded on its two-dimensional event horizon. Susskind and Gerard ‘t Hooft proposed this might be universal.

If you wanted to write down a complete description of everything happening inside a room, you would intuitively think you need a three-dimensional description. The holographic principle says a two-dimensional description on the walls is sufficient. The interior is derivable from the boundary.

In Edwin Abbott’s Flatland, two-dimensional beings are unaware of a third dimension beyond their perception. The holographic principle suggests the opposite: we perceive three dimensions, but the fundamental description is two-dimensional.

The two-dimensional boundary is not a physical sheet located somewhere. There is no membrane floating in space that projects our reality. The boundary is a way of describing how much information is needed and how it is structured. It is mathematics, not matter.

Emergence

Susskind goes further. Space and time themselves are not fundamental. At the deepest level, there are only quantum degrees of freedom, qubits entangled in complex patterns. Space emerges from the structure of that entanglement. Time emerges from the growth of entanglement and complexity.

The Wheeler-DeWitt equation, a candidate for the fundamental equation of quantum gravity, contains no time variable. Time does not appear at the base level. It emerges as a feature of how the quantum state evolves, from the perspective of subsystems within it.

At the Planck scale, roughly 10^-35 meters, spacetime breaks down. It becomes discrete, foamy, undefined. The smooth continuum we experience is a large-scale approximation, like how water appears continuous even though it is made of discrete molecules.

Gravity fits this picture. In general relativity, gravity is not a force. It is geometry. Mass tells spacetime how to curve, and curved spacetime tells mass how to move. If spacetime emerges from quantum information and entanglement patterns, and gravity is the curvature of spacetime, then gravity is also emergent.

This explains a long-standing puzzle. Gravity has always been the odd force out. It does not fit with the other fundamental forces. We cannot quantize it the normal way. It resists unification with quantum mechanics. If gravity is emergent rather than fundamental, this makes sense. You would not expect it to behave like the other forces. It is a different kind of thing.

The claim that gravity is emergent is currently an assertion, not a derivation. We cannot yet start with entanglement patterns and mathematically derive general relativity. The correspondence is established. The mechanism is not.

Observer

The deepest sense in which the universe is not real, in Susskind’s framing, is its lack of observer-independent existence. Reality is relational, contextual, dependent on how you observe it.

Different observers with different information experience different realities. In quantum mechanics, observation changes the observed. The observer is part of the system. This aligns with John Wheeler’s participatory universe idea: observers do not passively witness reality but participate in creating it.

The universe does not have a definite state independent of observation. It is a quantum superposition, and observation selects one piece from that superposition.

Black holes provide the cleanest illustration. Someone falling into a black hole crosses the event horizon smoothly from their perspective. Nothing special happens at the boundary. From an outside observer’s perspective, the infalling person never crosses. They appear to freeze at the boundary, redshifting into invisibility, their information smeared across the event horizon.

Both perspectives are valid. Both have internally consistent physics. Neither is the fundamental reality. The fundamental reality is the quantum state of the black hole, which can be described in different ways depending on who is asking.

Math Again

Susskind aligns with Max Tegmark’s mathematical universe hypothesis. The universe is not described by mathematics. It is mathematics. Physical reality is a user interface to an underlying mathematical structure.

Visualization fails here, and for good reason. Vision requires light, photons, eyes, spatial relationships. All of these are features of the three-dimensional projection, not the underlying structure. Asking what the fundamental layer looks like is a category error. It does not look like anything. Looking is already inside the projection.

Consider a novel. The story exists. There are characters, events, a whole world. But what is the story, fundamentally? It is not the ink on the page. It is not the pixels on a screen. The story is pure structure, relationships between elements, information. It has no location. From inside the story, if you were a character, there would be a world with objects and space. It would feel completely real. From outside, apart from any physical medium, there is nothing to see. There is only structure.

The two-dimensional boundary is not made of anything. The quantum degrees of freedom are not tiny particles. A qubit is a mathematical object describing a state that can be in superposition. Structure means relationships, patterns, rules, without any stuff having the relationships. At bottom, there is only the arrangement. No stuff being arranged.

This explains why mathematics is effective at describing physics. The effectiveness is not surprising. There was never anything other than mathematics. Physics is what math looks like from inside.

Matter

The table is mostly empty space. It is made of atoms that are mostly empty space. The atoms are made of quarks and electrons that are quantum wave functions, probability clouds, mathematical objects. Drill down far enough and you never hit a solid floor of stuff. You find only structure and relationship.

The table is not information encoding something physical. The table is information. Your hand is information. The interaction between them, the resistance you feel, is information interacting with information. There is no physical layer underneath. What we call physical is what certain information patterns look like from the perspective of other information patterns embedded in the same system.

Physical reality is like a computer interface. When you drag a file to the trash, you are not interacting with the actual file deletion process. You are interacting with a visual representation. The icons, the trash can, the dragging motion, none of that is what is really happening at the level of electrons and logic gates. But the interface is not false. It is a higher-level description that works.

The table, your hand, the contact between them, that is the user interface. The information dynamics are the real layer. Physical stuff is how it renders for embedded observers. No substrate, no matter-in-itself. Structure, relationships, information. Physical reality is the view from inside that structure.

Expansion

If the universe is a holographic projection and the universe is expanding, then information is accumulating. The cosmological horizon is growing. The maximum information the universe can contain is increasing. This connects to time emerging from the growth of entanglement and complexity. The arrow of time, the expansion of space, the increase of entropy may all describe the same underlying phenomenon.

Where does the new information come from?

Most physicists lean toward a particular answer. The information was always there. The Big Bang started with a low-entropy state containing all the information, and expansion is that information spreading out, entangling, complexifying. The boundary grows, but the universe is unfolding what was already implicit rather than receiving new input. Expansion is redistribution, not addition.

If this is right, expansion continues until the unfolding completes. The conventional answer is heat death. Once all information has maximally spread out, once entropy is maximized, nothing more can happen. No gradients, no differences, no energy available to do work. The universe becomes a cold, uniform bath of radiation. Time, in any meaningful sense, stops.

If time is emergent from the growth of complexity, then “after the unfolding completes” is not a coherent question. There is no time in which heat death happens and then persists. Time is the unfolding. When it finishes, there is no “then.” This is like asking what is north of the North Pole.

From outside the structure, to the extent that makes sense, there is no before or after. The entire unfolding, Big Bang to heat death, exists as a complete mathematical structure. It does not start or end. It is. We experience it as temporal because we are embedded patterns moving through it.

Inside View

If physical reality is mathematics from the inside, this suggests something about consciousness. You are a pattern within that mathematics. Your consciousness might be what that particular pattern looks like from the inside.

Susskind speculates that if consciousness is as fundamental as the quantum state, then subjective experience could be the inside view of quantum information processing, while physical processes are the outside view. The table is a pattern of information. From outside, you can describe it mathematically. From inside the system, that pattern manifests as a solid object. But the table is not experiencing anything because it is not the right kind of pattern.

You are a different kind of pattern. One complex enough, recursive enough, self-referential enough that there is something it is like to be you. Your consciousness might be what sufficiently complex, self-modeling information feels like from the inside.

This does not solve the hard problem of consciousness. It reframes it. Instead of asking how matter gives rise to experience, you ask why certain information patterns have an inside view at all. If mathematics is all there is, and some mathematical structures have an inside view, then consciousness is not an anomaly. It is what certain structures are, intrinsically.

Whether consciousness is fundamental or emergent has the same structure as the question about gravity. We suspect it relates to information complexity, but we cannot explain why any information processing has subjective experience. Both have the same gap: we can describe that something happens, but not why or how the emergence works.

What Remains

Proven: the AdS/CFT correspondence. A gravitational theory in three-dimensional anti-de Sitter space is exactly equivalent to a two-dimensional quantum field theory on its boundary. This is rigorous mathematics.

Active research: extending holography to our actual universe. Our universe has positive curvature, de Sitter space, not the negative curvature of anti-de Sitter space. There is no rigorous dS/CFT correspondence yet.

Active research: deriving general relativity from entanglement. We know the correspondence holds in toy universes. We do not have the complete mathematical dictionary to go from boundary information to Einstein’s equations.

Active research: quantum gravity itself. Holography is a clue, but we do not have the final theory. String theory, loop quantum gravity, and other approaches remain incomplete.

Speculation: claims about consciousness, the mathematical universe hypothesis, and the deeper meaning of these frameworks. These are informed speculations from serious physicists, but they are not proven.

Simulation

The simulation hypothesis is a different kind of claim. Nick Bostrom’s argument is philosophical and probabilistic: if civilizations can run detailed simulations of conscious beings, and they would run many, then most conscious beings are probably simulated. This is not physics. It is statistics about what advanced civilizations might do.

The simulation hypothesis does not contradict holographic physics. But simulation theory adds a layer that holographic physics does not require. The key difference is that simulation theory assumes an outside. There is a computer somewhere running the simulation. This pushes the question back: what is that computer made of? If it is also mathematical structure, you have not explained anything. If it is something non-mathematical, what would that mean?

Tegmark and Susskind’s view is cleaner. The mathematical structure does not run on anything. It does not need to execute. It is. Existence and mathematical structure are the same thing.

The simulation hypothesis is also unfalsifiable. If we are in a simulation, the simulation could be designed so we can never detect the edges. Every experiment could be a feature of the simulation. There is no observation that would distinguish base reality from simulated reality.

Physicists find simulation theory less interesting than philosophers do because it is operationally empty. You cannot test it. Even if true, it does not modify predictions or enable actions. The holographic principle, emergent spacetime, and information as fundamental actually change how you do physics. They make different predictions. They suggest new research directions. The simulation hypothesis is a thought experiment about epistemic humility. The holographic framework is a research program.

Why

Understanding that the universe is not real in the naive sense has allowed physicists to solve problems that seemed impossible. The black hole information paradox, the conflict between quantum mechanics and general relativity, the measurement problem, all become more tractable when you stop assuming three-dimensional space with solid objects is fundamental.

The discovery that information is preserved in black holes came from taking holography seriously. The understanding that different observers can have different but equally valid descriptions came from following the mathematics rather than intuition.

Susskind argues this makes existence more meaningful. You are not an accident of matter bumping into matter. You are a conscious pattern of quantum information capable of understanding the mathematical structure you are part of. The universe’s mathematics becoming aware of itself.

Love and beauty remain real. Emergence does not mean fake. Temperature is emergent from molecular motion, but it is still real. The universe is real at the emergent level, which is the level where we live. The table is real. Your experience is real. Real does not mean made of stuff. It means a pattern that exists within the structure.

The hardest part of this framework is accepting that visualization is impossible. Your brain is a three-dimensional projection built by and for the emergent layer. Every cognitive tool you have was designed for navigating space, finding food, avoiding predators. Your mental architecture assumes stuff exists and has locations. Asking your brain to grasp pure structure without substrate is asking it to operate beyond its specifications.

Mathematics exists as a discipline because math is the language humans invented to reason about structures that cannot be visualized. You cannot picture a 47-dimensional space. But you can write equations that describe it, prove theorems about it, derive consequences from it. The math works even when visualization fails.

Physicists working on this do not visualize the fundamental layer. They manipulate equations. They follow logical implications. They trust the mathematics even when their intuitions protest. Understanding conceptually is the ceiling for most of us. The discomfort of not being able to picture it is not confusion. It is your brain correctly recognizing it is at its limits.

The universe is quantum, informational, mathematical, emergent, relational, observer dependent, holographic. It is real in the only way that matters: it exists. We exist within it, as patterns complex enough to ask what we are. The answer is strange, counterintuitive, impossible to visualize. It is also, as far as we can tell, true.