Fumfer Physics 45: Fractional Dimensions, Quantum Time, and Simulated Futures

Author(s): Scott Douglas Jacobsen

Publication (Outlet/Website): Vocal.Media

Publication Date (yyyy/mm/dd): 2026/05/04

Photo by Djim Loic on Unsplash

“Ordinary time is one line. Quantum computation gives you a controlled blur of possible lines, and then reality, the old bastard, makes you pick one.” – Rick Rosner

Scott Douglas Jacobsen asks Rick Rosner about fractional dimensions, causality, quantum computing, and whether reality could temporarily “snap back” from non-integer spatial or temporal structures. Rosner distinguishes mathematical fractional dimensions from literal extra directions, explains compactification, positrons, superposition, decoherence, and simulated timelines, and argues that rerunning life would require impossible isolation from the universe’s information-recording machinery, leaving simulation as the only plausible route to alternate futures rather than literal reversal of time.

Fractional Dimensions and the Problem of Physical Meaning

Scott Douglas Jacobsen: There was a recent report about something we discussed many years ago. I pitched it to you as a thought experiment about strange physical effects and dimensionality: a dimension that is neither two-dimensional nor three-dimensional, but fractional, two and one-eighth dimensions, two and fifty-seven sixty-fourths dimensions, or something like that. Maybe two-point-something dimensions of space and one dimension of time.

What do you think happens if you fractionate space, time, or both into a non-whole-number dimension?

Rick Rosner: So, if you have a fractional dimension, dimensionality is basically about degrees of freedom: how many independent ways things can move, vary, or be connected. Space can be thought of, at least in one relational way, as being partly defined by the interactions among the things in it, the particles, fields, forces, and exchanges that make up the universe.

Graphs, Connections, and Degrees of Freedom

There is a famous puzzle every school kid knows, or at least every nerdy school kid. You have three houses and three utilities, say electricity, water, and gas, and you have to connect each utility to each house without any of the lines crossing. On a flat two-dimensional plane, you cannot do it. The graph is nonplanar. You need to cheat somehow: let one line pass over another, go through a third dimension, put the thing on a torus, or otherwise violate the flat-paper rules.

So you can view space partly in terms of what connections are possible among things: particles, forces, interactions, exchanges. How many independent directions can those interactions happen in?

You can model four-dimensional or twelve-dimensional spaces in a computer. But specifying a position in higher-dimensional space takes more information. In our usual physics, a point in spacetime needs four coordinates: three for space and one for time. In a twelve-dimensional spatial model, you would need thirteen coordinates: twelve spatial coordinates and one time coordinate. That is a lot of extra information. So the question is: where is that information coming from, physically? In the physics we actually observe, there is an efficiency in having three large spatial dimensions and one time dimension.

Fractals, Compactification, and Compromised Directions

To have a fractional number of dimensions does not literally mean you have two good dimensions and then one crappy little leftover dimension. That is my sloppy way of saying it. More accurately, a fractional dimension usually means the system scales as if it has a non-integer number of degrees of freedom. Fractals do this. Some mathematical models in physics do this. In some quantum-gravity ideas, the effective dimension of spacetime may even depend on scale. But that is different from saying you can walk north, south, east, west, and then one-eighth of “up.”

Still, as a metaphor, you could say: you have two full dimensions, and then some limited, constrained, or weird access to another kind of direction. The “shittiness” could come in different forms.

String theory gives one version of this, though not exactly fractional dimensions. String theory says there may be extra spatial dimensions, but most of them are compactified, rolled up so small that we do not detect them in everyday life. So compactness is one way an extra dimension can be hidden.

Another way might be restricted propagation. Maybe light or information moves freely across two dimensions, but in the extra effective direction, it moves in a pokey way, loses intensity faster, or becomes accessible only at certain scales. That is not necessarily a fractional dimension in the strict mathematical sense; it may be more like an anisotropic medium, a strange metric, or a constrained geometry. But you can imagine many ways to model a dimension that behaves less like an ordinary direction and more like a compromised direction.

I do not know the specialized math of it. I am not a Ph.D. in fractal geometry or quantum gravity. But I can imagine that fractional dimensions do some of what regular dimensions do, only in a more limited, scale-dependent, or otherwise messed-up way.

Time, Causality, and Positrons

With time, the issue is different. Time is causality in action. It is the ordering of events. Events at one point in time cause events at later points in time, and in ordinary experience, it almost never goes the other way.

In quantum field theory, there is the Feynman-Stueckelberg interpretation, where a positron, the antimatter counterpart of the electron, can be mathematically treated as an electron moving backward in time. But that does not mean positrons are little time-traveling bullets in the science-fiction sense. A positron is a real particle moving forward in time like everything else, with the opposite electric charge of an electron. The “electron moving backward in time” idea is a powerful mathematical interpretation, not an invitation to murder your grandfather.

We live in a world made mostly of matter rather than antimatter. Positrons usually do not last long around ordinary matter because, when a positron and an electron meet, they can annihilate and produce energy, usually gamma-ray photons. But positrons can be stored for significant periods in traps, using electromagnetic fields and vacuum conditions. That is not because they are outside causality. It is because you have prevented them from running into electrons.

So you cannot really say that a trapped positron is not participating in cause and effect. It is interacting with fields. It is being confined. It is part of the causal machinery. It is just being kept away from the kind of interaction that would destroy it.

The larger point still stands: causality seems to require a strongly ordered time dimension. In standard physics, spacetime has three large spatial dimensions and one time dimension. You can write mathematical theories with more than one time dimension, but they tend to produce serious problems with causality, stability, and predictability. So, for the universe we actually observe, time appears to be one-dimensional in a much stricter way than space is three-dimensional.

Quantum Superposition and Sloppy Multidimensional Time

Rosner: However, you can have something that you might sloppily call multidimensional time through the superposition of many possible states. That is also one way people talk about quantum computing, though you have to be careful because it is easy to turn quantum mechanics into science fiction with equations taped to it.

If we were holding that positron in a vacuum, isolated from ordinary matter, that is one kind of sequestering. With quantum circuits, you are doing something somewhat analogous: you are trying to keep the qubits isolated enough from the rest of the universe that they can maintain their quantum state while they compute. They are not outside causality. They are just protected from the kinds of interactions that would ruin the computation.

A qubit can be in an indeterminate state. More precisely, it can be in a superposition of possible states. That brings us to Schrödinger’s cat, which is the cat in the box. The cat is sealed off from the outside world with some quantum event that may or may not trigger the fatal mechanism. Until the box is opened, the standard story says the cat is treated as being in a superposition of alive and dead.

Now, if you are using the many-worlds interpretation, you can say there are two branches: one where the cat is alive and one where the cat is dead. But that is an interpretation of the math, not something everybody agrees is literally happening. The safer way to put it is that the system is in a superposition until measurement or interaction with the environment forces the result to become definite for the observer.

Quantum Computing, Possible Histories, and the Limits of the Metaphor

Quantum computing lets you exploit superposition, entanglement, and interference. The sloppy popular version is: “It runs many worlds at once.” The more accurate version is: it sets up a quantum state in which many possible outcomes have amplitudes, and the computation uses interference to amplify the useful answers and suppress the useless ones. It is not just a magical parallel-universe abacus, though that would be a terrific bad startup pitch.

So, in a loose sense, you could call that an extra fractional dimension of time. You have one ordinary timeline, but inside the quantum computation, you are letting many possible computational paths coexist briefly before the system is measured.

The old line about quantum computers having only 16 qubits is way out of date. Quantum computers now have far more physical qubits than that. IBM introduced its 1,121-qubit Condor processor in 2023, and its more recent Nighthawk system has 120 qubits arranged for more complex workloads. But raw physical qubits are not the same thing as large numbers of reliable, error-corrected logical qubits. That is the annoying but essential distinction. You can have lots of fragile qubits and still not have the kind of robust machine that can run huge, practical simulations.

But suppose that, in the future, you have a quantum computer with tens of thousands of high-quality, error-corrected qubits. Then maybe you could run more complex simulations: not a full reality simulator, because the universe is not cheap to imitate, but richer models than anything we can do now.

The 16-qubit version of a world simulator would not even be Pong. It would be worse than Pong. It would be a damp sneeze in Hilbert space. But with enough reliable qubits, you might simulate pieces of chemistry, materials, optimization problems, or probabilistic scenarios in ways classical computers struggle with.

Everyday Choice and Simulated Timelines

So take the everyday example we have talked about. Say you are in eleventh grade, and you like a girl, and you are trying to imagine the possible outcomes if you go up and talk to her. A future quantum-assisted simulator probably would not tell you, “Say this exact sentence and she will like you,” because human beings are not deterministic vending machines for affection. But it might model a large range of possible interactions and give probabilities: here are the twenty most likely ways this could play out, given the assumptions.

That could feel like multidimensional time. Each individual scenario still unfolds in one-dimensional time: this happens, then that happens, then the next thing happens. But you have a whole rainbow of possible short timelines laid out side by side. The “extra dimension” is not really another time dimension in physics. It is more like a structured space of possible histories.

So, yes, you could argue to me that this is one plus a fraction of time. Not literally, probably. But metaphorically, computationally, imaginatively, sure. Ordinary time is one line. Quantum computation gives you a controlled blur of possible lines, and then reality, the old bastard, makes you pick one.

Stability, Reversal, and the Universe Snapping Back

Jacobsen: If fractional spatial and temporal dimensions are possible, could there be a point at which this happens temporarily inside an already established universe, but the stability of the universe sort of snaps it back into a whole-number dimension, or at least an approximation of one?

Rosner: That is the first question. To do that, you would need the technology to sequester the events. For something to happen and then unhappen, the events that happened would have to leave no usable trace in the rest of the universe.

Take the eleventh-grade example again: you want to rerun your interaction with the girl you like. For that to work physically, that little world would have to happen in some kind of null space, inside a mirrored sphere, or whatever the science-fiction version is, where you and the girl are separated from the rest of space. What happens in the sphere is like what happens in Vegas, except with better physics: it stays in the sphere. It does not interact with anything else.

Maybe, if you could do that, you could pull the whole thing back and run it again. But I do not know how you would ever have the technology to separate you, the girl, the air, the photons, your bodies, your nervous systems, and every little thermal interaction from the rest of the universe. That is not a casual laboratory apparatus. That is God’s Tupperware.

You would need much more than a ten-thousand-qubit simulation. To simulate two human bodies at anything close to the atomic level, you are talking about astronomical complexity. Your body contains on the order of trillions of cells and vastly more atoms, and so does hers. So you cannot literally rerun time unless you can isolate the events you are trying to rerun from the rest of the world.

Information, Heat, and the Stickiness of the Past

The rest of the world is designed, in a sense, to be a recorder of information and a pusher-forward of information into the future. Things happen; the world records traces of what happened. Then more things happen, and those traces get folded into the next layer of reality. That is why the past is sticky.

We have talked about places where the world does not keep track very well, like the center of a star. So many interactions are happening so quickly, and the temperature is so high, that there is no stable, readable record of most specific events. The record is scrambled almost immediately by the chaos of the plasma. The core of the Sun, for example, is around 15 million degrees Celsius, where nuclear fusion occurs. That is not a filing cabinet. That is the universe running a paper shredder inside a bomb.

But even there, the information is not magically erased in the everyday sense. In modern physics, information, entropy, and heat are tied together in very deep ways. Landauer’s principle says that erasing one bit of information has a minimum thermodynamic cost, dissipated as heat. So when we say a place “does not keep records,” what we really mean is that local, usable, recoverable information is dispersed into inaccessible correlations and thermal noise.

To thoroughly record events, you need something more like Earth: an open system that can shed waste heat into space and preserve relatively stable structures, rocks, fossils, bodies, books, hard drives, scars, memories, browser histories, all the accusing little receipts of existence.

But you cannot run your interaction with the girl in the center of a star, because no useful record survives in a form you can recover. Also, dating advice generally suffers at 15 million degrees.

Decoherence, Simulation, and the Seduction of Rerunning Life

So I would buy the half-assed argument that, in the future, you might live through different possible futures by simulation before arriving at your actual future, the one that really happens. But it would have to be simulation. It would not be literal rewinding of the universe.

The key issue is decoherence. If a quantum system interacts with its environment, information about the system leaks into that environment, and the system loses the clean superposition you would need to preserve multiple possible histories. Decoherence is exactly the reason quantum states are so hard to maintain and why quantum computers need isolation, error correction, and controlled conditions.

In the novel I am writing, one of the things that can happen is that people get trapped in this. They get addicted to reliving the crucial points in their lives. They keep going back to the moments where they think everything turned: the girl, the job, the betrayal, the fight, the one sentence they should have said differently. They do not get to rewrite the actual universe. They get to run versions of it, over and over, until the simulation becomes more seductive than the life they are supposed to be living.

Jacobsen: Thank you very much for the opportunity and your time, Rick.

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