The Death of "Before and After": How Quantum Physics Shattered the Arrow of Time

Experiments from 2017–2019 confirm that "Cause and Effect" is not a rigid law, but a quantum variable that can be blurred, mixed, and superposed.

The Paradox: The Fixed Schedule vs. The Quantum State

For a century, quantum mechanics has taught us that a particle can be in a superposition of "Here" and "There." Yet, physicists clung to one final classical assumption: the Fixed Schedule.

We are used to thinking of time as a rigid to-do list. If you have two errands—going to the Beach (A) and going to the Restaurant (B) —you have to pick a sequence. You can go to the Beach then the Restaurant ( A > B ), or the Restaurant then the Beach ( B > A ).

Classically, you cannot do both. You occupy a single track on the timeline. Even in standard quantum computing, gates are arranged in a specific line. Line 1 runs, then Line 2 runs.

But this created a limitation. If a particle can be in two places at once, why can't a sequence of events be in a superposition of orders? Why is the schedule fixed?

The Test: The Quantum SWITCH

To test this, physicists developed a device called the Quantum SWITCH.

Imagine a computer or a laboratory that performs two operations, A and B. In a classical setup, the "control" logic decides the path:

1.       A > B (Control is 0).

2.       B > A (Control is 1).

The Quantum SWITCH introduces a "Control Qubit" in a superposition. This isn't about reversing time (turning an omelet back into an egg); it is about superposing the path through the operations.

What is "Indefinite Causal Order"?

When the Control is superposed, the photon enters a state where the "schedule" is undefined.

The photon experiences a reality where:

• It went to the Beach before the Restaurant...

• AND it went to the Restaurant before the Beach.

This is fundamentally different from simply not knowing which you did first. It is an Indefinite Causal Order (ICO). The "movie" of the experiment hasn't been rewound; rather, two different versions of the movie—with different plot sequences—are playing simultaneously on the same screen.

The Experimental Proof

Between 2017 and 2019, labs like Philip Walther’s in Vienna proved this using photonics.

They measured a "Causal Witness." This is a mathematical test that asks: "Did event A happen before B, or did B happen before A?"
If the universe had a fixed timeline, the answer would have to be one or the other (or a statistical mix).
The Result: The experiment violated the mathematical limit for any fixed order.
The Implication: The photon did not follow a fixed schedule. The "Before" and "After" labels were not just unknown; they did not strictly exist.

Why This Matters: The "Causal Activation"

This isn't just a philosophical trick; it solves problems that are impossible to solve with a fixed schedule.

Researchers (Ebler et al., 2018) discovered a phenomenon called Causal Activation. Imagine the Beach ( A ) and the Restaurant ( B) are both "noisy"—perhaps the road to both is blocked.

• In the order A > B, you never arrive.

• In the order B > A , you never arrive.

• In the Quantum Switch: The superposition of orders causes the "noise" (the blockages) to interfere with itself.

Because the photon travels through the noise in both orders simultaneously, the errors can cancel out destructively, allowing information to pass through perfectly. This is physically impossible in a universe where you must choose a single schedule.

The Verdict: The "Killer App" of Fuzzy Time

This discovery shattered the idea that Time is a background stage where events sit in a fixed row.

By removing the "scheduled time," the Quantum Switch allows us to perform tasks in a way that bypasses standard linear restrictions. The universe allows us to execute a to-do list without ever deciding which item is Number 1 and which is Number 2. The schedule itself is a quantum object.

The Stability of Chaos: How Spacetime Knots into Mass

Subtitle: Mass is not a separate substance added to the universe. As Scale Relativity suggests, it is a dynamic constraint—a specific type of stable path that emerges when spacetime tames its own fractal roughness.

Einstein’s Dream: The Path is the Object

General Relativity taught us that Gravity is the curvature of spacetime. But Scale Relativity takes this further: Spacetime is the only masterpiece. What we call "particles" or "mass" are simply specific behaviors of spacetime paths.

The difference between "Mass" and "Path" dissolves. Mass is not a static rock sitting on the road; Mass is a measure of the constraint applied to the path. It describes how tightly the geometry is bound to itself.

1. Large Mass: The Constraint of Stability

Why do macroscopic objects follow smooth, predictable lines? It is because they represent a high degree of geometric constraint.

We can hypothesize that for large masses, a mechanism similar to the Quantum Switch is at work. The geometry forces the "Forward Time" flows (dt+) and "Backward Time" flows (dt-) to interact so intensely that they lock together.

• This interaction creates a Destructive Interference of the fractal fluctuations.

• The path becomes "heavy" not because it has weight, but because it has stability.

For a large mass, the path is rigidly constrained. The "Quantum Switch" is flipped to a mode where the causal loops stabilize the trajectory, making it resist the chaotic jitter of the vacuum.

2. The Electron: Surfing the Fractal

As we look at the Electron, the constraint weakens. The geometric stability is not absolute.

Here, the "Mass" is small, which means the "grip" on the path is loose. The geometry cannot fully suppress the fractal nature of spacetime.

• The "roughness" breaks through. The electron acts like a surfer on a rough sea.

• It cannot follow a straight line; it is forced to ride the fractal waves.

The electron's mass is simply the finite resistance of the path to this roughness. It is trapped enough to stay localized (in an orbit), but free enough to exhibit interference. It is a path that is partially constrained, constantly negotiating between the order of the causal loop and the chaos of the fractal dimension.

3. The Photon: Pure Unbound Geometry

Finally, we arrive at the limit: Zero Mass.

If Mass is a constraint on the path, the Photon is the absence of constraint. The "Quantum Switch" is open; there is no interference to lock the path down.

• Infinite Roughness: Without the constraint of mass, the diffusion coefficient becomes infinite.

• Pure Geometry: The photon is not an object traveling through geometry; it is the geometry propagating at the speed limit of causality.

Because it has no mass to define a "proper time," it cannot distinguish between the forward and backward flows. It becomes indistinguishable from the fractal vacuum itself—pure, delocalized movement.

The Takeaway: The River and the Whirlpool

We can visualize this unified view of Spacetime and Mass using the analogy of a turbulent river.

The River is the flow of spacetime itself. It has a main direction (the arrow of time), but it is filled with chaotic, fractal currents.

• The Photon is a ripple moving with the current. It has no structure of its own; it is just the motion of the water.

• The Mass (Electron/Planet) is a Whirlpool.

A whirlpool is made of nothing but water (spacetime). It is not a separate object. However, it has stability. It has a constraint. Even though the main river flows one way, the whirlpool creates a localized structure that allows for internal, backward rotation (dt-).

Mass is simply a stable, self-sustaining knot in the flow of spacetime. It is the "silence" and stability that persists even as the chaotic river of time rushes by.

The Fractal Arrow: How Scale Relativity Unifies Time and Quantum Chaos

Subtitle: While Quantum Causal Models describe how to mix cause and effect, Laurent Nottale’s Scale Relativity explains why spacetime allows it—by revealing the fractal geometry of time itself.

Beyond the Switch: Finding the Geometry of Quantum Time

In our previous explorations, we saw that the "Arrow of Time" is not as rigid as classical physics assumed. We discussed the Quantum Switch, where events can happen in a superposition of orders (A > B and B > A).

But this leads to a deeper question: What does spacetime look like if it allows the arrow of time to split?

The answer may lie in Scale Relativity, a theory developed by Laurent Nottale. It suggests that the "fuzziness" of quantum causal order isn't just a computational trick—it is a result of the fact that spacetime itself is a fractal.

Feynman’s Legacy: The Path of Infinite Complexity

To understand this, we must look back to Richard Feynman. Feynman famously described quantum mechanics as a "Sum Over Histories." He argued that a particle doesn't take one path from A to B; it takes every possible path, including zig-zagging, chaotic trajectories.

Scale Relativity takes Feynman’s intuition and makes it geometric.

• In classical physics, we assume space is smooth (like a sheet of paper).

• In Scale Relativity, space is fractal (like a coastline). As you zoom in, it becomes infinitely rough and detailed.

• In a fractal space, the shortest path between two points (a geodesic) is not a straight line—it is a fractal curve that looks exactly like the jittery motion of a quantum particle.

The Splitting of the Time Arrow

This is where Scale Relativity offers a beautiful resolution to the causality debate.

In a smooth, classical world, time flows like a river with a single current. The speed of a particle is just  dx/dt.

But in a fractal world, the path is "non-differentiable" (too rough to have a single slope). Nottale shows that because of this roughness, the concept of velocity splits in two.

1.  dt+(Forward Time): The flow of time going into the future.

2.   dt- (Backward Time): The flow of time coming from the past.

In classical physics, these are identical. In Scale Relativity, due to the fractal "noise" of spacetime, they are independent. This echoes the insights of physicist G.N. Ord, who showed that the Schrödinger equation emerges when you combine these two time directions.

This is not a paradox where the future changes the past (Retrocausality). Instead, it implies that at the quantum scale, a particle is constantly navigating two flows—one from the past and one toward the future.

Fractal Noise and the "Quiet" Quantum State

You might ask: "Doesn't a fractal spacetime introduce infinite noise and chaos?"

Surprisingly, it does the opposite. This connects directly to the Quantum Switch discovery that superposing two noisy channels (A > B and B > A) creates a perfect, noise-free channel.

Scale Relativity predicts a similar phenomenon.

• The fractal nature of space creates "fractal noise" (infinite fluctuations).

• However, because the particle is "surfing" on both the forward (dt+) and backward (dt-)  time flows, these fluctuations average out.

• When you mathematically combine these two flows, the "noise" transforms into the Quantum Potential.

The chaos of the fractal path becomes the order of the Quantum State. The particle isn't "fine-tuning" its path to avoid signaling; it is simply following the only stable path that can exist in a fractal geometry.

The Takeaway

The experiments of the Quantum Switch prove that the causal order of events can be superposed. Scale Relativity provides the map for this territory.

It suggests that the "Arrow of Time" is not a single, sharp vector. At the quantum scale, the arrow is fractal—it is a structure that inherently contains both forward and backward components. By embracing this two-way flow, nature cancels out the noise of the quantum world, creating the stable reality we observe without needing any conspiracies.