It from Bit, Bit from It
If you have ever felt uneasy reading about quantum mechanics, you are in good company. For nearly a century, the idea that a cat can be both alive and dead — or that an electron exists in a cloud of probability until "looked at" — has struck even world-class physicists as unreasonable. We often try to fix this unease by imagining a "real" hidden state behind the scenes, or by proposing that consciousness somehow collapses the wave function.
But what if quantum mechanics isn't the problem? What if we've been carrying around a mistaken assumption about reality itself?
In 1996, physicist Carlo Rovelli proposed a radical shift called Relational Quantum Mechanics (RQM). His argument parallels Einstein's breakthrough with Special Relativity. Before Einstein, physicists struggled to explain Maxwell's equations because they assumed time was absolute. Einstein solved the problem by accepting that time is relative to the observer. Rovelli suggests we must do the same for quantum states: no "absolute state" of a system exists. A system's state is always relative to another system.
Any System Can Observe
The first step toward clearing up quantum confusion is abandoning the idea that an "observer" must be human, conscious, or even complex. In Rovelli's framework, any physical system can observe another. An electron interacting with a photon observes it. A table lamp interacting with a hand observes it.
Rovelli's "Hypothesis 1" is simple: all systems are equivalent. The laws that describe a single atom also describe you, me, and the entire laboratory. This removes the need for "special systems" — consciousness, gravity, or anything else — to explain wave function collapse. Collapse isn't magical. It's just what happens when two systems exchange information.
Two Observers, Two Truths
To see how this works, consider what Rovelli calls the "Third Person Problem."
Observer \(O\) measures a system \(S\) — say, an electron. \(O\) interacts with \(S\) and finds the electron is "Spin Up." For \(O\), the wave function has collapsed. Reality is definite: Spin Up.
Now imagine a second observer, \(P\), standing outside the room. \(P\) does not interact with the electron. Instead, she treats \(O\) and \(S\) together as a single quantum system. According to the Schrödinger equation, \(P\) describes them not as "Spin Up," but as an entangled superposition:
$$(\text{Electron Up} + \text{Observer seeing Up}) \text{AND} (\text{Electron Down} + \text{Observer seeing Down})$$
Who is right? Is the electron "really" Up, as \(O\) sees it? Or is it "really" in superposition, as \(P\) describes?
Standard quantum mechanics calls this a paradox. RQM calls it a feature. Both accounts are correct. "Spin Up" is true relative to \(O\). "Superposition" is true relative to \(P\). No contradiction exists because \(O\) and \(P\) describe the system from different frames of reference — just as a moving train looks different to a passenger inside than to a bystander on the platform.
Correlation Keeps Reality Consistent
This might sound like solipsism — each of us living in a private dream world — but Rovelli anchors his framework in physical reality through consistency.
If \(P\) enters the room and asks \(O\) what he saw, a physical interaction takes place. Rovelli proves that quantum mechanics guarantees \(P\) will always find a result consistent with \(O\)'s measurement. If \(O\) saw "Up," \(P\) will measure that \(O\) recorded "Up."
This brings us to RQM's core mechanism: correlation.
For \(P\), the "measurement" that \(O\) performed is not a collapse; it establishes a correlation — an entanglement — between \(O\) and \(S\). The fact that \(O\) has "information" about \(S\) is physically identical to saying \(O\) and \(S\) are correlated. Information is correlation.
The Quantum Zeno Effect
To see this logic at work, consider the Quantum Zeno Effect — specifically the "interaction-free" experiments Kwiat et al. pioneered in 1999.
A photon is repeatedly "checked" to see if an object (call it a "bomb") has absorbed it. If checked frequently enough, the photon freezes in its initial state and never triggers the bomb. If nothing else in the environment around the bomb accidentally triggers it during the experiment, then it's possible with some very high probability to detect whether the bomb is or is not present without triggering it. This is pretty weird stuff if you're not used to the concept of entanglement from quantum mechanics!
How does RQM explain this?
From the bomb's perspective: The photon's quantum state is trying to rotate toward the bomb's path. But the bomb's presence turns each cycle into a measurement — "Has the photon arrived yet?" Each measurement finds almost no amplitude in that path and collapses what little has accumulated. The rotation never completes; the photon stays frozen in its original path.
From the experimenter's perspective: The experimenter sees the photon and bomb interacting through a strong Hamiltonian. This interaction creates a perfect correlation between the photon's path and the bomb's state. No collapse occurs for the experimenter — just a unitary evolution that drags the photon along a frozen path because it is entangled with the bomb.
As Rovelli notes, "The unitary evolution does not break down for mysterious physical quantum jumps... but simply because \(O\) is not giving a full dynamical description of the interaction." \(O\) sees collapse because \(O\) participates in the interaction. \(P\) sees unitary evolution because \(P\) watches the correlation form.
"It from Bit" — or "Bit from It"?
This leads to a profound philosophical implication, often summarized by John Wheeler's phrase "It from Bit" — the physical world ("It") emerges from information ("Bit").
Rovelli pushes this further. In RQM, measurement is just information exchange. And information is just physical correlation.
"The fact that the pointer variable in \(O\) has information about \(S\)... is expressed by the existence of a correlation."
"Physics is the theory of the relative information that systems have about each other. This information exhausts everything we can say about the world."
In the lossless limit of the Zeno experiment — where the photon is never absorbed, yet its state freezes — we see this principle in its purest form. The photon is affected physically not by touching the bomb, but by the information that the bomb is present. The "Bit" (the answer "No, not absorbed") is the "It" (the physical freezing of state).
The Lossless Limit Cannot Be Reached
There is a catch. The lossless limit is never achieved in practice.
A pure information exchange without energy dissipation is an idealization. To measure the photon, the bomb must couple to it. Even if the photon is not absorbed, the potential for absorption drives the effect. In Kwiat's experiments, efficiency was high but never 100% — always some loss, some decoherence, some thermodynamic cost.
For me at least, this seems to imply that even if information is somehow the fundamental currency of reality, that information never comes without a cost. The "Bit" and the "It" are inextricably linked. You cannot have a "Bit" without a physical substrate to hold it, and you cannot update that "Bit" without a physical interaction.
If the lossless limit were reachable, we might inhabit a universe of pure information — ghost-like and cost-free. But the fact that it remains an asymptotic limit, something we can approach but never touch, reminds us that we live in a physical world of friction, energy, and substance. RQM tells us that relations are fundamental, but the failure of the lossless limit reminds us that those relations require a real, physical price.
The Synchronization Tax Returns
At this point, the connection to The Synchronization Tax should be clear. Time itself is the cost — the price we pay when two otherwise isolated systems must agree on what happened. Whether you are collapsing a quantum wavefunction, synchronizing a distributed database, or clearing a wire transfer, the mechanism is similar. To have a shared reality, systems must interact. And interaction costs (thermodynamic) entropy.
Rovelli's framework illuminates why. "Collapse" is not a mysterious event; it is the establishment of a correlation between systems. Before the correlation exists, the systems share no timeline — they are concurrent, superposed, each evolving in its own isolated frame. After the correlation, they share a fact. They agree on what happened.
But establishing that correlation requires physical interaction. And physical interaction dissipates energy. The "synchronization tax" I described — transaction fees, wire delays, the billable hours of lawyers and accountants — is the macroscopic echo of this quantum truth.
In the lossless limit, correlation would be free. Systems could agree without paying the price. But the lossless limit is unreachable — and so we pay. We pay with entropy in physics, with fees in finance, with the friction of every human institution that coordinates private knowledge into public fact.
We don't just have information about the world. We are part of the web of information that constitutes the world. We are not watching reality from outside; we are woven into it, one correlation at a time — paying the synchronization tax with every thread we spin.
Now we're ready to talk about free energy.