To explain reality, we must start with the only thing we truly know: our direct experience.
Quantum mechanics is famously successful. And famously weird. Electrons seem to be in many places at once, cats are said to be both alive and dead (until you look), and two particles can “know” about each other across a room or a galaxy.
For a century, physicists have agreed on how to calculate quantum predictions. Where they disagree is on what those calculations mean. That’s what an interpretation is: a story that links the equations to reality. The math doesn’t change; the interpretation is the lens you use to understand it.
Most lenses look “outside-in”: start with the world (a quantum state), then ask what an observer will see. The Experiential Interpretation (EI) flips that. It starts inside-out:
Begin with an experience, the total content of a moment in consciousness, and ask: which physical worlds are compatible with this experience?
From that simple inversion, a surprisingly clean picture emerges.
First, a few plain-English quantum terms
Superposition: a quantum system can be in a blend of possibilities at once (like a musical chord rather than a single note). When you measure, you get one note, but the chord shaped the odds.
Measurement: in the lab, this is when a device produces a definite reading. In daily life, it’s when you see or hear or feel something. In EI, the whole “what it’s like right now” is called an experience.
Entanglement: two systems share a single chord. Measure one and you instantly know the other’s note, no matter how far away. (No message travels faster than light; it’s a correlation, not a signal.)
Decoherence: the environment (air, light, dust, your retina) constantly records what happens. Those records make different macroscopic possibilities (pointer here vs. there; cat alive vs. dead) behave as if they can’t mix. Decoherence explains why the world looks classical.
Born rule: the rule that turns the quantum chord into odds for what you will actually see.
The EI idea, in one picture
Imagine you have a photograph in your hand. You ask: Which places on Earth match this photo? Many landscapes don’t; some do. Now imagine turning the page to the next photo. The set of matching places narrows again.
EI treats your experience like that photo. The “places on Earth” are physical states allowed by quantum theory. The interpretation says:
- Start with the experience you actually have (what’s on the screen, what you feel, what you remember).
- Collect the set of physical states that would make that experience true.
- Use standard quantum physics to forecast odds for your next possible experiences.
- When you actually have the next experience, shrink to the new set that fits it.
There’s no extra collapse law, no hidden machinery. Just: experience → compatible physical descriptions → odds for the next experience.
Why bother flipping the story?
Because many famous paradoxes are really mix-ups about whose description of the world we’re using and when.
- In Schrödinger’s cat, before you open the box your experience doesn’t include “alive” or “dead,” so both possibilities belong to the compatible set. When you look, your experience includes “alive” (say), and the set shrinks to states where the cat is alive. There is no mysterious collapse, just updating based on what you actually experienced.
- In Wigner’s friend, the friend inside the lab has an experience (“the detector clicked”). Wigner outside does not. EI says: each person conditions on their own experience. Their descriptions don’t have to match until they meet and compare notes, at which point their shared experience forces a common, recorded outcome. The paradox dissolves because we stopped pretending there was a single, all-observer description before they interacted.
- In the two-slit experiment, sending one particle at a time still paints an interference pattern over many shots. EI says: each dot you see is one experience that trims the compatible set; the long-run pattern comes from the Born odds, exactly the same odds standard quantum theory gives. In delayed choice and quantum eraser variants, EI simply uses the actual setup you experience at the end. There’s no need to “reach back in time”; you always condition on the present records.
- For EPR pairs and Bell’s theorem, EI embraces the quantum correlations and keeps the no-faster-than-light rule. What it avoids is the tempting but flawed assumption that there exists a single, pre-written list of outcomes for all the measurements you could have made but didn’t. This assumption that the particle “knew” in advance what it would show for any possible setting is what Bell’s theorem tests. EI sidesteps the paradox by stating that the only definite outcomes are the ones tied to an actual experience. The “what if” questions don’t have answers in reality, only in our imagination, so there is no single catalog to constrain.
This “inside-out” approach does not discard the immense success of traditional “outside-in” physics. Instead, it provides a deeper foundation for it. Einstein’s relativity did not prove Newton’s gravity “wrong”; it showed Newton’s laws were a successful approximation within a broader framework. Similarly, EI suggests that traditional physics is the correct and powerful description we get under the assumption that experience can be factored out. EI’s goal is to make room for a more fundamental theory that explains both the physics and the experience.
These examples show EI at work. But to apply it cleanly, we need to say what we mean by an “experience.”
What counts as an “experience”
EI takes an experience to be everything present to awareness in a moment: the click on a detector, the image on a screen, the memory of the last trial, the feeling of standing in your lab. That last bit matters. Memory is part of experience.
This explains continuity without magic. When you close your eyes, your sensory input narrows; many physical situations could feel like “eyes closed.” But your memory remains in the experience: how you got here, who you are, what you were doing. Those internal records keep the set of compatible physical states tight enough that your next experience is overwhelmingly likely to feel like “eyes still closed in the same room” and not some random jump.
In other words, EI doesn’t bolt continuity onto the world. Continuity rides along with the records already in your present experience. Modern decoherence theory explains why such records are so stable.
While “experience” includes the full richness of a moment, it also connects cleanly to the lab. For nearly all practical scientific purposes, an experience is the direct perception of a measurement outcome: seeing the detector flash, reading the number on a screen, or hearing a click. EI simply states that this direct perception is the real event on which our physical description of the world must be conditioned.
How EI compares to other interpretations
The Copenhagen interpretation puts outcomes first, but adds a special “collapse” rule. EI keeps outcomes first and drops collapse in favor of updating what is compatible with what you saw.
The Many-Worlds interpretation says that quantum processes always follow their smooth mathematical evolution and that all outcomes happen in separate branches. EI keeps that smooth evolution, but only talks about the outcomes you actually experience. It does not commit to a large branching picture.
Bohmian mechanics posits that there are actual particles with definite positions that are guided by a “pilot wave.” EI stays neutral about what the world is made of; it is a reasoning framework that works on top of whatever physical picture you start with.
Among the remaining interpretations, QBism and the Relational Interpretation (RQM) come closest to EI. All three reject the idea that quantum mechanics is a universal catalogue of “what is.” Instead, they tie the theory to agents, observers, or relations. The crucial difference is what each takes as primary.
QBism treats the quantum state as an agent’s personal betting odds for future experiences. The Born rule is not a physical law but a consistency rule for those beliefs. EI agrees that quantum states are not objective catalogues. Where it differs is in its anchor point: not belief but the actual content of present awareness. The probabilities you calculate are about physical continuations compatible with what you have already experienced.
Relational quantum mechanics argues that properties exist only in relation to another system. A measurement outcome is always tied to the observer who interacted. There is no global account that covers all observers at once. EI shares this rejection of a universal catalogue, but it grounds the idea in concrete experiences. Each moment of awareness defines the set of compatible physical states, which then evolve forward. In this way, the “relational” principle becomes a practical recipe for reasoning.
Seen together, QBism is belief-centered, RQM is relation-centered, and EI is experience-centered. All three avoid the paradoxes that come from forcing all possible outcomes into a single global description. EI’s distinctive move is to take lived experience, not belief or relation, as the footing on which physics is built.
Having compared EI with its rivals, it is equally important to be clear about what it does not claim.
What EI isn’t
EI stays within physics. Probabilities still follow the Born rule, and quantum dynamics remain unchanged.
EI does not add new predictions. As stated, it reproduces all the usual quantum results. Its value is conceptual clarity, especially for multi-observer puzzles, by keeping every statement tied to an actual experience.
EI does not deny the world or make science subjective. It simply demands that our description of the world begin with our actual experience of it. While that starting point is personal, the process is objective: the set of physical states compatible with an experience is determined by the laws of physics, not opinion. The rules for calculating the odds of the next experience are the same for everyone, ensuring that science remains a reproducible method for describing our shared reality.
Key open questions
No interpretation is without challenges. In the case of EI, several stand out.
The first is to pin down the map from experiences to physical states. In the lab that is straightforward: a detector reading is a detector reading. For the brain, we would like a principled way to say which large-scale neural and environmental records correspond to a given experience. Decoherence helps, but a full recipe would be better.
A second open question is how the next experience is selected from the set of possibilities. EI uses the standard quantum recipe for odds, but whether there is a deeper principle that picks out one actual experience remains an open problem. This is the same difficulty that other no-collapse views face. Some may choose to embed EI within a Many-Worlds framework, where all outcomes occur and experience is simply the local perspective within one branch. EI itself does not require this, but it remains compatible with it.
A third is to make the framework fully relativistic. In quantum field theory, experiences live in spacetime regions. There is active work outside EI on how to talk about localized records in a way that respects relativity, and EI would need to connect with that.
These are not shortcomings unique to EI. They mark the frontier where any serious interpretation must reach beyond established physics. What EI offers is a clean starting point for that journey: a framework that takes experience seriously and shows how far it can carry us using the tools of quantum theory itself.
Why this might be the interpretation you already use without realizing
When you run an experiment, you don’t ask, “What’s the true state of the universe?” You ask, “Given what I just saw, what does my theory say I’ll see next?” You look at your data (your experience), you restrict the set of possible explanations to those compatible with it, and you compute the odds for future experiences.
That’s EI. At its core, it doesn’t ask you to believe in extra collapses, hidden gears, or parallel worlds to get the job done. It asks you to be precise about something you already do: condition on what actually happened, keep track of whose point of view you’re using, and let the math do the rest.
If quantum mechanics is the best calculator we’ve ever built, EI is an instruction manual that starts on the right page: the page you’re looking at.