✱About this series
The aim of this series is to explore the metaphysical implications arising from the very nature of quantum theory. This first piece lays the ground and summarises five foundational problems of conventional quantum mechanics. The author has announced further instalments; the total number of parts is not stated, and so the piece stands here as an independent article rather than a numbered series.
The roadmap of the series — in the author's own description
TRIGGER
Five foundational problems
This piece. The unresolved problems of conventional quantum mechanics are summarised.
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Interpretations and formulations
The deeper interpretations of the theory and its alternative mathematical formulations are taken up.
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Metaphysical connections
The interpretations assessed in concord with the verses of the Qur'an.
OUTCOME
Speculation
How the theory might be shaped in the future from a perspective drawn out of readings of the Qur'an.
Quantum mechanics represents one of the most precise and powerful frameworks for describing nature. Its mathematical structures — wave functions, Hilbert spaces, matrix mechanics — offer magnificent explanatory power. Yet these same structures raise deep questions about reality. Awaiting answers on such fundamental matters as interpretation, the interaction between scales, and the structure of the universe, these questions have the potential not merely to shape physics but to open a new horizon for philosophy as well.
A map of the five foundational problems
The unresolved matters that mark the depth and reach of quantum mechanics
1 · The measurement problem
How does deterministic evolution pass into a probabilistic outcome?
2 · The quantum-to-classical transition
How does classical behaviour emerge from quantum mechanics?
3 · Quantum gravity
How is probability reconciled with spacetime geometry?
4 · Entanglement and non-locality
How far do the notions of locality and causality hold?
5 · The role of the observer
What defines an observer, or the act of measurement?
1 · The Measurement Problem
At the centre of quantum mechanics lies the measurement problem: the passage from the deterministic evolution of the wave function — governed by the Schrödinger equation — to the probabilistic outcomes observed upon measurement. What exactly is a measurement; is it an instant or a process; how can the moment at which it occurs be defined? Which physical mechanism reduces quantum superpositions to a single outcome during measurement? And how decisive is the observer's role in this process?
Two regimes of the same system
Before measurement — Schrödinger evolution
The wave function obeys a deterministic equation; the process is continuous and reversible.
Encompasses a superposition of all possible outcomes
From a given initial state, the equation yields the later state unambiguously
→This apparent discontinuity between the two regimes has never been explained; the precise nature of collapse remains the subject of serious debate and speculation.
At measurement — collapse
The wave function “collapses” into a definite state; the outcome is probabilistic.
All potential outcomes are reduced to a single observed result
There is no clear physical mechanism for this process
Its meaning: Treating the wave function as a real physical entity leads to interpretations such as Everett's Many-Worlds theory, which adopts branching universes in place of collapse. On this view the wave function does not collapse upon measurement; instead the universe branches for each possibility, producing parallel realities. In measuring an electron's position, universes arise corresponding to every possibility of its being at one position and at another. The approach raises the idea of an infinity of parallel universes in which the observer experiences different outcomes.
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This highlights a deep philosophical tension over whether the mathematical framework merely describes observations or reflects an underlying reality.
— Felsufi
✱Why this is a philosophical matter
The weight of the measurement problem comes from the fact that it does not stay inside physics. Granting the wave function ontological status — treating it as a thing that exists — produces consequences that bear directly on our understanding of existence and causality. The detailed exposition and critique of Everett's Many-Worlds theory is, as the author notes, left to later pieces in the series.
2 · The Quantum-to-Classical Transition
While quantum mechanics governs the behaviour of microscopic systems such as atoms and electrons, macroscopic objects visible to the eye obey the laws of classical physics. This apparent rupture between the quantum and classical domains raises deep questions about the nature of reality and about how the two frameworks coexist. Why are quantum effects confined to microscopic systems? Why do macroscopic objects not display the same superposition and entanglement?
Two scales, two behaviours
Distinctively quantum properties are plainly displayed.
Superposition — several states carried at once
Entanglement — separate particles sharing a single state
→The transition is usually attributed to decoherence: superpositions are destroyed through interaction with the environment. Yet this explanation does not fully account for why only one outcome is observed.
A deterministic order is followed in which those same properties have disappeared.
The laws of classical physics — definite position, definite outcome
In everyday experience quantum effects are not manifest
✱What decoherence settles and what it does not
Decoherence explains why superposition becomes invisible — the interference terms of a system interacting with its environment are rapidly suppressed. But this does not mean the possibilities become one: the post-decoherence state is still a set of possibilities. The question “why this outcome and not the other?” returns to the measurement problem. The two matters are therefore not independent; the second is the scale-facing side of the first.
3 · The Problem of Quantum Gravity
Quantum mechanics and general relativity are the two pillars of modern physics, yet they are incompatible with one another. Quantum mechanics accounts for the behaviour of particles through probabilities, while general relativity is built upon the continuity of spacetime and gravitational effects. In situations such as the interior of a black hole, quantum mechanics falls short of explaining the effect of gravitational forces at the level of particles, while general relativity disregards the indeterminacies of the quantum scale.
Two pillars that do not reconcile
Works with packets of energy as its fundamental units.
Behaviour is described through probabilities
A discrete, quantised structure
→In one sense this incompatibility shows that both theories fall short, at a very fundamental level, in modelling reality. It prompts the question whether nature, at some point, simply obeys wholly disjoint rules.
Rests upon a continuous geometric framework.
The continuity and curvature of spacetime
Disregards the indeterminacies of the quantum scale
✱The price: regions left without a theory
Quantum gravity aims to reconcile the probabilistic nature of quantum mechanics with general relativity's account of spacetime geometry. Without that unification, phenomena such as black-hole singularities or the first moments of the universe cannot reach a complete theoretical understanding. The matter is therefore not an abstract worry about consistency: the two most critical regions of the cosmos — its beginning and its densest points — are left without a model.
4 · Entanglement and Non-Locality
Quantum entanglement — described by Einstein as “spooky action at a distance” — challenges the classical notions of locality and causality. How entanglement operates, and why the correlations are so tight, remains a mystery. Does non-locality genuinely call the fundamental structure of space and time into question, or is it the outcome of some other mechanism not yet discovered?
From objection to experiment: the elimination of local hidden variables
TRIGGER
Einstein's objection
“Spooky action at a distance” — the theory must be incomplete; hidden variables must lie beneath.
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Bell's theorem
The objection becomes testable: local hidden variables must obey certain inequalities.
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The Aspect experiments (1982)
Measurements on entangled photons show that Bell's inequalities are violated.
OUTCOME
Non-locality
The correlations cannot be explained by local hidden variables; the fundamentally non-local nature of quantum mechanics is confirmed.
✱A technical distinction: correlation ≠ signal
The bond established by entanglement is not local, yet no controllable information can be sent across it — the outcome on each side is random in itself, and the correlation becomes visible only when the two parties compare results over a classical, light-speed-limited channel. In the literature this is the no-signalling principle. The conclusion the author stresses — that the correlations do not accord with classical physics — is untouched by this distinction; the distinction only sharpens what is non-local: the bond, yes; a signal, no.
Its meaning: These non-local correlations compel a rethinking of the structure of spacetime and the nature of information, raising deep questions about the interconnectedness of quantum systems. It is precisely here that the border between physics and metaphysics has to be redrawn.
5 · The Role of the Observer
The observer's role in quantum mechanics remains a mystery. What defines an observer, or the act of measurement? Why can one electron not observe and measure another? The sharpness of the question lies here: if measurement is an ordinary physical interaction, then every interaction ought to count as a measurement; and if it is not, then what sets it apart must be stated.
Wigner's Friend — when exactly does collapse occur?
TRIGGER
The isolated laboratory
Wigner's friend performs an experiment in a sealed laboratory — or observes Schrödinger's cat.
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The friend sees the result
Seen from inside the laboratory the result is definite: collapse has occurred here.
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Five hours later
Wigner enters the laboratory and examines the results. Seen from outside, the friend too was in superposition.
OUTCOME
The unanswered question
Did the superposition collapse at the moment the friend observed, or when Wigner became aware of the results?
✱Consciousness, information processing, physical interaction
This difficulty raises questions about the interplay of consciousness, information processing and physical interaction in defining reality. The idea that a measurement requires the presence of an observer leads to deep debates about the possible influence of consciousness upon quantum processes. The upshot is this: measurement in quantum mechanics appears to be a process dependent on the observer rather than an objective event in the classical sense.
A Mathematical Tool, or a Metaphysical Truth?
Because it rests on abstract mathematical structures, quantum mechanics tempts us toward matching those abstractions with physical reality. Yet as instances like the many-worlds interpretation show, this ontological commitment sets out on a journey toward metaphysics. And yet the mathematical formulation is often used as a tool rather than as a model of reality.
Two postures toward the formalism
The formalism describes observations; it tells us what we shall see, not what there is.
The wave function is an object of calculation
No ontological debt is incurred — collapse remains a mystery
→This is the common ground of the five problems: from the measurement problem to the role of the observer, each in fact asks what status we grant the formalism.
The formalism exhibits what exists; whatever is in the equation is there in reality.
The wave function is a real physical entity
The price is heavy: branching universes, infinite parallel realities
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By thinking more deeply about these problems — from the measurement problem to the role of the observer — we may better understand the limits of our present frameworks and the deep mysteries they are attempting to resolve.
— Felsufi
✱What follows, and about this text
The author announces that the next piece will take up the various formulations and interpretations of quantum theory; the detailed exposition and critique of Everett's Many-Worlds theory is left to it as well. The Turkish is the author's own pen; the English is a translation. The note headed “correlation ≠ signal” was added editorially as a terminological clarification that does not bear on the argument of the piece.