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Questions tagged [quantum-interpretations]

This tag is for questions relating to what, if anything, the quantum mechanical formalism and experimental results say about the way the world works.

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Why is the Copenhagen interpretation of quantum physics the most widely accepted one?

I've been digging a lot into quantum physics in the last few weeks. I didn't care much about the maths, just about what empirically happens to get a conceptual idea about quantum phenomena. The most ...
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0answers
22 views

Have there been any papers on a relativistic relative state (“MWI”) interpretation of QM with continuous spectra?

I've read the original papers on the relative state interpretation ("MWI") of Quantum Mechanics. They seem compelling, but they only addressed a nonrelativistic system and operators with discrete ...
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1answer
141 views

Why does MWI need decoherence theory and how can these models be combined?

As far as I understood decoherence theory, it explains, why we are not able to measure superposition of macroscopic objects in some specific basis, which turns out to be the position-basis in most ...
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2answers
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Implication of Born's rule on the superposition principle

BACKGROUND Born's rule quantifies the interference pattern of a single quantum particle going through two possibles paths A and B as $P = |A|^2 + |B|^2 + ⟨A|B⟩ + ⟨B|A⟩$. The standard interpretation ...
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1answer
113 views

Doubt about the probabilistic nature of quantum stuff and the field theory

To the quantum field theory, is it like there's "two layers of reality", one in which things are just probabilities waves that collapses into the quantum fields or is the quantum field and its waves ...
3
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2answers
371 views

Quantum Bayesianism (QBism) and the double slit experiment

How is the following experimental fact interpreted in Quantum Bayesianism (QBism)? In a double slit experiment we measure position directly after the slits. Because of that the interference pattern on ...
2
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1answer
132 views

MWI universal wave function question?

In MWI, there is only one wave function in the universe ( the universal wave function). So say if I detected a particle and its wave function decoheres, since the universal wave function never ...
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10answers
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On a measurement level, is quantum mechanics a deterministic theory or a probability theory?

Quantum mechanics is a non-commutative probability theory. As such, it fundamentally behaves differently from classical probability theories. This manifests itself most pronouncedly in the uncertainty ...
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0answers
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How fundamental is the uncertainty relation? [duplicate]

I was having a discussion over the uncertainty relation with some with of my friends with people splitting over the nature of uncertainty relation. So there were two groups formed (a) One of the ...
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14answers
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How could quantum effects occur in the early universe without an observer?

In inflationary cosmology, primordial quantum fluctuations in the process of inflation are considered responsible for the asymmetry and lumpiness of the universe that was shaped. However, according to ...
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4answers
121 views

How to interpret this construction of the states in QFT?

Non-Relativistic Quantum Mechanics To make this question clear it might be useful to contrast with non-relativistic quantum mechanics. In any quantum theory, the states of a system are unit rays in ...
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1answer
114 views

Does Bell's theorem imply nonlocality using a false assumption?

In https://arxiv.org/abs/1409.5158, the author concludes that Bell tests cannot refute local realism, because they employ a wrong analysis. He says: "The quantum joint prediction cannot be ...
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4answers
510 views

Is many-worlds interpretation only a philosophical matter?

Is many-worlds interpretation only a philosophical matter? It seems to me that we can't exclude a possible test for this hypothesis. I explain. For superposition principle each world would follow the ...
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1answer
64 views

Energy in Many-Worlds Interpretation

A few answers on here seem to suggest to something like the following: In the Many Worlds Interpretation, the amplitude of a branch exponentially decreases over time and so the energy of that branch ...
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2answers
75 views

Does something prevent superposition at our scale?

I often encounter the argument that quantum mechanics reduces to classical mechanics at sufficiently big scales, as soon as h becomes sufficiently small respect to the actions involved. I clearly ...
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2answers
70 views

Are superposition and uncertainty principles logically dependent?

If we assume superposition and define an Hilbert space with canonical commutation relations we can derive uncertainty relations. So it seems the uncertainty principle isn't required, or should be ...
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3answers
977 views

Why is wave-function collapse still being taught in quantum mechanics? [closed]

I don't really understand why wave-function collapse is still being taught while we seem to have better interpretations of QM available nowadays. During the early development of quantum mechanics the ...
3
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3answers
145 views

Can quantum randomness be somehow explained by classical uncertainty? [closed]

In quantum mechanics, the outcome of each measurement is random, distributed according to the squared amplitude of the wave function obtained from the Schrodinger's equation. Now, can someone suggest ...
1
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1answer
169 views

Is the MWI symmetric in time?

Reading the blog of Sean Carroll (I recognize he isn't the only voice) has made me more sympathetic to the notion of many worlds, but reading Susskind (also not the only voice) has made me think that ...
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5answers
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Conceptual understanding of operators in QM

Do operators in QM represent in some fashion the action of the measurement apparatus on a state being measured? Usually operators in QM are introduced as abstract transformations whose eigenvectors/...
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0answers
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Commutator $\vec{L}$ with $\vec{X}\cdot\vec{P}$

Let $\vec{X}=(X_1,X_2,X_3)^T$ and $\vec{P}=(P_1,P_2,P_3)^T$. Define $\vec{L}=\vec{X}\times\vec{P}$. Then, I can calculate $\vec{L}=(X_2P_3-X_3P_2,\,X_3P_2-X_2P_3,\,X_1P_2-P_1X_2)^t$. For all ...
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1answer
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What is the reason for the reported opposite-of-QM handedness of photons in a Bell test with circularly polarized photons?

In https://file.scirp.org/pdf/OPJ_2016111414355792.pdf, a Bell test using circularly-polarized photons is reported. The data shows that coincidences happen in the reverse handedness predicted by ...
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2answers
48 views

Are all Bell tests valid only for linearly-polarized photons? [duplicate]

In https://arxiv.org/abs/1407.2605, it is argued that all photons are necessarily circularly polarized, and linearly-polarized photons must be a superposition of such circularly-polarized photons. ...
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12answers
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Does the Many Worlds interpretation of quantum mechanics necessarily imply every world exist?

I know the Many Worlds interpretation is controversial among physicists, but it's been a pop culture hit nonetheless. I frequently see people making statements like, "Well in another universe I'm a ...
6
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1answer
184 views

Is it possible to reproduce the energy spectrum of quantum chaos using classical cellular automata?

Is it possible to reproduce the energy spectrum of quantum chaos using classical cellular automata? It's hardly impressive to reproduce harmonic oscillators.
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1answer
69 views

Why does superposition principle and Copenhagen interpretation not contradict with themselves?

In quantum mechanics, when we say that a particle in a state $|x_1\rangle$, physically the states $|x_1 \rangle $ and $c |x_1\rangle$ (for some $c\not = 0\in \mathbb{C}$) are the same, i.e they ...
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2answers
260 views

Single slit experiment and the uncertainty principle - contradiction?

I have read for example here that the single slit experiment can be seen as a visualisation(?) of Heisenberg's Uncertainty principle. Basically, the photons passing through the slit are given a fixed ...
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3answers
486 views

Ontology of the quantum field

I'll use QED as an example, but my question is relevant to any quantum field theory. When we have a particle in QED, where is its charge contained in the field? Is the field itself charged? If so, ...
5
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2answers
325 views

What specifically is incorrect about the Dirac Sea interpretation?

So taking the square root of $E^2 = (m_oc^2)^2 + p^2c^2$ yields two solutions. The Dirac Sea treats the negative solution as an infinite space of electrons with negative energy. All the observable ...
4
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3answers
681 views

Are quantum mechanics and determinism actually irreconcilable? [closed]

As a preface, I am not a physicist. I'm simply interested in abstract physics and fundamental principles of the universe and such. As such, if you can provide an answer for the layman (as non-...
2
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3answers
357 views

Why can't GRW theory be easily tested?

To me it seems that no matter if GRW theory is true, there would already be a lot of observations and evidence for/against it, since it will in quite simple situations make different predictions from ...
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4answers
2k views

Should it be obvious that independent quantum states are composed by taking the tensor product?

My text introduces multi-quibt quantum states with the example of a state that can be "factored" into two (non-entangled) substates. It then goes on to suggest that it should be obvious1 that the ...
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2answers
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What are non-local hidden variables?

It is said that Bell's Inequality basically denies all possible local hidden variables theories as solutions to entanglement but what does a non-local hidden variable theory mean and how does it get ...
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7answers
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How can a particle's position be random and uncertain in quantum mechanics if it is already pre-determined in relativity?

In relativity, to my knowledge, the path of an object is described by its worldline in spacetime, and since time is a part of the spacetime geometry, an object's worldline--in a sense--always exists ...
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1answer
490 views

Is the trajectory of a quantum particle a well defined concept and how does this depend on the interpretation of quantum mechanics?

A common statement about quantum physics is that the "trajectory" of a particle is no longer a well defined concept because of the uncertainty relations for position and momentum. If one interprets ...
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3answers
2k views

What is the preferred basis objection to the many-worlds interpretation of quantum mechanics?

I've seen the preferred basis problem referred to in many places, but have not seen a clear explanation of what the problem is. For example, this question asks whether the problem has been solved, but ...
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6answers
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How do we know that entanglement allows measurement to instantly change the other particle's state? [duplicate]

I have never found experimental evidence that measuring one entangled particle causes the state of the other entangled particle to change, rather than just being revealed. Using the spin up spin down ...
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3answers
225 views

Einselection locality in decoherence theory

Consider two polarity-wise entangled photons A and B in an EPR experiment. The process of measuring the polarization of photon A by Alice is described by the decoherence of the 2-photons system ...
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3answers
99 views

Observer in Many Worlds Interpretation [duplicate]

Something has been bothering me about the Many Worlds Interpretation. Proponents of it (e.g. Sean Carroll) often claim that it does away with the observer, or at least the paradox-inducing status the ...
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0answers
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Safer version of quantum suicide?

Quantum suicide imagines a gun which will shoot a person in a box, and this gun is rigged up to the release of radioactive decay which has a quantum probability of 50% chance of decaying or not ...
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1answer
131 views

How does the Many-Worlds Interpretation of Quantum Physics relate to Consciousness? [closed]

According to the Many-Worlds Interpretation of Quantum Mechanics, each quantum event causes the world to "branch" into a superposition of outcomes. How come "my" consciousness only chooses one of ...
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1answer
426 views

Do consciousnesses get “scattered” across the many worlds of the MWI?

According the many worlds-interpretation (MWI) of quantum mechanics, following a decision with possible outcomes $A$ and $B$, with respective probabilities $p_A=P(A)$ and $p_B=P(B)$, a proportion $p_A$...
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2answers
69 views

Can we have an arbitrary set of trajectories in Bohmian mechanics?

In Bohmian mechanics, the initial configurations and the pilot wave determine the future of the system. Given a set of initial positions for particles and a set of arbitrary trajectories, can we ...
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1answer
108 views

Bell inequality as a game: Why is it impossible to always win?

Another Bell's Theorem Question I am trying to follow the simple model of Bell's Theorem outlined in this paper: https://people.eecs.berkeley.edu/~vazirani/s07quantum/notes/lecture1.pdf. Please read ...
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1answer
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How did Big Bang determine the initial conditions of the universe?

My question is that how did the Big Bang determine the initial distribution of the particles and their wavefunctions? In theories like Bohmian mechanics or Many worlds, how was the universal ...
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2answers
69 views

Does retro-causality imply unpredictability?

In some interpretations of Quantum mechanics (e.g. transactional interpretation), the future affects present. Is this a source of unpredictability in such interpretations, which makes them have the ...
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1answer
70 views

Many World's Hypothesis [closed]

According to the Many Worlds interpretation of quantum mechanics by Hugh Everett, taking the double slit experiment as an example, every possible outcome that can happen does happen. And the chances ...
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What is the difference between realism in locality, and counterfactual definiteness?

I understand the EPR-experiment and the Bell inequalities. I can see how dropping 'locality' solves the issue, and how dropping 'realism' solves the issue (e.g. there are really no hidden variables ...
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1answer
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In light of quantum decoherence, are there still any “gaps” in our knowledge of quantum mechanics that need further interpretation?

With quantum decoherence, are there still any "gaps" in our knowledge of quantum mechanics that hint (either in terms of the physics, philosophy, or otherwise) at the need for further interpretation? ...
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Why is the application of probability in QM fundamentally different from application of probability in other areas?

Why is the application of probability in quantum mechanics (QM) fundamentally different from its application in other areas? QM applies probability according to the same probability axioms as in other ...